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Fairy rings are caused by a fungus that is in the soil. Actually
there are about 50 fungi that can cause fairy rings. These fungi
feed on decaying organic matter, such as from large roots of
trees that were in the area or from buried lumber. The dark
green circle part of the equation comes from extra nitrogen that
becomes available as the organic matter is broken down by the
fungus. Some prevention will help keep the problem from
occurring. Simply removing stumps, large roots and not burying
lumber help prevent this type of problem. As for a cure,
fungicide drenches have been successful on a very limited basis.
One option is to mask the symptoms of the dark rings by
fertilizing the surrounding grass with a high-nitrogen
fertilizer to make that grass green also.
As for the puffballs, toadstools or mushrooms, they are part
of the same complex as fairy rings. They are part of the natural
decay process that helps break down large wood items in the
ground. There is no real control, so mowing them off or knocking
them loose with a garden rake is about the best thing going.
Eastern tent caterpillar
This insect is poised and ready to come out. It doesn't seem
like that long ago when we were talking about eastern tent
caterpillars doing their thing on lots of different trees last
year. I have seen some small nests of the tent caterpillars
already, so be on the lookout.
To clarify things, these are the insects that make a big
webbed nest, usually at the angle of two limbs, then go out of
this nest to feed. Some people call these bagworms, but they are
actually tent caterpillars. Common species of trees affected
include apples, crab apples, cherries, box elder, ash, mountain
ash and others.
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Control can be achieved by spraying foliage, after seeing the
insects, with one of the following: acephate, malathion or one of
the Bt products. Remember that the Bt products are bacteria that
affect only the larvae of moths and butterflies and are sold under
trade names such as Dipel, Thuricide, Sok-bot and Caterpillar
Attack. These Bt products are the safest to use both physically and
environmentally. Their only drawback is that sometimes they don't
work as quickly as their traditional counterparts. Spruce
spider mites
Many of the problems with browning needles on the spruce trees in
our area are caused by spruce spider mites and their relatives. One
way to check for these pests is to hold a sheet of white paper under
the needles and then look for "running dust specks." If you have the
problem, a miticide is required (sometimes different from an
insecticide). One of the most effective ones, if you can find it, is
dicofol (Kelthane). Red mites that are faster moving than the others
are predatory mites. If you have a large number of predators, the
controls are usually unnecessary. Insecticidal soap, Talstar, Pentac
and dimethoate are other control methods. Dimethoate is probably the
easiest to find and can be purchased without a license. However,
this product may cause more damage, due to the oil solvent and the
nature of the chemical. A double rate of dimethoate can actually
kill plants. Please follow all label instructions when using any
pesticide.
Master Gardener plant sale
The highly anticipated Master Gardener plant sale will be
Saturday from 9 a.m. until noon (or sellout) in the Logan County
Fair South Exhibition Building. They have a good selection of day
lilies, rhubarb, hostas and other plants.
[John
Fulton, unit leader,
University of Illinois Extension,
Logan County Unit] |
