End of Season
Update
Winter weather is just around the corner, as Thanksgiving and
the Christmas season rapidly approach (not to mention the winter
turf conference season!). A recent warm-up and moderate rainfall
has given way to much cooler and dryer air; so now is the time
to evacuate the water from in-ground irrigation systems ("blow-out")
and to plan for that late-fall snow mold fungicide application.
We have had no reports of Microdochium
patch (pink snow mold), but recent weather patterns
would promote activity of this fungus, as well as cool
weather brown patch. Following is a brief roundup
of the pest control season for Illinois in 2003 - we hope everyone
had a successful year (turf-wise and golf/play-wise!).
Weather review:
In general, the 2003 growing season
was good for turf in northern and central Illinois - which was
much appreciated after problems from last winter and early spring.
Extreme cold temperatures with no snow cover last winter caused
turf loss in isolated areas due to desiccation. Then spring
was also abnormally cool and dry, which delayed recovery of
some winter-damaged turfs well into the golf season. Summer
continued with average to below average temperatures for the
most part, and, after the dry spring, many areas had above average
rainfall. For example, at Golf House we had only 11 days over
90F for the entire season, (as opposed to over 30 last year),
and received over 12 inches of rain in July alone.
Diseases:
The '03 season wasn't
without a few disease and insect problems, but the spectrum
of diseases was a little different this year, owing to the cooler
than normal conditions. The cool, dry conditions of early spring
were very good for reducing the severity of take-all of bentgrass,
and summer patch and necrotic ring spot on Poa species. Dollar
spot was slow to get started in June, but increased to moderate
to severe levels by the end of August. Leaf spots and cool temperature
Rhizoctonias were frequently observed, and cool and wet conditions
that prevailed in some areas favored diseases like yellow tuft
a lot more than Pythium blight or large brown patch. In central
Illinois, summer temperatures and humidity were higher than
in the north. This resulted in early leaf blights, brown patch,
rust, and dollar spot. However, the severities of these diseases
were generally moderate.
Basal rot anthracnose
was one of the more common diseases in 2003, both on Poa annua
and creeping bentgrass. It seems that the incidence of anthracnose
on bentgrass is increasing year to year over the last few seasons,
possibly due to changing weather patterns or changing turf management
schemes (cutting height, fertility, fungicides). On both grass
species, anthracnose can become embedded and chronic, since
it often manifests itself as a root and crown, stolon, or basal
stem rot. Also, because of the nature of the infection, systemic
fungicides are required and often do not give complete or lasting
control of ongoing infections.
Another disease
problem that has been getting a lot of press out of the Northeast
and Mid-Atlantic States the last couple of years is bacterial
wilt on Poa annua putting greens. We confirmed our first case
in northern Illinois this summer. Symptoms include a light green
to yellow color of infected shoots, which may wilt under stress.
Also, infected plants may turn reddish brown and die in scattered,
dime-size spots (similar to early symptoms of C-15 decline on
bentgrass). Diagnosis in the lab can be confirmed by bacterial
streaming from vascular systems of affected plants, followed
by culture on selective media.
Nematodes:
Nematode infestation of turfgrass is always a
concern, although most healthy turf swards can support a significant
nematode population if the host plants aren't placed under extremely
stressful conditions. Putting greens, of course, often have
those plants under stressful conditions and are most likely
to exhibit nematode feeding injury. The nematodes we most commonly
associate with injury are the stunt, lance and root knot. However,
in Illinois, we can add a new type of nematode to our list of
plant pathogens. We have identified cyst nematode (Heterodera
spp.) injury on greens for the first time. This nematode causes
swelling of roots similar to root-knot nematodes, which limits
root uptake and results in plants that are generally weakened
and easily drought stressed.
Insects:
Grub problems were
not severe in 2003, perhaps due to the cold winter with little
snow cover, and deep freezing conditions in soil. Observations
of frozen soil as deep as 15 inches in central Illinois and
30 inches in northern Illinois for 2 months or more were common,
which could have killed many overwintering grubs. Emergence
of Japanese beetle adults was also slow and late this year,
probably due to the winter and the prolonged cool spring. Also,
much lower JB numbers than previous years were reported in many
areas of central and northern Illinois, except a few areas where
very high populations still occurred (click
here to see additional grub information in the Home Yard and
Garden Newsletter).
In central and southern
Illinois, the severity and timing of cutworm activity seemed
to be right on par with previous years. In northern Illinois,
the prolonged, cool spring may have delayed the arrival of cutworms
and sod webworms, but apparently did not reduce the severity
of outbreaks once they got started. Tent caterpillars also showed
up early (late May) and often this year in the area, as well
as a rare localized outbreak of bagworms!
Weeds:
Broadleafs and crabgrass are the
normal story of any year, but the real "weed" of note
this year is moss. Moss is fast becoming a chronic problem on
golf greens throughout the US of A. We have little doubt that
the moss invasion is related to two major changes in putting
green maintenance: 1) ever lower mowing heights and related
techniques to maintain fast green speeds, and 2) loss of heavy
metal and other broad spectrum pesticides that probably suppressed
moss encroachment. Changing topdressing practices may also be
a major contributor to this problem, as frequent sand additions
may form moisture holding layers at the green surface (plus
have an effect on surface soil fertility). Regardless of what
causes it, there seems to be few effective control measures,
if you cannot or will not address the underlying turf health
issues. We have had some success spot treating moss with dish
soap (Ultra Dawn), soap plus baking soda, and granular Terracyte.
Some superintendents have also had some success with Junction
fungicide, or with various tank mixes, including a thiram +
mancozeb combination. Physical destruction / removal of the
moss remains the best answer for now.
+++++++++++++++++++++++
A more detailed "play-by-play" account
of this past year's pest activity is forthcoming on the website
and also in our seminar during the opening sessions of the NCTE
(Tuesday, December 2 @ 9 am). Individual pest and weather summaries
for each IT user will be distributed at this presentation, so
if you can't make this seminar, please let me know so I can
get this 2003 summary to you.
Thanks for your support of this, as well as all of our research
programs,
