Efficacy of naturally occurring kaolin and sulfur in the management of tomato insect pests and fungal diseases

Abstract

Tomato (Solanum lycopersicum L) is the most cultivated horticultural crop in Uganda whose production is extending to peri-urban areas. However, its production is constrained by several biotic factors notably pests and diseases which results in both quantitative and qualitative damage. Farmers in the country rely mainly on the appliance of chemical pesticides for their management. These pesticides play a significant role in the management of these pests and diseases but their excessive use results in residual problems. This study was conducted at Makerere agricultural research institute Kabanyolo (MUARIK) to assess the efficacy of naturally occurring kaolin and sulfur in the management of tomato insect pests and fungal diseases to reduce on the use of synthetic pesticides. The experiment was laid out in a complete randomized block design both inside and outside the green house using the Makerere tomato accession (MT56) and data was collected on incidence of pests which included aphids, thrips, whiteflies, leaf miners and tomato bollworm; while the major diseases included late blight, early blight, powdery and downy mildew. The treatments included: Azoxystrobin SC (20MmL/ 20L of water), Sulfur WP (30gm in 20L of water), Kaolin WP (500g in 20L of water), Mancozeb WP (50g in 20L of water), the untreated control and a treatment of chlorpyrifos+cypermethrin premix at the rate of 7 ml per 20L of water was added for comparison purposes with respect to insect pest incidence. Results from this study showed that kaolin and sulfur have significant effect on the incidence of tomato insect pests and fungal diseases. Kaolin WP treatment had the highest reduction effect on the incidence of all insect pests (mean of 0.00) except whiteflies which was best controlled by Chlorpyrifos+cypermethrin premix. Kaolin and Azoxystrobin had the lowest late blight disease incidence with a mean of (11.1) while Azoxystrobin and Mancozeb treatment gave the lowest early blight disease incidence (mean 11.1). There was no significant difference (p>0.05) in the effect of treatments on plant parameters except for plant height and leaf area canopy. Kaolin treated plants had the highest plant height mean and Sulfur treated plants had the biggest leaf area canopy (mean of 268.9). Significantly higher fruit yield was harvested in Azoxystrobin treated pots and it showed statistically similar to Mancozeb and Kaolin WP