Efficacy of Trichoderma Asperellum, Bacillus Subtilis and Farmyard Manure On Performance And Management Of Late Blight (Phytophthora Infestans) In Potatoes (Solanum Tuberosum L.)

Abstract

In Kenya, potato yields are declining while demand its increasing. The reduction in potato yields is due to a variety of factors, including late blight disease and poor soil fertility management. The main objective of this study was to increase potato production by using farmyard manure and biofertilizers to enhance soil fertility and manage late blight. The experiments were carried out at Egerton University and KALRO-Tigoni to assess the impact of farmyard manure (FYM), microbial biofertilizers/biocontrol (Trichoderma asperellum and Bacillus subtilis) applied at 150 mL/10 kg. NPK fertilizer was used as positive control to assess their effect on soil fertility and late blight management. Two varieties, Shangi and Kenya mpya, were used in this study. The experiments were carried out using a split-split plot design, with 3 replicates and potato varieties were main plot while fertilizer treatments as subplots. Late blight disease evaluation was conducted at KALRO-Tigoni and it involved evaluation of FYM (30 t ha-1), two biocontrols and fungicide (Ridomil). Data was collected on disease incidence and severity of late blight, yield and yield components of the crop. Results showed that there were significant differences (P<0.05) between treatments and varieties evaluated. Ccombination of FYM+ Trichoderma asperellum and FYM+ Bacillus subtilis increased potato yield and plant height by 19.8% and 18.9%, respectively. The combination also increased the weight of marketable tubers and dry matter by 10.86% and 13.16 %, respectively as compared to NPK. In nutrient uptake FYM and biofertilizers were not significantly different, though, FYM+ Trichoderma asperellum showed highest increase of nutrient uptake at N: 74.77 kg ha-1, P: 35.16 kgha-1, and K: 43.88 kg ha-1, Ca: 49.53 kg ha-1, Mg: 26.29 kg ha-1, Fe: 0.48 kg ha-1, Mn 0.22 kg ha-1, Cu 0.07 kg ha-1, Zn 0.14 kg ha-1. Tigoni site showed an increase in soil properties as compared to Egerton university site after harvesting the crop than before planting with at P: 0.70%, Fe: 0.66 mg/kg, and Ca: 0.68% among the highest. FYM+ Trichoderma asperellum and FYM+ Bacillus subtilis had significant (P<0.05) reduction in disease severity by 72.95% and 72.23%, and disease incidence by 74.12% and 72. 23%, respectively as compared to negative control. These findings showed that farmers can use the combination of FYM and microbial biofertilizers/biocontrol as an alternative to chemical fertilizers and fungicides for safe and enhanced potato production.