No-Till: Making It Work - Insect
Management
No-till crops are susceptible to the same number of pests - insects,
slugs, and nematodes - as conventional crops. However, with the slightly
different "habitat" found in no-till, some types do better and
others do not fare as well. General control methods are similar to any
other cropping system. The difference is that with no-till, the pests
may differ from those you're used to dealing with.
Living and dead vegetative cover creates sheltered, cooler and slightly
wetter environments above and below ground for pests. Delayed emergence
under these conditions may increase the risk of pest attack.
For example, cutworms and armyworms have life cycles that depend on pre-crop
vegetation.
The same habitat conditions that attract pests also attract beneficial
insects (e.g. wheat residue attracts beneficial spiders).
The increased diversity of animal life attracted to no-till fields also
helps to keep populations of any one species in control.
Figure 1. For many pests, the best control method is to
keep your fields as weed-free as possible.
Best Management Practices (Sample chart only)
Description
Larvae are whitish in colour with dark brown or black heads and black
or brown spots in rows down their backs. Moths are cream-coloured and
active at night
Damage Caused
Newly hatched larvae feed on developing leaves in the whorls before tunnelling
into the plant to feed on the tassel, stalk or ear shank. Plant becomes
susceptible to stalk rots and lodging.
Conditions Preferred
Full-grown larvae overwinter inside the base of corn stalks. In the spring,
they form cocoons and emerge as adult moths in early June.
Best Management Practices and Tips
Chemical control measures are rarely justified in field corn. Select
hybrids with good standability. New hybrids with built-in Bt resistance
to corn borer are now available in Canada. Bt is Bacillus thuringiensis,
a bacterial control effective against corn borer. Area-wide stalk chopping
may help to reduce corn borer populations, but will only be successful
if most growers participate.
Spider Mites
Description
Tiny round eight-legged arthropods that are white, green or red in colour
with dark spots on either sides of their bodies.
Damage Caused
In soybeans, mites suck plant juices from the undersides of leaves, giving
plants a sand-blasted look. Fine silky threads are spun on leaf undersides.
In heavy infestations, leaves turn yellow, then brown and die.
Conditions Preferred
Most numerous during hot, dry periods. Drought conditions will drive
them from fencerows, too. Mites can thrive in green vegetative crops or
cover crops and move onto young bean plants after spring burndown. High
winds will spread them across fields.
Best Management Practices and Tips
Four or five mites per leaf or one severely damaged leaf per plant can
cause yield depression. Can spot apply insecticide to prevent spreading
to rest of field.
Available in Published Version of No-till
- Best Management Practices for Management of Common Insects - chart
- Best Management Practices for Management of Non-Insect Pests - chart
