PT94500A - METHOD FOR INHIBITING POTATO GERMINATION USING CARBETAMIDE - Google Patents

Description

/ RHÔNE-POULENC AGRICULTURE LTD. " METHOD FOR INHIBITING POTATO GERMINATION USING CARBETAMIDE " The present invention relates to the control and inhibition of the germination of tuberous plants and more especially to the chemical inhibition of such germination by the application of carbe-tamida. Carbetamide is a compound of the formula known as D-N-ethyl-lactamide-phenylcarbamate or N-phenyl-1- (ethylcarbamoyl) ethylcarbamate (D-isomer).

Potatoes (solanum tuberosum) can be stored for prolonged periods from harvest to consumption. During these periods the tuber tends to germinate which causes a certain deterioration to be avoided. Various chemical agents capable of inhibiting germination are known in such circumstances (for example, chlorpropham, profam, tecnaze-ne) which however have some drawbacks. Carbetamide has recently been found to be an effective inhibitor of germination, which has some advantages over

currently used.

Accordingly the present invention provides a method which enables the inhibition of potato germination during storage which consists in applying to the tubers, before or during storage, a quantity of carbetamide sufficient to inhibit its germination. Carbetamide is a known selective herbicide that has been widely used in fodder crops and in the cultivation of brassicaceae and legumes and in a wide variety of other crops. It is also used to control weeds in fallow land, orchards, vineyards and nurseries. Carbetamide also exhibits plant growth regulating action and can be used as an effective inhibitor of the appearance of new branches in tobacco plants because it blocks or inhibits the growth of axillary buds by modifying meristematic activity. However, the mode of action according to the present invention is different because it inhibits all germination in a plant already harvested, whereas in tobacco the main action consists in the selective inhibition of the growth of special, ie non-terminal, buds in the plant still in development . The method according to the present invention for the treatment of potatoes may use any of the known compositions of carbetamide. These known compositions may be in the form of wettable powders, loose powder feet, solutions, emulsifiable concentrates, emulsions, concentrates for suspensions and aerosols, and generally comprise 1 to 95% by weight , of active material and the balance weight in the form of carriers, surfactants and other acceptable adjuvants such as adsorptive agents, binding agents, penetrating agents, stabilizing agents and other active materials. The term " vehicle " means an organic or inorganic material, natural or synthetic, as the carbobenzamide is associated in order to facilitate application, transport or handling. The carrier may be solid (e.g., a clay or a natural or synthetic silicate) or liquid (e.g., water or organic solvents including ketones such as acetone and 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). The surfactant may be a blowing agent, a dispersing agent or a wetting agent and may be ionic or nonionic. Suitable emulsifying agents include commonly used cationic, anionic, nonionic or amphoteric materials such as, for example, salts of polyacrylic acids, lignosulfonic acids and condensates of ethylene oxide with fatty alcohols, fatty acids and fatty amines.

Other adjuvants which may be included in such compositions for simultaneous application are fungicidal and insecticidal. Examples of fungicides that can be applied with the carbobetamide are imazalil and iprodione. It is preferable to apply the carbetamide as a dispersion in a liquid or solid medium typically in concentrations of 0.5 to 50% by weight. Carbetamide is water soluble at a ratio of about 3.5 g / liter. Accordingly, it is preferred to apply the carbetamide, when in liquid medium, as a dispersion emulsified in water via the emulsification of a concentrated solution in an appropriate solvent. The solvents, the active agent and the surfactants are prepared as emulsifiable concentrates which are then diluted with water, prior to application, to the appropriate concentration. Liquid concentrate compositions are preferred for the preparation of dispersions which are to be sprayed. However, these concentrates can be modified for dispersion application via aerosols or nebulizers. Modification techniques used are conventional techniques.

Liquid carbetamide formulas may be applied by manual methods such as hand spraying, watering cans, immersion tubes, etc., although conventional devices (eg, rolling tables) may be used in large-scale operations. Liquid formulas may also be dispensed using sprayers. Carbetamide may also be applied in the form of a solid, i.e. in the form of wettable powders, fine powders or granules. These compositions are applied by misting or dispersing the solids, in the desired amounts, onto the stored products to be treated, for example using granule dispersers. Solids or granules are preferred for applying solids.

