The Efficiency of some Control Agents in Resisting the Okra Root Rot Disease Caused by the Fungus Pythium aphanidermatum

Abstract

This study was conducted in the laboratory and plastic house belonging to the Department of plant protection – faculty of Agriculture - Anbar University to evaluate the efficiency of the biological control agent Trichoderma harzianum and the chemical inducing agents sodium bicarbonate NaHCO3 and melatonin C13H16N2O2 in inducing resistance in seeds and seedlings of okra to infection with the disease of seed rot and the fall of seedlings caused by the semi-pathogenic fungus Pythium aphanidermatum double transplantation of some isolates of the-biotic fungus T. harzianum that isolation T2 (centre of Organic Agriculture-Ministry of Agriculture-Iraq) achieved the highest ability in inhibiting the growth of pathogenic semi-fungus, reaching a degree of contrast of 1, while the result of measuring the effectiveness of volatile substances on the PDA medium of the same isolates showed that isolation T2 (center of Organic Agriculture-Ministry of Agriculture-Iraq) gave the highest percentage of inhibition against pathogenic semi-fungus P. aphanidermatum reached 36.4% and the test of the effectiveness of the inducing agents in protecting the seeds of okra, Petra on the medium of PDA showed the effectiveness of the inducing agents sodium bicarbonate and melatonin in protecting the seeds, as the germination rate reached 100% for both, while the bio-fungi isolates achieved isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) the best germination rate reached 100% and the results of the plastic house experiment showed that the treatment with bio-fungi by soaking for 20 minutes gave high efficiency in the percentage of germination reached 83.33% and reduced the percentage and severity of infection to 23.67% and 18.33% respectively, as for the soaking treatment with melatonin 200 micromuller, the percentage of germination decreased to 63.67% or the percentage and severity The infection rate reached 43.33% and 37% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Centre-Ministry of Agriculture-Iraq) after 15 days of germination reduced the percentage and severity of infection to 32.67% and 25% sequentially and the spraying treatment with melatonin after 15 days of germination achieved the percentage and severity of infection reached 49% and 39.33% sequentially, as for the spraying treatment with biological agent isolation T2 (Organic Agriculture Center-Ministry of Agriculture-Iraq) after 25 days of germination, it gave the highest efficiency in reducing the percentage and severity of infection 35.67% and 29.67% sequentially, while the percentage and severity of infection in the melatonin spraying treatment after 25 days of germination reached 51.33% and 43.67% sequentially compared to the comparison treatment Contaminated with semi-pathogenic fungus Pythium aphanidermatum .