Root-knot nematodes are tiny parasitic worms that infect plant roots. They form galls or knots on the plant roots that block the flow of nutrients and photosynthesis products.
In 2013 these nasty little worms invaded several root systems of my growing heirloom tomato plants. That really gets me MAD! The plants appeared normal even set a few tomatoes then they began to look sickly, stop setting fruit and grew weird, immature looking leaves that appeared to have a yellow color. It wasn’t until we began the seasonal garden clean-up that the cause became apparent. NEMATODES.
Prevention: Sources suggest growing resistant cultivars. There are virtually no heirloom tomatoes that are resistant. Hybrid tomatoes and other plants have been bred to resist disease. As promoters of heirloom growing, our best defense against disease is nutrient and beneficial microorganism rich soil. Crop rotation is an important mode of prevention. Solarize the soil before planting. Grow marigolds and till them into soil at season’s end.
Control: Shellfish meal has proven to be a good organic nematode control agent. It contains a substance called Chitin. Instead of attacking nematodes directly, chitin works by providing food for bacteria that eat chitin, increasing the population of these bacteria to the point that they can successfully attack nematode eggs and adults, both of which contain chitin. This year we are treating our Square Garden with Crab Meal from Down to Earth. Apply 5-10 pounds per 100 square feet. In addition to nematode control, Crab meal is also a great soil building source of organic nitrogen, phosphorus and calcium.