Goodbye Drought!!
During the first three weeks of May growing conditions
here in Chicago have been wet and cool. From May 10-22 the air
temperature averaged 9 degrees cooler than normal (Midway Airport
data), and on the 22nd Chicago set a record low of 36 F. Approximate
average air temperatures have been in the low 50s for Chicago's
north shore, mid 50s for the suburbs, and closer to 60 F in
southern Illinois. Frequent rain throughout the month has meant
soils have been consistently wet. For example, precipitation
occurred on 14 of 23 days here at Golf House in Lemont, IL.
A majority of our Chicago weather stations have reported at
least two inches of rain, with Lockport receiving the most (3.5
inches), whereas southern Illinois has accumulated three inches
thus far. These steady and widespread rains of May have officially
gotten all of Illinois out of the drought situation, with only
the Quincy area in the "abnormally dry" designation.
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Base 50 Degree Day Totals - May 25th
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Average Soil Temperature
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Location
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2006
|
2005
|
May 25 '06
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May 25 '05
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| N. Barrington |
204
|
257
|
58 F
|
61 F
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| Rockford |
253
|
305
|
57 F
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60 F
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| Lemont |
265
|
316
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58 F
|
61 F
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| Aurora |
293
|
332
|
61 F
|
62 F
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| Orland Park |
351
|
394
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| Bloomington |
453
|
487
|
67 F
|
57 F
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| Peoria |
463
|
525
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In Chicago, soil temperatures taken on May 25
averaged 3-4 degrees cooler than those taken on the same date
last year. In addition, base 50 degree day totals are 30 - 50
DD lower than last year, giving further evidence to the slower
than normal heat progression of this spring. However, the plus
- 90 F temperatures of this Memorial Day weekend should blast
northern IL right back on schedule in both of these departments.
Possibly jump starting us right into the summer season.
Dollar Spotless in Chicago
Although dollar spot (Sclerotinia homoecarpa) was listed as
our number one turfgrass pest to watch for during May, the cooler
than normal temperatures throughout Illinois were not conducive
for its development. Temperatures at night greatly influence
dollar spot activity, because the evening hours coincide with
necessary leaf wetness periods of 10 hours or more. We know
that ambient temperatures of 60 to 77 F are optimal for dollar
spot development. Instead nighttime temperatures here in Chicago
made it to the 50s by the second week of May, but then faded
back into the mid 30s and 40s delaying the onset of dollar spot
in 2006.
Nevertheless, during May 9-10 an isolated outbreak of dollar
spot surfaced at a Chicago golf course and damaged a creeping
bentgrass/Poa annua putting green. Profuse white cottony mycelium
was present (Fig. 1), and infection centers were grouped together
within a single 1-2 foot area in each of two greens (Fig. 2).
The superintendent was familiar with the symptoms, because a
similar atypical dollar spot outbreak had occurred the previous
fall during cool conditions in exactly the same places. One
explanation is that this dollar spot isolate is active under
cooler conditions, or is active across a greater range of temperatures.
Fig 1. An isolated outbreak of dollar spot on a bentgrass/Poa
putting green in Chicago, IL on May 10, 2006 during cool conditions.
Fig 2. (Mouse rollover) Closeup of dollar spot infection centers
with mycelium on a bentgrass/Poa green.
In 2001, Powell and Vargas at Michigan State reported
that dollar spot exists as several distinct genetic pools based
on whether the fungal isolates can grow together, and fuse their
mycelium (= related). This is called anastomosis, a time-tested
method used to determine the genetic relatedness of some plant
pathogenic fungi. Dan Dineli of The North Shore Country Club
participated in the study, where up to six vegetative compatibility
groups (VCGs) existed. They speculated that each of the six
S. homoeocarpa genetic groups may have different environmental
conditions necessary for growth. Although groups of S. homoeocarpa
did change within a year at North Shore, an individual group
was not consistently associated with summer versus fall dollar
spot epidemics. Further research is needed.
Off Color Bentgrass
Figure 3. Off color creeping bentgrass associated with
a clone within a putting green at a Chicago golf course on May
10, 2006. Figure 4. (Mouse Rollover) Relative size of off color
creeping bentgrass patches.
Throughout May, an issue for golf course superintendents
has been the inconsistent color and growth of putting greens
here in Chicago. The cooler than normal temperatures this month
aren't even supposed to be ideal for Poa annua growth (reportedly
79 F day/63 F night), but from our observations during golf
course visits the annual bluegrass didn't know the difference
and possessed excellent visual quality. During the same time
period, it was a much different story for the bentgrass component
of some older greens.
