Field management of <i>Phytophthora</i> blight disease of cocoyam <i>Colocasia esculenta</i> L.) With spray regimes of selected fungicides in Nsukka, south eastern Nigeria

Abstract

Cocoyam (Colocasia esculenta L). is an important edible tuber crop, but taro leaf blight caused by Phytophthora colocasiae has been the greatest constraint to cocoyam production in Nigeria since 2009. Field trials were conducted to determine the effect of fungicides and the spray regimes on leaf growth, disease incidence, disease severity and tuber yield of cocoyam. The trials were carried out at the Department of Crop Science Research Farm, University of Nigeria, Nsukka for two planting seasons. Treatments with three fungicides (Ridomil Gold Plus, Ridomil+ChampDp 50%:50% mixture and control) and five spray regimes (No spray, weekly spray, 2nd weekly spray, 3rd weekly spray and 4th weekly spray regimes) were laid out in a 3 x 5 factorial in randomized complete block design (RCBD) with three replications. Results showed that fungicide treatments had significant (P < 0.05) variation on number of leaves/stand, disease incidence, disease severity and tuber yields/hectare in both cropping seasons. Thus, there was no significant (P > 0.05) differences between Ridomil and Ridomil+Champ (50%:50%) mixture) on all measured parameters in both cropping seasons. The fungicides and the spray regimes significantly reduced taro leaf blight, improved growth and yields . Ridomil treated cocoyam plots at weekly spray regimes performed best compared to other fungicides and the spray regime treatment options..

Key words: Colocasia esculenta, Phytophthora colocasiae, Fungicides, Spray regimes, and
Nsukka.