The present invention primarily relates to the use of combinations based on the active ingredients (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, optionally (iii) thiencarbazone- methyl and/or salts thereof, and (iv) one or more safeners, or of compositions comprising said combinations of active ingredients (i), (ii), optionally (iii), and (iv) for controlling harmful plants in tuberous root crop plants, preferably in cassava. The present invention also relates to the use of said combinations of active ingredients (i), (ii), optionally (iii), and (iv) or of compositions comprising said combinations of active ingredients (i), (ii), optionally (iii), and (iv) as plant growth regulators for tuberous root crop plants, preferably as plant growth regulators for cassava. Furthermore, the present invention relates to a corresponding method of controlling harmful plants in tuberous root crop plants and to a corresponding method of regulating plant growth of tuberous root crop plants.

Cassava (Manihot esculenta Crantz) is a major source of carbohydrate for several hundred million people, mainly in Africa and to some extent in Asia and Latin America. In Africa, yields of cassava are generally comparatively low, which to a large extent is due to effects of weed competition or to uncontrolled or unsufficiently controlled weed growth. Hoe- weeding still is a common practice among cassava farmers.

The Proceedings of the 11th ISRTC-AB, Kinshasa, Democratic Republic Congo, 4-8 October 2010, pages 269- 275 report on the evaluation of commercially available herbicides for weed control in cassava. The treatments there comprised pre-emergent herbicides employing such as chloroacetanilide, prometryn or S-metolachlor.

In the Crop recommendation #17 of the Ministry of Agriculture of Barbados the following herbicides for weed control in cassava are mentioned: paraquat (optionally mixed with diquat), glyphosate, sulfosate, pendimethalin, metolachlor, fluazifop-butyl, sethoxydim or propaquizafop.

CN102428919A teaches a post-emergence cassava field herbicide with mesotrion as an active component.

CN103392724A suggests the use of a ternary herbicide composition as cassava field herbicide with the active components of halosulfuron, oxyfluorfen and an amide herbicide selected from the group of butachlor, propisochlor and metolachlor.

GB 1,028,976 discloses a process for the treatment of plants with storage organs, for example cassava, sweet potato or yam, which comprises spraying the plants with a substituted benzoic acid herbicide in a specific time frame before harvest. There, herbicides like (optionally further substituted) di-, tri- or tetrachlorobenzoic acids are preferred. African Crop Science Journal 1994, 519-530 reports on weeds and their control in cassava. There, mainly the following herbicides were tested: metobromuron, fluometuron, prometryn (optionally in combination with ametryne), terbutryn, paraquat and diuron. Planata Daninha, 2010, 28(4), 807-816 describes the application of different herbicides on weeds in cassava. Inter alia the effects of herbicides like diuron, metribuzin, isoxaflutole, atrazine, ametryn, and several combinations comprising said herbicides are reported therein on two cassava varieties grown in the state of Parana, Brazil. WO 2013/037955 Al mentions cyprosulfamide as plant growth regulator.

WO 2016/079035A1 relates to the use of herbicide combinations comprising (i) indaziflam and (ii) metribuzin or isoxaflutole for controlling harmful plants in tuberous root crop plants, preferably in cassava.

In their application, herbicidal crop protection agents (herbicides) known to date for controlling harmful plants or unwanted vegetation in tuberous root crop plants have some disadvantages, be it (a) that they have no or else insufficient herbicidal activity against specific harmful plants, (b) that the spectrum of harmful plants which can be controlled with the herbicides is not broad enough, and/or (c) that the selectivity of herbicides in and the compatibility with tuberous root crop plants is too low, thereby causing unwanted damage and/or unwanted reduced harvest yields of the tuberous root crops.

Overall, the herbicidal activity (above aspects (a) and (b)) and/or the selectivity / compatibility (above aspect (c)) of the herbicides used so far in tuberous root crop plants still allows improvement.

For the reasons mentioned above, there still is a need for alternative, highly herbicidally active compositions for the selective application for controlling harmful plants or unwanted vegetation in tuberous root crop plants.

Surprisingly, it has now been found that certain combinations of active ingredients or compositions comprising said combination of active ingredients exhibit the desired herbicidal activity and are able to selectively control harmful plants or unwanted vegetation in tuberous root crop plants.

The present invention primarily relates to the use of a combination of active ingredients (active ingredient combination) or of a composition comprising a combination of active ingredients for controlling harmful plants in tuberous root crop plants, and/or - as plant growth regulators in tuberous root crop plants, wherein said combination of active ingredients comprises or consists of (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, and (iv) one or more safeners, and wherein preferably said safener is selected from isoxadifen-ethyl or cyprosulfamide. Preferably, the present invention relates to the use of a combination of active ingredients or of a composition comprising a combination of active ingredients, wherein the combination of active ingredients comprises or consists of

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, and (iv) isoxadifen-ethyl, or

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, (iii) thiencarbazone-methyl and/or salts thereof, and (iv) cyprosulfamide.

In particular, the present invention relates to the use of a combination of active ingredients or of a composition comprising a combination of active ingredients, wherein the combination of active ingredients comprises or consists of

- (i) foramsulfuron and/or foramsulfuron-sodium, (ii) iodosulfuron-methyl-sodium, and (iv) isoxadifen-ethyl, or

- (i) foramsulfuron and/or foramsulfuron-sodium, (ii) iodosulfuron-methyl-sodium, (iii) thiencarbazone-methyl, and (iv) cyprosulfamide. The present invention further releates to the use of a composition as defined herein in the context of the present invention which additionally comprises one or more further components selected from the group consisting of formulation auxiliaries, additives customary in crop protection, and further agrochemically active compounds (i.e. agrochemically active compounds different from components (i), (ii), optionally (iii), and (iv) as defined above, i.e. agrochemically active compounds other than foramsulfuron and/or salts thereof, iodosulfuron-methyl and/or salts thereof, thiencarbazone-methyl and/or salts thereof, isoxadifen-ethyl and cyprosulfamide).

However, when a combination of active ingredients (active ingredient combination) used in the context of the present invention consists of components (i), (ii), optionally (iii), and (iv) as defined above, this means that in such a case the combination of active ingredients used in the context of the present invention or the composition comprising said combination of active ingredients used in the context of the present invention does not contain any further (i.e. no additional) agrochemically active compound.

In this context, the term "further agrochemically active compound" refers to the agrochemically active compounds (pesticides), respectively, listed in "The Pesticide Manual", 16th edition, The British Crop Protection Council and the Royal Soc. of Chemistry, 2012 other than components (i), (ii), optionally (iii), and (iv) as defined above.

The combination of active ingredients and the compositions comprising said combination of active ingredients used in accordance with the present invention not only exhibit an excellent herbicidal activity in controlling harmful plants or unwanted vegetation in tuberous root crop plants, but also show good compatibility with tuberous root crop plants, i.e. said combinations of active ingredients do not cause significant damage and/or unwanted reduced harvest yields of the tuberous root crops. The combinations of active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention and the compositions comprising said combinations used in accordance with the present invention allow excellent (total) weed control at an agronomically acceptable level of damage of the tuberous root crop plants. Further, the type of damage observed with the combinations and the compositions comprising said combinations used in accordance with the present invention is less harmful and/or less severe, and the tuberous root crop plants affected largely or fully recover from said type of damage.

These advantageous effects are particularly achieved when the combinations of active ingredients (i), (ii), optionally (iii), and (iv) as defined herein or a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein are used in post-emergence applications, as explained in more detail below.

It was found that combinations of active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention and the compositions comprising said combinations used in accordance with the present invention had no significant negative impact on the tuberous root crop plant growth, in particular the cassava plant growth, i.e. plant height, plant vigor (vigorous growth) and population (number of plants / ha). Generally, very good to excellent control of harmful plants was achieved, typically about 80 - 96% against dicotyledonous (broadleaf) weeds and about 88 - 99% against monocotyledonous weeds (grasses). Further, the combinations used in accordance with the present invention and the compositions comprising said combinations used in accordance with the present invention can be used as plant growth regulators for tuberous root crop plants, preferably as plant growth regulators for cassava, thereby increasing harvest yields tuberous root crop plants (in particular the weight of the tuberous root) and/or increasing the plant growth of the tuberous root crop plants (in particular the growth of the leaves of the tuberous root crop plants), in each case in comparison to tuberous root crop plants not treated with agrochemically active compounds (untreated control).

