JPS637521B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for preventing tobacco axillary buds, which is performed using the following formula: O-ethyl-O-(2-nitro-5-
The present invention is characterized in that methylphenyl)-N-secondary-butylphosphoroamidothionate is blended with vegetable oil and applied to tobacco plants. The method of the present invention not only enhances efficacy and reduces drug dosage, but also kills axillary buds that have grown several centimeters in length, and also kills secondary and tertiary buds without decreasing efficacy even in continuous rainy weather. Since it completely inhibits the occurrence of axillary buds, it has the effect of significantly reducing the labor involved in preventing axillary buds. Tobacco farming involves many labor-intensive and time-consuming tasks such as nursery work, main field work, and post-harvest drying and cooking, but one thing that puts pressure on the busy season is removing the axillary buds right before the harvest. This work is necessary to ensure the yield and quality of leaf tobacco, but if it were done by hand, the axillary buds would have to be removed one after another within three days. For this reason, a method of spraying an axillary bud inhibitor has been developed and is becoming popular. The tobacco axillary bud inhibitors currently in practical use in Japan are maleic hydrazide ethanolamine salt, maleic hydrazide potassium salt, and maleic hydrazide choline salt.
Problems with these agents include that the applied concentration is relatively high, which sometimes causes a deterioration in the quality of tobacco, and that they have insufficient rain resistance, resulting in insufficient efficacy when rain continues. As a practical matter, the axillary bud generation period of tobacco falls during the rainy season, so there are many rainy days, so conventional axillary bud prevention agents lose their effectiveness due to lack of rain resistance and suppress the emergence of secondary and tertiary buds. It is not possible to do so, and it has to be done manually. In addition, if it continues to rain during the axillary bud development period, the appropriate time for spraying will be missed because it will not be possible to spray the chemical, and the axillary buds will often have already grown several centimeters by the time they are sprayed. For this reason, there is a strong desire for an axillary bud inhibitor that has excellent rain resistance and can selectively kill already elongated axillary buds without adversely affecting adult leaves. The present inventors have been engaged in research to meet these demands, and found that O-ethyl-O
It has been discovered that when -(2-nitro-5-methylphenyl)-N-secondary butyl phosphoroamidothionate (hereinafter referred to as butamiphos) is blended with vegetable oil and applied to tobacco plants, a surprising synergistic effect appears. The present invention was arrived at after confirming that it was suitable for that purpose. It is known from Japanese Patent Publication No. 53-12980 that butamiphos is effective in preventing axillary buds of tobacco.
As described in the above-mentioned publication, butamiphos exhibits a high axillary bud growth inhibiting effect on tobacco axillary buds grown in pots under rainless conditions by spraying a low-concentration diluted solution in water at an application concentration of 500 ppm. However, when tested by general farmers to prevent axillary buds from tobacco planted in fields under rainfall conditions, it was found that
In row cattle at a high concentration of 3000 ppm, some effect is seen on axillary buds in the early stages of development, but it is not effective on axillary buds that have grown to 5 to 6 cm, and the efficacy is considerably reduced by rain immediately after spraying. On the other hand, it is well known that vegetable oil is effective to some extent in preventing the axillary buds of tobacco, and is said to have been traditionally used in farming villages in the southern Kyushu region. Test site report, No. 12 (1955) pages 1-10]
There is. According to this report, it was stated that it was effective to make a 60% emulsion of rapeseed oil, dilute the stock solution twice, and apply it to the axillary buds of tobacco. However, the method of making such a highly concentrated emulsion of vegetable oil and applying it to the axillary buds is not practically desirable and seems to have been forgotten with the advent of maleic acid hydrazide salts. According to the experimental studies carried out by the present inventors, the effect of diluting a vegetable oil emulsion with water and spraying it was not high, and that when diluted to an oil content of 10% or less, the effect of preventing axillary buds was extremely low. . However, according to the present invention, when a butamiphos solution with a concentration that does not have a practical effect as a tobacco axillary bud-preventing agent alone is mixed with a vegetable oil in an amount that shows almost no axillary bud-preventing effect and applied, a surprising synergistic effect is obtained. Not only can it inhibit the elongation of axillary buds in the early stages of development, but it can also kill axillary buds that have already elongated, significantly improving rain resistance and completely or almost completely inhibiting the development of secondary and tertiary buds. No chemical damage is observed in the adult leaves. Vegetable oils are classified into drying oils (linseed oil, edible oil, tung oil, etc.), semi-drying oils (sesame oil, rapeseed oil, cottonseed oil, soybean oil, etc.), and non-drying oils (camellia oil, olive oil, etc.) depending on their solidification strength. However, as illustrated in Example 3, the type of vegetable oil used in the present invention may be drying oil, semi-drying oil, or non-drying oil, from the standpoint of enhancing efficacy. good. Among these, rapeseed oil is suitable for practical use, but the type of vegetable oil used in the present invention is not limited since the practicality varies depending on factors such as the price and availability of the vegetable oil. The concentration of the butamiphos-vegetable oil mixture applied to tobacco plants in the present invention is not particularly limited, but for butamiphos it is 250 to 2000 ppm, more preferably 500 to 2000 ppm, and for vegetable oil it is 0.5 to 10%.
More preferably, it is used in an amount of 1 to 5%. When the butamiphos concentration is low, the vegetable oil concentration may be high, and when the butamiphos concentration is high, the vegetable oil concentration may be low. These concentrations and ratios should be appropriately determined depending on the variety of tobacco, the state of development of axillary buds, the weather, the time of application, etc., but the effects of the present invention can be fully realized within the above ranges. The butamiphos-vegetable oil mixture is usually applied to tobacco plants by spraying it on the axillary bud formation site, but of course it can also be applied by coating. Generally, the effect of preventing axillary buds is expressed by the inhibition rate against the amount of axillary bud elongation of untreated plants, and practically a level of 95% or more is desired. According to the present invention, this level can be easily exceeded under rainy conditions and with a relatively low concentration of butamiphos solution, and practically it is possible to almost completely suppress axillary buds. The method of blending vegetable oil with butamifos is extremely easy. That is, it is carried out by diluting a butamiphos emulsion in water to a desired concentration and adding and stirring a vegetable oil emulsion prepared to a certain concentration, for example, 90%. Since butamiphos is compatible with vegetable oil, the present invention can also be carried out by using vegetable oil as a solvent and adding a suitable surfactant to formulate a butamiphos-vegetable oil mixed emulsion. The present emulsion can be easily formulated by a known method using a nonionic surfactant, an anionic surfactant, or a mixture of the two, as exemplified in part in Example 4. EXAMPLES Examples will be given below to clarify the content and effects of the present invention. Example 1 Tobacco planted and cultivated in the field (variety BY-4)
At the beginning of flowering, the axillary buds and apical buds that had grown over 3 cm were picked, and a mixture of each test chemical diluted in water and rapeseed oil was sprayed on the site where the axillary buds appeared using a small hand sprayer (20 ml per plant). did. After 30 days of treatment, the axillary buds that had developed were picked and the fresh weight of the axillary buds was measured. Then, the weight of one axillary bud was determined, and the inhibition rate was determined using the following formula and is shown in Table 1. Axillary bud suppression rate (%) = {1-fresh weight per axillary bud in treated area/fresh weight per axillary bud in untreated area} x 100

