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 hard-to-control weeds and woody plants.
It also improves control of violets. It can be combined with one
or more additional chemicals to provide broad-spectrum control.
Some blends now contain triclopyr, so check the label.
The old standby is 2,4-D. It is good on carpetweed, chicory,
dandelion, lamb's-quarters, plantains and wild carrot. MCPP 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 in hot and humid
conditions, the products can drift as a vapor for up to two
weeks after spraying.
Cedar apple rust
Cedar apple rust is caused by a fungus that attacks two
different groups of trees. The first group is apples and
crabapples, and the second is juniper and eastern red cedar. In
order to survive, the fungus must "move" from one group or host
to the other.
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On juniper, or eastern red cedar, small galls (3/8 to 1 3/16 inches
in diameter) develop throughout the tree on needles and small twigs.
When mature, these galls swell considerably and repeatedly produce
orange, jello-like horns during rainy spring weather. As spring
rains subside, the galls die, which may cause death of the twig from
the gall to the tip.
On susceptible crabapples and apples, tiny yellow spots appear on
the leaves after infection in the spring. As the spots mature, they
become yellow-orange and swollen, with a red border, and develop
tiny black dots in the center of the lesion. By midsummer, small
cuplike structures with tubes are visible on the undersides of
mature leaf lesions. The fungus may also infect fruit and tender
twigs of very susceptible crabapple and apple varieties.
The entire life cycle takes about two years, with a year on each
host. The apple phase is easily recognized on the leaves and fruit
by just about anybody who has grown apples. The teliospore phase on
the cedars is quite striking, but is noticed much less frequently.
Fungicides in spray programs do a good job of controlling the
apple phase, while the cedar phase is best controlled by buying
resistant varieties. Some homeowners cut the galls off before they
break out into the "orange blob," but the result is the same: You
are likely to lose the tips on those branches.
University of Illinois
Extension director for Logan, Menard and Sangamon counties]