Abstract:
Potato (Solanum tuberosum L.) is the most important tuber crop in Ethiopia. Late blight caused by the fungus Phytophthora infestans is widespread and destructive disease of potato. Survey for prevalence, incidence and severity of late blight of potato was conducted in the two major potato growing districts of Awi administrative Zone namely Fagita Lekoma and Banja. Field experiment was conducted at Amesha Shinkuri Kebele administration at Farmers training center in Fagita Lekoma district during 2019 main cropping season to evaluate the effect of variety and fungicide combinations for late blight management. A total of 60 potato fields were surveyed from two districts in 10 Kebeles and in field experiment four potato varieties and three fungicides including unsprayed control were used with a total of 12 treatment combinations. The experiment was laid out in factorial arrangement in RCBD with three replications. The survey data revealed that late blight of potato was prevalent in 70.4% of potato fields with varied incidence and severity. Mean prevalence (61.78 and 79.00%), incidence (51.06 and 70.63%) and severity (25.57 and 45.71%) of potato late blight were recorded at Fagita Lekoma and Banja districts, respectively. The highest disease incidence (100%) at 52 days after planting (DAP) and percent severity index (76.68 and 63.92%) at 87 DAP was obtained from unsprayed plots of Key and Zengena varieties, respectively. On the other hand, the lowest disease incidence and percent severity index was obtained from Belete and Gudene varieties both sprayed with Ridomil Gold 68% WG. Lower disease incidence was recorded from all varieties sprayed with Ridomil Gold 68% WG. The highest rate (0.0930unit day-1) and AUDPC (1630.70%-days) were obtained from unsprayed plots of Key variety. Whereas, the lowest rate (0.0405unit day-1) and AUDPC (258.35%-days) were calculated from Belete variety sprayed with Ridomil Gold 68% WG. The highest tuber yield, 31.66 t ha-1, was obtained from Belete variety sprayed with Ridomil Gold 68% WG. The maximum MRR (1631.18%) obtained from key when sprayed with Ridomil Gold 68% WG. The highest net profit was obtained from Belete sprayed with Ridomil Gold 68% WG. Therefore, combination of moderately resistant variety (Belete) with the different fungicide applications, especially Ridomil Gold 68% WG is better for the management of late blight and sustainable production of potato at Fagita Lekoma district and also recommended that further repeated experiment is needed for confirmation.