Journal of Plant Pathology & Microbiology

Abstract

Comparative Study of Powdery Mildew (Erysiphe polygoni) Disease Severity and Its Effect on Yield and Yield Components of Field Pea (Pisum sativum L.) in the Southeastern Oromia, Ethiopia

Teshome E and Tegegn A

Field pea or “dry pea” (Pisum sativum L.) is an annual cool-season food legume which grows worldwide and is the major pulse crop in the highlands of Bale next to Faba bean. The experiment was conducted for two consecutive cropping seasons; 2011/12 and 2012/13 at Sinana agricultural research center (SARC) on-station research site. The objective was to find out the effect of Powdery mildew disease on field pea yield and yield components. Local field pea cultivar was used with a fungicide Benomyl at a rate of 2.5 kg/ha and four fungicide application schemes (spraying every 7 days, 14 days, 21 days and no fungicide spray) arranged in randomized complete block design (RCBD) with 3 replications. Logistic model (ln [y/ (1-y)]) was employed to analyze the Field experiment data using SAS procedure. The association between disease parameters and yield and yield components were assessed using regression and correlation techniques. ANOVA has shown significant difference (p ≤ 0.05) among treatments for disease severity. The highest diseases severity (41.98%) and Area Under Disease Progress Curve (AUDPC) (1458.33% days) and the lowest disease severity (13.89%) and AUDPC (471.15% days) were recorded from a plot with no fungicide treatment and plot sprayed every 7 days, respectively. Similarly, the highest disease progress rate (r) (0.044227 units-day-1) and the lowest r (-0.006122 units-day-1) were recorded from a plot with no fungicide treatment and plot sprayed every 7 days, respectively. Regarding the yield and yield related parameters; ANOVA has shown significant variations (P ≤ 0.05) between treatments for number of pods per plant, seeds per plant, TKW and grain yield. The highest number of pod per plant (21.75), seed per plant (89.5), TKW (189.81 g) and grain yield (2945.6 kg/ha) were recorded from plots sprayed every 7 days; while the lowest were from non-sprayed plots. On the other hand, the higher grain yield loss of 21.09% and the lowest loss (8.53%) were recorded from plots without fungicide spray and plot received spray at 7 days interval, respectively. The linear regression between powdery mildew severity index and grain yield revealed significant difference (P ≤ 0.0001) between treatments; and the estimated slope of the regression line obtained for Powdery mildew severity index was -34.16. Correlation analysis has shown that Powdery mildew disease severity have significantly strong negative correlation with grain yield (r= -0.76120, P ≤ 0.01). Similarly, grain yield has significant strong negative correlation (r= -0.76298, P ≤ 0.0001) with AUDPC.