The present invention relations to a method of reducing damage to a crop, especially a potato crop. In particular the invention relations to a method of reducing nematode populations, especially by preventing hatching of nematodes.

The potato (Solanum tuberosum) is a starchy, tuberous crop belonging to the Solanum family. Alongside maize, wheat and rice, the potato has a fundamental role in global food production. Potato production is adversely affected by a number of major diseases and pests, for example, the Potato Cyst Nematode (PCN). PCN are known to exist in a number of environments, for example in soil, and they feed on the roots of potatoes and other plants of the Solanaceae family. Perhaps the best known species of PCN in the UK are Globodera rostochiensis and Globodera pallida, commonly known as yellow PCN and white PCN, respectively. In the UK, prior to the use of cultivars such as Maris Piper, G. pallida was generally less abundant than G. rostochiensis. However an increase in prevalence of planting cultivars resistant only to G. rostochiensis has led to an increase in G. pallida populations.

Across Europe the potato industry has suffered from losses amounting to millions of pounds as a result of PCN infestations. These losses are manifested through significant reductions in yield and quality of potato. According to a 2002 study of UK potato farms, 64% of the 484 sampled sites contained PCN.

The damage caused by PCN is believed to be due to the invasion and infestation of the potato roots, and interference with ion transport mechanisms at the potato root surface. Potato plants infested with PCN exhibit symptoms which may include stunted shoot growth, smaller leaves, wilting, and senescence. Potato plants infested with PCN may also exhibit a decrease in tuber number and size. This is believed to be due to a reduced uptake of potassium, magnesium and phosphorous ions. Furthermore, as a result of the systemic changes that occur within the host plant during invasion and feeding of PCN, it is believed that the host plant may become more susceptible to attack by fungal pathogens.

In the absence of a host, PCN may survive in cutinized remains of a dead female nematode, known as "cysts", each of which containing hundreds of eggs. The active phase of a G. rostochiensis life cycle begins with the hatching of a second stage juvenile (J2) from a dormant egg. The J2 cuts an opening in its egg using its stylet and subsequently exits through the opening. Hatching may be stimulated by chemicals released by the host plant known as potato root diffusate (PRD). PRD is produced along the length of a potato root, most potently at the potato root tip, during plant growth, and can stimulate up to 80% of eggs to hatch. Hatching may also be affected by other factors such as the species of PCN, species of the host, photoperiod of the host and temperature. J2 move between soil particles with the aim of locating and subsequently invading the roots of a potato. After penetrating the rhizodermis of a potato using its stylet, the vermiform J2 migrates intracellular^ to a cortex or endodermis of the potato thereby creating a path of destroyed cells. In the cortex or endodermis, the J2 further uses its stylet to probe and select a feeding site, known as the syncytium. The cell contents are then ingested by the J2. As the J2 further mature, they are sexually differentiated by epigenetic factors such as quantity and quality of food at the syncytium. In the presence of adequate food and space, J2 will likely mature to a female. In contrast, J2 will likely mature to a male if there is insufficient food and space. Adult female nematodes develop a saccate shape and their gonads grow until rupture of the potato root tissue. To increase their chances of fertilisation, the unfertilised female nematodes then produce a chemical to attract the male nematodes. Once fertilised, 200 to 500 embryos develop, and the female subsequently dies. The female's body wall cutinizes, forming a cyst which comprises a protective layer around the egg mass. The cyst detaches from the root as the plant cell dies or through physical disturbance.

Historically, nematicides have been used to control PCN populations. However, as a consequence of stricter legislation many nematicides have been removed from use and those remaining have been discouraged by supermarkets. As of 2014, there are only three UK registered nematicidal compounds for use on potato crops, corresponding to Ethroprophos, Fosthiazate and Oxamyl.

Ethoprophos is an acetylcholinesterase inhibitor for managing the populations of a broad range of soil-dwelling insects including nematodes. Although Ethoprophos is currently approved for use in the UK, it is not approved for use in a number of European countries including Germany and France.

