DETERMINATION OF DISEASE PREVALENCE, BEST TREATMENT COMBINATIONS AND TEST OF INTEGRATED MANAGEMENT ON TOMATO (Solanum lycopersicon Mill) PROTECTED FROM CROP PESTS USING AGRONETS IN KENYA

Abstract

Tomato is an important economic and food security crop in Kenya grown under rain fed and irrigation systems mainly by small-scale farmers as source of income, vitamins A, C, Lycopene and alicin strong anti oxidants that fight free radicals. Diseases and pests are major constraint to tomato production in Kenya. However, Agronets have been successfully used in control of pests in Kenya. Agronet use is a new agro technology that aims at preventing pest attack by acting as exclusion barrier in addition to microclimate creation that enhances crop growth. Studies on Agronets efficiency and influence to plant physiology have been done before. However, research regarding the effect of Agronets microclimatic modification in influencing disease development and possible management strategies have not been carried out hence there was need to carry out such studies that would give comprehensive package on the technology. This research was carried out to determine prevalence and severity on tomato grown under Agronet in the nursery and field condition, test of integrated management on severity and determining the best treatment combination. The study was carried out on-station at KARI, Kabete. Factorial design was used in the study, where two factors; Agronets and management strategies. Each factor had different levels in nursery and field conditions. Agronets had five levels in nursery; insecticide impregnated 0.9 mm Agronet, non impregnated 0.9 mm mesh Agronet, 0.4 mm mesh Agronet, shading with grass (common farmers practice) and the no net (control). Integrated management had three; seed dressing, seed dressing plus monitored sprays and no application (control). Data was collected on weekly basis for the disease incidence, severity and pest population was entered into excel sheet format and Means sort by subjecting data to ANOVA using Genstat software. Significance was tested at 95% level and means separated using Fisher’s Protected Least Significant difference. Data was transformed using square root transformation (x+0.05)0.5to normalize. Results showed that significant (P<0.05) microclimatic conditions were observed across the Agronet levels in the nursery and field conditions. Four major diseases; early blight, damping off, tomato yellow leaf curl disease and late blight were prevalent in the nursery. Severity of TYLCD varied significantly (P<0.05) across the Agronet levels with control and shading recording high severity compared to Agronet covered plot which had lower severity levels. With additional management, significant difference (P<0.05) on severity of the diseases was recorded except for damping off in season 1. In the field, prevalent diseases included; late blight, tomato yellow leaf curl virus, bacterial leaf spot and Septoria leaf spot. Significant (P<0.05) variation across Agronet were observed in TYLCD, bacterial spot and tomato mosaic disease. With additional management, severity varied significantly (P<0.05) across the management strategy for powdery mildew, early blight, and late blight. There was no significant (P>0.05) interaction of Agronet and additional management. Both Agronet and management factors had significant (P<0.05) effect on yield while similar significant interaction of the factors was observed to influence the yield effect. Best treatment combinations were observed with use of Agronet with drenching plus monitored sprays which resulted to higher quantity of marketable yields. From this study, it was concluded that Agronets and management acted independently and that using Agronet technology calls for scouting for diseases at all stages of tomato growing.