Root-knot Nematode Damage to Low Desert Bell Pepper

Nematodes have not been reported as a problem in bell pepper production in California. However, in the Coachella Valley in Riverside County, CA, bell pepper growers are suspecting nematodes of causing widespread damage. In this low desert region approximately 5,000 acres are cropped with bell pepper with an estimated gross crop value of $90,000,000. The general consensus among Coachella Valley growers is that root-knot nematodes can result in major crop damage if not controlled, research data on damage thresholds and tolerance limits for desert growing conditions are not available.  This research project assessed the damage potential of the nematodes to bell pepper in the Coachella Valley, characterized root-knot nematode populations occurring in bell pepper fields, and evaluated damage thresholds and tolerance limits of bell pepper for a locally occurring root-knot nematode population compared to the resistant varieties. Under field conditions, nematode infested bell pepper plants appeared to show typical nematode damage and heavy chlorosis of leaves.  Soil samples from the grower’s fields confirmed obvious symptoms (root galling) and plant damage. Morphological analysis of perineal patterns and a differential host range test revealed that the problem was caused by Meloidogyne incognita (Southern root-knot nematode) race 3.  In a greenhouse trial, the nematodes did not significantly affect total fruit yield (g per plant) in the two resistant cultivars ‘Carolina Wonder’ and ‘Charleston Belle’, while that of the ‘MiniBells’ (variety grown by Coachella valley growers) was severely affected.  The yields from ‘MiniBells’ inoculated with nematodes were reduced by approximately 50% compared to the no-nematode control.