Fosthiazate is an acetylcholinesterase inhibitor for managing the populations of a broad range of ground insects including nematodes. Fosthiazate is currently approved for use in the UK, Germany, France, Italy and a number of other European counties.

Oxamyl is an acetylcholinesterase inhibitor used for managing the populations of a range of field and crop-based insects including nematodes. The granulated form of Oxamyl has been banned in the US but is currently approved for use in the UK, France, Italy and a number of other European countries. Oxamyl can be used in the US in liquid form.

Acetylcholinesterase inhibitors function by causing paralysis of the second stage (J2) juvenile nematodes. In Europe, Ethroprophos, Fosthiazate and Oxamyl are registered until 2017, 2016 and 2018, respectively, and under EU regulation EC 1 107/2009, all are "candidates for substitution". As such, introduction of an alternative nematiciade with improved safety may result in a ban of these compounds.

Trap crops, for example, Solanum sisymbrifolium, are used for the management of PCN populations. Trap crops stimulate hatch of PCN in soil but do not allow the PCN to complete their life cycle. Often a sacrificial crop or plant species, trap crops generally have no intrinsic economic value other than for their sole purpose as a nematicide. The use of trap crops is, however, an expensive and labour intensive option with varying efficacy on different populations of PCN.

Cysteine proteinases, a form of plant extract, are known to have a detrimental effect on the hatch of PCN, but the overall effectiveness of cysteine proteinases is generally inconsistent.

However there remains a need for improved alternative means for controlling PCN, especially a method having reduced toxicity.

According to a first aspect of the present invention there is provided a method of inhibiting the hatching of nematodes, the method comprising contacting soil in which nematode eggs are present with:

(a) one or more quaternary ammonium compounds. The present invention relates to a method of inhibiting the hatching of nematodes. Suitably the invention may be used to inhibit the hatching of nematodes which live in the soil around the root of the plant (ectoparasites).

The present invention relates to a method of inhibiting the hatching of nematodes.

The invention may be used to inhibit the hatching of any species of nematode which lay their eggs in soil.

Such species will be known to the person skilled in the art, and include, for example Belonolaimus spp. (sting), Hemicycliophora spp. (sheath), Xiphinema spp. (dagger), Paratrichodorus spp. (stubby root), Trichodorus spp. (stubby root), Tylenchorhynchus spp. (stunt), Criconemoides spp. (ring), Helicotylenchus spp. (spiral), Rotylenchus spp. (spiral), Pratylenchus spp. (lesion), Hoplolaimus spp. (lance), Meloidogyne spp. (root knot nematodes), Nacobbus spp. (false root knot nematodes), Globodera spp. (potato cyst nematode), Heterodera spp. (cyst nematodes), Rotylenchulus spp. (reniform) and Tylenchulus spp. (citrus).

Suitably the invention may be used to inhibit the hatching of one or more species of nematodes selected from cyst nematodes and root knot nematodes.

Suitable cyst nematodes include those of the Heterodera and Globodera species, for example sugar beet cyst nematode (H. schachtii), soybean cyst nematode (H. glycines), cereal cyst nematodes (H. avenae and H. filipjevi), pea cyst nematodes (H. goettingiana), pigeonpea cyst nematode (H. cajani), tobacco cyst nematode (G. tabacum), alfalfa cyst nematode (H. medicaginis), G. rostochiensis and G. pallida.

Suitable root knot nematodes include those of the Meloidogyne species, for example M. hapla, M. incognita, M. javanica, M. arenaria

Preferably the invention is used to inhibit the hatching of one or more species of cyst nematodes. Cyst nematodes are characterized by the tanning and drying (cutinisation) of the body wall of the sedentary adult female following fertilization and production of embryonated eggs. The resultant cyst allows the succeeding generation to survive for extended periods until a suitable host is growing in the near vicinity. It is this ability to persist for many years in the soil in the absence of a host that contributes to the economic importance of this group in agricultural situations.

Preferably the invention is used to inhibit the hatching of Globodera rostochienisis or Globodera pallida nematodes.

The method of the present invention involves contacting soil with (a) one or more quaternary ammonium compounds. Component (a) comprises a quaternary ammonium salt.