The present invention preferably relates to the use of a combinations of active ingredients or of a composition comprising a combinations of active ingredients as defined in the context of the present invention, wherein the tuberous root crop plants are selected from the group consisting of sweet potato (Ipomoea batatas), cassava (Manihot esculenta), and yam (plant species in the genus Dioscorea), more preferably wherein the tuberous root crop plant is cassava {Manihot esculenta).

The active ingredients used in the context of the present invention are known per se, and described inter alia in "The Pesticide Manual", 16th edition, The British Crop Protection Council and the Royal Soc. of Chemistry, 2012 and the literature cited therein. The active ingredients used in the context of the present invention are described in more detail hereinbelow.

The combinations of active ingredients used in the context of the present invention and also certain compositions comprising the combinations of active ingredients used in the context of the present invention as such are known. The combinations of active ingredients used in the context of the present invention and also certain compositions comprising said combinations used in the context of the present invention are commercially available.

Tuberous roots (also called root tubers) are perennating organs, thickened roots that store nutrients over periods when the plant cannot actively grow, thus permitting survival from one year to the next. Tubers should not be confused with tuberous roots. Tubers are modified shoots, whereas tuberous roots are modified roots.

A tuberous root is a modified lateral root, enlarged to function as a storage organ. The enlarged area of the root- tuber, or storage root, can be produced at the end or middle of a root or involve the entire root. It is thus different in origin but similar in function and appearance to a stem tuber. Examples of plants with notable tuberous roots include the sweet potato, cassava, yam and dahlia.

Cassava (Manihot esculenta Crantz), also called manioc, yuca, balinghoy or kamoteng kahoy (in the Philippines), tabolchu (in Northeast India), mogo (in Africa), mandioca, tapioca-root, kappa (predominantly in India) and manioc root, a woody shrub of the Euphorbiaceae (spurge) family native to South America, is extensively cultivated as an annual crop in tropical and subtropical regions for its edible starchy tuberous root, a major source of carbohydrates. Cassava, when dried to a powdery (or pearly) extract, is called tapioca; its fermented, flaky version is named garri.

Cassava is the third largest source of food carbohydrates in the tropics, after rice and maize. Cassava is a major staple food in the developing world, providing a basic diet for over half a billion people. It is one of the most drought-tolerant crops, capable of growing on marginal soils. Nigeria is the world's largest producer of cassava, while Thailand is the largest exporting country of dried cassava.

Cassava grows poorly in weedy fields and consequently produces fewer and smaller storage roots.

Yam is the common name for some plant species in the genus Dioscorea (family Dioscoreaceae) that form edible tubers. These are perennial herbaceous vines cultivated for the consumption of their starchy tubers in Africa, Asia, Latin America, the Caribbean and Oceania. There are many cultivars of yam. Although some varieties of sweet potato (Ipomoea batatas) are also called am in parts of the United States and Canada, it is not part of the family Dioscoreaceae. Yams are monocotyledons, related to lilies and grasses. Native to Africa and Asia, yam tubers vary in size from that of a small potato to over 60 kilograms. There are over 600 varieties of yams and 95 percent of these crops are grown in Africa.

According to the present invention the expression "composition" includes compositions comprising a combination of active ingredients (i), (ii), optionally (iii), and (iv) as defined herein, and can be used in various acceptable or agronomically typical forms and formulations, for example in a single "ready-mix" form.

The active ingredients (i), (ii), optionally (iii), and (iv) used in the combinations used in the context of the present invention and the compositions comprising said combinations used in the context of the present invention may be a combined spray mixture composed from separate formulations of the single active compounds, such as a "tank-mix", or said composition can be a combined use of the single active ingredients when applied in a sequential manner, i.e. one after the other within a reasonably short period, such as a few hours (and preferably less than 24 hours).

The active ingredients (i), (ii), optionally (iii), and (iv) employed in the combinations used in the context of the present invention include all stereoisomers and their mixtures, in particular also racemic mixtures and - if enantiomers are possible - the respective biologically active enantiomer.

If, in the context of this description, the short form of the common name of an active compound is used, this includes in each case all customary derivatives, such as the esters and salts, and isomers, in particular optical isomers, in particular the commercially available form or forms. If the common name denotes an ester or salt, this in each case also comprises all other customary derivatives, such as other esters and salts, the free acids and neutral compounds, and isomers, in particular optical isomers, in particular the commercially available form or forms. The given chemical compound names denote at least one of the compounds embraced by the common name, frequently a preferred compound. In the case of sulfonamides such as sulfonylureas, salts also include the salts formed by exchanging a hydrogen atom on the sulfonamide group by a cation.

The salts of compounds used in the context of the present invention may be used in the form of the respective alkali metal salts, alkaline earth salts or ammonium salts, preferably in the form of the respective alkali metal salts, more preferably in the form of the respective sodium or potassium salts, most preferably in the form of the respective sodium salts.

The active ingredients (i), (ii), optionally (iii), and (iv) employed in the combinations used in the context of the present invention are known per se, and described inter alia in "The Pesticide Manual", 16th edition, The British Crop Protection Council and the Royal Soc. of Chemistry, 2012 and the literature cited therein.

Constituent (i):

Foramsulfuron and its salts are known and described for example in EP 0 757 679 Al. Preferred constituents (ii) in the context of the present invention are foramsulfuron (IUPAC-Name: 1 -(4,6- dimethoxypyrimidin-2-yl)-3-[2-(dimethylcarbamoyl)-5-formamid ophenylsulfonyl]ure CAS Reg. No. 173159- 57-4) and its sodium salt, i.e. foramsulfuron-sodium.

Constituent (ii): Iodosulfuron, its esters and its salts are known and described for example in WO 92/13845 Al. Preferred constituents (ii) in the context of the present invention are:

Iodosulfuron-methyl (IUPAC-Name: methyl 4-iodo-2-[(4-methoxy-6-methyl- 1,3,5 -triazin-2- yl)carbamoylsulfamoyl]benzoate, CAS Reg. No. 144550-06-1) and iodosulfuron-methyl-sodium (IUPAC- Name: sodium ({[5-iodo-2-(methoxycarbonyl)phenyl]sulfonyl}carbamoyl)(4-me thoxy-6-methyl-l,3,5-triazin-2- yl)azanide, CAS Reg. No. 144550-36-71).

More preferably, constituent (ii) of the combination of active ingredients comprises or consists of iodosulfuron- methyl and/or iodosulfuron-methyl-sodium, particularly preferred is iodosulfuron-methyl-sodium as constituent (ii).

Optional constituent (iii): Thiencarbazone, its esters and its salts are known and described for example in WO 01/005788 Al.

Preferred constituents (iii) in the context of the present invention is thiencarbazone-methyl (IUPAC-Name: methyl 4- [(4,5 -dihydro-3 -methoxy-4-methyl-5 -oxo- 1H- 1 ,2,4-triazol- 1 -yl)carbonylsulfamoyl] -5 - methylthiophene-3-carboxylate, CAS Reg. No. 317815-83-1).

More preferably, constituent (iii) of the combination of active ingredients comprises or consists of thiencarbazone-methyl.

Constituent (iv):

Safeneres suitable to be used as constituent (iv) in the context of the present invention are known per se, and described for example in WO 2013/092500 Al on pages 87, line 25 to 100, line 25, and the literature cited therein. The preferred safeneres to be used as constituent (iv) in the context of the present invention are isoxadifen-ethyl (IUPAC-Name: ethyl 4,5-dihydro-5,5-diphenyl-l,2-oxazole-3-carboxylate, CAS Reg. No. 163520-33-0), known and described for example in WO 95/07897 Al, and cyprosulfamide (IUPAC-Name: N-[4- (cyclopropylcarbamoyl)phenylsulfonyl]-2-methoxybenzamide, CAS Reg. No. 221667-31-8), known and described for example in WO 99/16744 Al and US 6,251,827 Bl . More preferably, constituent (iv) of the combination of active ingredients comprises or consists of isoxadifen- ethyl or cyprosulfamide.

