Agriculture Reference
In-Depth Information
Apple Maggots
One of the most widespread and serious fruit pests in North America, apple
maggot has long limited organic production. This insect primarily attacks
apple trees, but it also infests cherry, crab apple, hawthorn, pear, plum, and
quince trees. Adults are black flies that are a bit smaller than houseflies and
have black bands on their wings. They emerge from the soil in spring to
lay eggs under the fruit skins. The eggs hatch into small, white larvae that
tunnel throughout the fruits, eventually dropping to the ground and forming
pupae that overwinter. There is only one generation per year. Maggot-dam-
aged fruit is unmarketable and usually unsuitable for home use.
Control starts with early detection. Adult flights can be detected and
monitored using yellow sticky traps or red sticky spheres hung in your trees
at about eye level. Unfortunately, the traps do not capture enough flies to
manage the population. In western North America, the adults start laying
eggs about 10 days after they begin flying. Applying Surround, beginning
at petal fall, will somewhat control apple maggot. Spinosad significantly re-
duced maggot damage on apple trees in Cornell tests. Begin these applica-
tions at petal fall.
Fruit Flies
The most serious fruit flies for stone fruit growers are cherry fruit flies, of
which there are several species ranging across North America. Fruits dam-
aged by maggots are unusable, and maggots in processed cherries are con-
sidered contaminants. The real problem is for commercial growers because
there is a zero tolerance policy for maggots in packed fruit. A single larva
found in a shipment will cause that shipment to be refused. In the Pacif-
ic Northwest, the western cherry fruit fly is the primary commercial cherry
pest and requires perfect control. Spotted-wing drosophila was recently in-
troduced into California and is considered an extremely serious emerging
pest of cherries, raspberries, strawberries, blueberries, and perhaps of other
stone fruits because of similar quarantine issues.
