Management of Angular Leaf Spot in Common Bean ( Phaseolus vulgaris L.) with Molybdenum and Fungicide

The yield of common bean (Phaseolus vulgaris L.) is affected by several factors, including diseases such as angular leaf spot (Phaeoisariopsis griseola) and N deficiency caused by lack of nodulation. In Minas Gerais State, Brazil, farmers have been using both fungicide and molybdenum (Mo) applications to improve crop yield. The objective of this research was to investigate the effect of Mo application in conjunction with variably applied fungicide on common bean in the management of angular leaf spot (ALS). Field experiments were conducted in two seasons, wet and dry, with eight fungicide treatment schedules, with and without Mo. Angular leaf spot severity, plant growth, photosynthesis, and yield were measured. A single application of Mo 25 d after sowing (DAS) decreased the area under the disease progress curve by 38% and increased the area under the leaf area progress curve by 20%, leaf photosynthesis by 26%, and yield by 51%. When combined with the Mo applications, fungicide spray applied once (at an early growth stage) or twice in the bean flowering period (25-45 DAS) should provide substantial control of ALS.