Seed Treatment and Foliar Application of Fungicide for the Control of Bean Anthracnose

Abstract

Bean anthracnose (Colletotrichum lindemuthianum Sacc & Magn.) is one of the most devastating seed-borne diseases of common bean (phaseolus vulgaris L.). The primary source of inoculum of the disease is infected seed. Field experiments were conducted at
Ambo and Bako (Ethiopia) to assess effectiveness of fungicides to control bean anthracnose. Three fungicides were tested: benlate 500 g a.i. /kg WP (at a rate of 2 g a.i /kg as seed dressing and 1 kg a.i./750 L as foliar spray), mancozeb 800g a.i./kg WP (at a rate of 200g a.i./100 L as foliar spray) and difenoconazole 250 ml a.i./EC (at a rate of 87.5 g a.i/ha as foliar spray). Treatment combinations were benlate seed treatment, benlate seed treatment + benlate foliar spray, benlate seed treatment + mancozeb foliar spray, benlate seed treatment + difenoconazole foliar spray, mancozeb foliar spray, difenoconazole foliar spray, benlate foliar spray, and an untreated control. Foliar sprays were applied three times at 20 days intervals commencing seven days after inoculation with C. lindemuthianum. Compared with other treatments, seeds treated with benlate followed by difenoconazole, or difenoconazole alone reduced anthracnose severity by 62% and 64% respectively at Ambo, and by 31% and 25% respectively at Bako. At Ambo, all treatments resulted in significantly (P < 0.05) high yields, and the yield after seed treatment + difenconazole was four times higher than that of the control.