Many of the combinations of active ingredients used in the context of the present invention or the compositions comprising a combination of active ingredients as defined herein are known per se. For example, it is known from EP 0 790 771 Al or WO 00/08932 that foramsulfuron and its salts can be used in combination with safeners and/or other herbicides. WO 95/08919 Al discloses combinations of iodosulfuron, its esters and/or salts thereof and certain safeners. WO 03/026426 Al discloses combinations of (a) thiencarbazone-methyl and (b) foramsulfuron or iodosulfuron-methyl-sodium, and optionally (c) one or more safeners. WO 03/073853 A2 mentions combinations of (a) foramsulfuron or its salts, (b) iodosulfuron-methyl or its salts, (c) certain further herbicdes, and one or more safeners.

Many of the combinations of active ingredients used in the context of the present invention or the compositions comprising a combination of active ingredients as defined herein are commercially available, (for example under the brand name MaisTer®, mentioned in US 2014/187515A1).

In accordance with the present invention, the combinations of active ingredients as defined herein or the composition comprising a combination as defined herein comprise a herbicidally effective amount of said combinations of active ingredient and may comprise further components, for example agrochemically active compounds of a different type and/or formulation auxiliaires and/or additives customary in crop protection, or they may be employed together with these.

In accordance with the present invention, the combinations of active ingredients as defined herein or the composition comprising a combination as defined herein may be applied as a split application over time. Another possibility is the application of the individual active ingredients (i), (ii), optionally (iii), and (iv) or the combinations comprising the active ingredients (i), (ii), optionally (iii), and (iv) in a plurality of portions (sequential application), for example after pre-emergence applications, followed by post-emergence applications or after early post-emergence applications, followed by applications at medium or late post-emergence. Preferred is the simultaneous or nearly simultaneous application of the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein. In the latter context, a nearly simultaneous application of the active ingredients (i) and (ii) as defined herein means that the active ingredients (i), (ii), optionally (iii), and (iv) are applied within 24 hours, preferably within 12 hours, more preferably within 6 hours, even more preferably within 3 hours.

In a particularly preferred embodiment, the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein are used together, i.e. at the same time. Thus, in a particularly preferred embodiment a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein is used. In a preferred embodiment, the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention or a composition comprising the active ingredients(i), (ii), optionally (iii), and (iv) used in accordance with the present invention are only used once per season. It was found that one application per season of the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention or of a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention is sufficient to achieve the effects described in the context of the present invention, in particular regarding herbicidal activity (above aspects (a) and (b)) and/or the selectivity / compatibility (above aspect (c)).

In a preferred embodiment, the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention or a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention is applied once, twice or three times per Gregorian calendar year, i.e. in one application, in two applications or in three applications per year according to the Gregorian calendar.

In a preferred embodiment, the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention or a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention is applied one time per Gregorian calendar year, i.e. in one application per year according to the Gregorian calendar.

In a preferred embodiment, the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention or a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) used in accordance with the present invention is applied one time in about 12 months, i.e. in one application in about 12 months.

The effects observed when using the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein or a composition comprising the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein allow a more potent herbicidal action, the control of hitherto uncontrolable species (activity gaps), an extended application period and/or a reduced number of required individual applications and - as a result for the user - more advantageous weed control systems both from an economical and ecological point of view.

Preferaby, the combination of active ingredients (i), (ii), optionally (iii), and (iv) as defined herein or a composition comprising the combination of active ingredients (i), (ii), optionally (iii), and (iv) as defined herein is used in post-emergence applications.

In the combinations of active ingredients used in accordance with the present invention and in the compositions comprising a combination used in accordance with the present invention the ratio by weight of the total amount of (i) foramsulfuron and salts thereof to the total amount of (ii) iodosulfuron-methyl and salts thererof preferably is in the range of from 100 : 1 to 5 : 1, more preferably in the range of from 50 : 1 to 10 : 1, and particularly preferably in the range of from 40 : 1 to 20 : 1. In the combinations of active ingredients used in accordance with the present invention and or in the composition comprising a combination used in accordance with the present invention the ratio by weight of the total amount of (i) foramsulfuron and salts thereof to the total amount of (iv) safeners, in particular isoxadifen- ethyl and cyprosulfamide, preferably is in the range of from 8 : 1 to 1 : 3, more preferably in the range of from 5 : 1 to 1 : 2, and particularly preferably in the range of from 3 : 1 to 2 : 3.

If the optional constituent (iii) thiencarbazone-methyl and/or salts thererof is used, in the combinations of active ingredients used in accordance with the present invention and in the compositions comprising a combination used in accordance with the present invention the ratio by weight of the total amount of (i) foramsulfuron and salts thereof to the total amount of (iii) thiencarbazone-methyl and salts thererof preferably is in the range of from 10 : 1 to 1 : 2, more preferably in the range of from 5 : 1 to 1 : 1 , and particularly preferably in the range of from 3 : 1 to 3 : 2.

The preferred application rates [indicated as g a.i./ha, i.e. grams of active ingredient per hectare] of the active ingredients used in the context of the present invention as defined herein are as follows:

(i) foramsulfuron and salts thereof is preferably applied at a rate in the range of 10 to 90 g a.i./ha, more preferably at a rate in the range of 20 to 60 g a.i./ha., and particularly preferably at a rate in the range of

25 to 50 g a.i./ha, and/or

(ii) iodosulfuron-methyl and salts thererof is preferably applied at a rate in the range of 0.25 to 4.9 g a.i./ha, more preferably at a rate in the range of 0.5 to 2.5 g a.i./ha., and particularly preferably at a rate in the range of 0.75 to 1.50 g a.i./ha.

The preferred application rates of the preferred constituents (iv) used in the context of the present invention as defined herein are as follows: isoxadifen-ethyl is preferably applied at a rate in the range of 10 to 90 g a.i./ha, more preferably at a rate in the range of 20 to 60 g a.i./ha., and particularly preferably at a rate in the range of 25 to 50 g a.i./ha, cyprosulfamide is preferably applied at a rate in the range of 5 to 60 g a.i./ha, more preferably at a rate in the range of 10 to 50 g a.i./ha., and particularly preferably at a rate in the range of 12 to 30 g a.i./ha.

If the optional constituent (iii) thiencarbazone-methyl and/or salts thererof is used, in the combinations of active ingredients used in accordance with the present invention and in the compositions comprising a combination used in accordance with the present invention (iii) thiencarbazone-methyl and salts thererof is preferably applied at a rate in the range of 4 to 25 g a.i./ha, more preferably at a rate in the range of 6 to 10 g a.i./ha., and particularly preferably at a rate in the range of 8 to 15 g a.i./ha.

Preferably, the total amount of the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein used in accordance with the present invention does not exceed 200 g/ha, more preferably does not not exceed 150 g/ha, and particularly preferably does not not exceed 100 g/ha.

The active ingredients (i), (ii), optionally (iii), and (iv) as defined herein are more preferably applied in the more preferred rates as defined above (as defined after the term "more preferably"), and particularly preferably applied in the particularly preferred rates as defined above (as defined after the term "particularly preferably"). Furthermore, the active ingredients (i), (ii), optionally (iii), and (iv) as defined herein can be used together with other agrochemically active compounds, for example from the group of the other safeners, fungicides, insecticides, other herbicides and other plant growth regulators, or with formulation auxiliaries and additives customary in crop protection. Additives are, for example, fertilizers and colorants. Preference is in each case given to the ratios by weight mentioned above for the active ingredients (i), (ii), optionally (iii), and (iv), and the application rates or the application rate ranges mentioned above for the active ingredients (i), (ii), optionally (iii), and (iv).

The most important and most noxious weed species in cassava fields in Colombia reported are (African Crop Science Journal 1994, 519-530): Pteridium aquilinum L. Kuhn, Imperata cylindrica L. Beauv., Melinis ninutiflora Beauv., Sida acuta Burm F., Cyperus rotundus L., Commelina diffusa Burm F. sub-species diffuse J.K. Morton, Ageratum conyzoides L. and Portulaca oleraceae L., Cyperus rotundus L (purple nutsedge), Rottboellia exaltata (Lour) Clayton (Raoul grass), Sorghum halepense L. Pers (Johnson grass) and Ipomoea sp. (morning glory).

