Agriculture Reference
In-Depth Information
If you must spray, treating at prebloom and bloom times is more effective
than treating postbloom. Unfortunately, organic insecticides, other than
rotenone, are not generally listed for control of this pest. Because of potential
human health problems, rotenone is typically no longer available to organic
fruit growers. Neem products, insecticidal soaps, and spinosad products are
about the only materials available for this pest. Apply insecticides from
prebloom until the first blossoms begin opening, and again at petal fall.
Scales
Scales are sucking insects that include San Jose scale, oystershell scale, and
fruit lecanium scale. Unlike aphids, which are soft-bodied and easy to kill,
adult scales cover themselves with hard shells that fit tightly against the
bark, leaves, and fruits. Scales are common and serious pests of tree fruits
across Canada and the United States. The adults' and nymphs' feeding weak-
en and can kill trees, and the scales on fruit make the fruit unmarketable.
These pests overwinter as eggs and larvae in fruit trees and many other
woody hosts. It's important to scout carefully for them. During the dormant
season, look for the flattened shells on twigs and limbs. In early spring, about
the time codling moth emerges, use pheromone traps to monitor the flights
of male San Jose scales. From spring through fall, attach black sticky tape,
with the sticky side out, around twigs and small branches to detect crawlers.
It is at the crawler stage that the scales are most susceptible to predators
and pesticides, but with up to five generations per year, you can almost al-
ways find the crawlers during the growing season.
A very effective way of controlling scales is to apply a dormant lime sul-
fur spray about 30 days before bud swell, followed by a dormant horticultur-
al oil spray during bud swell through green tip. Using summer-weight horti-
cultural oils during May and June can also be effective, but they may cause
phytotoxicity on your fruit crops. Azadirachtin can control crawlers and mo-
bile adults during the growing season.
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