CURRENT STATUS AND INTEGRATED MANAGEMENT OF GARLIC RUST (Puccinia allii R.) IN NORTH WOLLO, ETHIOPIA

Abstract

Garlic rust (Puccinia allii R.) is the most prevalent disease in all garlic-growing areas of North Wollo, Ethiopia that limit production potential of garlic crop. Hence, this study was conducted with the objectives to assess the distribution, importance and association of biophysical factors with garlic rust, and to evaluate the effect of integrated disease management through host resistance and alternate fungicide application on rust epidemic and bulb yield during 2018/19 cropping season. Field experiments were conducted at Lalibella zuria and Gidan on three garlic varieties and two systemic fungicides with alternate and alone applications. Treatments were factorial arranged in RCBD with three replications. Survey of garlic rust was conducted in four major garlic-producing districts of North Wollo in main rainy and irrigation periods. A total of 137 farms were visited, i.e. 78 farms in irrigation and 59 farms in main rainy season, to determine the prevalence, incidence and severity of garlic rust. The level of incidence was highest in most assessed districts, namely Gidan, Lalibella Zuria and Lasta. Mean severity within the three assessed districts varied from 49.9 at Lasta to 63.5% at Gidan, respectively. Minimum mean severity (12.8%) and incidence (36.4%) were recorded in Meket district. Independent variables: district, season, growth stage, cropping pattern, weed density, management practice, preceding crop and altitude were significantly associated with high incidence and severity of garlic rust as a single predictor in the logistic regression model. Highest disease incidence (>80%) and severity (>40%) had high probability of association with irrigation season, mature growth stage, medium to high altitude ranges, poor management practice and in some preceding crops. Thus, field survey has confirmed that garlic rust was the most production constraints and hence appropriate and urgent management intervention on the most disease associated variables were needed so as to manage the disease. Analysis of variance revealed that interaction effect of Nativo, Tilt and their alternate applications with Chelenko-1 and Tseday varieties showed very low disease severity, AUDPC and disease progress rate compared to treated local variety and unsprayed plots. Except bulb diameter and weight in Lalibella Zuria, there was no interaction effect on varieties with alone and alternate fungicide applications of bulb yield and yield components in both location. At Lalibella, the variety Chelenko-1 showed better yield (9 t ha-1) and had 28 and 21% yield advantages over Tseday and local, respectively. However, there was no significant difference among fungicides on bulb yield in both location but minimal and lower relative bulb yield losses were obtained on the fungicide Nativo and Tilt alone. Their economic analysis also confirmed their high profit and effectiveness against garlic rust. Hence, proper field management with Tilt and Nativo fungicides alone were advisable and xviii economically profitable in Lalibella Zuria and related agro-ecologies for the management of garlic rust on the variety Chelenko-1. However, since there was no significant variation in bulb yield of all garlic varieties in Gidan district, same fungicides with local garlic variety are commendable for rust management. Moreover, additional management strategies should be undertaken through host resistance integrated with cultural and agronomic practice, and cost effective fungicides to provide alternatives for managing the disease.