My tomatoes and eggplant that had started out so beautifully, turned yellow and started to decline as they reached full maturity. Most never fruited. Annoyed at anything that does not produce in my garden, I began to yank them out of the ground. To my dismay, the first plant, and all that I angrily pulled, had short roots with large, garbanzo-bean-sized knobs all over the roots. Root-Knot Nematodes.
My mission was now clear. How could I fight these invisible creatures beneath my soil?
Alas, many methods must be employed to successfully control, but not permanently remove root-knot nematodes if you are an organic gardener. This is what is required:
Rotate Crops. Some plants are more susceptible to root-knot nematodes. After a susceptible plant is grown and removed, plant a crop Arugula, Beans, Bok choy, Broccoli, Brussels sprouts, Cabbage, Cauliflower, Chinese cabbage, Collard greens, Daikon radish, French Marigolds*, Horseradish, Kale, Kohlrabi, Land cress, Mustard greens, Peas, Peanuts, Radish, Rutabaga, Shepherd's purse, Soybeans, Turnip, or Watercress before planting another root-knot nematode susceptible plant.
Inter-crop. Susceptible plants can be inter-planted with dwarf French Marigolds*. The substance in the French Marigold's roots adversely affects the legume family. Therefore do not inter-plant beans, peas, peanuts, and soybeans with French Marigolds.
*French Marigolds (Tagetes patula). French Marigold's are usually smaller and bushier plus their flowers are not as full as the American Marigolds. French Marigold roots exude a substance that kills root-knot nematodes in the vicinity of their roots. Use them as a rotational crop or inter-plant them with susceptible plants. French marigolds have difficulty growing during the worst part of our summers when it is very hot and wet. Plants them in March, April, September, October, and November here in SW Florida.
White flies hate the smell of all marigolds so plant them all over your garden except around your beans, peas, and peanuts. Till under the entire marigold plant to leave their killer substance in the ground and to self-sow the next crop of marigolds (unless you plant on growing legumes next in this space).
Amend the soil. Enhancing your sand/soil with peat moss and/or compost helps bring in healthy bacteria and WORMS. After first moving to SW Florida I was told "if you don't have worms in your soil, you have root-knot nematodes". Mix compost well with your current soil/sand to prevent it from "caking".
Lee County Solid Waste sells OrganicLee™Compost by the bag, cubic yard, and delivered by the truckload. Lee County Waste-To Energy Facility Complex, 10500 Buckingham Rd, 239-533-8000. As of today: compost loaded on your truck is $10, plus tax, per square yard; 25 yards delivered is $315; bagged compost is $2.45 plus tax. Mulch is also available to be loaded on your truck for $10 plus tax per square yard.
Solarize the soil. This needs to be done during the summer months (June, July, August, September) so the soil is literally baked. To solarize your soil: till the soil (amend at this time, it if you wish), smooth and prepare it as if you are ready to plant, water, then cover with clear plastic. Not the super thin plastic, our sun will disintegrate that in a couple of days. Pull the plastic super-tight so that water does not sit on it and wait 4-6 weeks until your soil is "fried". Uncover and plant WITHOUT DIGGING. The first 4 inches of soil are treated, but the soil below is not. This process kills fungi, nematodes, bacteria, weeds, and insects in the upper soil levels.
Cover crops. Research suggests that green manuring with Brassica family or agricultural mustard to help fight root knot nematodes, suppress weeds, and soil diseases. Turn under before going to seed. Mix seed with sand to broadcast seed more evenly.
Buy nematode resistant varieties. When you buy seeds, read the label to see if it says anything about resistance to nematodes. The label may list capital letters VFN. These letters indicate that the variety has resistance to certain diseases: V = Verticillium wilt resistant; F = Fusarium wilt resistant; and N = root-knot nematode resistant. Resistant plants may not be necessarily immune; some varieties may show sign of infection without being seriously affected.
Root-knot nematode resistant varieties:
Southern Peas (partial list):
Floricream
Magnolia Blackeye (Open Pollinated)
Mississippi Cream Mississippi Purple (Open Pollinated)
Mississippi Silver (Open Pollinated)
Lima Beans:
Nemagreen
Cangreen
Hot Pepper:
Carolina Cayenne
Charleston Hot
Bell Pepper:
Carolina Wonder (Open Pollinated)
Charleston Bell
Pimento pepper:
Mississippi Nemaheart
Truhart-NR
English pea:
Wando
Snap bean (pole):
Alabama No. 1
Sweet Potato:
U.S. Plant Introduction (PI) 399163
Sumor
Nemagold
Tomato (partial list):
Better Boy VFN Hybrid
Better Bush VFN Hybrid
Beefmaster VFN Hybrid
Bush Early Girl Hybrid
Celebrity Hybrid
Fletcher Hybrid
Goliath Hybrid
Kewalo (Open Pollinated)
Lemon Boy VFN Hybrid
Parks Whopper Hybrid
Ultra Boy VFN Hybrid
Paste Tomato:
Roma (Open Pollinated)
Cherry Tomato (partial list):
Sweet Chelsea VFNT Hybrid
Sweet Million FNT Hybrid
Sweet Quartz VFNT Hybrid
Sweetie (Open Pollinated)
Tiffany VFNT Hybrid
