EVALUATION OF FUNGICIDES/ FUNGICIDE COMBINATIONS AGAINST POTATO LATE BLIGHT IN AUTUMN TPS GROWN CROP IN MEGHALAYA HILLS.

Abstract

Autumn TPS grown crop has been recognized as an important means to produce quality seed in Meghalaya hill condition for its subsequent utilization in the summer season and late blight is one of the devastating diseases of potato that cause considerable yield losses in the crop. Field experiments were conducted during the year 2003 and 2004 in autumn season with TPS grown crop (hybrid 92-PT-27) at Shillong to evaluate four fungicidal spray schedules for their effectiveness in controlling late blight of potato. Three commercial fungicides namely Dithane M-45 (mancozeb 75% WP @ 0.2%), Indofil M-45 (mancozeb 75% WP @ 0.2%) and Ridomil MZ-72 (metalaxyl 8%+ mancozeb 64% WP @ 0.25%) were tested alone and in different combinations. The experiment was conducted in randomized block design and each treatment was replicated four times. Two years pooled data revealed that all fungicidal treatments were significantly superior to untreated plots in reducing AUDPC and in increasing the yield. The blighting rate (AUDPC) was least (83.95) in the treatment consisted of two sprays of Ridomil MZ-72 plus three sprays of Indofil M-45 in the sequence of systemic, contact, systemic, contact and contact, which was followed by two sprays of Ridomil MZ-72 plus three sprays of Dithane M-45. However, both the treatments were rated at par in checking the blighting rate. Plots receiving two sprays of Ridomil MZ-72 plus three sprays of Indofil M-45 recorded maximum yield (146.8 q/ha). Two sprays of Ridomil MZ-72 plus three sprays of Dithane M-45 gave result at par with previous treatment. The present study confirmed that alternate spray of Ridomil MZ-72 @ 0.25% at 15 days interval along with mancozeb @ 0.2% at 8 days interval would be useful for effective and economic management of late blight and minimize the yield losses in autumn grown TPS crop in Meghalaya hills.