Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 21, 2011
Publication Date: March 25, 2011
Citation: Meyer, S.L., Zasada, I.A., Orisajo, S.B., Morra, M.J. 2011. Mustard seed meal mixtures: management of Meloidogyne incognita on pepper and potential phytotoxicity. Journal of Nematology. 43(1):7-15. Interpretive Summary: Plant-parasitic nematodes are microscopic worms that cause ten billion dollars in U.S. crop losses annually. A major problem facing growers is the lack of safe and effective methods for reducing crop losses caused by nematodes. Mustard seed meals are byproducts resulting from crushing seed to provide oil for the production of biodiesel. Two seed meals, made from the mustard plants Brassica juncea and Sinapis alba, were tested alone and in combinations for toxicity to plants and for suppression of root-knot nematode populations on pepper. Overall, B. juncea seed meal was the least toxic to pepper seedlings, while seed meal from S. alba did not inhibit lettuce seed germination but did reduce shoot growth. The number of nematode eggs on pepper plants was lowest with certain B. juncea treatments and with some of the mixtures of the two seed meals. The results are significant because they indicate that B. juncea seed meal and some mixtures can be applied close to transplant to suppress root-knot nematode populations on pepper; consequently, a seed meal mixture could be selected to provide activity against more than one pest or pathogen. This research will be used by scientists developing environmentally safe methods for managing diseases caused by nematodes.
Technical Abstract: Meals produced when oil is extracted from brassicaceous seeds have been shown to suppress weeds and soilborne pathogens. These seed meals are commonly used individually as soil amendments; the goal of this research was to evaluate seed meal mixes of Brassica juncea Bj and Sinapis alba (Sa) against Meloidogyne incognita. Seed meals from Bj ‘Pacific Gold’ and Sa ‘IdaGold’ were tested alone and in combinations to determine rates and application times that would suppress M. incognita on pepper (Capsicum annuum) without phytotoxicity. Rates of soil application (% w/w) for the phytotoxicity study were: 0.5 Sa, 0.2 Bj, 0.25 Sa:0.25 Bj, 0.375 Sa:0.125 Bj, 0.125 Sa:0.375 Bj, and 0, applied 0–5 weeks before transplant. Overall, 0.2% Bj was the least toxic to pepper seedlings. Meals did not affect lettuce seed germination at weeks 1-5, but hypocotyl growth was reduced by all except 0.2% Bj at weeks 1, 4 and 5. Bj and Sa were tested for M. incognita suppression at 0.2, 0.15, 0.1 and 0.05%; mixtures were 0.1% Sa:0.1% Bj, 0.15% Sa:0.05% Bj, and 0.05% Sa:0.15% Bj. All treatments were applied 2 weeks before transplant. The 0.2% Bj and 0.05% Sa:0.15% Bj treatments overall had the longest shoots and highest fresh weights; 0.2% Sa tended to decrease pepper plant growth compared to 0.2% Bj. Eggs and galls/g root were lowest with 0.1– 0.2% Bj treatments and the seed meal mixtures. The results indicate that Bj and some Bj:Sa mixtures can be applied close to transplant to suppress M. incognita populations on pepper; consequently, a seed meal mixture could be selected to provide activity against more than one pest or pathogen. For pepper, care should be taken in formulating mixtures so that Sa rates are low compared to Bj.