[Table] Salt was used.
Example 2 The apical buds and primary axillary buds of tobacco (Burley No. 21) planted and cultivated in the field were harvested when they reached the peak flowering stage, and then when the secondary axillary buds had grown to about 1 cm, water containing Butamiphos emulsion was added. A predetermined concentration solution prepared by mixing the diluted solution and the water diluted solution of rapeseed oil emulsion at a ratio of 1:1, respectively, was sprayed at 20 ml per plant onto the axillary bud generation site. The axillary buds that had developed 30 days after the treatment were picked, and the inhibition rate was determined in the same manner as in Example 1 and is shown in Table 2.

[Table] Rain.
Example 3 When the tobacco grown in the field (BY-4) reached the early stage of flowering, the axillary buds and apical buds that had grown to 3 cm or more were picked, and each vegetable oil emulsion was added to a 500 ppm solution of Butamiphos emulsion at a concentration of 2.3%. The emulsion was mixed and stirred so that 20ml per plant was sprayed on the axillary buds of the tobacco plants using a small hand sprayer. 30 days after the treatment, the fresh weight of the axillary buds was measured in the same manner as in Example 1, and at the same time the suppression rate was determined. The chemical damage to the leaves was observed and shown in Table 3.

【table】

[Table] Example 4 (1) 50 parts of O-ethyl-O-(2-nitro-5-methylphenyl)-N-secondary butyl phosphoramidothionate, 35 parts of xylene and polyoxyethyl lauryl ether (surfactant) ) were uniformly mixed to form a butamiphos emulsion. (2) A rapeseed oil emulsion was prepared by uniformly mixing 90 parts of rapeseed oil, 1 part of oleic acid, 4 parts of polyoxyethylene nonyl phenyl ether, 3 parts of polyglyceride laurate, and 2 parts of polyoxyethylene lauryl ether. . (3) 5 parts of O-ethyl-O-(2-nitro-5-methylphenyl)-N-secondary butyl phosphoramidothionate, 85 parts of rapeseed oil, 4 parts of polyoxyethylene nonyl phenyl ether
1 part, 3 parts of polyglyceride laurate, and 3 parts of polyoxyethylene lauryl ether were uniformly mixed to prepare a butamiphos-rapeseed oil mixed preparation.

Claims (1)

[Claims] 1. A method for preventing tobacco axillary buds, which comprises applying O-ethyl-O-(2-nitro-5-methylphenyl)-N-secondary-butylphosphoroamidothionate to tobacco plants in combination with vegetable oil.