In Nigeria, broad-leaved species were the most frequent weeds in all areas, averaging 71-78% of all the species recorded. Only 17-19% of the weed species present were grasses and 4-7% were sedges. Five weed species, namely, Ageratum conyzoides L., Alternenthera sessilis L. R. Br. ex Roth, Mimosa invisa Mart, Digitaria horizontalis Willd, and Panicum maximum Jacq occurred in the entire area surveyed.

In south western Nigeria it was observed that annual weeds, especially broad-leaved weeds, were the most common in cassava, and the prevalent species were Euphorbia hirta L. and Talinum triangulate Willd.

African Crop Science Joumal 1994, Vol. 2. No.4, pp. 519-530 summarizes the ten most common weed species in cassava fields in Umuahia, southern Nigeria:

Ageratum conyzoide, Calopogonium mucunoides, Alternenthera sessilis, Boreiria ocymoides, Commelina erecta, Chromolaena odorata, Mimosa invisa, Commelina benghalansis, Tridax procumbens, Brachiaria delfexa, Platostoma africanum, Digitaria adscendens, Synedrella nodiflora, Panicum maximum, Cyperus rotundus, Cyperus esculentus.

Further relevant weed species occurring in cassava fields in Nigeria are (grasses, sedges and broadleaf weeds): Imperata cylindrica, Cynodon dactylon, Pennisetum polystachion, Mariscus alternifolius, Euphorbia heterophylla, Talinum triangulare.

A relevant parasitic weed species occurring in cassava fields (for example in Nigeria) is Cuscuta australis.

The combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein have an outstanding herbicidal activity against a broad spectrum of economically important harmful monocotyledonous and dicotyledonous harmful plants in tuberous root crop plants, particularly in cassava.

In the context of the present invention "controlling" denotes a significant reduction of the growth of the harmful plant(s) in comparison to the untreated harmful plants. Preferably, the growth of the harmful plant(s) is essentially diminished (60-79%), more preferably the growth of the harmful plant(s) is largely or fully suppressed (80-100%), and in particular the growth of the harmful plant(s) is almost fully or fully suppressed (90-100%).

Preferably, the present invention relates to the use of the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein, wherein one, several or all harmful plants are selected from the group of weed species consisting of Ageratum spp., Calopogonium spp., Altemanthera spp., Boreiria spp., Commelina spp., Chromolaena spp., Mimosa spp., Tridax spp., Brachiaria spp., Platostoma spp., Digitaria spp., Synedrella spp., Panicum spp., Cyperus spp., Imperata spp., Cynodon spp., Pennisetum spp., Mariscus spp., Euphorbia spp., Talinum spp., Pteridium spp., Melinis spp., Sida spp., Portulaca spp., Rottboellia spp., Sorghum spp., Ipomea spp., Dactyloctenium spp., Spigelia spp., Boerhaavia spp., Aspilia spp., Aneilima spp., Hyparrhenia spp., Andropogon spp., Paspalum spp., Rhynchelytrum spp., Eleusine spp., Setaria spp., Triumfetta spp., Stachytarpheta spp., Desmodium spp., Gomphrena spp., Tephrosia spp., Acanthospermum spp., Hyptis spp., Cenchrus spp., Urena spp., Vernonia spp., Cleome spp., Crotalaria spp., Kyllinga spp., Corchorus spp., Ipomoea spp., Mitracarpus spp., Melanthera spp., Centrosema spp., Emilia spp., Croton spp., Phyllanthus spp., Passiflora spp., Axonopus spp., Oldenlandia spp., Schwenckia spp., Acalypha spp., Solenostemon spp., Celosia spp., Indigofera spp., Heterotis spp., Acmella spp., Leucaena spp., Boerhavia spp., Spermacoce spp., Oplismenus spp., and Fimbristylis spp.. In a preferred aspect, the present invention relates to the use of the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein, wherein one, several or all harmful plants are selected from the group of weed species consisting of Ageratum spp., Calopogonium spp., Altemanthera spp., Boreiria spp., Commelina spp., Chromolaena spp., Mimosa spp., Tridax spp., Brachiaria spp., Platostoma spp., Digitaria spp., Synedrella spp., Panicum spp., Cyperus spp., Imperata spp., Cynodon spp., Pennisetum spp., Mariscus spp., Euphorbia spp., Talinum spp., Pteridium spp., Melinis spp., Sida spp., Portulaca spp., Rottboellia spp., Sorghum spp., Ipomea spp., Dactyloctenium spp., Spigelia spp., Boerhaavia spp., Aspilia spp., Aneilima spp., Hyparrhenia spp., Andropogon spp., Paspalum spp., Rhynchelytrum spp., Eleusine spp., Setaria spp., Triumfetta spp., Stachytarpheta spp., Desmodium spp., Gomphrena spp., Tephrosia spp., Acanthospermum spp., Hyptis spp., Cenchrus spp., Urena spp., Vernonia spp., and Cleome spp..

Particularly, the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein are used to control one, several or all harmful plants selected from the group of weed species consisting of Ageratum spp., Calopogonium spp., Alternanthera spp., Boreiria spp., Commelina spp., Chromolaena spp., Mimosa spp., Tridax spp., Brachiaria spp., Platostoma spp., Digitaria spp., Synedrella spp., Panicum spp., Cyperus spp., Imperata spp., Cynodon spp., Pennisetum spp., Mariscus spp., Euphorbia spp., Talinum spp., Pteridium spp., Melinis spp., Sida spp., Portulaca spp., Rottboellia spp., Sorghum spp., Ipomea spp., Dactyloctenium spp., Spigelia spp., Boerhaavia spp., Desmodium spp., Gomphrena spp., Tephrosia spp., Acanthospermum spp., Hyptis spp., Cenchrus spp., Urena spp., Vernonia spp., and Cleome spp..

More particularly, the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein are used to control one, several or all harmful plants selected from the group of weed species consisting of Ageratum spp., Calopogonium spp., Alternanthera spp., Boreiria spp., Commelina spp., Chromolaena spp., Mimosa spp., Tridax spp., Brachiaria spp., Platostoma spp., Digitaria spp., Synedrella spp., Panicum spp., Cyperus spp., Imperata spp., Cynodon spp., Pennisetum spp., Mariscus spp., Euphorbia spp., Talinum spp., Pteridium spp., Melinis spp., Sida spp., Portulaca spp., Rottboellia spp., Sorghum spp., Ipomea spp., Dactyloctenium spp., Spigelia spp., and Boerhaavia spp..

Specifically, examples may be mentioned of some representatives of the monocotyledonous and dicotyledonous weed flora which can be controlled by the combinations according to the present invention.

In a more specific aspect, the present invention relates to the use of the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein, wherein one, several or all harmful plants are selected from the group consisting of Ageratum conyzoides, Calopogonium mucunoides, Alternanthera sessilis, Boreiria ocymoides, Commelina erecta, Chromolaena odorata, Mimosa invisa, Commelina benghalensis, Tridax procumbens, Brachiaria delfexa, Platostoma africanum, Digitaria adscendens, Digitaria horizontalis, Synedrella nodiflora, Panicum maximum, Cyperus rotundus, Cyperus esculentus, Imperata cylindrica, Cynodon dactylon, Pennisetum polystachion, Pennisetum purpureum, Pennisetum violaceum, Mariscus alternifolius, Euphorbia heterophylla, Euphorbia hirta, Talinum triangulare, Pteridium aquilinum, Melinis ninutiflora, Sida acuta, Sida rhombifolia, Commelina diffusa, Portulaca oleraceae, Rottboellia exaltata, Rottboellia cochinchinensis, Sorghum halepense, Ipomea triloba, Dactyloctenium aegyptium, Brachiara lata, Spigelia anthemia, Boerhaavia erecta, Aspilia africana, Aneilima beniniense, Hyparrhenia involucrate, Andropogon gayanus, Paspalum conjugatum, Paspalum orbiculatum, Rhynchelytrum repens, Eleusine indica, Setaria barbata, Setaria megaphylla, Triumfetta cordifolia, Stachytarpheta cayennensis, Desmodium scorpiurus, Gomphrena celosioides, Tephrosia bracteolata, Acanthospermum hispidum, Hyptis suaveolens, Cenchrus biflorus, Urena lobata, Vernonia ambigua, Cleome viscosa, Cuscuta australis, Corchorus olitorius, Mitracarpus villosus, Melanthera scandens, Centrosema pubescens, Emilia coccinea, Croton hirtus, Phyllanthus amarus, Corchorus trilocularis, Passiflora foetida, Ipomoea involucrate, Axonopus compressus, Oldenlandia corymbosa, Acalypha ciliata, Schwenckia americana, Solenostemon monostachyus, Celosia trigyna, Indigofera hirsute, Heterotis rotundifolia, Acmella brachyglossa, Leucaena leucocephala, Boerhavia diffusa, Spermacoce ocymoides, Oplismenus burmannii, Fimbristylis littoralis, Cyperus iris, and Kyllinga erecta.

