BACKGROUND OF THE INVENTION

This invention relates to a method of preserving one or more cut flowers with the use of a sulphur dioxide (SO2) generating device. The method further relates to an SO2 generating device for the preservation of one or more cut flowers. The device may be in the form of a strip for attachment to a flower sleeve or in the form of an article of any shape for placement inter-bunch and above the flower heads.

The cut flower industry is a fast-growing, global industry, which in recent years has shown a global trade volume of over US$100 billion.

The loss of flowers susceptible to fungal infection, including Botrytis has resulted in millions of lost revenue by flower sellers.

Present methods for preservation of flowers include dipping of the flower heads in antimicrobial solution such as commercial bleach, followed by drying, or treatment of the water holding the flower stems with a solution comprising various components including bleach, sugar, various antifungal chemicals and the like.

However, there is currently no product that actively prevents Botrytis growth on flower heads during the retail phase or during so-called "wet" transport in buckets. The "dipping" technique is only applied prior to transport and has a limited period of efficacy, and sulphur dioxide based products and potassium permanganate based products have only been applied successfully in enclosed cartons during dry transport, also limiting the period of efficacy.

A device for effective preservation of the flower heads of cut flowers for use during wet transport and during the retail phase while the flowers are displayed in buckets that extends their shelf life would therefore be greatly beneficial.

SUMMARY OF THE INVENTION

According to a first embodiment of the invention, there is provided a method of preserving one or more cut flowers with the use of a sulphur dioxide (SO2) generating device. The device may be in the form of a strip for attachment to an end of a flower sleeve or in the form of an article of any shape for placement within the bunch and above the flower heads.

The method may comprise the steps of:

(i) providing one or more cut flowers;

(ii) providing a flower sleeve having a SO2 generating strip affixed at one end for wrapping the one or more cut flowers and wrapping the flower sleeve around the cut flowers, such that the end to which the SO2 generating strip is affixed is adjacent to, but not in direct contact with, one or more flower heads of the cut flowers contained within the flower sleeve; and/or

(iii) positioning an SO2 generating article of any shape within the cut flowers and above the one or more flower heads, such that the article is above, but not in direct contact with, the flower heads of the cut flowers.

Typically, the article may be positioned above the flowers by affixing the article to an end of an elongate member, whereby the length of the elongate member is positioned within the cut flowers and the affixed article is held above the cut flower heads on the end of the elongate member. The article may be affixed to the elongate member by either an adhesive means or a mechanical means. For example, the article may be affixed to the elongate member by means of glue, a clasp mechanism or staples. For example, the elongate member may be a floral cardholder or similar device.

Typically, the SO2 generating strip is affixed to an inner face of the flower sleeve end adjacent to, but not in direct contact with the one or more flower heads. The SO2 generating strip may be affixed to the sleeve by either an adhesive means or a mechanical means. For example, the SO2 generating strip may be affixed to the sleeve by means of glue or staples.

The method of preservation may comprise inhibition of growth of a microbial organism. For example, the microbial organism may be a fungal organism such as Botrytis.

According to a further embodiment of the invention, there is provided a SO2 generating strip for attachment to a flower sleeve or an SO2 generating article for affixing to an elongate member, such as a floral cardholder, for positioning together or within one or more cut flowers, the strip or article comprising a substance which in the presence of moisture generates SO2. Such a substance is well known to those in the art and may be sodium metabisulphate, an acidic mixture comprising sodium metabisulphate and fumaric acid, an acidic mixture comprising sodium sulphite and potassium bitartrate, or a mixture of both of the acidic mixtures.

