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Leaf symptoms usually appear as some sort of abnormal growth.
This can include twisting, cupping, elongation and rolling.
Since the chemicals are systemic growth regulators, they move
throughout the trees (or shrubs or flowers) and then show the
most damage on the newest growing points. Think of what a
dandelion looks like after it has been treated with 2,4-D and
you get the general idea. Where the products come from on your
trees is generally a big mystery. The chemicals can drift during
the actual spraying process (called spray drift), or they can
come back up off the ground as a vapor and move with winds
(called vapor drift). The difficulty with vapor drift is that it
can occur for up to a week and a half after the application and
then can drift for up to a mile and a half.
Different species of trees are more susceptible than others,
and the full-size leaves are less likely to show symptoms.
Redbuds, oaks and lilacs are among the most susceptible trees.
Grapes and tomatoes are among the most susceptible garden
plants.
If you do have damage from herbicide drift, the end results
can vary. Generally, on established perennials, the damage is
ugly leaves for at least part of this growing season. You can
also have some "wave" to the ends of branches and possibly the
loss of some small branch ends. On younger stock, transplanted
in the last year or so, the damage may be fatal. It usually
takes several weeks to get an indication of the amount of damage
done, but a year is even better.
As for treatment, water when the weather stays dry. Don't
fertilize at this time. Remember that growth regulator
herbicides make things "grow themselves to death." You have to
walk a fine line between keeping the tree healthy and making
matters worse.
[to top of second column]
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 West Nile virus
West Nile virus has, unfortunately, become a household phrase.
The virus was first isolated in Uganda, Africa. It can harm humans,
birds and other animals. It is transmitted by infected mosquitoes,
primarily the northern house mosquito. The mosquito becomes infected
after biting wild birds that are the primary host of the virus. The
mosquito is actually able to transmit the virus after 10-14 days
after biting the infected bird.
The mosquito life cycle has four life stages: egg, larvae, pupa
and adult. The female mosquito lays eggs on water or moist soil.
Most of the larvae hatch after 48 hours, and the larvae and pupae
live in the water. The females need a blood meal before they can lay
eggs, so only the females bite. They bite every few days during
their adult lives, which may last several weeks.
Preventing mosquitoes is a first step. Homeowners can best
accomplish this by eliminating standing water. Tires and old
containers are obvious places to start. Drill holes in the bottom of
recycling containers, clean clogged gutters, don't allow stagnant
water in anything such as birdbaths, change landscape slopes to
eliminate standing water, and use larvacides in standing water that
can't be eliminated. Bt Israeli is the strain that is effective
against mosquito larvae -- not the Bt variety commonly used on trees
and gardens! The mosquitoes have already begun hatching, so
treatment time is at hand.
Also protect yourself from bites. Mosquitoes can travel up to
three miles from their breeding sites! Make sure that screens and
doors are tight, use proper outside lighting such as fluorescent
lights, stay indoors at dawn and dusk when mosquitoes are most
active, wear long-sleeved shirt and long pants when you must go
outside, and use insect repellents properly applied. Exposed skin
should be sparingly treated with a repellent containing up to 30
percent DEET, or up to 10 percent for children. Make sure to treat
thin clothing as well, since mosquitoes can bite through the thin
clothing.
[John
Fulton, unit leader,
University of Illinois Extension,
Logan County Unit] |
