best to rotate patches to crops not associated with each
other—for example, Atlantic giant squash, tomato and
other vine type vegetables are closely related, so simply
rotating these vegetables in the garden will not keep rootdamaging nematode populations under control.
Solarization or covering the infested patch areas with
clear plastic tarps in the summer is another effective
control method. Growers are advised to frequently turn
the soil deeply or double dig two spade depths. This allows
delayering of the soil and ensures the sunshine cooks the
insects far below the surface, but this is a non-selective
treatment that harms beneficial insects as well.
Barren, fallowed patches that are kept free of weeds for a
year or two usually have a high degree of reduction in rootknot nematode populations. This plant-free interlude can be
completed in one season by using several intervals of tilling
the soil all summer long. Both solarization and leaving the
area fallow require extensive organic matter replenishment
to restore the soil’s bio-diversity after completion.
Marigolds grown near a pumpkin plant’s roots can also
be used to deter nematodes. The symbiotic relationship
of marigold host roots and rhizo-bacteria is thought to
impede root lesion and other types of parasitic nematodes.
This type of nematode control benefits susceptible crops
when non-host plants or marigolds are grown in rotation or
nearby vulnerable plant roots.
Other treatments include chitosan as a natural bio-control.
Derived from the crushed shells of shrimp and crab, chitosan
promotes the growth of fungi that consume chitin, which
makes up the eggs and shells of nematodes. The bio-control
action of chitosan begins spontaneously and promotes
defense responses within the plant to resist the attack of
insects such as nematodes.
Mustard is also useful as cover crop
in annual crop rotations. It can produce a large amount of rich, nitrogen-laden organic matter. Nematode
inhibition occurs in the release of a
chemical comparable to cyanide that
performs as a soil fumigant. Endonematodes larvae also pierce the
mustard roots and are unable to exit,
drastically reducing the number of
nematodes in the soil.
Beneficial or predatory nematodes
can reduce populations of plant
parasitic nematodes in soils. Aerobic
compost types of nematodes also
consume plant parasitic nematodes when found together in soils.
Populations of beneficial nematodes
can be raised by adding organic soil
amendments that foster bacterial
and fungal growth. These predatory nematodes can also be bred by
soaking fresh, diverse, composted
organic matter in water and brewing
it like a compost tea.
The above techniques work best in
the environment of a healthy soil food
web. Adequate organic matter levels
sustain a varied mixture of microorganisms. A well-balanced soil
rhizosphere supports a host of
natural biological creatures
that together manage
infestations at acceptable levels, allowing
plants to thrive.
Marigolds
grown near the
pumpkin plant’s roots
can also be used to
deter nematodes.”
Maximum Yield USA | February 2014
153