In a more preferred aspect, the present invention relates to the use of the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein, wherein one, several or all harmful plants are selected from the group consisting oiAgeratum conyzoides, Calopogonium mucunoides, Alternanthera sessilis, Boreiria ocymoides, Commelina erecta, Chromolaena odorata, Mimosa invisa, Commelina benghalensis, Tridax procumbens, Brachiaria delfexa, Platostoma africanum, Digitaria adscendens, Digitaria horizontalis, Synedrella nodiflora, Panicum maximum, Cyperus rotundus, Cyperus esculentus, Imperata cylindrica, Cynodon dactylon, Pennisetum polystachion, Pennisetum purpureum, Pennisetum violaceum, Mariscus alternifolius, Euphorbia heterophylla, Euphorbia hirta, Talinum triangulare, Pteridium aquilinum, Melinis ninutiflora, Sida acuta, Sida rhombifolia, Commelina diffusa, Portulaca oleraceae, Rottboellia exaltata, Rottboellia cochinchinensis, Sorghum halepense, Ipomea triloba, Dactyloctenium aegyptium, Brachiara lata, Spigelia anthemia, Boerhaavia erecta, Aspilia africana, Aneilima beniniense, Hyparrhenia involucrate, Andropogon gayanus, Paspalum conjugatum, Paspalum orbiculatum, Rhynchelytrum repens, Eleusine indica, Setaria barbata, Setaria megaphylla, Triumfetta cordifolia, Stachytarpheta cayennensis, Desmodium scorpiurus, Gomphrena celosioides, Tephrosia bracteolata, Acanthospermum hispidum, Hyptis suaveolens, Cenchrus biflorus, Urena lobata, Vernonia ambigua, Cleome viscosa, and Cuscuta australis.

Particularly, the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein are used to control one, several or all harmful plants selected from the group consisting of Ageratum conyzoides, Calopogonium mucunoides, Alternanthera sessilis, Boreiria ocymoides, Commelina erecta, Chromolaena odorata, Mimosa invisa, Commelina benghalensis, Tridax procumbens, Brachiaria delfexa, Platostoma africanum, Digitaria adscendens, Digitaria horizontalis, Synedrella nodiflora, Panicum maximum, Cyperus rotundus, Cyperus esculentus, Imperata cylindrica, Cynodon dactylon, Pennisetum polystachion, Mariscus alternifolius, Euphorbia heterophylla, Euphorbia hirta, Talinum triangulare, Pteridium aquilinum, Melinis ninutiflora, Sida acuta, Commelina diffusa, Portulaca oleraceae, Rottboellia exaltata, Sorghum halepense, Ipomea triloba, Dactyloctenium aegyptium, Brachiara lata, Spigelia anthemia, Boerhaavia erecta, Desmodium scorpiurus, Gomphrena celosioides, Tephrosia bracteolata, Acanthospermum hispidum, Hyptis suaveolens, Cenchrus biflorus, Urena lobata, Vernonia ambigua, Cleome viscosa, and Cuscuta australis. More particularly, the combination of active ingredients as defined herein or the composition comprising a combination of active ingredients as defined herein are used to control one, several or all harmful plants selected from the group consisting of Ageratum conyzoides, Calopogonium mucunoides, Alternanthera sessilis, Boreiria ocymoides, Commelina erecta, Chromolaena odorata, Mimosa invisa, Commelina benghalensis, Tridax procumbens, Brachiaria delfexa, Platostoma africanum, Digitaria adscendens, Digitaria horizontalis, Synedrella nodiflora, Panicum maximum, Cyperus rotundus, Cyperus esculentus, Imperata cylindrica, Cynodon dactylon, Pennisetum polystachion, Mariscus alternifolius, Euphorbia heterophylla, Euphorbia hirta, Talinum triangulare, Pteridium aquilinum, Melinis ninutiflora, Sida acuta, Commelina diffusa, Portulaca oleraceae, Rottboellia exaltata, Sorghum halepense, Ipomea triloba, Dactyloctenium aegyptium, Brachiara lata, Spigelia anthemia, Boerhaavia erecta and Cuscuta australis. If a combination of active ingredients used according to the present invention or if a composition comprising a combination of active ingredients used in the context of the present invention is applied to the soil surface before germination, then the weed seedlings are either prevented completely from emerging, or the weeds grow until they have reached the cotyledon stage but then their growth stops, and, eventually, after three to four weeks have elapsed, they die completely. If a combination of active ingredients used according to the present invention or if a composition comprising a combination of active ingredients used in the context of the present invention is applied post-emergence to the green parts of the plants, growth likewise stops drastically a very short time after the treatment and the weed plants remain at the growth stage of the point of time of application, or they die completely after a certain time, so that in this manner competition by the weeds, which is harmful to the crop plants, is eliminated at a very early point in time and in a sustained manner.

The use of a combination of active ingredients used according to the present invention and the use of a composition comprising a combination of active ingredients used in the context of the present invention is characterized by a rapidly commencing and long-lasting herbicidal action.

In particular when the combination of active ingredients as defined in the context of the present invention and the compositions comprising a combination of active ingredients as defined in the context of the present invention are employed application rates may be reduced, a broader spectrum of broad-leaved weeds and grass weeds maybe controlled, the herbicidal action may take place more rapidly, the duration of action may be longer, the harmful plants may be controlled better while using only one, or few, applications, and the application period which is possible to be extended. The abovementioned properties and advantages are of benefit for weed control practice to keep agricultural crops free from undesired competing plants and thus to safeguard and/or increase the yields from the qualitative and quantitative point of view. These combinations markedly exceed the technical state of the art with a view to the properties described. While the combinations of active ingredients according to the present invention have an outstanding herbicidal activity against monocotyledonous and dicotyledonous weeds, the crop plants are damaged only to a minor extent, if at all.

Moreover, some of the compositions according to the present invention have outstanding growth-regulatory properties on the crop plants. They engage in the plants' metabolism in a regulatory manner and can thus be employed for provoking directed effects on plant constituents and to facilitate harvesting such as for example by triggering desiccation and stunted growth. Moreover, they are also suitable for the general control and inhibition of undesired vegetative growth without simultaneously destroying the plants. An inhibition of vegetative growth is very important in a large number of monocotyledonous and dicotyledonous crops since yield losses as a result of lodging can thus be reduced, or prevented completely. Owing to their herbicidal and plant-growth-regulatory properties, the compositions according to the present invention can be employed for controlling harmful plants in genetically modified crop plants or crop plants obtained by mutation/selection. These crop plants are distinguished as a rule by particular, advantageous properties, such as resistances to herbicidal compositions or resistances to plant diseases or causative agents of plant diseases such as particular insects or microorganisms such as fungi, bacteria or viruses. Other particular properties relate, for example, to the harvested material with regard to quantity, quality, storability, composition and specific constituents. Thus, for example, transgenic plants are known whose starch content is increased or whose starch quality is altered, or those where the harvested material has a different fatty acid composition.

The tuberous root crop plants can also have been genetically modified or been obtained by mutation selection. For example, WO 97/44473 Al relates to transforming and producing cassava plant (protoplasts). WO 92/05259 Al descibes transgenic plants having modified carbohydrate content, inter alia cassava plants.

The present invention also relates to a method of controlling undesired vegetation (e.g. harmful plants) in tuberous root crop plants, which comprises applying a combination of active ingredients and compositions as defined in the context of the present invention or applying a composition comprising a combination of active ingredients as defined in the context of the present invention, preferably by the post-emergence method, to the plants, for example harmful plants, parts of these plants, plant seeds or the area where the plants grow, for example the area under cultivation.

