Midwest Vegetable Guide - 2022 - 77

Nematode Management Strategies
Nematode Management
Strategies
Reviewed by Marisol Quintanilla - September 2021
The soil contains many nematode species, and some species
are parasites of plants and animals. Even so, most plants can
be parasitized by at least one of the plant-parasitic nematodes.
Most plant-parasitic nematodes feed on roots while some feed
within leaves.
Plant-parasitic nematode feeding does not necessarily result
in characteristic secondary (aboveground) symptoms. For this
reason, nematode problems often go undiagnosed. Typical
aboveground symptoms of nematode infections include
stunting, yellowing, and wilting. In some situations,
nematodes can cause considerable yield losses; however,
nematodes can reduce yields without plants showing any
noticeable aboveground symptoms.
The best defense against nematodes is to avoid them. It is
possible to prevent moving nematodes that are not present in
your field by following simple sanitation methods such as
washing machinery after using it in an infested field. Once a
nematode is established in your field, eradicating is usually
not a viable option. There are many different types of plant
parasitic nematodes, some are more serious than others and
some specialize on a specific crop. Most soil has at least a
few plant parasitic nematode species. Due to their
microscopic nature and abundance in soil, avoiding
nematodes is nearly impossible, so nematode infestations in
some fields are inevitable, but it is possible to prevent or
delay the movement of nematodes not found in your field
with sanitary practices.
Nematodes can travel long distances on machinery, human
foot traffic, in plant material, on animals, in water, and in the
wind. The bottom line: Anything that moves soil, may move
nematodes. Many of these factors are uncontrollable.
However, growers can control how they move and sanitize
their machinery. If field samples indicate that pathogenic
nematode species are present at damage threshold levels, take
steps to reduce the population densities of these organisms.
Here are five effective tactics for controlling nematode
populations.
Cultural Controls
Cultural nematode management are one of the most effective
methods of managing nematodes. Cultural methods that can
be effective are: crop rotation with non-hosts, options include
choosing crop plants or cover crops that are not hosts for the
problem nematode, selecting the optimal planting date,
planting companion plants, and so on. We recommend
rotating with a non-host. For example, grasses are non-hosts
to northern root-knot nematodes, so rotating with a grass
(such as corn, wheat, etc.) will reduce northern root knot
nematode populations. Using cultural tactics requires you to
properly identify which plant-parasitic nematodes are present.
Genetic Controls
Plant resistance is often one of the most sustainable control
tactics. For example, many tomato varieties have resistance to
root-knot nematodes. However, most vegetables do not have
resistance against nematodes, and currently, there are no
genetically modified varieties available. Some vegetable
varieties may better tolerate nematode feeding, but this
information is not always readily available.
Chemical Controls
Nematicides are compounds that kill nematodes. There are
two main types of synthetic nematicides: fumigants and
nonfumigants.
Fumigants are typically sold as liquids or gases that react
with water in the soil to produce gases that kill a wide variety
of organisms (including plants) depending on the compound.
They are wide- spectrum biocides. If you fumigate, you
should do it in the fall (preferably) or spring when soil
temperatures are adequate and before the crop is planted.
Fumigating can be effective, but also quite costly, so in many
cases using a nonfumigant nematicide will make more
economic sense.
Nonfumigant nematicides do not volatilize in soil water.
They can be applied before, during, or even after planting in
some situations. These compounds are often not as broad in
their spectrum as fumigants. Nonfumigants may be less
detrimental to beneficial organisms since some of these
compounds are more specifically targeted to nematodes and
some are systemic in the plant and thus target mostly
nematodes feeding on the plant. It is important to select a
nematicide to meet your nematode management needs and
economic thresholds.
Fumigant and nonfumigant nematicides labeled for use in
vegetable production are shown in the Nematicide Table.
Biological Controls and
Bionematicides
Most nematodes in the soil are beneficial. They typically feed
on bacteria, fungi, or small animals including other
nematodes. Some methods to increase soil health is crop
rotation, reducing tillage, using cover crops, and using
compost and manures.
In addition, many other organisms are parasites or pathogens
of nematodes. Most of these occur naturally in soils, but they
Midwest Veg Guide 2022
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Midwest Vegetable Guide - 2022

Table of Contents for the Digital Edition of Midwest Vegetable Guide - 2022
