Groundnut Rust (Puccinia arachidis) Management through Integration of Host Resistance with Fungicides at Babile, Eastern Ethiopia

The field experiment was carried out at Babile Research Sub-Station of Haramaya University in 2010 main cropping season to evaluate the efficacy of four fungicides (chlorothalonil a rate of 0.2 kg-ha-1, copper hydroxide at a rate of 2.3 kgha-1, mancozeb at a rate of 0.25 kg-ha-1 and triadimefon at a rate of 0.5 kg-ha-1) on groundnut rust (Puccinia arachidis) development and grain yield. The experiment was laid out in a randomized complete block design (RCBD) in factorial arrangement with three replications. Two groundnut varieties were used for the experiment namely, Shulamith (susceptible) and Sedi (moderately resistance). The fungicide treatments resulted in different levels of disease severity on the two groundnut varieties used [i.e. Shulamith (susceptible) and Sedi (moderately resistant) varieties]. Plots sprayed with triadimefon had significantly (p ≤ 0.001) lower level (257.37%-days) of AUDPC of groundnut rust than plots treated with other fungicides. Three times spray with triadimefon at a rate of 0.5 a.i. kg-ha-1 at 15-day-interval proved to be the best groundnut rust management system giving the lowest disease parameters and highest yield 1644.44 kg-ha-1. Four times spray with mancozeb at a rate of 0.25 a.i. kg-ha-1 at 10-day interval proved to be the second best fungicide in significantly reducing the disease. Percentage severity indexes (PSI), area under disease progress curve (AUDPC) and disease progress rate were negatively correlated with groundnut seed yield. The highest rust severity 67.65%and lowest yield 1014.60 kg-ha-1were recorded on the unsprayed control shulamith plots. On Shulamith variety, rust severity of up to 67.65% and relative yield loss of 35.55% were recorded in unsprayed plots. Generally, the current research results indicate that effective management of groundnut rust and significant yield benefit can be obtained when triadimefon fungicide spray is started just before or at the onset of the disease and properly continued at 15-day interval.