Cucurbits, bagworms, evergreens
By John
Fulton
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[June
13, 2013]
Everything in the squash, melon, pumpkin
and cucumber families is a cucurbit. There are several potential
insect problems with them, and today's column attempts to help
minimize or prevent these problems.
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In the first group of insects are the cucumber beetles. These
can be green, black and yellow striped, or black and yellow
spotted. The importance of the beetles is not that they eat
small holes in the leaves, but that the beetles can transmit a
bacterial wilt to the plants as they eat. The first thing you
see is you have a plant that suddenly wilts on various runners,
or the entire plant can wilt. The best means of controlling this
disease is a good beetle control program. Current
recommendations for homeowners would include these products,
with the days to harvest restrictions in parentheses: carbaryl
(0), bifenthrin (three days) or rotenone (one day). Of course,
Japanese beetles love cucurbits as well. Their damage is direct
leaf feeding. Remember they feed in groups, so once they get
started, you will have a battle on your hands. The carbaryl and
bifenthrin are both good control measures. Look for Japanese
beetles to start in earnest in about two weeks.
Squash bugs are the next problem to discuss. Squash bugs are
usually dark gray to black in color and like a long stink bug.
Their eggs usually hatch in mid-June to mid-July. The best
timing for control is when the eggs first hatch. Nonrestricted
products are sabadilla (one day), which is an organic product
that might be a little hard to find, and bifenthrin (three days
to harvest). One last note: If the squash bugs get past their
early growth stages, then physically removing them is about the
only control method available, or as the old joke goes, you
brick them (one brick in each hand clapped on the squash bug).
The last insect problem on cucurbits is squash vine borers.
These borers usually drill into the new runner areas and kill
off individual runners one at a time. The adults of these larvae
are red and black clearwinged moths. Scout your plants and look
for the adults, as well as entrance holes and the chewed-up
plant material. Treat as soon as early damage occurs and use one
of the following homeowner products: carbaryl, bifenthrin or
rotenone. Days-to-harvest restrictions have already been covered
(and these would also apply to pumpkin blossoms).
Bagworm check
If you haven't checked for bagworms yet, now would be a good
time. Small bags have been noticed in the county for the last
few weeks. Re-treatment may be necessary in some cases. Carbaryl
(Sevin) will work on the smaller bagworms, while the Bt products
may be required for the larger ones. All products work best on
the smaller bagworms, but the key is to have them all hatched
out if you are shooting for a one-application program.
Remember, bagworms frequently start in the tops of trees.
Bagworms are the larvae of clearwing moths that don't fly too
well. If you control the bagworms well, you may not have high
populations for a few years.
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Pruning evergreens
This is the time of year to begin pruning chores on evergreens.
This includes both needle-type and broadleaf evergreens. If you're
wondering what a broadleaf evergreen is, that includes holly,
rhododendron and azalea. The logic behind pruning your yews at this
time is to allow sufficient time for regrowth to become hardened off
before winter, and to keep new growth from becoming too rank before
the winter months. Start now, and complete your evergreen pruning
chores by the end of the month.
Pruning evergreens is part art and part science, but mostly art.
A few simple rules to follow make the job results much more
pleasing. Upright-growing evergreens, such as pines and spruces,
should not have the main leader cut off. That destroys the natural
shape and makes the resulting growth more susceptible to breaking
off. If individual branches are being cut off, they should be cut
back to a bud. This will allow the bud to become the new main
branch. You can also control growth direction of branches in this
way. If you are growing trees for cut Christmas trees, all bets are
off, as you are dealing with the trees only through the first seven
years or so of their life.
Make sure you use the proper equipment. Individual pruning cuts
are best done with bypass loppers or pruning shears. These make
clean cuts without much damage to the remaining wood. The old
anvil-type shears and loppers cut to a point, then crush the
remaining wood. For yews, junipers and arborvitae that are trained
to a certain size or shape, you will want to use hedge shears
(electric or manual) that are sharp and properly tightened. Most of
these types of shears can cut up to about a quarter of an inch in
size.
When pruning evergreens, remember there is a dead zone. This is
the area toward the center of the plant that doesn't receive much
light. It also has few needles or active buds. Cutting into the dead
zone will cause many years (or forever) of little green growth. Also
remember to prune so that the base of plants is wider than the top.
This allows sunlight to hit the bottom area as well and keeps the
bottom from dying.
[By
JOHN FULTON,
University of Illinois Extension] |