The SO2 generating strip may have a width such that when affixed to a flower sleeve containing one or more cut flowers it extends from the end of the flower sleeve to the top of one or more flower heads of the cut flowers contained in the flower sleeve such that the SO2 generating strip is not in direct contact with the one or more flower heads. Typically, the width of the SO2 generating strip is about 22 mm. However, it is to be appreciated that the width of the strip may vary depending on the length of the flower sleeve and the depth of placement of the one or more cut flowers in the flower sleeve when in use. Typically, the total area of the SO2 generating article is about 50 mm ² , but the total area may vary from less than this to about two or three times this area. It is to be appreciated that the shape and dimentions of the SO2 generating article may vary depending on a number of factors, including but not limited to: the concentration of SO2 comprised in the SO2 generating article, the surface area of the cut flower heads required to be treated or the number of cut flowers, aesthetic considerations of the user, type or variety of flower(s) used within the bunch, amount of foliage present in the bunch in relation to the amount of flowers/petals, and temperature of the bunch during transport, storage and/or display. Such factors would be a matter of routine experimentation to determine.

According to a further embodiment of the invention, there is provided a composite SO2 generating device for use in the preservation of one or more cut flowers, which may be in the form of:

(i) a flower sleeve comprising a SO2 generating strip at one end, or

(ii) a holder comprising an elongate member, such as a flowercard holder, having a SO2 generating article of any shape affixed at one end, or integrally formed on one end of the elongate member.

Typically, the flower sleeve comprises a SO2 generating strip affixed to an inner face of the flower sleeve end which in use is adjacent to, but not in direct contact with, one or more flower heads of one or more cut flowers contained within the sleeve. The SO2 generating strip may be affixed to the sleeve by either an adhesive means or a mechanical means. For example, the SO2 generating strip may be affixed to the sleeve by means of glue or staples. Alternatively, the SO2 generating strip may be integrally formed with the flower sleeve.

Typically, the holder is positioned such that the length of the elongate member is within the cut flowers and the SO2 generating article is held above the cut flower heads when in use. The article may be affixed to the elongate member by either an adhesive means or a mechanical means. For example, the article may be affixed to the elongate member by means of glue, a clasp mechanism or staples. Alternatively, the SO2 generating article may be integrally formed on the end of the elongate member. The cut flowers may be any cut flower that is susceptible to Botrytis infection. Preferably, the cut flowers may be selected from the group consisting of roses, chrysanthemums or gerberas.

BRIEF DESCRIPTION OF THE DRAWINGS

(A) shows a representative illustration of a side view of a flower sleeve containing a bunch of flowers with a SO2 generating strip of the invention at the top end of the flower sleeve, and (B) shows a representative illustration of a bunch of flowers into which a holder comprising an SO2 generating article of the invention has been positioned; shows the scores for development of Botrytis infection over time on different varieties of treated and control roses; shows the average Botrytis infection scores for treated versus control roses; shows Botrytis infection scores for eight different rose cultivars over time; and

Figure 5 shows the average Botrytis infection scores for eight different rose cultivars over the total period of monitoring.

DETAILED DESCRIPTION OF THE INVENTION

The current invention provides a method of preserving one or more cut flowers with the use of a sulphur dioxide (SO2) generating device. The method further relates to an SO2 generating device for the preservation of one or more cut flowers. The device may be in the form of a strip for attachment to a flower sleeve or in the form of an article of any shape for placement inter-bunch and above the flower heads. There is presently no means of preserving the flower head of cut flowers during wet transport in buckets, or during the retail phase when the flowers are displayed in a store. As a result, fungal infection, in particular Botrytis infection, can set in during this period, resulting in damage to the flower head and the flower or even entire flower bunch must then be discarded resulting in a financial loss to the retailer.

The applicant sought to develop a method that could be used to preserve cut flowers from microbial growth, in particular fungal infection, such as Botrytis in a flower bunch, either within a flower sleeve or not, for use either during wet transport in a bucket or during display in a store. The applicant determined that surprisingly, it was possible to preserve the flower heads of the cut flowers with the use of a sulphur dioxide (SO2) generating device, either in the form of an SO2 generating strip affixed to the top end of a sleeve containing the cut flowers, or with the use of a SO2 generating article positioned above the flower heads by means of an elongate member, or by the use of both the strip and the article.

The use of the strip comprises the steps of firstly producing or providing a flower sleeve, such as a paper or plastic flower sleeve used by commercial flower sellers for wrapping one or more cut flowers, in particular those susceptible to fungal infection, such as Botrytis infection, including roses, chrysanthemums, gerberas or the like, the flower sleeve (10) comprising a SO2 generating strip at one end (20).

