Per Clemson Extension in SC:

"Root-knot nematodes can be a serious problem on okra. If a plant is stunted, pull the plant out of the ground and check for galls on the roots. These galls are caused by the nematodes, which are microscopic worms. An effective nematode control program should include crop rotation and sanitation. More information about controlling nematodes in the home garden is available in HGIC 2216, Root-Knot Nematodes in the Vegetable Garden.

Crops should be rotated to help reduce disease and nematode problems. Okra plantings should not follow vine crop plantings such as squash or sweet potatoes."

Just thought I'd give you this link.

Here is a link that might be useful: Okra