On Crops: Celery and many other vegetable crops
Worldwide, wherever celery and other host crops are grown
When celery plants become infected with root-knot nematodes, they may wilt on hot days even when the soil is moist. Other types of stress can cause this symptom, so if wilting persists or worsens you will need to dig up a sample plant to examine the roots. Celery infected with root knot nematodes will have numerous knobby growths on the roots. Small feeder roots will have been destroyed, with irregular galls growing in their place.
Root knot nematodes are tiny 'eelworms' that live in soil and become plant parasites when they use celery roots as their nurseries. Celery requires more water than other crops, so when nematodes interfere with moisture uptake, plants begin to wilt, new growth comes to a standstill, and leaves may take on a yellowish cast because they are not getting enough nutrients from the compromised roots.
Good crop rotations prevent nematode buildup in many gardens, but root knot nematodes may be unavoidable in sandy soils in warm climates. Nematodes are not very active in cool weather, so sometimes winter celery will be successful even in soils where some nematodes are present.
Pull up affected plants and dispose of them in the bin. Mark the area where the troubled celery grew, and do not grow carrots, celery or okra there again.