Agriculture Reference
In-Depth Information
Leafminers
At least three species of leafminers infest pome and stone fruit crops across
the United States and Canada, including apple blotch leafminer, spotted
leafminer, and western tentiform leafminer. These pests are small moths
about 1/10 inch long. Adults have brownish wings with white bands that ap-
pear silvery as the moths fly.
The adults deposit eggs on the undersides of the leaves, and the larvae
tunnel into the centers of the leaves and tunnel through the leaf between the
upper and lower surfaces. The first three stages (instars) of the larvae have
sucking mouthparts, and the fourth and fifth stages have chewing mouth-
parts and eat the leaf tissues. The later larval stages web together the sides
of the tunnels, creating tent-like shapes. The larvae then pupate inside the
fallen leaves, emerging as adults in early spring as new leaves begin unfold-
ing.
Parasites normally control these pests, and serious outbreaks are infre-
quent. During mid-spring, examine 100 leaves per block of trees. If there are
fewer than two or three tunnels per leaf, you probably do not need to control
them. If there are more than two or three tunnels, you may want to begin
a management program. Applying azadirachtin products, insecticidal soaps,
and spinosad products just before bloom should help manage leafminers.
Good sanitation practices that involve removing or destroying overwintering
leaves on the orchard floor may also help reduce leafminer populations.
Flies, Sawflies, and Midges
Several fly, sawfly, and midge insects are serious pests on fruit crops. Among
the most serious are apple maggot and various fruit flies. While damage to
the fruit may often appear minor, even a small percentage of infested fruit
can render a fruit shipment unmarketable.
