Managing Nematodes in Vineyards
Controlling Nematodes in the Vineyard
Resistant Rootstock Varieties
Nematode-resistant rootstocks offer the most effective, long term control of nematodes in vineyards. However, when considering rootstocks the characteristics imparted to grafted vines should be taken into account, as the viticultural impacts may not be desirable for a given vineyard situation.
Soil fumigation before planting grapevines is an effective approach for controlling soil-inhabiting nematodes. Fumigants typically used to reduce the population of pathogenic nematodes in soil include Vapam (metam-sodium), Telone II (1,3-Dichloropropene), and Basamid G (dazomet). These fumigants will also help in reducing the levels of soil-borne plant pathogens and viable weed seeds.
Solarization involves capturing the heat of the sun by covering the soil with transparent polyethylene plastic sheets during warm, sunny months. The soil temperatures under the plastic increase to levels lethal to many soil-borne plant pathogens, weed seeds, seedlings, and nematodes. Solarization reduces the nematode population drastically but will not totally eradicate nematodes.
Soil Water Management
Soil and water management efforts that minimize vine stress can increase vine tolerance to nematode attack. Soil practices include preventing compaction and stratification of the soil and improving the structure through the addition of organic matter and adjusting the fertility and soil pH to near optimum conditions.
Nematodes can move only short distances in the soil, but can spread to previously un-infested areas through the introduction on planting material, by movement of soil or water, and in soil adhering to machinery and other equipment.
Nematode populations may be reduced even further by planting a cover crop. For example, Brassica species (rapeseed, Brassica napus) is an option in that it releases chemical compounds (e.g., glucosinolate) that may be toxic to nematodes. However, to be effective, the brassica crop must be used as a green manure.
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