Briefly, the oldest (original) creeping bentgrass putting greens
in Chicago were established when a seed mixture of bentgrasses
known as South German bentgrass became available in the early
1900s. The seed was harvested from naturalized fields of Agrostis
spp. in Europe, and although only 1% of the mix contained creeping
bentgrass (A. palustris) seed it proved best adapted to the
Great Lakes region given putting green cultural practices and
quickly displaced velvet (A canina) and colonial bentgrasses
(A. tenuis) as well as red top (A. alba). Some of these remaining
older creeping bentgrasses have a distinct bronze-green leaf
color, and can create greater potential for discoloration compared
to improved bentgrass cultivars.
According to Randy Kane, an older bronze-green creeping bentgrass
variety exists in Chicago and is frequently referred to as "Washington"
(exact pedigree unknown). In 1924 a popular vegetative variety
Washington did exist and was named by Dr. John Montieth. Anecdotal
information indicates 'Washington" is sensitive to rapid
shifts in temperature and the combination of cool temperatures
with growth regulators can have devastating effects. We recently
observed an older green in Chicago with off-color patches which
appeared to affect a single creeping bentgrass cultivar within
the green (Fig. 3 and 4). The central leaf blade remained green
and the crown appeared healthy, but all other leaf tissue appeared
either clear or was discolored tan to brown under 10X magnification.
The event was caused by a pair of unusually cold nights (~33
F) on May 6 and 7th, and symptoms may have intensified due to
a Proxy/Primo application that preceded the freezing temperatures.
Cutworm activity:
Figure 5. First cutworm moth capture on May 23, 2006 at Golf
House in Lemont, IL.
Cutworms have arrived here in Chicago, and a moth
was caught this week here at Golf House in Lemont, IL (Fig.
5). Preventive control measures should now begin in Chicago
based on the presence of adults. Cutworms are native to North
America, but are semi-tropical and can only over winter in the
deep south. The adult we captured has likely flown a great distance
from the Gulf region. Once adults emerge they immediately mate,
and a single female will lay 1200-1600 eggs on grass blade tips
within the span of a week. It is the black cutworm (Agrostis
ipsilon) that is the major player responsible for damage
of our highly maintained turfgrass. However, cutworms do not
feed on Kentucky bluegrass, and ingestion of its leaf blades
have been shown to be toxic to the caterpillar. This is why
cutworms are not an issue for home lawns here in Illinois.
Scouting for signs of the cutworm feeding, or
the tell-tale signs of bird damage becomes increasingly important
as we enter the warm summer periods. Here in the north 2-4 generations
can occur during one growing season, and larval development
speeds as temperatures increase. Cutworm damage thresholds can
be useful when deciding when to apply insecticides for golf
fairways or sod growers, but this determination will vary according
to turf quality needs. For putting greens, zero tolerance of
cutworm damage is the norm because any sunken feeding center
will disrupt the surface necessary for consistent ball roll.
The caterpillars are nocturnal and peak feeding occurs in the
early morning hours prior to dawn. Therefore, pesticides should
be applied prior to dusk, and irrigation should be withheld
for a period of 12-24 hours. This will maximize control, because
the majority insecticides labeled for cutworm must be ingested.
Where curative treatments are employed, a single boom pass around
the treated area is suggested to prevent cutworms from reinfesting
from the surrounding turfgrass perimeter.
Pink patch (Limonomyces roseipellis)
outbreak
Figure 6. Damage to a golf course rough caused by pink patch
(Limonomyces roseipellis) Chicago, IL on May 19, 2006. Figure
7. (Mouse rollover) The membranous pigmented mycelium of pink
patch covering the surface of a Kentucky bluegrass leaf blade.
An outbreak of pink patch caused by the fungus
Limonomyces roseipellis was recently reported in May here in
a Chicago suburb. Temperatures that favor pink patch development
are 65-75 F, but outbreaks can occur anytime because the pathogen
grows across a wide range of temperatures (40 to 90 F). The
pink patch outbreak was first noticed by the superintendent
the beginning of May, and continued wet conditions allowed further
disease development. Tan to pink patches 1 to 6 inches in diameter
appeared in a fine fescue rough blend on an exposed hillside
of a putting green (Fig 6.). A pink pigment in the fungal mycelium
(or hyphae) is formed on leaf blades and can look like a membrane
when it covers the entire blade width (Fig. 7). Sometimes small
basidiocarp structures (mushroom-like) can be observed on the
leaf surface, but none were found in the present outbreak. The
fungus penetrates the leaf through the leaf stomates, small
openings that open and close to allow the gas exchange necessary
for photosynthesis. Although pink patch was once classified
as a form of red thread, it is not. The pink patch pathogen
is not severe and its patches slowly expand compared to red
thread. The disease is best controlled by an application of
0.5 to 1 lb nitrogen per 1000 sq. ft. Iprodione, triadimefon,
and vinclozolin fungicides provide very effective control as
well.
