Effect of azadirachtin pre-treatment on major pests, diseases and yield of seed yam

摘要

Pests and diseases infested material of seed yams have led to sub optimal yield levels. Neem was applied as substitute for chemical pesticides and as environmentally safe bio-pesticide to reduce the crops annual loss due to herbivore pests and their resulting diseases. Field trials were conducted during the 2016 and 2017 major planting seasons in four communities each of Ejura-Sekyedumase and Atebubu-Amantin districts of the Ashanti and Brong Ahafo regions respectively. Yam minisetts sizes were pre-treated with Mancozeb at a rate of 100 g and Lambda cyhalothrin at 40 ml in 10 L water as cocktail. Yam minisetts of 30 g each were planted on ridges at 100 cm between and 30 cm within rows on a 20 m × 20 m plot size. Neem leaf powder was applied on five rows per plot and another five served as check for assessment. Harvesting was done approximately 6 to 7 months after planting. Scale insects, mealybugs, beetles, termites and millipedes infestations. Galling due to root-knot nematodes, cracks, soft and wet rot were assessed on a scale of 1-5. Tuber yields were also assessed. Neem treated plots were observed to have significantly reduced arthropod pest populations and nematode galling as well as damage signs compared to the control plots. Yields of seed yam were higher on the neem treated plots than the control, probably due to the reduced damage on the treated plots. Seed yam yield increased for plots treated with Azadirachta indica leaves by 40 and 41% at Ejura-Sekyedumase district as well as 45 and 20% at Atebubu-Amantin district for 2016 and 2017 respectfully. Plots of seed yams treated with neem recorded reduced pests and damages in terms of parameters measured and subsequently translated into yield. It is paramount to seed yam producers to adopt neem leaf powder as pre-treatment for higher productivity.