The concentrated, liquid, solid or semi-solid compositions are diluted prior to application to ensure uniform distribution. The degree of dilution required depends on the mode of application. When carbetamide is nebulized as a liquid via an aqueous dispersion, the concentration level of the active ingredient may range from 4.5 to 50% by weight.

The solid compositions are used so as to provide approximately the same concentration of active ingredient provided by the liquid compositions.

As stated above, carbetamide is compatible with other active substances, such as fungicides and insecticides and can therefore be applied to the harvests stored in association therewith. Such an application may be sequential or simultaneous. By way of example, the following compositions may be used in the method according to the present invention. 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)

Emulsifiable concentrate

Carbetamide 300 g

Acetophenone (vehicle) 180 g

Nonylphenol-oxyethyl-17 (wetting agent) 200 g

Cyclohexanone (vehicle) q.s. 1000 cc Carbetamide has an acute LD50 in rats of 11000 mg / kg body weight of the animal and is practically free of chronic toxicity. Topical applications in rabbit eye (5 mg) and skin of the same animal (5 creme cream) also indicate no irritant effects.

Thus, carbetamide is less toxic or irritant to mammals than the germination inhibitors previously used and is safer for workers without professional knowledge who use it. Furthermore, in the absence of significant toxicity, the debris detected in the tubers represents a significantly lower risk to the environment and to the health of handlers and consumers. Carbetamide also produces fewer stains on the treated tubers, which makes them more acceptable for consumption. Carbetamide is also much less volatile than the presently used germination inhibitors. This feature thus allows for selectivity of treatment and prevents cross-contamination since the area of effect of a treatment will not expand. Consequently, it is not necessary to separate treated tubers from other untreated or other crops

stored or used complex isolation techniques during treatment, as with the presently used inhibitors.

With the treatment according to the present invention there is also no loss of p-e-s higher than conventional treatments. The following example illustrates the use of the carbamamide according to the present invention.

Example

Four potato varieties were treated with different amounts of a wettable powder containing 65% w / w carbetamide. The level of inhibition of germination was determined by comparison with untreated potatoes after storage for 3 months. The results were as follows:

(%) potato composition (g / ton) 3 months 3 months Sguire 50 69 99 100 96 99 150 99 99 300 99 99 Roman 50 * 75 100 * 93 150 * 96 300 * 97 Desiree 50 71 98 100 97 98 150 99 99 300 100 99 Cara 50 88 87 100 98 98 150 100 99 '300 100 99 t * Variety that germinated later -9-

In comparative experiments a similar assay was performed using instead of carbetamide. BYGRAN S (a commercial composition containing tecnazene) in a proportion of 1300 g / ton., The results were as follows:

Variety of Inhibition (%) to potatoes 3 months 5 months Squire 78 92 Roman * 75 Desiree 93 83 Face 85 82

The weight losses of the potatoes submitted to the various treatments were also determined and compared with those obtained after conventional treatment and with the untreated controls.

The average values for all varieties of mashed potatoes are as follows: T ration Weight loss (¾) at 3 months 5 months None (control) 1.8 3.3 Carbetamide 50 g / ton. 1.4 2.8 " 100g / ton. 1.5 2.8 " 150g / ton. 1.3 2.2 " 300g / ton. 1.5 2.3 Bygran S 1300g / ton. 1.9

Claims (7)

A method for inhibiting the germination of potatoes, characterized in that a quantity of said active principle sufficient to inhibit germination between 17 and 20 by means of atomizing an aqueous dispersion or suspension of carbetamide is applied thereto. 200 g / ton of potatoes. A method according to claim 1, characterized in that the carbetamide is applied before or during storage to inhibit germination during it. O 3. A method according to claims 1 and 2, characterized in that the carbetamide is applied after a drying period following the harvesting of the potatoes. -11- 4. A method according to claim 1, 2 or 3, characterized in that the potatoes are not washed prior to application of the carbetamide. A method according to claim 1, characterized in that an amount of carbetamide is between 30 and 70 g / ton of potatoes. 6. A method according to claim 1, wherein the carbetamide is applied to potatoes prior to semen in order to retard germination. 7. A method according to claim 1 or 6, characterized in that an amount of carbetamide of from 17 to 50 g / ton of potatoes is used. Lisbon, June 26, 1990 The A.53.ife Gicici! of Industrial Property