Suitable quaternary ammonium cationic biocides have the structure shown in formula (V):

R +

R ² N R ⁴ X

R ³

(V) where each of R , R ² , R ³ and R ⁴ is an optionally substituted alkyl, alkenyl, alkylaryl or aryl group and X ^" is a suitable anion. Preferably each of R , R ² , R ³ and R ⁴ is an optionally substituted alkyl or alkylaryl group, more preferably an unsubstituted alkyl or alkylaryl group.

Any suitable anion X ^" may be used. X may be selected from halide, acetate, nitrite, a lower alkosulfate, carbonate or alkyl carboxylate. Preferably X is chloride or bromide.

Each of R , R ² , R ³ and R ⁴ may be an unsubstituted alkyl group having from 1 to 30 carbon atoms or an alkylaryl group, for example a benzyl group.

Preferably at least one of R , R ² , R ³ and R ⁴ is an unsubstituted alkyl group having at least 6 carbon atoms, preferably at least 8 carbon atoms. In one preferred embodiment R is an alkyl group having from 6 to 30 carbon atoms, preferably from 8 to 24 carbon atoms, suitably from 8 to 20 carbon atoms, for example from 10 to 18 carbon atoms and most preferably from 12 to 16 carbon atoms; each of R ² and R ³ is an alkyl group having from 1 to 4 carbon atoms, preferably methyl and R ⁴ is an alkylaryl group, preferably benzyl. Thus a particularly preferred cationic biocide for use herein is a benzyldimethylalkyl ammonium chloride or bromide in which the alkyl group has from 12 to 16 carbon atoms. The skilled person will appreciate that such compounds may often be present as a mixture of homologues.

In another preferred embodiment the cationic biocide of formula (V) is one in which each of R and R ² is an alkyl group having from 6 to 20 carbon atoms, preferably from 6 to 16 carbon atoms, suitably from 8 to 12 carbon atoms, for example from 8 to 10 carbon atoms; and R ³ and R ⁴ is each an alkyl group having 1 to 4 carbon atoms, preferably methyl. One especially preferred cationic biocide for use herein is didecyldimethyl ammonium chloride or bromide. Component (a) is preferably present in the composition contacted with the plant in an amount of at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, preferably at least 500 ppm, suitably at least 1000 ppm, preferably at least 2000 ppm, preferably at least 2500 ppm, for example at least 2800 ppm. Component (a) may be present in the composition contacted with the plant in an amount of up to 50000 ppm, suitably up to 20000 ppm, preferably 10000 ppm, more preferably up to 7000 ppm, suitably up to 5000 ppm, preferably up to 4000 ppm, preferably up to 3500 ppm, for example up to 3200 ppm. For the avoidance of doubt "ppm" in this specification refers to parts per million by weight.

Component (a) may comprise a mixture of two or more quaternary ammonium compounds. In such embodiments the above amounts refer to all such compounds present in the composition.

Component (a) may be incorporated into the composition along with a diluent or carrier. The above definitions refer to the amount of active component present. In some preferred embodiments the method of the present invention further involves contacting the soil with (b) one or more non-ionic surfactants.

Thus the method of the present invention may involve contacting the soil with components (a) and (b). In such embodiments these components may be contacted with the soil separately or in combination. When they are contacted separately they may be contacted in any order. In preferred embodiments components (a) and (b) are contacted with the soil in combination. Preferably the method of the present invention involves contacting the soil with a composition comprising components (a) and (b). Preferred compositions are aqueous compositions. Although the present invention may involve contacting the soil with two or more compositions in preferred embodiments a single composition is used. References in this specification to the composition which is contacted with the soil preferably refer to such a single composition comprising components (a) and (b). However it is within the scope of the invention to use a plurality of compositions such that some components are contacted separately.

Suitable non-ionic surfactants include alkoxylated compounds, alkyl polyglucosides, sugar esters and other compounds known to the person skilled in the art.

Preferred non ionic surfactants are alkoxyated alcohols or esters and alkyl polyglucosides.

