Treating for bagworms to planting pumpkins
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[June 10, 2008]
After some very severe infestations of
bagworms the past several years, the calls have been coming in all
year on the correct treatment times for bagworms this year. Year in
and year out, the correct treatment time for bagworms is June 15.You
can mark this date on your calendar for next year and be within a
few days of the correct treatment time. With a very cool spring, a
week later may be a possibility. The opposite is true for a very
warm spring. The idea is to have all the eggs hatched before
treatment but not wait until the bagworms are almost mature.
The next problem is what to use. 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 where they can kill the bagworm.
If you are in
doubt about whether you have bagworms, check your trees and
shrubs around June 15. 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. The spring we have had is probably going to add a week
to the timing, meaning the last week or so of June should be
Most people think that bagworms only affect evergreens. While
evergreens may be their preferred host group, bagworms have a
huge number of potential hosts. Through the years I have seen
them on oak trees, grapevines, apples and about any other
growing thing you can think of. Make sure to check the tops of
tall trees. An infestation may get started in a tall tree simply
because you can't reach the top when applying a control. In that
case, you'll have to use a taller ladder.
Island chlorosis of hackberry
There is a disease of hackberry leaves that appears as blocky
yellow spots. The spots often have green tissue surrounding them
(but not always), so the disease has earned the name of island
chlorosis. In addition to causing the yellowing symptoms, the
chlorosis can cause some leaf drop. The disease is mainly a
curiosity on established hackberry trees and causes little
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Branch dieback of juniper and arborvitae
After several years of relatively few problems of junipers and
arborvitae, we've had a resurgence in the shoot blights.
The most common is phomopsis tip blight, which affects the new
growth. New growth is susceptible until it loses its lighter color.
Symptoms are a "shepherd's crook" shape to the dead tips and the
small black dots of the fungal fruiting bodies. Control consists of
removing infected areas and spraying new growth with protectant
fungicides until it gets the dark green color.
Kabatina and Cercospora blights affect older needles of
evergreens. Kabatina blight is not as common, and it is not
controlled by fungicides. Cercospora blight tends to infect the
older needles on lower branches first. The appearance of branches is
having only the new growth at the branch tips being green. Repeated
applications of fungicides will have some effect on Cercospora.
There are varieties resistant to these diseases, but you can't
find one resistant to all three.
With the weather we've had, gardening has either been a chore or
it has been ignored. We are to the normal planting time for
Halloween pumpkins. Father's Day is a good time to plant them in
order to have them ripen for the fall decoration season but not
ripen too early to have rot problems in advance.
University of Illinois Extension, Logan County]