Chapter 23

Managing Nematodes in Vineyards

Controlling Nematodes in the Vineyard

Pre-plant Control

Resistant Rootstocks

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 Management

Before planting a vineyard it is good practice to implement soil management procedures that reduce the nematode populations.

Soil Fumigation

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.

Soil Solarization

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.

Post-plant Control

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.

Sanitation

Nematodes can be spread in soil trapped on machinery (e.g. contractors), equipment (e.g. grape bins), vehicles, people and planting material. A designated wash-down area should be available for all machinery and equipment to use.

Chemical Pest Control

Chemicals effective against nematodes (nematicides) which are registered for use in viticulture are limited. Only those nematicides registered for application to grapevines can legally be used, and are best applied only if infestation levels are high enough to justify treatment. Application should be concentrated in the areas in the vineyard where nematode populations are highest—this is usually along the vine rows, rather than in the inter-row strip.

Biological Pest Control

A wide range of fungi, bacteria and invertebrates parasitize or prey on nematodes. Potential biological control agents include the bacterium Pasteuria penetrans which occurs naturally in many soils and which might provide some natural suppression in long established vineyards.

Cover Crops

Cover crops are used to manage nematodes because nematodes can move only very short distances on their own (Figure 23.2).

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