As for control, the straight 2,4-D that is used
on dandelions seems to act like a fertilizer for chickweed and other
problem weeds. The 2-4D is a growth regulator, and if it doesn't
actually kill a weed, it does make it grow faster. Combinations that
contain 2,4-D, MCPP and dicamba are rated very effective on
chickweed, henbit, red sorrel, purslane, white clover and others.
Just remember the control time for most broadleaf weeds is early
May, but the winter annuals are going strong now.
These combinations are sold under several different trade names.
You can find the products at most hardware, discount, and lawn and
garden stores. Just check the label under active ingredients and
check for two long chemical names and dicamba. You can also check to
see that it says it will control chickweed and henbit.
This group of chemicals is effective in the 50-degree range and
up. It just takes a lot longer for control with very cool
As with any chemical control, read and follow label instructions
very carefully. The labels will have some cautions you should be
aware of concerning injury to sensitive plants. This is because
dicamba can drift as a vapor for a few weeks after you apply it, if
the weather gets hot and sunny.
Fairy rings, mushrooms and puffballs
Throughout the year I get several calls and samples brought in
dealing with puffballs or toadstools. Even this early in the season,
we have had calls about dark green grass in rings that kind of look
like a target pattern. These rings are called fairy rings, and they
frequently have the puffballs or toadstools growing in the area.
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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 large roots from 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.
University of Illinois Extension]