Nematicidal Efficacy of Biofumigation by Defatted Brassicaceae Meal for Control of Meloidogyne incognita (Kofoid et White) Chitw. on a Full Field Zucchini Crop

The use of Brassicaceae biocidal green manure crops (e.g., Raphanus sativus ssp oleiformis and Eruca sativa ssp oleiformis) is an agronomic technique for the control of several nematodes including Heterodera schachtii and Meloidogyne incognita. Recently, these crops have been extensively studied and even commercially applied in horticulture rotations. In addition, the possibility of producing a formulation based on Brassicaceae defatted seed meals characterized by biocidal activity has been developed. These meals are able to amend soils with organic matter containing nematicidal volatile compounds, derived from the enzymatic hydrolysis of endogenous glucosinolates. This option opens new perspectives for an organic and low environmental impact nematode control. In this study, the effect of a treatment with industrial defatted meals on a commercial zucchini cultivation in greenhouse, on sandy soil heavily and uniformly infested by root-knot nematode Meloidogyne incognita was evaluated. This effect was compared with the effectiveness of six liquid applications during zucchini crop using Oxamyl distributed by drip irrigation, a technique allowed, recommended and commercially applied on zucchini in the area where the experiment was conducted. During harvesting time, the nematode level both in roots and in soil, and some qualitative (length, weight and diameter) and quantitative (yield) zucchini parameters were evaluated. Compared with the chemical control, defatted seed meal application clearly limited nematode infestation and allowed plant roots with a lower root gall index (2.0 to 3.5 versus 3.5 to 4.5). The zucchini yield in biocidal seed meal treated plot was the same as the control in the first month of harvesting, but it was 9% higher in the second month of harvesting due to the lower infestation of zucchini roots. In addition, in the plot treated with defatted seed meal, harvesting time was one week longer than chemical plot with a final 14% total yield improvement.