دراسة مكافحة مرض القشرة السوداء على البطاطا-البطاطس (Rhizoctonia solani Kuhn)‎ باستخدام بعض عزلات Trichoderma koningii Oudem. و مبيد تولكلوفوس ميثيل

Abstract EN

No.

5 Isolate of Trichoderma koningii Oudem.

strongly inhibited the growth of Rhizoctonia solani on PDA medium in vitro.

However, its efficiency against the disease under field conditions was moderate.

Results indicated that tolclofos methyl 50% (0.5 g a.i./L., 1 g a.i./L.

and 2 g a.i./L.) was very effective against R.

solani growth on PDA medium in vitro.

Similar results were obtained by using tolclofos methyl 10% (0.2 g a.i./kg) or tolclofos methyl 50% (2 g a.i./L.) to treat potato seed tubers infected artificially or naturally with the pathogen under field conditions.

The tolclofos methyl 50% WP efficiency was 89.3% in 1995 and 93.8% in 1997, whereas the tolclofos methyl 10% D efficiency was 96.2% in 1997.

The efficiencies of T.

koningii isolates ranged from 50.0 to 66.4% in 1995, while efficiency of No.

5 isolate were 66.4 and 74.0% in 1995 and 1997, respectively.

The growth and yield of treated potato plants were increased.

The effectiveness of fungicide was increased by soil incorporation with tolclofos methyl 50% (0.5 g a.i./1 m of row) during the potato growing season, in addition to seed tubers dressing or dipping before planting.