Preferred non-ionic surfactants include alkoxylated compounds, for example alkoxylated alcohols or esters. Preferred alkoxylated compounds are polyalkoxylated compounds.

Preferred alkoxylated compounds include a hydrocarbyl group and one or more ethylene oxide and/or propylene oxide residues. Preferred hydrocarbyl groups are alkyl and alkenyl groups, preferably having from 4 to 30 carbon atoms. Preferred are alkyl groups, having for example from 6 to 20 carbon atoms. Non-ionic surfactants including one or more ethylene oxide residues are preferred. Especially preferred non-ionic surfactants for use herein are alcoholalkoxylate compounds, in particular alcoholethoxylate compounds. Preferred non-ionic surfactants are those of formula CH3(CH2)nO(CH2CH ₂ 0) _m H wherein n is from 5 to 20, preferably from 6 to 15 and m is from 1 to 12, preferably from 3 to 10.

An especially preferred non-ionic surfactant comprises a mixture of isomers in which n is 9 or 1 1 and m is 4 to 8.

In some preferred embodiments component (b) comprises an alkylpolyglucoside. Suitable compounds of this type will be known to the person skilled in the art. Especially preferred alkylpolyglucosides are monoalkyl-polyglucoside.

In some preferred embodiments component (b) comprises a compound of formula (IV):

(IV) wherein n is from 5 to 12, preferably from 6 to 10, more preferably from 7 to 9 and m is from 1 to 6, preferably from 1 to 4, more preferably 1 or 2.

The present invention may involve contacting the soil with one or more non-ionic surfactants, component (b).

In preferred embodiments component (b) is applied in an aqueous solution, component (a) and component (b) are applied together in a single solution.

In some embodiments component (b) comprises an alcohol ethoxylate.

In some embodiments component (b) comprises an alkyl polyglucoside

In some embodiments component (b) comprises an alcohol ethoxylate and an alkyl polyglucoside. In some preferred embodiments component (b) comprises an alcohol ethoxylate or an alkyl polyglucoside.

Preferably the composition contacted with the soil comprises at least 1 ppm of non-ionic surfactant component (b), preferably at least 10 ppm, more preferably at least 50 ppm, suitably at least 100 ppm, preferably at least 300 ppm, more preferably at least 500 ppm, suitably at least 800 ppm, preferably at least 1000 ppm.

The composition suitably comprises up to 20000 ppm non-ionic surfactant component (b), preferably up to 15000 ppm suitably up to 10000 ppm, preferably up to 7000 ppm, suitably up to 5000 ppm, for example up to 4000 ppm or up to 3500 ppm.

When the composition comprises an alcohol ethloxylate this is suitably present in an amount of at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, suitably at least 300 ppm, preferably at least 500 ppm, more preferably at least 800 ppm, for example at least 1000 ppm.

The alcohol ethoxylate when present is suitably provided in an amount of up to 20000 ppm, preferably up to 10000 ppm, suitably up to 5000 ppm, preferably up to 3000 ppm, more preferably up to 2000 ppm, for example up to 1500 ppm or up to 1400 ppm.

When the composition comprises an alkyl polyglucoside this is suitably present in an amount of at least 1 ppm, preferably at least 10 ppm, more preferably at least 100 ppm, preferably at least 500 ppm, more preferably at least 1000 ppm, suitably at least 1500 ppm, for example at least 2000 ppm or at least 2200 ppm.

The alkyl polyglucoside when present may be provided in an amount of up to 20000 ppm, suitably up to 10000 ppm, preferably up to 8000 ppm, more preferably up to 5000 ppm, suitably up to 4000 ppm, for example up to 3000 ppm, up to 2800 ppm or up to 2600 ppm.

Component (b) may be incorporated into the composition along with a diluent or carrier. The above definitions refer to the amount of active component present.