Diseases/Pests on the horizon…
As soil temperatures now begin to rise rapidly, we will begin
to experience our warm temperature diseases and pests. Of these
none are more difficult to control than the patch diseases cause
by ectotrophic root infecting fungi. Additionally, few turfgrass
pathogens are more challenging to control. Because translocation
of fungicides downward is poor, cultural practices are key components
of an IPM program to combat root pathogens.
Two Important root pathogens that cause patch diseases..
1. Necrotic Ring Spot (Ophiosphaerella korrae).
Necrotic ringspot, caused by the soilborne fungus Ophiosphaerella
korrae, is primarily a problem of Kentucky bluegrass, but may
also be found on red fescue and annual bluegrass. Necrotic ringspot
symptoms usually appear in late spring or early fall, but can
continue into the summer months. Symptoms of necrotic ringspot
results are circular to arc-shaped patches of dead or dying
turfgrass a foot or more in diameter. The Kentucky bluegrass
becomes matted along the ring, but the center remains green
and healthy -the "frogeye". Typically, the patches
appear two years after sodding and then become an annual problem
at the location. Plants have very few white healthy roots, and
instead most are dead and rotted appearing dark brown to black.
Fungicides should be applied when the soil temperature reaches
65 F. Standard fugnicides that provide good control are azoxystobin,
fenarimol, myclobutanil, and propiconazole. Cultural practices
should be used to maintain vigorous turfgrass growth. Plant
stress can be alleviated by increasing mowing heights, applying
moderate amounts of slow-release fertilizers, and maintaining
adequate soil moisture levels. A continuous program of aggressive
aerification is most important, and allows the remaining viable
roots to have good soil contact versus rooting in an organic
thatch layer which has little water-holding capacity.
2. Summer patch (Magnaporthe poae). The summer
patch pathogen, Magnaporthe poae is another important soil borne
fungus that attacks Kentucky bluegrass. It initially infects
roots and crowns in May and early June. The fungus initially
grows on the root surface, but eventually penetrates the root
tissue discoloring and rotting the roots. The patch and frogeye
symptoms are usually not evident in spring, because cool wet
conditions help compensate the loss of roots by fungal infection.
At midsummer plants rapidly wilt and collapse because roots
are either dead or not functioning. Circular patches are the
hall-mark of fungal diseases because they grow in a radial pattern
from an initial center point. This fungus persists in the soil,
and like necrotic ring spot dead patches can appear year after
year in the same location (Fig. 8).
Figure 8. Residual damage of an unknown patch disease (summer
patch?) of a Kentucky bluegrass rough at a Chicago suburb golf
course on May 5, 2006.
Here are some excellent fungicide recommendations
from my former major professor, Ned Tisserat. Chemical control
has not been completely effective in eradicating the disease,
but it can reduce disease severity if used in conjunction with
good turf management. Timing of fungicide applications is critical
for effective control . Make the first preventive application
in spring when the soil temperature at a depth of 2 inches remains
above 65 degrees F. This varies with geographic location, but
generally the first fungicide application should be made in
early to mid-May, or about 2 to 3 weeks after the crabgrass
germinates. A second application should be made one month after
the first. The fungicides azoxystrobin, propiconazole, triadimefon,
and myclobutanil are recommended for the early season, preventive
applications. Follow label directions concerning irrigation
immediately following fungicide application. Summer patch is
more difficult to control with chemicals once symptoms have
developed. The fungicide thiophanate methyl (Cleary's 3336,
Fungo, and others) has been reported to be the most effective
curative compound and can be used to suppress further disease
development.
As always, we hope this month's newsletter has
contained useful information which will help interactivetuf.com
users. If you have any suggestions of material you would like
included in these monthly newsletters please let us know.
+++++++++++++++++++++++
Thanks for your support of this, as well as all
of our research programs,
Lee
Miller
CDGA
Manager of Turfgrass Research
Midwest Golf House
11855 Archer Ave
Lemont, IL 60439
630-685-2305
Derek
Settle
CDGA
Manager of IPM Programs
Midwest Golf House
11855 Archer Ave
Lemont, IL 60439
630-257-2307
