ASTUDY OF THE EFFECT OF THREE ORGANIC ACIDS AND THE FUNGUS Trichoderma harzianum AND ITS FILTRATE ON THE GROWTH AND PATHOGENESIS OF Alternaria alternata AND IN STIMULATING TOMATO PLANT RESISTANCE AGAINST IT

The present study has investigated the activity of three organic acids (Benzoic, Salicylic and Oxalic and the effect of Trichoderma spp activity and its filtrate on the growth of Alternaria spp. And its role in stimulating the resistance of tomato plant against infection with /(treatment procedure) inoculating with fungi sprouts at 5 ×10³ concentration as the filtrate of Trichoderma spp. In a 10-day incubation period showed high inhibitory efficiency for the colony growth diameters of Alternaria spp. In vitro, after 7 days, an average was 21.67 mm compared to the control treatment that gave an average diameter of 50 mm. Trichoderma spp. Also gave a high inhibitory ability against the fungus Alternaria spp. The antagonistic experiment reached 22. 84% also gave organic acids (benzoic, salicylic and oxalic) a high inhibition against Alternaria spp. It reached 100% in laboratory media for 7 days at a concentration of 9 ml of benzoic acid and a concentration of 12 ml of each of salicylic and oxalic. The results of spraying plants showed an increase in the severity of infection as an indication of an increase. The number and area of spots in the control treatment that included inoculating tomato plants with Alternaria spp. To 3.14 spots/leaf per number and 7.69 mm² per area, while it reached when the treatment was sprayed with organic acids and the filtrate of Trichoderma spp. Before inoculation with Alternaria spp. The average number of spots was (0.96, 1.00 and 1.27). And 0.50) spot / sheet and area rate.