A mixture of two or more non-ionic surfactants may be present in component (b) of the compositions used in the present invention. In such embodiments the above amounts refer to all such non-ionic surfactants present. In preferred embodiments the method of the present invention involves contacting the soil with a composition comprising one or more quaternary ammonium compounds, an alkyl polyglucoside and an alcohol ethoxylate. The compositions contacted with the soil in the method of the present invention are preferably aqueous compositions. In some embodiments the composition may comprise a further solvent preferably a water-miscible solvent. Suitable water-miscible solvents may be present in an amount of up to 10 wt%, suitably up to 7.5 wt%, preferably up to 5 wt%, for example up to 2.5 wt%. Suitable solvents for use herein include alcohols and esters including polyhydric alcohols.

Preferably the compositions contacted with the soil in the method of the present invention comprise at least 70 wt% water, preferably least 80 wt%, preferably at least 90 wt%, more preferably at least 95 wt%, suitably at least 97 wt%, for example at least 99 wt%.

In some preferred embodiments water is the only solvent present in the composition and it comprises less than 1 wt% other solvents or diluents. Preferably the composition applied to the grass-carrying surface is substantially free of solvents other than water. Preferably the composition comprises less than 1 wt% alcohols, preferably less than 0.1 wt%, preferably than 0.01 wt%, preferably less than 0.001 wt% or less than 0.0001 wt%.

In some preferred embodiments the composition used in the method of the present invention consists essentially of component (a), component (b) and water.

In some embodiments it may further comprise a wetting agent.

Preferably any further components (other than component (a), component (b) and water) are present in an amount of less than 1 wt%, preferably less than 0.1 wt%, more preferably less than 0.01 wt%, for example less than 0.001 wt% or less than 0.0001 wt%.

In preferred embodiments the composition contacted with the soil in the method of the present invention is substantially free of guanidine derived cationic biocide compounds, for example guanidine based compounds, diguanidine based compounds and polymeric guanidine based compounds.

Suitably the composition contacted with the soil comprises less than 1 wt% guanidine derived cationic biocide compounds, preferably less than 0.1 wt%, more preferably less than 0.01 wt%, suitably less than 0.001 wt%, for example less than 0.0001 wt%. The method of the present invention involves contacting soil in which nematode eggs are present with a composition comprising component (a) and optionally component (b). In preferred embodiments the method of the present invention involves contacting the soil with an aqueous composition. Suitably it involves contacting the soil with a dilute aqueous composition. Such a composition may be suitably prepared from a concentrated precursor composition. In some embodiments however the method of the present invention may involve using a solid material comprising components (a) and (b).

In some embodiments the method may involve treating soil before planting. In some embodiments the method may be used to treat soil in which a plant is already growing.

In especially preferred embodiments the method the present invention is carried out on soil in which it is intended potatoes will be grown and/or in which potatoes have been planted and/or are growing.

In some embodiments the method suitably involves treating the general area in which a plant grows or will be grown and allowing the treatment composition to disperse into the soil. In some embodiments the method of the present invention involves contacting the composition with the soil. This may be carried out for example before a crop is planted.

In embodiments in which the composition is contacted to the soil, the skilled person will appreciate that the composition will not remain on the surface and will typically be absorbed into the soil. Thus a suitable treatment level may depend on the nature of the soil on which the plant is growing or will be grown.

In embodiments in which a plant is already growing the composition may suitably be directed to the rhizosphere.

Without wishing to be bound by theory it is believed that treating soil in which nematode eggs are present according to the invention interupts the mechanism by which nematodes are stimulated to hatch. For example in the case of cyst nematodes it is believed that the composition in some way interacts with and/or coats the surface of the cysts and/or eggs. This means that the nematodes do not receive the chemical triggers in the soil which induce them to hatch.

Thus in the example of potato cyst nematodes it is believed that the method of the present invention blocks the mechanism by which juveniles in the cyst sense potato root diffusate (PRD).

Thus the method of the present invention is particularly effective if the composition is contacted with the soil in which nematode eggs are present immediately preceding and/or during the period of potato growth in which PRD levels are highest.

The method the present invention involves inhibiting the hatching of nematodes. Suitably it is not a method of killing nematodes i.e. it is preferably not a nematicidal method. Rather the method of the present invention suitably prevents at least a proportion of nematodes present in eggs in the soil from hatching.

