 Fire blight is a bacterial disease; therefore, there is little
chance for you to treat it. The common treatment in commercial
operations is streptomycin, but it has to be applied before
symptoms appear. I don't think you will get a prescription for
that much antibiotic, so Bordeaux mixture can also help prevent
the disease (applied before the infection next year). Prune out
disease cankers when dormant. This disease cost Illinois its
pear industry.Apple scab is also easily seen -- once again.
Insects are plentiful this year. They have great systems of
survival, and it was a mild winter. Once again we are seeing
some earwigs. This is a little bit of a surprise since it has
been so dry this year. Earwigs tend to be in high-organic areas,
as they feed primarily on dead insects and plant material.
However, they can and do eat living plant material such as
marigolds, zinnias, strawberries and others. They may be a prime
suspect if you notice damage but never see any insects during
the day. Control can be obtained with insecticides such as
bifenthrin or permethrin.
As anticipated after the dry year, grasshopper numbers are
large. You may want to spray border areas, where the
grasshoppers congregate, before mowing or trimming. As with most
insects, control of small grasshoppers is easier than control of
large ones. Sevin, permethrin or bifenthrin should provide
control.
Leatherwing beetles, or soldier beetles, have been with us a
few weeks -- particularly where linden trees are pollinating.
They look like pale lightning bugs but don't have the light.
These beetles are elongate, soft-bodied and about a half-inch
long. Colors of soldier beetles vary from yellow to red with
brown or black wings or trim. A common and easily spotted
species is the Pennsylvania leatherwing, which is yellow with
one large black spot on each wing. Most larvae are carnivorous,
feeding on insects in the soil. Larvae overwinter in damp soil
and debris or loose bark. The adults are also predators, eating
caterpillars, eggs, aphids and other soft-bodied insects. They
will alternatively eat nectar and pollen if no insects are
around. They do not damage plant foliage. Adults are often found
on flowers such as goldenrod, where they lie in wait for prey,
feed on pollen and mate. Since soldier beetles are beneficial,
it is inadvisable to kill them.
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Potato leafhopper populations have exploded in the last week.
These are the small, pale green, wedge-shaped insects we often
see around lights at night. The main garden crop they affect is
-- guess this one -- potatoes. They suck sap and inject a toxin
back into the plant. The first sign is a yellow "V" at the tip
of the leaf. These areas then turn brown or black. Entire plants
or branches can die from these tiny insects. Control with Sevin,
bifenthrin or permethrin.
Cicada killer wasps are also beginning to be seen. Cicada killers
are more common in areas with bare soil, so mulching, planting
ground covers or putting down sod can reduce problems. Applying
permethrin or Sevin (some suggest the Sevin dust gives better
control) to the burrowed area should kill females in high-traffic
areas.
The last insect to discuss is the bagworm. Bagworms are notorious
pests of evergreens such as spruce trees. We're about to June 15,
the traditional date for control. With the warmer spring, we
actually ran about two to three weeks early. The idea is to have all
the eggs hatched before treatment, but not wait until the bagworms
are almost mature. For control, the traditional standby has been
Sevin, but the Bt products such as Dipel and Thuricide have really
taken their share of the market the past several years. The Bt
products have several good points, including safety to mammals and
toxicity to larger bagworms. Since they are bacteria that affect
only the larvae of moths and butterflies, it does take a while for
the bacteria to build up to the point that they can kill the
bagworm. If you are in doubt about whether you have bagworms, check
your trees and shrubs. You can actually see the small bags as the
larvae build them. They become very noticeable at about
one-sixteenth of an inch long. Treat bagworms early, since larger
ones are more difficult to control.
[By
JOHN FULTON,
University of Illinois Extension]
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