Temporal epidemics and management of ascochyta blight (Ascochyta rabiei) of chickpea (Cicer arietinum L.) in Central Rift Valley, Ethiopia

The production of chickpea, an important legume grown all over the world, is severely constrained by ascochyta blight, which can cause up to a 100% yield loss. The most reliable, economical, and effective management techniques for this disease is fungicide treatments and host plant resistance. The objectives of the present study were to evaluate chickpea varieties and fungicide application intervals against chickpea ascochyta blight epidemics; identify the most effective fungicide application time interval; and determine the association of ascochyta blight incidence and severity with yield and yield components of chickpea. The study was carried out in two hotspot regions (Dhera and Dugda) during the main growing seasons of 2020 and 2021. Three chickpea varieties (Dhera, Habru, and Mariye) and four fungicide spray schedules (Mancozeb 80% WP at a rate of 2.5 a.i. kg/ha) were utilized as treatments, and they were treated up until the crop reached full physiological maturity. Twelve treatments were set up in a factorial arrangement with three replicates using a randomized complete block design (RCBD). Both the Gompertz model and the logistic model were used to assess dependent variables under various treatments. For the disease progres rate under various treatments, the slope of the regression line was determined. The results of the data analysis revealed considerable variations between the treatments. Fungicide application time schedule, varieties, and their interactions had substantial effects on ascochyta blight. The Mariye variety had the highest incidence (100%) and severity (70.68%) of ascochyta blight, with 100% yield loss seen from untreated plots, whereas the Dhera variety experienced the lowest incidence (6.35%) and severity (11.01%) following fungicide management on the 7th day of the interval. The analysis of the means revealed that applying fungicide at intervals of 7 and 14 days was an effective strategy to reduce the severity, incidence, and AUDPC of ascochyta blight. This strategy led to the highest yield of seeds per pod, pods per plant, and grain yield when compared to the untreated plots and the plot treated at a 21-day interval. To handle polycyclic outbreaks of the disease successfully, both the logistic and Gompertz models were used. The study's extent of variety resistance was enough to control the disease in two cropping seasons and locations. This investigation led us to the conclusion that a program to control ascochyta blight of chickpea in Ethiopia may include the integration of fungicides and resistant varieties. Additionally, methods for integrated management of the Ethiopian ascochyta blight on chickpeas must be developed.