Influence of growth habit, row spacing, and seed infection on bean anthracnose development

Bean anthracnose, caused by Colletotrichum lindemuthianum, has been responsible for severe seed yield and quality losses in many dry bean (Phaseolus vulgaris) producing regions of the world. A 2-year study conducted at two field locations in Manitoba examined the effect of differences in seed-borne infection level, row spacing, and growth habit oil anthracnose development and any associated losses in seed yield and quality in four navy bean entries and two pinto heart entries. Row spacing had little or no effect oil anthracnose severity, but the narrow row spacing (30 cm) always produced the highest yield. A sced-borne infection level of 10% resulted in a significant decrease in the percent seedling emergence of the navy bean entries but usually did not reduce the emergence of the pinto bean cultivars. Nevertheless, anthracnose ratings were most severe oil the pinto bean cultivars early in the growing season. The results suggest that the larger seed size of the Pinto bean cultivars might have resulted in the emergence of a higher percentage of infected seedlings, which Would have Cause(] the disease to rapidly spread in these cultivars. The effect of seed-borne anthracnose infection On the Crop canopy and oil the pods became evident late in the growing season and resulted in higher incidences of anthracnose seed discoloration. Growth habit did not consistently influence anthracnose severity. since the entries with the lowest disease ratings were a viny navy bean line and an indeterminate, upright navy bean line.