The SO2 generating strip (20) is typically affixed to an inner face of the flower sleeve end adjacent to, but not in direct contact with the one or more flower heads (30). The SO2 generating strip may be affixed to the sleeve by either an adhesive means or a mechanical means. For example, the SO2 generating strip (20) may be affixed to the sleeve (10) by means of glue or staples, or other means known to those skilled in the art. Alternatively, the strip may be integrally formed with the flower sleeve.

Next, one or more cut flowers are wrapped in the flower sleeve, according to standard practice. When wrapping the cut flowers, the flower sleeve is positioned such that the SO2 generating strip (20) is in close proximity or adjacent to the one or more flower heads (30) of one or more cut flowers contained within the flower sleeve but opposed to the flower stems and leaves (40). The SO2 generating strip (20) must not be in direct contact with the flower heads (30).

In practice, the method of wrapping one or more cut flowers in a flower sleeve results in a generally conical flower sleeve with the narrow end of the cone enclosing the base of the flower stem(s) which extend from the bottom of the sleeve and are placed in water with or without a flower treatment solution. The opposed open top end of the flower sleeve encloses but is not in contact with the flower head(s). A representative illustration of one embodiment of the flower sleeve of the invention, with the SO2 generating strip (20) and containing a bunch of roses is shown in Figure 1A. Accordingly, when affixed to the open top end of the flower sleeve, the SO2 generating strip is inherently not in direct contact with the flower head(s). There may optionally be a space provided between the top of the flower head(s) (30) and the end of the SO2 generating strip (20) when viewed from the side.

The use of the SO2 generating article (50) comprises the steps of producing or providing a holder (60) comprising the SO2 generating article (50) affixed one end of an elongate member (70), such as a floral cardholder and placing the length of the elongate member (70) of the holder (60) adjacent or within one or more cut flower stems (80) such that the SO2 generating article (50) is above and not in contact with the flower heads (90) of the one or more cut flowers. Typically, the SO2 generating article is positioned substantially centrally in the cut flower bunch.

The SO2 generating article or strip may be printed on, embellished or decorated and may be any colour desired by the user. The SO2 generating article may further be any shape or dimention desired by the user.

It is possible to use both the sleeve comprising the SO2 generating strip and the holder comprising the SO2 generating article with the cut flowers at the same time if desired.

The SO2 generating strip or article of the invention typically comprises a substance which in the presence of moisture generates SO2. Such a substance is well known to those in the art and may be sodium metabisulphate, an acidic mixture comprising sodium metabisulphate and fumaric acid, an acidic mixture comprising sodium sulphite and potassium bitartrate, or a mixture of both of the acidic mixtures.

SO2 generating strips or articles can be processed by cutting SO2 generating sheets known to those skilled in the art to the desired shape and dimentions. Any cutting technique known to those skilled in the art that utilizes a sharp blade and does not produce frayed edges, product delamination, crystallization, melting, activation, discolouration or contamination as an effect during or after the process may be used. Although any SO2 generating sheet which in the presence of moisture generates SO2, may be used, but sheets produced as disclosed in the published patents ZA8900691 , ZA9507170 and US 7,045, 182 are preferably used for generation of the SO2 generating strips or articles of the invention.

The SO2 generating strip may have a width such that when affixed to a flower sleeve containing one or more cut flowers it extends from the end of the flower sleeve to the top or near the top of one or more flower heads of the cut flowers contained in the flower sleeve. There may optionally be a space provided between the top of the flower head(s) (30) and the SO2 generating strip (20). Of importance, is that the SO2 generating strip (20) is not in direct contact with the one or more flower heads (30). Typically, the width of the SO2 generating strip is about 22 mm. However, it is to be appreciated that the width of the strip may vary depending on the length of the flower sleeve and the depth of placement of the one or more cut flowers in the flower sleeve when in use.

