Effect of Varieties and Fungicide Application Frequencies on Late Blight (Phytophthora infestans) Disease Development and Fruit Yield of Tomato in North Western Tigray, Ethiopia

Abstract

Diseases like late blight are among the major constraints that limit tomato production in most tomato growing regions. Field experiment was conducted in North Western Tigray in 2018 main season with objectives: to investigate the effect of varieties and fungicide application frequencies on late blight disease development and tomato fruit yield. The treatments consisted of four tomato varieties (Melkashola, Melkasalsa, Sirinka-1 and Gelilema) and five application frequencies of the fungicide Matco 72% WP including the control. The experiment was laid out in a split plot design with three replications. Results indicated that integration of varieties and fungicide spray frequencies significantly reduced late blight disease development and maximizes tomato fruit yield. Melkasalsa variety is found better with lowest disease incidence (36.87%), disease severity (26.83%), AUDPC (587.5% days), DPR (0.0604unit per days) and highest marketable (50.05 tha-1) and highest total fruit yield (54.63 t ha-1) when sprayed four times. The highest percent disease incidence (81.50%), disease severity (74.60%), AUDPC (1558.3% days) and Disease Progress Rate (DPR) (0.1074 units per day) were obtained from untreated Gelilema variety. The lowest fruit yield (35.02 tha- 1) was harvested from none sprayed Gelilema variety. Highest MRR of 3058% was obtained on Melkasalsa variety treated thrice. Thus it is recommended to use 3 sprayings of the fungicide Matco 72% WP at 10 days interval where the variety Melkasalsa is to be used in the study area. However, other management practices should be employed to this variety to confirm its resistance ability and to maximize its fruit yield in the presence of the disease in main season.