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Anthracnose spots generally start along the leaf edges or
between the veins. Eventually, the spots enlarge to become large
blotches. Many of the affected leaves actually drop from the
damage. Most often affected are sycamores, good-quality maples
and other good-quality shade trees. In fact, anthracnose is one
of those diseases that can affect everything from turf grass to
tomatoes to trees. With most fungi (that's plural for fungus),
there are preventive applications available but no cure. The
good news is that anthracnose on trees is usually a "limited
damage" disease. Depending on the infection time, damage can
include leaf loss, bud death or twig death. Large limb death
means we have to look for another cause. In severe cases,
anthracnose can make a tree lose all its leaves. For trees in
good condition, a new set of leaves is usually out in less than
six weeks.
Anthracnose can infect until nighttime temperatures reach and
maintain about 65 degrees. This means we will probably have a
while to feel the effects of the disease.
As for treatment, there isn't any direct, curative treatment
available. You might have prevented it -- if you sprayed three
or more times and had equipment that would spray the entire
tree. The best thing to do is make sure all the small things are
done. This includes watering when it is dry, fertilizing the
tree at the lawn fertilizer rate and generally keeping the tree
in good shape.
There are other fungal diseases that affect other types of
trees. Apple scab gets production apples and crab apples; tar
spot gets silver maples; etc. Fungal leaf spot diseases are all
grouped together, with the same effects and recommendations.
[to top of second column]
 |
 Broadleaf weed control
It is time to control your broadleaf weeds in the lawn in
earnest. The first item of business is to know what type of weeds
you want to control. This will make a big difference in what product
or products you select.
The main products used for broadleaf weed control in lawns are
2,4-D, MCPP, dicamba, a combination of those three products and
triclopyr.
Let's start with the triclopyr since it's probably the easiest to
discuss. Its place in weed control is for violet control. It is
death on violets. It can be added to one or more other chemicals to
provide broad spectrum control. The locally available formulation
from Ortho is Chickweed, Clover and Oxalis Killer.
The old standby is 2,4-D. It is good on carpetweed, chicory,
dandelion, lamb's-quarters, plantains and wild carrot. MCPP (mecoprop)
is good on chicory, lamb's-quarters and white clover. Dicamba is
good on black medic, chickweeds, chicory, dandelion, dock, henbit,
knotweed, lamb's-quarters, pearlwort, purslane, red sorrel,
thistles, white clover, wild carrot and yarrow. The combination of
all three products will pick up all of those listed for the
individual products, plus a few more, such as mallow, speedwell and
wild onion. The combinations are sold under many different trade
names, so check the active ingredient list for ones you need.
My annual disclaimer for application of these types of products
is: "Beware of potential drift from these products." Not only can
the spray move under windy conditions while you are spraying, but
particularly with dicamba, the product can drift as a vapor for up
to two weeks after spraying in hot and humid conditions.
No brands are particularly endorsed. Brands named are as a
convenience in finding products. The same active ingredients should
be equally effective. Read and follow the label of any pesticide
used.
[John
Fulton, unit leader,
University of Illinois Extension,
Logan County Unit] |
