Effect and Underlying Mechanisms of Cultivar Mixtures on Weed and Disease Suppression in Organic Field Pea

The project will evaluate the effect of growing mixtures of semileafless (cv. CDC Dakota) and leafy (cv. CDC Sonata) field peas on Mycosphaerella blight development, weed suppression, lodging, and yields. The objectives of the project are to identify an optimum ratio of semileafless to leafy peas for organic production, and to investigate the effect of different pea canopy environments on Mycosphaerella blight development. The peas will be grown in field plots in five ratios of semileafless to leafy peas (semileafless only, 25:75, 50:50, 75:25, and leafy only), and at the seeding rates recommended for conventional and organic production (88 and 132 plants/m²). The temperature and relative humidity beneath the canopy of each mixture will be monitored using sensors to evaluate the effects of canopy microclimate on Mycosphaerella blight.

To further investigate the effects of different environmental conditions on Mycosphaerella blight development, indoor experiments will be conducted using detached pea stipules (cv. CDC Dakota) held at different temperatures under constant humidity. The formation of the two types of fruiting structures responsible for spread of Mycosphaerella blight, pycnidia and pseudothecia, will be assessed at each of six temperatures (5, 10, 15, 20, 25, and 30^oC) over time.

Left: Early symptoms of Mycosphaerella blight below the canopy of a mixture of semileafless and leafy peas