Root Knot Nematodes
Nematodes broke-through the m1 gene in our resistant tomatoes this year. Also, soil temps got into the 80's well before harvest, thereby rendering the resistant gene ineffective. The tomato plots, which are drip irrigated and comprise 35 thousand sq ft, are so severely infested that we are either going to have to fumigate this fall or take that area out of production and clean fallow/solarize for several years. (The degree of infestation is beyond crop rotation or trap crop solutions).
Our project technical advisor has limited experience with nematicides like Vydate or Telone and is not comfortable with them. Methyl Bromide is no longer legal and Vapam is very expensive, difficult to obtain, dangerous to apply and often ineffective. The bottom line is that we simply don't have the expertise to safely work with these highly toxic chemicals.
According to the experts at TX A&M. LSU and U of Florida and our own review of the literature, there are no really effective organic nematicides that would work - especially in our coarse, sandy soil which has little organic matter. Solarization and clean fallow for several years appears to be our only solution.
Since nematodes are inactive at soil temps below 70 degrees, we are considering the following strategy as an
alternative and would welcome any comments:
(1) Remove and burn all tomato plants from infected areas when harvest ends in a few weeks. (2) Till deeply and clean fallow with glyphosate and/or solarize under plastic the rest of the summer. (3)When the soil temp drops below 70 in the fall and the nems are inactive, plant our winter greens in those areas and harvest them through spring until soil temps reach 70 again. (4) Till-in the crop residues and again clean fallow the infected plots all summer until fall. (5) Plant our tomatoes elsewhere and repeat this brassica/fallow rotation for several years until soil tests show that the RKN population has declined sufficiently.
We understand that brassica residues also help suppress RKN activity to some extent. If they have nothing to eat during their active months, we should starve them out...???
Thanking you in advance for your comments. We are a church-affiliated grower providing fresh vegetables to the public at no charge. We do accept donations from those who wish to contribute.
Gardeners for Jesus Ministry