Weather effects - The weather this year was
so variable that forest health specialists ran out of cliches to describe what
was going on. Beginning in March with 60 degree temperatures, the weather
flip-flopped from warm to cold and back again just about every month through
December. This kept everyone guessing, including the trees. But fortunately,
damage due to the weather extremes was minimized by the frequent reversals in
Foliar infections and insect damage in April and
June/July were checked by heat spells in May and August. The drought stress of
May and August was checked by the rains of June and September. October was
again warm, and the fall was long and dry. November saw the first cold weather,
but no hard freezes. In late November, the temperature climbed again setting
new record highs. Hard freezes finally occurred in late December.
while some species experienced damage associated with narrow windows of stress
and storm- related wind and hail, most faired well. And the unusually long
season of frost-free weather prompted substantial overall growth. If it wasn't
for the August heat, which shut trees down early, fall foliage colors would
have been spectacular.
Because of the long dry fall, trees are
somewhat dry going into winter. Several species put on late flushes of growth
and a few shrub species bloomed. Some winter injury due to this late-season
growth activity is likely. Winter watering is going to be particularly
important for trees under stress, evergreens, and new transplants. Tree wrap
may help young trees and those that continued to put on growth late into the
||Gypsy moth - The Missouri Cooperative Gypsy Moth
Survey continued its statewide detection program in 1998 by placing and
monitoring more than 11,000 pheromone traps. A total of 17 moths were captured
this year in four widely separated areas. Eleven moths were caught in the St.
Louis area, three were caught near Kansas City, two were caught near Branson in
southwestern Missouri, and one was caught in Bollinger County in southeastern
A few moths have been captured every year since 1980 in St.
Louis and since 1991 in the Branson area. Gypsy moths have also occasionally
been caught in past years in the Kansas City area.
Fortunately, however, no established populations have yet been
found in Missouri. The high volume of interstate traffic going through urban
areas and through the many popular vacation and recreation sites around Branson
obviously provides many opportunities for gypsy moths to hitchhike into those
A record eight gypsy moths were caught in one trap in a St.
Louis park in 1998. This is the highest number of moths ever taken in a single
trap in Missouri's gypsy moth survey. Examination of the site by state and
federal entomologists revealed no other gypsy moth life stages. However, that
number of moths in a single trap is a matter of concern, and the site will be
closely monitored in the future. All sites in Missouri where gypsy moths were
detected in 1998 will be trapped at an increased intensity in 1999.
Sycamore anthracnose - Warm weather in March, which caused buds to break
early, and cold weather in April provided favorable conditions for foliar
diseases on some tree species. Those hardest hit were those that generally leaf
out early in the season such as maple, ash and sycamore. Those that flush out
later were protected from foliar diseases by the hot, dry weather in May. May's
weather also protected the second flush of growth on those trees that lost the
first to disease.
Of the species showing high rates of foliar
disease, sycamore was the most obvious. Across the state, trees lost their
first flush of growth and were slow to put on a second. Even when viewed at
highway speeds, the bare white branches standing above the dark green forest
were noticeable. Because this is the third year of four that anthracnose has
caused severe damage on sycamore, we are now beginning to see the onset of
decline symptoms on some trees. These include thin sparse crowns, late leaf
out, early leaf drop and branch die-back. No increase in mortality has been
seen so far, but it may yet occur if the trees aren't able to recover over the
next several years.
Heavy populations of jumping oak gall wasps
were evident on white oaks in eastern Missouri in 1998. Severe browning and
premature leaf drop was present on over 1.8 million acres in 12 counties near
St. Louis. The wasp, probably Neuroterus saltatorius, induces pin-head
size galls to form on oak leaves in the spring. Each gall contains a single
wasp larva. Galls eventually drop from the leaves and may be seen to "jump"
like "jumping beans" once they have fallen to the ground. On heavily infested
trees, leaves turn brown and drop by mid-summer, and new leaves are produced.
These trees will survive, but the defoliation and subsequent production of new
leaves is stressful. High populations of this insect have periodically appeared
in eastern and southwestern Missouri in past years. The mild winter in 1998 may
have been a contributing factor to the outbreak seen this year.
forest insects that generated tremendous amounts of public concern and media
attention in 1998 were periodical cicadas and the multicolored Asian
lady beetle. This spring Missouri and other parts of the Midwest witnessed
a rare phenomenon that only occurs once every 221 years, a combined emergence
of 13-year and 17-year periodical cicadas. A 13-year brood emerged over most of
Missouri except the northwest and southeast corners of the state, while a
17-year brood emerged in the western and northwestern parts of the state.
Intensity of emergence was patchy with some areas having extremely heavy
populations, and others none at all. Flagging, or branch damage, due to cicada
oviposition became apparent by July and increased as the summer progressed. The
crowns of many hardwood trees throughout Missouri were heavily spotted with
dead branch tips by the end of summer.
Although not a pest of trees,
the multicolored Asian lady beetle is an exotic species that resides in the
forests of Missouri and other southern and eastern states and can at times
become a serious nuisance for homeowners. These beetles are predators that feed
on aphids and other small insects on trees, however, in the fall, huge numbers
of swarming lady beetles congregate on buildings and often get inside houses as
they look for overwintering sites. Asian lady beetles were first detected in
Missouri in 1993 and have since expanded their range across much of the state.
In 1998, a week of cold temperatures at the end of October followed by a few
days with high temperatures in the 70's apparently triggered a rapid increase
in swarming behavior which caused considerable public concern throughout much
of central and southern Missouri.
For additional information on Missouri forests and pest
management call or write: MDC, Conservation Research Center, 1110 S. College
Avenue, Columbia, MO 65201 (573) 882-9880, FAX: (573) 882-4517. For e-mail use
For more information contact:
Jefferson City, MO 65102
||Forest Health Protection
State & Private Forestry
USDA Forest Service
1992 Folwell Avenue
St. Paul, MN 55108