IE902201L - Inhibition of potato sprouting - Google Patents

Abstract

The invention relates to the use of carbetamide to inhibit the sprouting of potatoes, for example during storage. [CA2019518A1]

Description

IE 902201 - A- INHIBITION OF POTATO SPROUTING This invention relates to the,control and inhibition of sprouting of potatoes and more particularly to the chemical inhibition of such sprouting by the application of 5 carbetamide.

Carbetamide is the compound of the formula: C6H5-NH-COO-CH(CH3)-CO-NH-C2H5 It is otherwise known as D-N-ethyl-lactamide phenylcarbamate or N-phenyl-1-(ethylcarbamoyl)ethylcarbamate 10 (D-isomer).

Potatoes (Solanum tuberosum^, can be subjected to extended periods of storage between harvesting and consumption. During such periods the harvested crop tends to « A sprout. Such sprouting results in a degree of spoilage, 15 which it is desirable to avoid. A number of chemical agents are known which will inhibit such sprouting (e.g. chlorpropham, propham, tecnazene) but all suffer from various disadvantages. We have now found that carbetamide is an effective sprouting inhibitor (which in turn reduces moisture 2 0 loss and maintains turgidity), which possesses several advantages over the currently used materials. In addition to the inhibition of sprouting during storage it has also been discovered that carbetamide can be used to delay sprouting of seed potatoes before planting, release occurring when p.iSTE ftPPELE " — o c pTFt-i prrtj ** IE 902201 planting has taken place.

The inhibition of sprouting refers to a reduction in the number of sprouts per tuber and/or a reduction in the mean sprout length. 5 The present invention accordingly provides a method for inhibiting the sprouting of potatoes, which comprises applying thereto an amount of carbetamide sufficient to inhibit the sprouting thereof. The carbetamide may be applied, for example, prior to or during storage to inhibit 10 the sprouting of stored potatoes, Carbetamide is preferably applied at or after the normal curing period after lifting the crop prior to storage. The tubers should preferably not be washed prior to treatment (although washing in water at carefully controlled temperatures is feasible). 15 ^ Carbetamide is a known selective herbicide which has been widely used in the cultivation of forage, domestic, and seed brassicae and legumes and a wide variety of other crops. It is also used for weed control in fallow lands, orchards, vineyards and nurseries. 20 Carbetamide also shows plant growth regulatory activity and can be used as an effective sucker inhibitor in tobacco plants where it blocks or inhibits the growth of axillary buds by modifying meristeraatic activity. However the present mode of action is different as all sprouting is 25 inhibited in an already harvested crop, whereas in tobacco the main action is the selective inhibition of the growth of particular (i.e. non-terminal) buds in the still-growing P T tr t | Drn I IE 902201 - 3 - plant.

The method of the present invention for treatment of potatoes can employ any of the Known compositions of carbetamide. Suitable compositions for use in the method of 5 the invention comprise carbetamide in association with a diluent or carrier. These compositions can be prepared in the form of e.g. wettable powders, powders for dusting, solutions, emulsifiable concentrates, emulsions, suspension concentrates and aerosols and generally comprise from 1 to 10 95% by weight of active material; other ingredients which may be present include surfactants and other acceptable adjuvants such as absorbents, binders, penetration agents, stabilisers and other active materials, for example fungicides and insecticides. The term "carrier" denotes an organic or 15 inorganic, natural or synthetic material with which the carbetamide is combined in order to facilitate its application, transport, handling or adherence to the potato. The carrier can be solid (e.g. a clay or a natural or synthetic silicate) or fluid (e.g. water or organic solvents 20 including ketones vuch as acetone, acetophenone, and cyclic ketones such as cyclohexanone; dimethylformamide; lower alkanols, such as methanol or denatured ethanol; chlorinated hydrocarbons, such as methylene chloride; aromatic solvents, such as toluene and xylene; and petroleum fractions). 25 Preferred solid carriers are water soluble and of food grade, e.g. polyvinyl alcohol (PVA) and sugar-based products.

The surfactant can be an emulsifying, dispersing or - 4 - wetting agent and can be ionic or non-ionic. Suitable emulsifiers include the commonly used cationic, anionic, non-ionic or zwitterionic materials such as, for example, the salts of polyacrylic acids, ligno-sulphonic acids, and 5 condensates of ethylene oxide with fatty alcohols, acids and amines.

