J. M. Kilonzi,1* J.J. Mafurah2 and M.WNyongesa3
1,2Egerton university, Department of Crops, Horticulture and Soil,
P.O Box 536, Njoro
3Kenya Agricultural Livestock and Research Organization- Tigoni,
P.O Box 338-0217, Limuru
*Corresponding Authors: email@example.com: +254725605844
The overuse of fungicides to manage late blight has led to emergence of more aggressive strains raising environmental, economic and health concerns. The objectives of the study were to determine the cost benefit and efficacy of T. asperellum (3 × 106, 7 × 106 and 1 × 106 CFU/mL) seed treatment and Ridomil® (Metalaxyl 4% + Mancozeb 64%) application interval (21, 14 and 7 days interval) in managing late blight on potato tuber and apical cutting seed crop by either peridermal injection or dipping. Costs and benefits associated with apical cutting and tuber seed treatment were analyzed using partial budgeting to calculate marginal rate of return percent (MRR %). Results showed that there was no significant difference between 7 and 14 days interval in terms of yield and disease severity. Apical cuttings were highly infected by late blight resulting to lower yield and net loss compared to tuber seed crop. T. asperellum at 33% concentration was ineffective in managing P. infestans. T. asperellum at 66% and 100% concentration reduced early late blight infection and were not significantly different in terms of disease severity and yield in all Ridomil® application regimes. Combination of T. asperellum at 66% concentration with 14 days interval had the highest (969%) MRR% compared to any other combination. Peridermal injection had significantly higher yield and benefits than dipping. The results of the study suggest that T. asperellum seed treatment at 66% concentration can increase fungicide application interval by 7 days while effectively managing late blight. This will not only reduce the amount of fungicides applied and their negative effects but also will contribute to improved yield as well improve farm net income.
Keywords: Apical cuttings, Efficacy, Ridomil® Trichoderma asperellum