GB2154879A

GB2154879A - Foliage desiccant or defoliant

Info

Publication number: GB2154879A
Application number: GB08504995A
Authority: GB
Inventors: Selwyn Everest-Todd
Original assignee: COALITE GROUP PLC
Current assignee: COALITE GROUP PLC
Priority date: 1984-02-29
Filing date: 1985-02-27
Publication date: 1985-09-18
Also published as: GB8504995D0

Description

SPECIFICATION Foliage desiccant or defoliant This invention relates to foliage desiccants or defoliants and has particular application to foliage desiccants or defoliants for use in plants to assist harvesting.

Foliage desiccants or defoliants are well known in the art and great publicity has been given to their uses in warfare. In such use the object is to effect destruction of the green tissue without concern for the plant and thus most such desiccants or defoliants as are commercially available are so severe that the plant will die and, where the plant is grown for a crop, the crop is so contaminated or burned by the desiccant or defoliant as to be useless.

The present invention seeks to provide a foliage desiccant or defoliant which can be applied to plants having green and non-green tissue to effectively destroy the green tissue without killing off the non-green tissue of the plant. The invention also seeks to provide a method of defoliating plants or harvested crops.

The invention further seeks to provide a foliage desiccant or defoliant which can be applied to certain plants grown for crops to assist havesting of the crop.

According to the present invention there is provided a contact foliage desiccant or defoliant, capable of effecting destruction of green tissue, and which desiccant or defoliant comprises or inclues a biocide.

The invention also provides a method of defoliating plants or crops (whether prior to or after harvesting) which comprises applying to said plants or crops, e. g. by spraying, a contact foliage desiccant or defoliant capable of effecting destruction of green tissue, which desiccant or defoliant also comprises or inclues a biocide.

The desiccant or defoliant may be the biocide alone or may be a composition comprising the biocide, as an active ingredient, together with a suitable carrier. The same compound may be active in both desiccant or defoliant and as biocide.

Preferably the contact desiccant or defoliant comprises 2-chloro-6-methyl-4-benzylphenol or o cresol.

One aspect of the invention comprises a foliage desiccant or defoliant composition comprising a contact foliage desiccant or defoliant together with a biocide.

British patent specification no. 1509520 discloses the use of 4-chloro-2-methylphenol as an intermediate for the synthesis of plant protection agents and describes how, from the prerunnings in the manufacture of that compound, the compound 2-chloro-6-methyl-4-benzylphenol can be extracted. The said specification no. 1509520 identifies the compound 2-chloro-6methyl-4-benzylphenol as being useful but the widest disclosed use is restricted to its good action against bacteria and fungi which are pathogenic to humans and animals. There is no disclosure of a use of the compound for plant life but from the advantages to humans and animals the reader may expect some beneficial results with plant life.

Contrary to this expectation it has been found that the compound 2-chloro-6-methyl-4 benzylphenol is an effective contact defoliant or desiccant. Further it has been found that when applied to a plant or harvested crop to defoliate the plant or crop the compound retains biocidal activity.

Other compounds in the pre-runnings from the process described in British patent 1509520 may also be used in the present invention as the defoliant or foliage desiccant.

The result of these two effects on a plant or crop is that the compound effectively destroys the soft green tissue of the plant or crop and, if the compound contacts non-green tissue, it will initially burn the tissue but the biocidal effect sterilizes the wound.

Thus when the compound is applied to the plant or crop e. g. as a spray, the non-green tissue may be subjected to spot burns but, being almost immediately sterilized, the spot burns are neutralised and said non-green tissue is not destroyed by the compound.

This effect is of particular advantage in those areas of desiccation where the leaf tissue should be destroyed in order to prevent the entry of pathogens into the plant.

When the compound is applied to plants bearing a non-edible crop, such as cotton, the compound has little effect on the crop and can greatly assist in harvesting the crop.

When the compound is applied to a food plant or crop where the edible part of the crop is protected by a natural shield, such as a case or shell, the compound will affect only the shell or case and the crop will be unharmed.

When the compound is applied to a food plant or crop which is exposed, or the natural protection is restricted to a skin or rind, as is the case with large fruit such as apples, pears and the citrus fruits, the skin of the fruit may be so scarred by the compound as to be unattractive but such fruits are still suitable for processing, particularly where the fruit is peeled before being processed.