Other adjuvants which may be included in the composition for simultaneous application are fungicides and insecticides. Examples of fungicides which may be applied 10 with carbetamide are imazalil and iprodione.

It is preferred to apply carbetamide as a dispersion in or on liquid or solid media typically at concentrations of 0.01 to 80%, e.g. 0,5 to 50%, by weight.

Carbetamide is soluble in water to the extent of 15 about *3.5g/litre. In liquid media the carbetamide is therefore preferably applied in the form of an emulsified dispersion in water via the emulsification of a concentrated solution in a suitable solvent. Carbetamide can also be applied as an aqueous suspension formed from a wettable 20 powder. The solvents, active agent and surfactants are prepared in the form of emulsifiable concentrates which are then diluted with water, before application, to the appropriate concentration. Liquid concentrate compositions are preferred for the preparation of dispersions for spray 25 application. However, such concentrates may be modified for dispersion application via aerosols, mists, or fogs. Such modification techniques are well known. 1,02306 31 IE 902201 The liquid formulations of carbetamide may be applied by hand methods such as hand spraying, sprinkling cans, dipping etc. but in large scale operations conventional apparatus (e.g. roller table mounted equipment) may be used, 5 Liquids may also be distributed by foggers.

Carbetamide is preferably applied by spraying of an aqueous dispersion or suspension of a wettable powder. This is conveniently carried out using roller table mounted equipment for the potatoes: it is important to ensure 10 complete coverage in particular of the eyes of the tuber.

Carbetamide may also be applied in solid form, i.e. via wettable powders, dusts or granules. These are applied by dusting or dispersing the solids, in requisite amounts, onto the stored crop to be treated, for example by powder 15 granule dispersers. Wettable powders or granules are preferred for application of solid agents.

The concentrated compositions, liquid, solid or semisolid, are diluted before application to ensure uniform distribution. The degree of dilution required depends upon 20 the mode of application. When carbetamide is sprayed in liquid form via an aqueous dispersion or suspension, the concentration level of active ingredient may range from 0.01 to 80%, e.g. 4.5 to 50%, by weight.

Wettable powders comprising about 65% by weight of 25 carbetamide are preferred,, as are solutions of carbetamide comprising 100 to 300g/l of carbetamide.

Solid compositions are used to give about the same n t _ o - D t cn prrn IE 902201 — 6 — concentration of active ingredient as are the liquid compositions.

As stated above, carbetamide is compatible with other active substances, such as fungicides and insecticides, and 5 it can therefore be applied to the stored crops in combination therewith. Such application may be separate, sequential or simultaneous.

The amount of carbetamide applied is generally from 17 to 200 g.a.i.(active ingredient)/tonne of potatoes. 10 In the temporary Inhibition of sprouting in seed potatoes after planting from 17 to 50 g.a.i./tonne is preferably used. It is believed that the carbetamide is subject to degradation in the soil: the greater the amount of carbetamide used the longer the delay in sprouting. 15 * In the inhibition of sprouting in stored potatoes from 17 to 200 g.a.i./tonne is preferably used, most preferably from 30 to 70 g.a.i,/tonne.

In general the lower the temperature the lower the amount of carbetamide required to inhibit sprouting. The 20 amount of carbetamide required may also vary depending on the variety of potato, some varieties being more prone to sprouting than others.

By way of example, the following compositions may be used in the method according to the present invention. c< r.c T C uPPC' c * 4- -Mr — 4- 4- — 4- 4- t? r r r i o c r I i a © IE 902201 ✓ 7 - Wettable powders (percentage by weight) carbetamide 70 50 nonylphenol oxyethyl-17 (wetting agent) 2 2 polycarboxylate (dispersing agent) 2 2 silica (carrier) 26 25 calcium carbonate (carrier) 0 21 Emulsifiable concentrate carbetamide 300 g acetophenone (carrier) 180 g nonylphenol oxyethyl-7 (wetting agent) 200 g cyclohexanone (carrier) qs 1000 cc Carbetamide has an acute in rats of 11,000 mg/kg animal body weight and is practically devoid of chronic toxicity. Topical applications in the rabbit eye (5 mg) and to rabbit skin (5% cream) also indicate absence of irritant effects.

