IDENTIFICATION OF SOURCES OF RESISTANCE AND BIOCHEMICAL MANAGEMENT OF LATE BLIGHT OF POTATO (PHYTOPHTHORA INFESTANS)

Abstract

A bulk of potato varieties were screened against historical Phytophthora infestans causing the late blight of potato. Almost the potato germplasm showed a varying response against the devastating pathogen at Okara and Sahiwal. Field trails were consisted of screening of germplasm, area under disease progress curve and chemical management of the disease by using the various fungicides. Randomized complete block design was used for the research at both locations. Out of 68 genotypes/ varieties 16 were susceptible, 20 moderately resistant, five highly susceptible and 27 as moderately susceptible. Maximum disease incidence was recorded on Desiree and Cardinal (90%) followed by Santee (83.33%). The maximum mean disease severity 9.48 was noted on Cardinal, followed by Desiree 9.11 and Karoda 9.0 with the area under disease progress curve 28.55, 27.33 and 26.00 respectively. The results showed that 5gm/ L was the best dose against the suppression and control of the potato late blight under the field conditions. Azoxystrobin which is a new chemistry fungicide found to be the best chemical treatment against the late blight of potato followed by the copper oxychloride-based fungicides Cobox which also showed best response. Aliette, Antracol, Tebuconazole and Mancozed were also played a role to minimize the disease yet their higher concentration was even not so effective to combat the disease. Mancozeb was not found to be effective to control the disease as compared to the other three fungicides. The abrupt climate change is also facilitating the occurring of disease in all areas of the world.