Effect of planting dates on late blight severity and tuber yields of different potato varieties

Abstract

An experiment was conducted at Holetta Agricultural Research Centre (HARC) in1993, 1994 and 1996 main growing seasons, to  investigate the effect of varieties and planting dates on late blight severity and potato tuher yield with and without fungicide
application. The length of time between crop emergence and the first late blight symptom was positively correlated (R2 = 0.41) with tuber yield. Disease severity expressed as area under the disease progress curve (AUDPC) was significantly (p < 0.05) higher in early planting than in the late planting. Yield differences between planting dates and interaction between variety and planting dates were significant (p < 0.05), but yield decreased as planting dates were delayed. The effect of planting date was more important to reduce late blight, to help escape the crop from early stage disease attack and increase tuber yield in both susceptible and moderately susceptible varieties. Moreover, fungicide applications significantly (p < 0.05) reduced the AUDPC and increased tuber yield. This study showed integrating host resistance, early planting and reduced frequency of fungicide application best-controlled late blight and increased tuber yield