For example the method of the preview suitably reduces the number of nematodes which hatch in the soil by at least 5%, preferably at least 10%, more preferably at least 15% or at least 20%.

PCN may lie dormant in soil for up to 30 years and are suitably stimulated to hatch upon exposure to PRD. PRD is secreted at highest concentrations during initial growth stages. This is when a plant is weak and more vulnerable and thus particularly susceptible to damage by nematodes. However if hatching can be inhibited when PRD levels are highest then the juvenile may not hatch.

Moreover any nematodes which hatch later when a plant is more established will be able to do less damage. Infection by nematodes on more robust root systems will have less impact on plant health and yield due to an increase in surface area for the plant to uptake nutrients as well as a reduced dependency on the root system once the above ground canopy is established. The cyst nematode life cycle lasts for 50 - 100 days. A delay in hatch may prevent the life cycle from completing, particularly when combined with early lifting of tubers. In some embodiments the method of the present invention may involve contacting the soil in which nematode eggs are present with a composition comprising (a) one or more quaternary ammonium compounds and optionally (b) one or more non-ionic surfactants more than once. The method may involve first contacting the soil with the composition comprising components (a) and optionally (b) before a crop is planted in the soil and then contacting the soil for a second time with the composition comprising components (a) and optionally (b) after the crop has been planted. In some embodiments the method may involve contacting the soil for a third time with the composition comprising components (a) and optionally (b). In the case of a potato crop, for example, the method may involve contacting soil with a composition comprising components (a) and optionally (b) immediately prior to planting and then contacting the soil with a composition comprising components (a) and optionally (b) within four weeks of planting. The present inventors have found that treatment according to the present invention can increase potato yield by more than 10%.

According to a second aspect of the present invention there is provided a method of increasing potato yield, the method comprising contacting soil in which potatoes are growing or will be grown with a composition comprising (a) one or more quaternary ammonium compounds.

Preferably the composition used in the method of the second aspect further comprises (b) one or more non-ionic surfactants. Preferred features of the second aspect as defined in relation to the first aspect.

The method of the second aspect suitably increases the yield of potatoes by at least 5%, preferably at least 10%. The method of the second aspect may improve the yield by more than 15%, for example by more than 20%. The invention will now be further described with reference to the following non-limiting examples.

Example 1 G. pallida cysts were extracted from soil from field in which potato crops had been grown at least once in the past 1 to 5 seasons. Potato root diffusate (PRD) was obtained from 3 week old potato plants and diluted to 50% using tap water. After species confirmation via PCR, the efficacy and viability of cysts was checked by a standard hatching assay. Cysts and PRD were stored at 4°C and all experimental incubation steps were at 15°C.

Batches of 25 cysts were soaked in water for 7 days. After 7 days, the cysts were transferred to test solutions for 24 hours. The compositions of the test solutions are detailed in Table 1 . Table 1. Test solutions.

APG is alkyl polyglucoside comprising a mixture of isomers of formula:

where n = 7 or 9 and m = 1 to 5

BAC is a benzyl dimethyl alkyl ammonium chloride wherein alkyl represents a mixture of C ₂ to C ₆ alkyl groups

After 24 hours of contact with test solutions, the cysts were transferred into PRD solution. Cysts were moved to fresh PRD solution and the number of hatched juveniles (J2) from the cysts were counted every week for 6 weeks. After 6 weeks, the cysts were crushed and the number of remaining eggs were counted. The total number of juveniles hatched and the number of remaining juveniles (in eggs) were used to calculate the percentage hatch of juveniles in each sample.

After counting, the unhatched eggs were tested for trehalose to confirm viability. Trehalose is a disaccharide present at high concentration in the perivitelline fluid of PCN eggs, which allows for the desiccation of the nematode while preserving its membrane integrity. The initial event in the hatching process is the Ca ²⁺ mediated change in eggshell membrane permeability which results in the escape of trehalose from the perivitelline fluid through the eggshell within 8hrs of exposure to PRD. This reduces the osmotic pressure on the unhatched J2, allowing its water content and metabolic activity to increase and enabling it to become sufficiently hydrated and metabolically active for continuous movement within the egg. There was no difference in the amount of trehalose found per egg between treated and untreated samples, therefore the treatments did not affect the membrane permeability of the eggs and thus the juveniles within remain viable. Figure 1 shows the total percentage of eggs to have hatched after 6 weeks.

