Rainy, warm weather and diseases: West
Nile and leaf fungus
Send a link to a friend
[June 02, 2008]
West Nile virus has quickly, and
unfortunately, become a household phrase. With Illinois leading the
nation in deaths from the virus, it behooves us all to take proper
precautions. The excess moisture in much of the Midwest has led to
one of the worst springs for mosquitoes in recent history. This is a
more full-blown accounting of WNV.
WNV 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.
mosquito life cycle has four life stages: egg, larva, 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.
The first symptoms of WNV are often the deaths of susceptible
bird species, such as crows and blue jays. We have had bird
deaths in the county many of the past summers, and I'm sure that
this year will be no exception. The Illinois Department of
Public Health is the agency in charge of testing birds for WNV.
Symptoms of WNV are rare in humans. A small percentage of
people do develop fever, headaches, body aches, swollen lymph
glands and a body rash. Encephalitis develops in less than 1
percent of infected people, and this group can have headache,
high fever, neck stiffness, tremors and other symptoms.
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 larvicides
in standing water that can't be eliminated. Bt israelensis is
the strain that is effective against mosquito larvae -- not the
Bt variety commonly used on trees and gardens!
[to top of second column]
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 (up to 10
percent for children), and make sure to treat thin clothing as well,
since mosquitoes can bite through the thin clothing.
Elimination of mosquito breeding sites, treatment of larvae and
proper protection for people will go a long way in reducing the
incidence of WNV in our area this summer. Further information on WNV
can be found at
Leaf spot fungal diseases
It seems the leaf spot fungal diseases are present with a
vengeance. Anthracnose and apple scab are very noticeable now. If
you think your trees have escaped infection, hold a leaf up to the
light to make sure. If you see light areas along the edges or
between veins, you'll probably have the full-blown symptoms within a
As there is no cure, keep the plants watered with an inch a week
during dry spells. A little fertilizer also will help. Severe leaf
drop early in the season will usually lead to another set of leaves
being out in four to six weeks.
University of Illinois Extension, Logan County]