Thus, carbetamide is less toxic or irritant to mammalian species than the previously used sprouting inhibitors arid is safer for use by unskilled workers. Furthermore, in the absence of significant toxicity, residues on the tubers provide a significantly lower IE 902201 health and environmental hazard to processors and ultimate consumers.

Carbetamide also produces less taint in the treated tubers, rendering them more acceptable for consumption. 5 Furthermore, carbetamide is much less volatile than the sprouting inhibitors at present in use. This therefore allows selectivity of treatment and prevents cross-contamination as the area of effect of a treatment will not spread. There is therefore no need to segregate treated 10 tubers from untreated tubers or other stored crops, or to use complex isolation procedures during treatment, as is required with presently used inhibitors. The very low volatility also avoids any vapour exposure risk to operatives in potato stores. 15 ^ Treatment according to the invention also results in no greater weight losses than in conventional treatments.

The following Example illustrates the use of carbetamide according to the present invention.

EXAMPLE 20 Four varieties of potato were treated with varying amounts of a wettable powder containing 65% w/w of carbetamide. The level of sprouting inhibition was determined by comparison with untreated potatoes after storage for three months. The results were as follows: t£ 902201 - 9 - Potato Application rate of Inhibition (%) at variety composition (g/tonne) 3 months 5 months Sguire 50 69 99 100 96 99 150 99 99 300 99 99 Romano 50 * 75 100 * 93 150 * 96 300 * 97 . Desiree 50 71 98 100 97 98 150 99 99 300 100 99 Cara 50 68 87 100 98 98 150 100 99 300 100 99 * Late sprouting variety IE 902201 - 10 ~ In comparative experiments a similar test was carried out except that treatment was with BYGRAN s (a commercial composition based on tecnazene) at a rate of 1300g/tonne. The results were as follows: Potato variety Inhibition (%) at 3 months 5 months Squire 78 92 Romano * 75 Desiree 93 83 Cara 85 82 Weight losses of the potatoes subjected to the various treatments were also measured and compared with those resulting from conventional treatment and for the untreated controls. Average values for all varieties of potatoes tested are as follows: IE 902201 11 - Treatment Weight loss (%) at 3 months 5 months None (control) 1.8 3.3 Carbetamide SOg/tonne 1.4 2.8 lOOg/tonne 1.5 2.8 M 150g/tonne 1.3 2.2 tr 300g/tonne 1.5 2.3 Bygran S 1300g/tonne 1.9 3.5 "

Claims (12)

IE 902201 / - 12 -CLAIMS

1. A method for inhibiting the sprouting of potatoes which method comprises applying thereto an amount of carbetamide sufficient to inhibit sprouting. 5

2. A method according to claim 1 in which the carbetamide is applied prior to or during storage to inhibit sprouting during storage.

3. A method according to claim l or 2 in which the carbetamide is applied after a curing period following 10 lifting of the potatoes.

4. A method according to claim l, 2 or 3 in which the potatoes are not washed prior to applying the carbetamide.

5. A method according to any one of the preceding claims in which the amount of carbetamide is 17 to 200 g /tonne of 15 potatoes.

6. A method according to claim 5 in which the amount of carbetamide is 30 to 70 g /tonne of potatoes.

7. A method according to any one of the preceding claims in which the carbetamide is applied by spraying of an aqueous 20 dispersion or suspension of carbetamide.

8. A method according to claim l in which the carbetamide is applied to potatoes prior to planting in order to delay sprouting.

9. A method according to claim 1 or 8 in which the 25 amount of carbetamide is i7 to 50 g /tonne of potatoes. -■ -r rr 1DDCI IT C' T r ' ! OCT I 1 A 1 c 9°2201 - 13 -

10. A composition which comprises carbetamide and an acceptable diluent or carrier for use in the inhibition of the sprouting of potatoes.

11. A method according to claim 1 for inhibiting the sprouting of potatoes, substantially as hereinbefore described and exemplified.

12. A composition according to claim 10, substantially as hereinbefore described. Dated this the 18th day of June, 1990 F. R. K^LLY & TO. BY: EXECUTIVE 27 Clyde Road, Ballsbridge, Dublin 4 AGENTS FOR THE APPLICANTS