Furthermore, the SO2 generating strip may have any length. For example, it may be the length or near length of the open top end of a flower sleeve and provided as multiple strips to producers of flower sleeves or flower sellers using flower sleeves for affixing one strip each to the top of a sleeve. Alternatively, it may be provided as a role of a length suitable for cutting into a plurality of strips, each strip once cut, having the length or near the length of one end of a flower sleeve.

Typically, the total area of the SO2 generating article is about 50 mm ² , but the total area may vary from less than this to about two or three times this area. It is to be appreciated that the shape and dimentions of the SO2 generating article may vary depending on a number of factors, including but not limited to: the concentration of SO2 comprised in the SO2 generating article, the surface area of the cut flower heads required to be treated or the number of cut flowers, aesthetic considerations of the user, type or variety of flower(s) used within the bunch, amount of foliage present in the bunch in relation to the amount of flowers/petals, and temperature of the bunch during transport, storage and/or display. Such factors would be a matter of routine experimentation to determine.

Although the production of the flower sleeve of the invention may comprise a step of attaching the SO2 generating strip to the flower sleeve by adhesive or mechanical means after making or obtaining the flower sleeve, the SO2 generating strip may also be integrally formed with the flower sleeve during the manufacturing process of the sleeve. Similarly, the production of the holder may comprise a step of attaching the SO2 generating article to an end of the elongate member by adhesive or mechanical means after making or obtaining the elongate member, for example by gluing, stapling or a clasp mechanism, the SO2 generating article may also be integrally formed with the end of the elongate member of the holder.

The invention will be described by way of the following examples which are not to be construed as limiting in any way the scope of the invention.

EXAMPLES

Example 1 : Manufacture of the SO2 generating strip

SO2 generating strips were processed by cutting SO2 generating sheets to the desired strip width and length by means of a sharp blade. Manufacture of the SO2 generating sheets does not form part of this invention, and any SO2 generating sheet which in the presence of moisture generates SO2, may be processed to an SO2 generating strip of the invention. In this example, sheets produced as disclosed in the published patents ZA8900691 , ZA9507170 and US 7,045, 182 were processed into SO2 generating stips of the invention. Example 2: Manufacture of plastic flower sleeves comprising a SO2 generating strip

Standard commercial plastic flower sleeves were used for manufacture of the SO2 generating plastic sleeves. Plastic flower sleeves are typically wrapped around flower bunches to form a generally cone-shaped sleeve enclosing the flower bunch, with the base of the cone-shaped sleeve having the narrowest diameter being wrapped around the base of the cut flower stems, and the diameter of the sleeve then broadening with the top of the cone-shaped sleeve having the broadest diameter adjacent to or slightly above the flower heads.

In this experiment, a SO2 generating strip of about 20 mm in width was affixed to or near the top of each plastic sleeve such that it was in close proximity to the flower heads, but not in direct contact with the flower heads.

Furthermore, the SO2 generating strip was affixed to run the entire length or near the entire length of the top opening of the flower sleeve. However, the width of the strip and position of the strip in the sleeve may be selected dependent on the length of the flower sleeve and the depth of placement of the flowers in the sleeve, with the proviso that the SO2 generating strip must be in close proximity to the flower heads but not the stems or leaves of the cut flowers. This is because the leaves and stems have a much higher count of stomata than flower heads and respire at a much higher rate due to the presence of photosynthesizing tissues and therefore are more at risk from SO2 burn and /or bleach than flower petals.

The SO2 generating strips were simply stapeled to the inner surface of the plastic sleeve for enclosing a flower bunch. However, the SO2 generating strips may be affixed by any suitable means known to those skilled in the art, including by an adhesive means such as glue. Example 3: Rose Flower Trial

1. Objective

The objective of the trial was to test the performance of a SO2 generating strip affixed to a flower sleeve containing commercially grown and packaged cut flowers for use as an active control mechanism against Botrytis cinerea on rose (Rosa sp.).

2. Materials and Methods

Export quality roses from the northern region of South Africa (North West Province) were used in the trial. Eight different rose varieties were tested: Coolwater, Mantra, Tropical Amazon, Bibi, Red One, Bella Rose, Avalanche and Vandela. The flowers were grown under greenhouse conditions, harvested, handled and packed as for export and sent to the Cape Town depot of a large commercial rose supplier in South Africa.