Thus, in a further aspect, the present invention relates to a method for controlling undesired plant growth, and/or controlling harmful plants in tuberous root crop plants, and/or regulating plant growth in tuberous root crop plants, comprising the step of applying a combination of active ingredients or a composition comprising a combination of active ingredients as defined hereinabove onto the tuberous root crop plants, parts of tuberous root crop plants, seeds of tuberous root crop plants, the area where the tuberous root crop plants grow or the area where the tuberous root crop plants will grow or are intended to grow.

Preferably, in a method according to the present invention as defined above , the tuberous root crop plants are selected from the group consisting of sweet potato (Ipomoea batatas), cassava (Manihot esculenta), and yam (plant species in the genus Dioscorea), more preferably the tuberous root crop plant is cassava {Manihot esculenta).

In another aspect, the present invention relates to a method according to the present invention as defined above, wherein one, several, or all harmful plants as mentioned above are controlled. In another aspect, the present invention relates to a method according to the present invention as defined above, wherein the tuberous root crop plants have been genetically modified, preferably said tuberous root crop plants are transgenic plants or obtained by mutation/selection.

Preferably, a combination of active ingredients or a composition comprising a combination of active ingredients as defined herein is used in post-emergence application in the method according to the present invention. It was further found that very good to excellent (total) weed control at an agronomically acceptable level of damage of the tuberous root crop plants can be achieved if the size of the aerial part of the tuberous root crop plants is at least 40 cm, preferably at least 50 cm, more preferably at least 60 cm.

This aspect is of particular relevance in case of the so-called intercropping. Intercropping is the cultivation of two or more crops that differ in productivity, growth habit and phonological characteristics together on the same field. It also means the growing of two or more crops on the same field with the planting of the second crop after the first one has significantly progressed or largely completed its development. It has been noted that intercropping gives higher total returns per unit area of land and this allows larger financial gains for farmers, see Journal of Agricultural Science 2014, Vol. 6, No. 8, 35-40. Often, tuberous root crop plants like cassava are intercropped with maize, sometimes also with legumes such as chickpea or lentil. Thus, the method according to the present invention is preferably performed such that the combination of active ingredients or a composition comprising a combination of active ingredients as defined herein is used when the size of the aerial part of the tuberous root crop plants, preferably the cassava plants, is at least 40 cm, preferably at least 50 cm, more preferably at least 60 cm. It was further found that excellent (total) weed control at an agronomically acceptable level of damage of the tuberous root crop plants can be achieved in the method according to the present invention, wherein in a first application step (i) a pre-emergence herbicide or a combination of pre-emergence herbicides is applied onto the tuberous root crop plants, parts of tuberous root crop plants, seeds of tuberous root crop plants, the area where the tuberous root crop plants grow or the area where the tuberous root crop plants will grow or are intended to grow, and in a second application step (ii) the combination of active ingredients or a composition comprising a combination of active ingredients as defined herein in the context of the present invention is applied.

In the method according to the present invention, step (ii) is preferably carried out 20 days or later after step (i) has been performed. More preferably, step (ii) is carried out 30 to 105 days, even more preferably 40 to 100 days, particularly preferably 50 to 95 days, and very particularly preferably 60 to 90 days after step (i) has been performed.

In this way, the application of a pre-emergence herbicide or a combination of pre-emergence herbicides in the first step (i) allows the tuberous root crop plants, preferably the cassava plants to develop and grow largely in the absence of harmful plants. Later, at a point in time when the pre-emergence herbicide or a combination of pre-emergence herbicides is not active or effective anymore, (some of) the harmful plants reappear, and then in a second application step (ii) the combination of active ingredients or a composition comprising a combination of active ingredients as defined herein in the context of the present invention is applied.

At this stage, the size of the aerial part of the tuberous root crop plants, preferably the cassava plants, is at least 40 cm, preferably at least 50 cm, more preferably at least 60 cm, and the reappearing harmful plants are comparatively small. Typically, the second application step (ii) of the method according to the present invention is carried out when the reappearing harmful plants are at the 4-6 leaf growth stage.

In addition, it is preferred to use a spray shield when carrying out the second application step (ii) in order to further reduce or minimize any unwanted damage and/or unwanted reduced harvest yields of the tuberous root crops. Preferred pre-emergence herbicides or a combination of pre-emergence herbicides applied in step (i), i.e. before the combination of active ingredients or a composition comprising a combination of active ingredients as defined herein in the context of the present invention is applied, are preferably selected from the group consisting of: aclonifen, atrazine, butachlor, diflufenican, fluazifop-butyl, flufenacet, flurtamone, indaziflam, isoxaflutole, metolachlor, S-metolachlor, metribuzin, oxyfluorfen, pendimethalin, prometryn, propaquizafop, sethoxydim, and mixtures of two or three of these herbicides.

More preferably, the pre-emergence herbicides or a combination of pre-emergence herbicides applied in step (i) are selected from the group consisting of: aclonifen, diflufenican, flufenacet, flurtamone, isoxaflutole, metribuzin, and mixtures of two or three of these herbicides.

In view of the preferred embodiments mentioned above, a preferred method according to the present invention for controlling undesired plant growth, and/or controlling harmful plants in tuberous root crop plants, preferably cassava plants, and/or regulating plant growth in tuberous root crop plants, preferably cassava plants, in a first application step (i) a pre-emergence herbicide or a combination of pre-emergence herbicides is applied onto the tuberous root crop plants, parts of tuberous root crop plants, seeds of tuberous root crop plants, the area where the tuberous root crop plants grow or the area where the tuberous root crop plants will grow or are intended to grow,

and

in a second application step (ii) a combination of active ingredients or a composition comprising a combination of active ingredients is applied thereto, wherein the combination of active ingredients comprises or consists of

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, and (iv) isoxadifen-ethyl, or

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, (iii) thiencarbazone-methyl and/or salts thereof, and (iv) cyprosulfamide, wherein step (ii) is carried out

30 days or later after step (i) has been performed, preferably, step (ii) is carried out 40 to 100 days, after step (i) has been performed,

and/or when the size of the aerial part of the tuberous root crop plants, preferably the cassava plants, is at least 40 cm, preferably at least 50 cm, more preferably at least 60 cm.

In view of the more preferred embodiments mentioned above, a more preferred method according to the present invention for - controlling undesired plant growth, and/or controlling harmful plants in tuberous root crop plants, preferably cassava plants, and/or regulating plant growth in tuberous root crop plants, preferably cassava plants, in a first application step (i) a pre-emergence herbicide or a combination of pre-emergence herbicides is applied onto the tuberous root crop plants, parts of tuberous root crop plants, seeds of tuberous root crop plants, the area where the tuberous root crop plants grow or the area where the tuberous root crop plants will grow or are intended to grow, wherein said pre-emergence herbicide or combination of pre-emergence herbicides is selected from the group consisting of aclonifen, atrazine, butachlor, diflufenican, fluazifop-butyl, flufenacet, flurtamone, indaziflam, isoxaflutole, metolachlor, S-metolachlor, metribuzin, oxyfluorfen, pendimethalin, prometryn, propaquizafop, sethoxydim, and mixtures of two or three of these herbicides, preferably selected from the group consisting of aclonifen, diflufenican, flufenacet, flurtamone, isoxaflutole, metribuzin, and mixtures of two or three of these herbicides,

and

in a second application step (ii) a combination of active ingredients or a composition comprising a combination of active ingredients is applied thereto, wherein the combination of active ingredients comprises or consists of

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, and (iv) isoxadifen-ethyl, or

- (i) foramsulfuron and/or salts thereof, (ii) iodosulfuron-methyl and/or salts thereof, (iii) thiencarbazone-methyl and/or salts thereof, and (iv) cyprosulfamide, wherein step (ii) is carried out

40 days or later after step (i) has been performed, preferably, step (ii) is carried out 50 to 95 days, after step (i) has been performed,

and/or when the size of the aerial part of the tuberous root crop plants, preferably the cassava plants, is at least 50 cm, preferably at least 60 cm.

The method according to the present invention with the first application step (i) followed by a second application step (ii) as defined above, in particular in the preferred or more preferred embodiments, were found to be particularly beneficial and efficient in case cassava was intercropped with maize.

In the latter case, it was found that generally higher maize grain yield was achieved, without a substantial negative impact on the cassava plant growth, i.e. plant height, plant vigor (vigorous growth) and population (number of cassava plants / ha).