Example 2

The procedure of example 1 was repeated in this case using the compositions detailed in table 2 below:

Table 2. Test solutions.

UN65 is an alcohol ethoxylate comprising a mixture of isomers of formula CH ₃ (CH ₂ )nO[CH ₂ CH ₂ 0] _m H where n = 9 or 1 1 and m = 4 to 8 Figure 2 shows the total percentage of eggs to have hatched after 6 weeks.

Figure 3 shows the cumulative total number of juveniles hatching over 6 weeks.

Example 3

In a field trial potatoes were treated according to the method of the present invention. An aqueous composition comprising 750 ppm of BAC, 600 ppm of APG and 300 ppm of UN65 was applied to a tonne bag of soil in which potatoes were grown. BAC, APG and UN65 are as defined in examples 1 and 2.

The composition according to the invention was applied to the soil on incorporation, on planting, two weeks after planting and four weeks after planting.

In a control tonne bag untreated potatoes were grown and in a comparative test potatoes were grown in soil that was treated once on incorporation with the commercially available nematicide Nemathorin at the maximum recommended dose of 30kg/ha. Nemathorin (RTM) is one of the current market leading products and contains fosthiazate as the active ingredient. However it has to be applied at least 17 weeks prior to harvest due to minimum residue levels and is classified as harmful and dangerous to the enivronment. It cannot be applied once seed has been planted. The results in table 3 show that treatment according to the method of the present invention provided a significant increase in yield, with a performance comparable to a current leading product but without the associated disadvantages.

Table 3

Example 4 For experimental assays, batches of 25 cysts of Globodera pallida nematodes were placed in hatching baskets and soaked in 1 .5ml water for 7 days in 24-well plates at 15°C. After 7 days, baskets were transferred to new plates and 1 .5mls of each test solution was added. Plates were incubated for 24hrs at 15°C. After the 24hr treatment, baskets were removed to new plates and 1 .5ml of PRD diluted 1 :1 with water was added. Every 7 days, the baskets were transferred to fresh PRD and the number of juveniles hatching from each batch of cysts were counted. After 8 weeks, the cysts were removed from baskets, crushed gently in water and the remaining eggs and juveniles were counted. The percentage hatch of juveniles in each sample was calculated using the following equation: % hatch = No. hatched juveniles x 100

No. hatched juveniles + remaining eggs

The % hatch of juveniles in each population was determined to predict the likely percentage hatch in juveniles in the control group of experimental assays. Hatching assays are commonly used as a marker of viability as they mimic the exposure of encysted nematodes to the hatching factors released by the roots of growing host plants. Although hatching assays underestimate the viability of nematodes as they do not include juveniles in dormant stages, they are indicative of the number/percentage that would hatch if in contact with a growing host plant. Therefore, they are a good predictor for the severity of infection that would occur in the field and are an effective method to compare treatments that are intended to affect hatching of nematodes.

The test solutions used and the results obtained are detailed in table 4: Table 4

BAC, APG and UN65 are as defined in examples 1 and 2. The results are also shown in Figure 4. Example 5

The procedure of example 4 was repeated using the test solutions detailed in table 5 on two different populations of Globodera pallida juveniles.

Table 5

The results are also illustrated in Figure 5.

Example 6

A composition comprising 0.03wt% BAC, 0.024wt% APG and 0.012wt% UN65 was used as a test solution in the method of example 4. The method was repeated but modified to include a single rinsing step, 3 rinsing steps and 6 rinsing steps following the 24 hour treatment with the test solution.

In a further experiment the cysts were continuously contacted with the test solution for 8 weeks.

The above experiments were carried out on two different populations of Globodera pallida nematodes.

The results are shown in figure 6.