Rotylenchulus reniformis Management and Vertical Distribution in Summer-Winter Crop Rotations Including Carinata

Brassica carinata (carinata) is an emerging winter biofuel crop in the southeastern United States. Rotylenchulus reniformis (reniform nematode) is an important yield-robbing parasite on cotton in the region. A better understanding of rotation systems involving carinata would guide R. reniformis management and crop selection decisions. This study aimed to determine the effect of winter crop rotations with or without carinata, in combination with summer crops, on R. reniformis at two soil depths in a field study in North Florida. Two-year winter rotations included fallow-carinata, fallow-fallow, and oat-carinata. Winter rotations were crossed with corn, cotton, soybean, and peanut each year. Soil samples were taken from 0-30 cm and 30-120 cm depth after both summer and winter crop harvest for 4 yr. Rotylenchulus reniformis soil abundances were greater at 0-30 cm than at 30-120 cm deep, but crop effects were generally similar at both depths. Cotton supported greater R. reniformis soil abundances than corn, peanut, or soybean. Winter rotations did not consistently affect R. reniformis, regardless of prior summer crop, although carinata tended to decrease R. reniformis soil abundances. In summary, carinata production expands options for winter crop rotations to manage R. reniformis.