Tests leaf spot

The leaf spot test or the barley test (Blixt and Mossberg, 1967) may provide a rapid and inexpensive screening test for mutagenicity both respond to the same compounds. Blixt and Gelin (1965, and personal communication) have developed a suitable technique. 

The fungicidal activity of 1 //-pyrrolo[2,3-6]pyridine derivatives has been tested. The 3,3 -bis sulfide derivative (119) shows medium to high fungicidal activity, especially against rice blast and rice leaf spot damage <92BCJ2992>. 

The most common and simplest procedure is to place a few microliters of the test solution over a small puncture wound on a detached leaf. The puncture wound enhances the access of the toxin to the leaf tissue. The leaf is then placed in a petri dish containing a filter paper saturated with water. The top cover of the plate is sealed with parafilm, and the plate is incubated under controlled light and temperature conditions. Toxin activity is usually indicated by chlorotic, necrotic, or colored spots on the leaf. Other methods for bioassay involving CO2 fixation, or effects on organelles, whole plants, protoplasts, tissue cultures, or plant parts are outlined (, 7). 

Roots with black, dead, hard spots in flesh. Cause Boron deficiency. Roots may be wrinkled or cracked. Plants can be stunted leaf edges may be brown and lower l af surfaces may be reddish purple. Preveitt deficiency problems by spraying plants with seaweed extract as soon as the first true leaves appear, and every few weeks thereafter. Check deficiency with a soil test. Correct by adding 1 tablespoon of borax dissolved in 1 gallon water, or 10 pounds of kelp, per 1(X) square feet of soil. 

This is tested in a laboratory generally and it takes considerable time to do so. A quick test is to dip a piece of thick bright white paper sheet into the filtered liquid. Presence of black spots on the paper sheet will indicate unsatisfactory filtration and need for recycling it. This can be used for checking quality of filtered sulphur coming out from a pressure leaf filter. 

Leaf and pod spot (Ascochyta fabae) is probably the most important seed-bome disease of beans although it affects peas as well. Most disease stems from infected seed, but volunteer plants and the movement of tractors and other machinery from crop to crop can also spread it. The testing of seed stocks for Ascochyta is routine. However, modem seed treatments have greatly improved control of this disease. 

Certified seed is advised but if using home-saved seed it should be tested for germination and seed-borne leaf and pod spot (Ascochyta fabae) infection. Low levels of this disease may be treated with thiram. It is recommended that all field bean seed is tested for stem and bulb nematode (Ditylenchus dipsaci) and should not be used for seed if nematodes are present. PGRO offer a testing service. 

Acaricidal and insecticidal activities of the synthesized compounds were determined as follows. In the case of two-spotted spider mite (T. urticae), female adult mites were placed on the excised leaf of kidney bean seedling, and then, the test solution (test confounds were dissolved in acetone at 20 to 200 ppm) was sprayed onto die leaf. Mortality was determined 2 days after the treatment. In the case of western flower thrips (F. occidentalis), first instar larvae were released on released on the excised leaf of kidney bean seedling (15 larvae per a disk), which was then sprayed with the test solutioa Mortality was determined 2 days after the treatment. In die case of silver leaf Miitefly B. argentifolii), adult whiteflies were released on die cabbage leaf and allowed to oviposit for 24 hours. Adults were removed from the leaf and the leaf was stood for 7 days. A leaf disk of 20 millimeters in diameter was excised from the leaf and sprayed with the test solution. Mortality was determined 6 days after the treatment. The acaricidal and insecticidal activities were indicated as activity indexes 3,2 and 1 which represent the mortality of 100%, 99% to 50% and less dian 49%, respectively. 

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