Ath the same time, very good to excellent control of harmful plants was achieved, typically about 80 - 96% against dicotyledonous (broadleaf) weeds and about 85 - 100% against monocotyledonous weeds (grasses), including difficult to control harmful plants like Commelina benghalensis, Euphorbia heterophylla, Imperata cylindrica, and Rottboellia cochinchinensis.

As already mentioned above, the combination of active ingredients as defined in the context of the present invention can not only be used as mixed formulations, if appropriate together with further agrochemically active compounds, additives and/or customary formulation auxiliaries, which are then applied in the customary manner as a dilution with water, but also as so-called tank mixes by jointly diluting the separately formulated, or partially separately formulated, components with water.

The combination of active ingredients as defined in the context of the present invention and the compositions comprising a combination of active ingredients as defined in the context of the present invention can be formulated in various ways, depending on the prevailing biological and/or chemical-physical parameters. The following are examples of general possibilities for formulations: wettable powders (WP), water-soluble concentrates, emulsifiable concentrates (EC), aqueous solutions (SL), emulsions (EW) such as oil-in-water and water-in-oil emulsions, sprayable solutions or emulsions, suspension concentrates (SC), oil dispersions (OD), oil- or water-based dispersions, suspoemulsions, dusts (DP), seed-dressing materials, granules for soil application or for broadcasting, or water-dispersible granules (WG), ULV formulations, microcapsules or waxes.

The individual formulation types are known in principle and are described for example, in: Winnacker-Kiichler, "Chemische Technologie", Volume 7, C. Hauser Verlag Munich, 4 ^th Edition, 1986; van Valkenburg, "Pesticide Formulations", Marcel Dekker N.Y., 1973; K. Martens, "Spray Drying Handbook", 3rd Ed. 1979, G. Goodwin Ltd. London.

The formulation auxiliaries required, such as inert materials, surfactants, solvents and other additives are also known and are described, for example, in Watkins, "Handbook of Insecticide Dust Diluents and Carriers", 2nd Ed., Darland Books, Caldwell N.J.; H.v. Olphen, "Introduction to Clay Colloid Chemistry"; 2nd Ed, J. Wiley & Sons, N.Y. Marsden, "Solvents Guide", 2nd Ed., Interscience, N.Y. 1950; McCutcheon's, "Detergents and Emulsifiers Annual", MC Publ. Corp., Ridgewood NJ.; Sisley and Wood, "Encyclopedia of Surface Active Agents", Chem. Publ. Co. Inc., N.Y. 1964; Schonfeldt, "Grenzflachenaktive Athylenoxidaddukte" [Surface- active ethylene oxide adducts], Wiss. Verlagsgesellschaft, Stuttgart 1976, Winnacker-Kuchler, "Chemische Technologie", Volume 7, C. Hauser Verlag Munich, 4 ^th Edition 1986.

Based on these formulations, combinations with other agrochemically active substances, such as further active ingredients not belonging to constituents (i), (ii), optionally (iii), and (iv) as defined in the context of the present invention, e.g. other herbicides, other safeners, fungicides, insecticides, fertilizers and/or other growth regulators, may also be prepared, for example in the form of a readymix or a tank mix. Wettable powders (sprayable powders) are products which are uniformly dispersible in water and which, besides the active compound, also comprise ionic or nonionic surfactants (wetters, dispersants), for example polyoxethylated alkylphenols, polyethoxylated fatty alcohols or fatty amines, alkanesulfonates or alkylbenzenesulfonates, sodium lignosulfonate, sodium 2,2'-dinaphthylmethane-6,6'-disulfonate, sodium dibutylnaphthalenesulfonate or else sodium oleoylmethyltauride, in addition to a diluent or inert material. Emulsifiable concentrates are prepared by dissolving the active compound in an organic solvent, for example butanol, cyclohexanone, dimethylformamide, xylene or else higher-boiling aromatics or hydrocarbons with addition of one or more ionic or nonionic surfactants (emulsifiers). Examples of emulsifiers which may be used are: calcium salts of alkylarylsulfonic acids, such as calcium dodecylbenzene sulfonate, or nonionic emulsifiers such as fatty acid polyglycol esters, alkylaryl polyglycol ethers, fatty alcohol polyglycol ethers, propylene oxide/ethylene oxide condensates, alkyl polyethers, sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters or polyoxethylene sorbitol esters.

Dusts are obtained by grinding the active compound with finely divided solid materials, for example talc, natural clays such as kaolin, bentonite and pyrophyllite, or diatomaceous earth.

Suspension concentrates (SC) can be water- or oil-based. They can be prepared, for example, by wet grinding by means of commercially available bead mills and, if appropriate, addition of further surfactants as they have already been mentioned for example above in the case of the other formulation types.

Emulsions, for example oil-in-water emulsions (EW), can be prepared for example by means of stirrers, colloid mills and/or static mixers using aqueous organic solvents and, if appropriate, further surfactants as have already been mentioned for example above in the case of the other formulation types. Granules can be prepared either by spraying the active compound onto adsorptive, granulated inert material or by applying active compound concentrates to the surface of carriers such as sand, kaolinites or granulated inert material with the aid of binders, for example polyvinyl alcohol, sodium polyacrylate or else mineral oils. Suitable active compounds may also be granulated in the manner conventionally used for the production of fertilizer granules, if desired in a mixture with fertilizers. As a rule, water-dispersible granules are prepared by customary processes such as spray drying, fluidized-bed granulation, disk granulation, mixing with high-speed mixers and extrusion without solid inert material. Regarding the production of disk granules, fluidized-bed granules, extruder granules and spray granules, see, for example, the methods in "Spray-Drying Handbook" 3rd ed. 1979, G. Goodwin Ltd., London; J.E. Browning, "Agglomeration", Chemical and Engineering 1967, page 147 et seq; "Perry's Chemical Engineer's Handbook", 5th Ed., McGraw-Hill, New York 1973, pp. 8-57.

As regards further details on the formulation of crop protection products, see, for example, G.C. Klingmam, "Weed Control as a Science", John Wiley and Sons, Inc., New York, 1961, pages 81-96 and J.D. Freyer, S.A. Evans, "Weed Control Handbook", 5th Ed., Blackwell Scientific Publications, Oxford, 1968, pages 101-103. As a rule, the agrochemical formulations comprise 1 to 95% by weight, of active compounds, the following concentrations being customary, depending on the type of formulation:

The active compound concentration in wettable powders is, for example, approximately 10 to 95% by weight, the remainder to 100% by weight being composed of customary formulation constituents. In the case of emulsifiable concentrates, the active compound concentration may amount to, for example, 5 to 80% by weight. Formulations in the form of dusts comprise, in most cases, 5 to 20% by weight of active compound, sprayable solutions approximately 0.2 to 25% by weight of active compound. In the case of granules such as dispersible granules, the active compound content depends partly on whether the active compound is present in liquid or solid form and on which granulation auxiliaries and fillers are being used. As a rule, the content amounts to between 10 and 90% by weight in the case of the water-dispersible granules. In addition, the abovementioned active compound formulations may comprise, if appropriate, the conventional adhesives, wetters, dispersants, emulsifiers, preservatives, antifreeze agents, solvents, fillers, colorants, carriers, antifoams, evaporation inhibitors, pH regulators or viscosity regulators.

The herbicidal action of the combination of active ingredients according to the present invention can be improved, for example, by surfactants, preferably by wetters from the group of the fatty alcohol polyglycol ethers. The fatty alcohol polyglycol ethers preferable contain 10 - 18 carbon atoms in the fatty alcohol radical and 2 - 20 ethylene oxide units in the polyglycol ether moiety. The fatty alcohol polyglycol ethers can be nonionic or ionic, for example in the form of fatty alcohol polyglycol ethers sulfates, which can be used, for example, as alkali metal salts (e.g. sodium salts or potassium salts) or ammonium salts, but also as alkaline earth metal salts such as magnesium salts, such as sodium Ci2/Ci4-fatty alcohol diglycol ether sulfate (Genapol ^® LPvO, Clariant); see, for example, EP-A-0476555, EP-A-0048436, EP-A-0336151 orUS-A-4,400,196 and also Proc. EWPvS Symp. "Factors Affecting Herbicidal Activity and Selectivity", 227 - 232 (1988). Nonionic fatty alcohol polyglycol ethers are, for example, (Cio-Cis)-, preferably (Cio-Ci4)-fatty alkohol polyglycol ethers containing 2 - 20, preferably 3 - 15, ethylene oxide units (e.g. isotridecyl alcohol polyglycol ether), for example from the Genapol ^® series, such as Genapol ^® X-030, Genapol ^® X-060, Genapol ^® X-080 or Genapol ^® X-150 (all from Clariant GmbH).

