Cover cropping in Ontario
John W. Potter
Agriculture Canada, Vineland Station, Ontario, L0R 2E0
In Ontario, Canada, we are researching cover crops with the following objectives in mind: 1) Suppression of reproduction of the root-lesion nematode Pratylenchus penetrans and the northern root-knot nematode Meloidogyne hapla; 2) Identification of fungal- and nematode-resistant cover crops which also balance C:N ratios in sandy soils; 3) Screening of minimal-growth weed-competitive permanent sod plants for orchard understories.
Overall, our goal is to achieve non-fumigant pest control in the context of sustainable Integrated Crop Management (ICM) systems. We are addressing nematode suppression primarily by investigating allelopathic plants. Prime candidates are the Brassicas, especially the high-glucosinolate mustards; Compositae, especially Tagetes marigold cultivars and Rudbeckia; sorghums and sudans with high-dhurrin content; and flax. For orchard covers, we are studying dwarf or minimal-mowing grasses, particularly the endophytic ryegrasses which have shown weed suppression.
Results to date show 15 varieties of marigolds as being highly
resistant to Pratylenchus; one variety vigorously suppressed
yellow nutsedge grass also. Mustards as green manures look promising
for both fungi and nematodes; in one field test, mustards incorporated
just before anthesis resulted in potato yields equivalent to those
in soil fumigated with Telone or Vorlex, with potato variety "Superior"
which is highly susceptible to the Early Dying complex of Verticillium
fungus and Pratylenchus nematodes. Specific cultivars of
sorghum/sudan are proving to be quite antagonistic to nematodes,
and provide high C, which can balance organic-waste amendment
sources of N.
Cover Crop Research and Education Summaries