GB1565496A - Method of controlling the foliage of plants - Google Patents

Description

(54) METHOD OF CONTROLLING THE FOLIAGE OF PLANTS (71) I, MAURI ILMARI TAKALA, a citizen of Finland, of SF-36600 Palkane, Myttaala, Finland, do hereby declare the invention for which I pray that a patent may be granted to me and the method by which it is to be performed, to be particularly described in and by the following statement: Delayed ripening of crops, foliage of plant stand, adventitious shooting and weeds are the worst factors which restrict the combine harvesting of peas, broad beans (horse beans), turnip rape and spring rape. These result often in large quantitative and especially qualitative losses in yield. There are chemical defoliants, which at the same time also control weeds. These include compounds which contain among others organic nitrogen such as paraquat and diquat as well as organic phosphoric acid derivatives (U.S. 2 891 486, 71-71).

However, the crop treated with these compounds contain poisonous residues which restrict their use as defoliators of crop plants. Of the inorganic compounds one can use among others mineral acids such as sulfuric acid (Fryer, J., Makepeace, R., Weed control handbook II Recommendations 6th ed. Bartholomew Press, England 1970, p. 37). Sulfuric acid is a strong acid and is therefore difficult to handle, corrodes sprays and exhibits harmful effects in the field.

The present invention provides a method for destroying the foliage of peas, broad beans (horse beans), turnip rape and spring rape as well as weeds before combine harvesting, using a phosphoric acid spray solution, which comprises treating a plant stand ready for combine harvesting 1 to 2 weeks prior to the harvesting with about 400 liters per hectare of a 15% to 20% by weight solution of orthophosphoric acid containing about 0.25% by weight of a surface tension reducing wetting agent.

When 15-20% orthophosphoric acid solution is used to control foliage one ob tains better results with this than with the use of earlier mentioned compounds.

This is due to a slower destruction of foliage which allows afterripening of crop to take place. Spraying the crop with said solution approximately 1-2 weeks prior to combine harvesting at the rate of 4001 per hectar a larger and qualitatively better yield is obtained as compared to usual combine harvesting. This method can also save the crop already considered as lost under very severe conditions for harvest.

To improve the effectiveness of treatment a common surface tension reducing wetting agent normally for sale at the store has to be added to solution at the rate of about 0.25 per cent by weight.

In a preferred embodiment of the invention, the cultivated area is subjected to a first spraying with the orthophosphoric acid solution prior to the emergence of cropplant seedlings.

Furthermore, spraying of orthophosphoric acid, which contains 12% by weight PsOó has given comparably good results as a pre-emergence treatment for crops.

A said solution is applied at the rate 400 liters per hectar. To improve the effectiveness of treatment a commercially available surface tension reducing wetting agent is added to the solution in an amount of 0.2 per cent by weight. This spray solution destroys all emerged weed seedlings and reacts at the same time with alkalis present in soil transforming them into unreactive salts while crop plants emerging later on are not damaged. Onion seedlings will stand the spray solution unharmed. The facts, that salts of orthophosphoric acid generally are added to the soil as fertilizer, since plants depend on phosphorous for growth, and that phosphoric acid is always present in the form of different salts in food and that food processing industry uses it as food additive, make the use of the present method safe.

Calculations on spraying costs will have to take into consideration, that the whole compound will be present in the field and will affect as P-fertilizer on yield of crops for years to follow.

WHAT I CLAIM IS: - 1. A method for destroying the foliage of peas, broad beans (horse beans) turnip rape and spring rape as well as weeds before combine harvesting, using a phosphoric acid spray solution, which com prises treating a plant stand ready for combine harvesting 1 to 2 weeks prior to the harvesting with about 400 liters per hectare of a 15% to 20% by weight solution of orthophosphoric acid, containing about 0.25% by weight of a surface tension reducing wetting agent.

2. A method as in claim 1, comprising a first spraying of the cultivated area with said orthophosphoric acid solution prior to the emergence of cropplant seedlings.

3. A method as claimed in claim 1 substantially as hereinbefore described.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. food and that food processing industry uses it as food additive, make the use of the present method safe. Calculations on spraying costs will have to take into consideration, that the whole compound will be present in the field and will affect as P-fertilizer on yield of crops for years to follow. WHAT I CLAIM IS: -

1. A method for destroying the foliage of peas, broad beans (horse beans) turnip rape and spring rape as well as weeds before combine harvesting, using a phosphoric acid spray solution, which com prises treating a plant stand ready for combine harvesting 1 to 2 weeks prior to the harvesting with about 400 liters per hectare of a 15% to 20% by weight solution of orthophosphoric acid, containing about 0.25% by weight of a surface tension reducing wetting agent.

2. A method as in claim 1, comprising a first spraying of the cultivated area with said orthophosphoric acid solution prior to the emergence of cropplant seedlings.

3. A method as claimed in claim 1 substantially as hereinbefore described.