The roses were packed dry in standard rose cartons. Each carton contained 8 varieties with 3 bunches of 10 stems per variety packed to bring the final total to 240 stems. The buds of each bunch were protected by a sleeve of corrugated carton to limit mechanical damage.

After arrival at the commercial flower supplier in Cape Town, the cartons were transported intact to a cold room at the testing facility where the cartons were stored for a further 24 hours at 4°C. This was done to simulate a total period of cooled in- box transport of 72 hours.

The roses were removed after this period of simulated export and placed in 10L buckets containing 3L of water for 72 hours to mimic the three days normally spent under supermarket conditions. Specifically, the corrugated sleeves surrounding each bunch of each variety of roses were removed and replaced with either a plastic flower sleeve alone, or a plastic flower sleeve to which the SO2 generating strip was affixed at or near the top of the sleeve. Accordingly, each variety was tested either with or without a SO2 generating sleeve.

Stems were shortened by cutting off 2 cm from the base of the stem as is normal practice before placing the sleeve-enclosed flower bunches in the buckets containing water. The water was treated with 1 ml per liter of a commercial rose solution (specifically, Chrysal RVB and a Chrysal T-bag for use in 3 liter of water). The buckets containing the flower sleeves with the SO2 generating strips were stored at room temperature (20 °C) with a relative humidity of 70%.

Following the simulated in-store period, the cut flower bunches had their sleeves and rubber bands removed and each bunch of 10 stems were placed in a separate vase for 7 days to simulate the display of roses in the home environment. The water in the vases contained a standard commercially available cut flower solution for roses.

The different test and control rose varieties were evaluated on five separate occasions, firstly on the last day of simulated in-store storage (i.e. day 3 post transport phase), then on the first, third, fifth and seventh day of the simulated home- display period (i.e. days 4, 6, 8 and 10 post transport phase. The flower heads were evaluated for any signs of damage, including signs of Botrytis, bruising and SO2 burn.

Flowers were not artificially inoculated with Botrytis, but the trial was conducted during a period of the year when weather conditions were suitable for the development of Botrytis. The 8 varieties of rose used were cultivars known to be more sensitive to Botrytis.

Flowers were inspected for signs of Botrytis and these included spots of infection, petals with brown or tan blotches indicating a spreading infection as well as well- established infections where the entire flower head wilts, turns brown and in some cases detaches from the flower stem.

Flower damage was scored from 1 to 3 according to typical practice, where a score of 1 indicates that damage is present, but a non-trained eye will not detect it, a score of 2 indicates that the damage is visible to most people, but does not detract from the overall appearance of the bunch and a score of 3 indicates that the damage is of such severity that the flower step needs to be removed from the bunch. Accordingly, each bunch of 10 stems is given a total score based on the level of damage present in each stem.

3. Results and Discussion

A significant difference was visible over time between SO2 treated roses compared with control roses (see Fig. 2). The delay in development of Botrytis infection was expected, since the Botrytis infection would have spread slowly over the course of three days at 4 °C and there was therefore no significant difference between the treatment and control at the end of the simulated in-store period. However, at day 10, the difference was significant and the score of the control roses was almost twice that of the treated roses, taking into account that the higher the score, the greater the effect of Botrytis development.

Treatment of roses with the SO2 generating strip resulted in significantly improved control of Botrytis infection compared with control roses when determined over the whole period of testing as shown in Fig. 3. Significant differences in the Botrytis infection score were also identified between cultivars over time (Figs. 4 and 5) with some cultivars being much more sensitive to Botrytis than others.

On average Coolwater and Mantra were found to be very sensitive to Botrytis infection during the trial whereas Tropical Amazon, Bibi and Red One performed better on average than the other varieties.

In conclusion, the SO2 treatment method was effective in controlling Botrytis infection in a number of rose cultivars. This effect was particularly visually noticeable in each treated bunch of roses towards the end of home-display vase life compared with untreated control roses.