The present invention furthermore embraces the combination of active ingredients (i), (ii), optionally (iii), and (iv) as defined above with the wetting agents mentioned above from the group of the fatty alcohol polyglycolethers which preferably contain 10 - 18 carbon atoms in the fatty alcohol radical and 2 - 20 ethylene oxide units in the polyglycol ether moiety and which can be present in nonionic or ionic form (for example as fatty alcohol polyglycol ether sulfates). Preference is given to C Cw-fatty alcohol diglycol ether sulfate sodium (Genapol ^® LRO, Clariant); and isotridecyl alcohol polyglycol ether with 3 - 15 ethylene oxide units, for example from the Genapol ^® X series, such as Genapol ^® X-030, Genapol ^® X-060, Genapol ^® X-080 or Genapol ^® X-150 (all from Clariant GmbH). It is furthermore known that fatty alcohol polyglycol ethers such as nonionic or ionic fatty alcohol polyglycol ethers (for example fatty alcohol polyglycol ether sulfates) are also suitable for use as penetrants and activity enhancers for a number of other herbicides, inter alia also for herbicides from the group of the imidazolinones (see, for example, EP-A-0502014).

Moreover, it is known that fatty alcohol polyglycol ethers such as nonionic or ionic fatty alcohol polyglycol ethers (for example fatty alcohol polyglycol ether sulfates) are also suitable as penetrants and synergists for a number of other herbicides, inter alia also herbicides from the group of the imidazolinones; (see, for example, EP-A-0502014).

The herbicidal effect of the combination of active ingredients according to the present invention can also be increased using vegetable oils. The term vegetable oils is to be understood as meaning oils from oil-plant species, such as soya oil, rapeseed oil, corn oil, sunflower oil, cottonseed oil, linseed oil, coconut oil, palm oil, safflower oil or castor oil, in particular rapeseed oil, and their transesterification products, for example alkyl esters, such as rapeseed oil methyl ester or rapeseed oil ethyl ester.

The vegetable oils are preferably esters of C10-C22-, preferably C12-C20- fatty acids. The Cio-C22-fatty acid esters are, for example, esters of unsaturated or saturated Cio-C22-fatty acids, in particular those with an even number of carbon atoms, for example erucic acid, lauric acid, palmitic acid and, in particular, Cis-fatty acids such as stearic acid, oleic acid, linoleic acid or linolenic acid.

Preferred Ci-C2o-alkyl-Cio-C22-fatty acid esters are the methyl, ethyl, propyl, butyl, 2-ethylhexyl and dodecyl esters. Preferred glycol- and glycerol-Cio-C22-fatty acid esters are the uniform or mixed glycol esters and glycerol esters of C io-C22-fatty acids, in particular those fatty acids which have an even number of carbon atoms, for example erucic acid, lauric acid, palmitic acid and, in particular, Cis-fatty acids such as stearic acid, oleic acid, linolic acid or linolenic acid.

The vegetable oils can be present in the compositions according to the present invention for example in the form of commercially available oil-containing formulation additives, in particular those based on rapeseed oil such as Hasten (Victorian Chemical Company, Australia, hereinbelow termed Hasten, main constituent: rapeseed oil ethyl ester), Actirob ^® B (Novance, France, hereinbelow termed ActirobB, main constituent: rapeseed oil methyl ester), Rako-Binol ^® (Bayer AG, Germany, termed Rako-Binol hereinbelow, main constituent: rapeseed oil), Renol ^® (Stefes, Germany, termed Renol hereinbelow, vegetable oil constituent: rapeseed oil methyl ester), or Stefes Mero ^® (Stefes, Germany, hereinbelow termed Mero, main constituent: rapeseed oil methyl ester).

In a further embodiment, the present invention embraces the combination of a combination of active ingredients as defined in the context of the present invention with the vegetable oils mentioned above. Thus, in a further embodiment, the present invention embraces the use of compositions comprising a combination of active ingredients as defined in the context of the present invention comprising the vegetable oils mentioned above, such as rapeseed oil, preferably in the form of commercially available oil-containing formulation additives, in particular those based on rapeseed oil such as Hasten ^® (Victorian Chemical Company, Australia, hereinbelow termed Hasten, main constituent: rapeseed oil ethyl ester), Actirob ^® B (Novance, France, hereinbelow termed ActirobB, main constituent: rapeseed oil methyl ester), Rako-Binol ^® (Bayer AG, Germany, termed Rako-Binol hereinbelow, main constituent: rapeseed oil), Renol ^® (Stefes, Germany, termed Renol hereinbelow, vegetable oil constituent: rapeseed oil methyl ester), or Stefes Mero ^® (Stefes, Germany, hereinbelow termed Mero, main constituent: rapeseed oil methyl ester).

For use, the formulations, which are present in commercially available form, are optionally diluted in the customary manner, for example using water in the case of wettable powders, emulsifiable concentrates, dispersions and water-dispersible granules. Preparations in the form of dusts, soil granules, granules for broadcasting and sprayable solutions are usually not diluted further with other inert substances prior to use.

The active compounds can be applied to the plants, parts of the plants, seeds of the plants or the area under cultivation (soil of a field), preferably to the green plants and parts of the plants and, if appropriate, additionally to the soil of the field.

A composition comprising a combination of active ingredients n used in the context of the present invention has the advantage of being easier to apply, and the quantities of the components are advantageously already presented in the correct ratio to each other. Moreover, the adjuvants in the formulation can be matched optimally to each other.

Examples

1. Products used The following commercially available products were tested (available from Bayer Crop Science):

Product PI contained 300g/kg foramsulfuron, 10 g/kg iodosulfuron-methyl-sodium, and 300 g/kg isoxadifen- ethyl, and was a water-dispersible granules (WG) formulation. Product P2 contained 31.5 g/L foramsulfuron-sodium, 1 g/L iodosulfuron-methyl-sodium, 10 g/L thiencarbazone-methyl, and 15 g/L cyprosulfamide, and was an oil dispersion (OD) formulation.

2. Biological Trials

Trials were conducted on cassava plants on a Research Farm in Nigeria.

Table 1 shows the respective weed control ratings for the different products tested in post-emergence. In each case the total weed control takes into account the control of monocotyledonous weeds (grasses) and dicotyledonous (broadleaf) weeds (BLW) present in the plot.

The products were applied to the harmful plants under the cassava canopy using a spray shield.

Inter alia controlling of the following weeds was assessed: Ageratum conyzoides, Calopogonium mucunoides, Centrosema pubescens, Chromolaena odorata, Commelina benghalensis, Corchorus trilocularis , Desmodium scorpiurus, Euphorbia heterophylla, Imperata cylindrica, Panicum maximum, Phyllanthus amarus, Rottboellia cochinchinensis, Spermacoce ocymoides, and Spigelia anthemia.

Table 1 : Ratings of weed control in plots treated post-emergence with the respective product

Table 2 shows the plant heights of cassava plants 14 weeks after treatment with the respective product in comparison to hoe-weeding.

Table 2: Plant height of cassava plants 14 weeks after treatment with the respective product

Product or treatment Amount of Product applied Height of cassava plants

PI 0.15 kg/ha 170 cm

P2 1 L/ha 165 cm

Hoe-weeding (Reference) - 175 cm Table 3 shows the plant growth regulating effect of product P2 on cassava crop plants after harvest relative to hoe-weeded cassava crop plants (as reference). The plant growth regulating effects were measured as the respective fresh root cassava yields, in each case as perecentage in comparison to the fresh root cassava yield of hoe- weeded cassava crop plants as reference (defined as 100%). Table 3 : Plant growth regulating effect of product P2 on tuberous root crop plants indicated as fresh root yield

Product or treatment Amount of Product applied Yield of fresh root yield (in

comparison to hoe-weeding)

P2 1 L/ha 105%

Hoe-weeding 100%

(Reference)