Influence of Fungicides and Fungicide Spray Regimes on Vegetative Growth and Yield of Three Cultivars of Cocoyam (Colocasia esculenta L.) in Early and Late Planting Seasons in Nsukka Derived Savanna

摘要

Field trials were conducted at the Teaching and Research Farm of the Department of Crop Science, University of Nigeria, Nsukka during early planting season (April - November) and late planting season (July – December) in 2013 to determine the impact of fungicides and fungicide spray intervals on vegetative growth and yield of three cultivars of taro ("Nachi", "Ugwuta" and "Odogolo") in early planting and late planting season respectively in Nsukka derived savanna. The experimental design was a 3 x 3 x 5 factorial trial in a randomized complete block design (RCBD) with three replications. The treatments consist of three cultivars of taro ("Nachi", "Ugwuta" and "Odogolo"), three fungicides treatments [(Ridomi lGold 66WP plus; active ingredient (a.i) 6% metalaxyl and 60% copper, Ridomil Gold 66WP plus + Champ DP; (a.i) copper hydroxide 50%:50% mixture w/_w and no fungicide (control)] and five fungicide spray regimes ( no spray, 1 weekly spray, 2 weekly spray, 3 weekly spray and 4 weekly spray) in all treatment combinations (forty-five treatment combinations). The Result showed that "Odogolo" had the tallest height at 60 days after planting (34.54 cm), 90 days after planting (79.63 cm), 120 days after planting (81.44 cm) and 150 days after planting (63.81 cm) than the other cultivars when sprayed with Ridomil Gold 66WP plus at one weekly interval in the early planting season."Nachi"(12.13) and "Odogolo" (11.95) had the highest number of leaves at 120 days after planting and at 150 days after planting at one weekly spray interval in the late and early planting season respectively."Ugwuta" had the highest percentage establishment at 15 days after planting (65.56%) and 30 days after planting (81.56%) in the late planting season. "Odogolo" had the widest corm diameter with a value of 6.63 cm, number of cormel per stand (16.20), weight of cormel per stand (0.31 kg plant-1), weight of corm per stand (0.81 kg plant-1), weight of cormel per hectare (12228 kg ha-1), weight of corm per hectare (7297 kg ha-1), total tuber yield per stand (0.49 kg ha-1) and total tuber yield per hectare (19524 kg ha-1) than the other cultivars when sprayed with Ridomil Gold66WP plus at one week interval in the early planting season at harvest. The use of Ridomil Gold66WP plus; active ingredient (a.i) 6% metalaxyl at one weekly spray regime is recommended. "Odogolo" cultivar and early season planting proved to be the most promising technology for the cultivation of taro in Nsukka agro-ecology.