Evaluation of some chemicals for soil drenching in controlling stem canker and black scurf of potato

M. M. Rahman, M. A. Ali, T. K. Dey, M. U. Ahmad, and M. Sultana, 2016. Evaluation of some chemicals for soil drenching in controlling stem canker and black scurf of potato. Banglaseh J. Plant Pathol. Vol. 32(1&2): 83-88 An experiment was conducted to find out the effectiveness of soil drenching with Amistar 250 SC (azoxystrobin) @ 0.05, 0.10 & 0.15%, Boric acid @ 2.0, 2.5 and 3.0%, Provax-200 (carboxin) @ 0.15, 0.20 & 0.25%, and Bavistin 50 WP (carbendazim) @ 0.05, 0.1 & 0.15% to control stem canker and black scurf disease of potato caused by Rhizoctonia solani. The experiment was conducted during 2008-09 cropping season at Tuber Crops Research Sub-Centre, of Bangladesh agricultural Research Institute (BARI), Bogra, Bangladesh The maximum of 41.24% stem canker incidence and 21.04 PDI were recorded from control plot where soil was drenched with plain water. The minimum incidence of 14.99 was obtained with soil drenching with Amistar 250 SC at 0.10% followed by Amistar 0.10% and Provax-200 at 02.0% and Amistar at 0.05%. The incidence was 14.9918.74% under those treatments. The incidence was 19.99-23.74% under other treatments. All treatments with fungicides and Boric acid reduced disease severity (PDI) considerably over control. The lowest PDI was recorded from treatments with Amistar 250 SC at 0.15% followed by Amistar 250 SC at 0.05 and 0.10 and Bavistin 50 WP at 0.15% showing PDI of 5.629.99. Soil drenching with all treatments with fungicides and boric acid reduced number and weight of russet, deformed and sclerotia infested tubers over control. Considerable reduction was achieved with three treatments with Amistar 250 SC. Number and weight of healthy tubers per plot, and tuber yield per hectare increased by 2.79-105.39, 42.49-165.57 and 4.54-36.78 over control, respectively. Boric acid was ineffective to control the disease and to increase yield. Among the fungicides, higher reduction in incidence and severity of stem canker and black scurf and increase in tuber yield were obtained with Amistar 250 SC. So, Amistar 250 SC was considered as the best fungicides to control the disease and to increase the yield of potato.