Rotations with Crotalaria spp. do not suppress populations of Meloidogyne incognita in cotton

Authors: KHANAL, CHURAMANI - Clemson University; GALBIERI, RAFAEL - Instituto Mato-Grossense Do Algodao (IMAMT); Timper, Patricia

Submitted to: Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/21/2021
Publication Date: 3/17/2021
Citation: Khanal, C., Galbieri, R., Timper, P. 2021. Rotations with Crotalaria spp. do not suppress populations of Meloidogyne incognita in cotton. Nematology. 0:1-9. https://doi.org/10.1163/15685411-bja10086.
DOI: https://doi.org/10.1163/15685411-bja10086

Interpretive Summary: Field studies were conducted in Mato Grosso, Brazil and Georgia, USA to evaluate the efficacy of Crotalaria species as rotational cover crops for managing the southern root-knot nematode in cotton. The two experiments differed in how Crotalaria was incorporated into the cotton production system to reflect differences in climate (tropical vs subtropical) and production systems typical for the two regions. In Mato Grosso, sunn hemp (C. juncea) and showy rattlebox (C. spectabilis) were planted after soybean in late summer, grown for approximately 300 days, and incorporated into the soil 6 to 15 days prior to cotton planting. In Georgia, sunn hemp and cowpea (Vigna ungiculata) were planted after corn in the late summer, grown until killed by frost in the early winter, and cotton was planted in the next season. The cover crops in both experiments did not appear to suppress the root-knot nematode. However, Crotalaria significantly increased cotton plant height at the time of harvest. Except for one of the experiments in Brazil, incorporation of Crotalaria in rotational scheme did not increase cotton yield. Results suggest that Crotalaria do not suppress the southern root-knot nematode in cotton when used as rotational cover crops.

Technical Abstract: Field studies were conducted in Mato Grosso, Brazil and Georgia, USA to evaluate the efficacy of Crotalaria spp. as a rotational cover crop for managing M. incognita in cotton. The two experiments differed in how Crotalaria spp. were incorporated into the cotton production system to reflect differences in climate (tropical vs subtropical) and production systems typical for the two regions. In Mato Grosso, C. juncea and C. spectabilis were planted after soybean in late summer, grown for approximately 300 days, and incorporated into the soil 6 to 15 days prior to cotton planting. In Georgia, C. juncea and Vigna ungiculata were planted after maize in the late summer, grown until killed by frost in the early winter, and cotton was planted in the next season. The cover crops in both experiments did not appear to suppress M. incognita. However, Crotalaria spp. significantly increased cotton plant height at the time of harvest. Except for one of the experiments in Brazil, incorporation of Crotalaria spp. in rotational scheme did not increase cotton yield. Results suggest that Crotalaria spp. do not suppress M. incognita in cotton when used as rotational cover crops.