مكافحة بيولوجية لمرض تعفن جذور اللوبياء Vigna unguiculata المتسبب عن الفطر Rhizoctonia solani باعتماد بعض الأ نواع البكتيرية و الفطرية

Abstract EN

Cowpea is a plant susceptible to infection with the pathogenic fungus Rhizoctonia solani, which causes significant economic losses annually worldwide.

45 isolates of R.

solani were isolated from different cropping areas in the middle and south of Iraq.

Pathogenicity tests in vitro revealed that the isolate Nrs-8 was the most severe which prevented completely the germination of the seeds compared to the control (100%).

The results of the in vitro antifungal activity test of the different bioagents Bacillus licheniformis (Bl), Bacillus clausii (Bc), Paenibacillus polymyxa (Pp), Trichoderma viride (Tv) and Saccharomyces cerevisiae (Sc) against Nrs-8 on the potato dextrose agar indicated that all of them significantly inhibited the growth of R.

solani; with inhibition rate of Bl, Bc, Pp, Sc ranged from 68.61 to 90.28%, whereas the inhibition rate of Tv was 94.64%.

Under greenhouse conditions, the treatment of the mixture (Bl+Bc+Pp+Sc+Tv) was superior in controlling the root rot disease, and led to 100% seed germination, compared to the negative control which gave 67.5% seed germination.

The mixture reduced the disease incidence and severity to 0.0% compared to 77.5% and 51.3% for the negative control, respectively.

The treatments with three, four or five bioagents led to a significant increase in the plant growth parameters represented by the dry weight, whereas the mixture of five bioagents treatment was superior and exhibited 1.69 g/plant compared to 0.54 g/plant and 1.31 g/plant for the negative and positive controls, respectively.