The compound and method proposed by the invention are useful on all plants and crops having green tissue and not just on tree, bush and shrub crops. By way of example, the compound offers advantage as a desiccant of green tissue to destroy potato foliage and green tissue in grain crops to terminate metabolic function of the plants. The invention is especially useful in connection with crops such as cotton, beans and other leguminous crops, sugar cane, potatoes, tobacco and coffee.

The present invention can be effective on certain stored crops, such as potatoes, to prevent premature germination, by killing off the soft green tissue of sprouts, and is believed that the compound is beneficial in such uses where its biocidal activity can combat many diseases to which the stored crop may be susceptible.

Whilst the dosage rate for applying the compound may vary widely from trees to ground crops the compound is beneficial to agronomic practise within the dosage rate of 1.0 to 20.0 kg. per hectare of suitable formulation active principal.

The invention will now be described by way of the following Examples.

EXAMPLE 1.

9.0 gm 2-chloro-6-methyl-4-benzylphenol and 1.0 gm caster oil soap were mixed together using a standard laboratory stirrer and the whole diluted with water to a total volume of 900 ml.

After agitation the resultant emulsion was applied to 45 square metres of a crop of potatoes by Knapsack sprayer. At the time of application the foliar tissue was vital but mature and the progeny tubers in a marketing condition.

Twenty four hours after application the crop foliage became chlorotic thereby terminating metabolic function.

EXAMPLE 11.

A formulation of 2-chloro-6-methyl-4-benzylphenol made up as in Example I was applied to 90 square metres of a mature crop of barley.

This application effectively desiccated green tissue within the crop without damage to the grain.

EXAMPLE//I To a mixing vessel were added: 100 gm 2-chloro-6-methyl-4-benzylphenol 400 gm Polyethyleneglycol 10 gm Caster oil soap and agitated with a laboratory stirrer.

The resulting mixture was applied to various crops and the results are set out below.

Claims

TEST RESULTS Test Plant Concentration Volume applied % Defoliation active ingred. litres/hectare after 72 hours Potato 0.5% 200 litres 49 Potato 1.0% 200 litres 98 Potato 0.5% 100 litres 25 Potato 1.0% 100 litres 64 Barley 0.5% 200 litres 78 Barley 1.0% 200 litres 93 Cotton 1.0% 200 litres 47 Cotton 1.0% 400 litres 95 Cotton 2.0% 200 litres 81 Cotton 2.0% 400 litres 99 CLAIMS

1. A contact foliage desiccant or defoliant, capable of effecting destruction of green tissue, and which comprises a biocide.

2. A desiccant or defoliant according to claim 1, comprising 2-chloro-6-methyl-4-benzylphe nol or o-cresol.

3. A desiccant or defoliant according to claim 1, comprising a compound which can be found in the pre-runnings from the process described in British patent 1509520.

4. A method of defoliating plants or crops comprising applying to said plants or crops a desiccant or defoliant according to any of claims 1 to 3.

5. A method according to claim 4, wherein the plant or crop has green tissue.

6. A method according to claim 4 or 5, wherein the plant or crop is non-edible or is a non food plant or crop.

7. A method according to claim 5, wherein the plant or crop is cotton or tobacco.

8. A method according to claim 4 or 5, wherein the plant or crop is a food plant or crop.

9. A method according to claim 8, wherein edible parts of the plant or crop are protected by a natural shield.

10. A method according to claim 8, wherein edible parts of the plant or crop are exposed or protected only by a skin or rind.

11. A method according to claim 8, wherein the desiccant or defoliant is applied to potato foliage to effect destruction thereof.

12. A method according to claim 8, wherein the desiccant or defoliant is applied to a grain crop to terminate metabolic function of the plants.

13. A method according to any of claims 4 to 6 and 8 to 10, wherein the plant or crop is beans or other leguminous crop, sugar cane, potatoes or coffee.

14. A method according to any of claims 4 to 13, wherein the desiccant or defoliant is applied at a dosage rate of 1.0 to 20.00 kg. of active principal per hectare.

15. A method according to any of claims 4 to 10, wherein the crop is a stored crop to which the desiccant or defoliant is applied to prevent or inhibit premature germination and/or to combat disease.