Get Your April
Showers?
Figure 1. Irregular green-up of a creeping
bentgrass fairway at Sunshine Golf Course during dry spring
conditions in Lemont, IL on March 30, 2006.
Weather:
Although weather data summaries indicate record
wet conditions, the rainfall in many cases was not always uniform
within Chicago or other Illinois regions. The transition between
March and April was very dry for us here at Golf House in Lemont,
IL and was true for many other locations within the state. Dry
periods in this timeframe resulted in relatively slow turfgrass
green-up especially on slopes or areas without supplemental
irrigation (Fig. 1).
March in Review
Much needed rain arrived during March, and the month ranked
as the 16th wettest since records began in 1895. However, most
precipitation occurred during the first two weeks in Chicago.
For example here at Golf House in Lemont, IL we received a total
rainfall of 3.5 inches for March, but nearly all (3.0 inches)
occurred during the 8 day period of March 5-13th. Southern Illinois
was even wetter during the same period, with Carbondale, IL
totaling over 8 inches rain. Temperatures for March were normal
- 37.5 F here southwestern Chicago suburbs, and averaged10 degrees
higher for southern Illinois.
April in Review
April began very dry, because the last two weeks in March only
saw trace amounts of precipitation in many areas in and around
Chicago. On Easter, 1 inch or more rain was recorded at the
majority of our weather station sites. The greatest amount of
rain on 16 April was 2.5 inches, and coincidentally occurred
here at Golf House. Heavy 1 inch + rains again have hit in these
last few days of April, vaulting most areas to above average
rainfall for the 4th consecutive month (see table below).
Many have asked if this was a drought buster, and finally I
can say YES! We are still categorized as abnormally dry, but
at least we're not in the drought category which we were stuck
in for well over a year (click
here to see current US Drought Monitor Map).
Temperatures for April have been very mild, primarily
due to an unusual stretch of warm days from April 10-24. On
average high temperatures in Chicago were 71 degrees during
the 15 day period and overall temperatures were 11% greater
than normal. In most areas, these warmer temperatures have resulted
in increased DD50 totals over 2005, which together
with ample rainfall and a warm forecast could kick off pest
outbreaks (notably dollar spot) earlier in May than last year.
|
|
Base 50 Degree Day Totals - May 1st
|
Average Soil Temperature
|
% Normal Precipitation
|
|
Location
|
2006
|
2005
|
2004
|
May 1
|
April - 2006
|
| N. Barrington |
115
|
113
|
130
|
53 F
|
79%
|
| Glenview |
132
|
112
|
135
|
53 F
|
139%
|
| Rockford |
138
|
160
|
144
|
53 F
|
155%
|
| Lemont |
161
|
133
|
166
|
54 F
|
131%
|
| Aurora |
166
|
156
|
178
|
54 F
|
96%
|
| Naperville |
174
|
156
|
159
|
55 F
|
125%
|
| Peoria |
269
|
261
|
283
|
57 F
|
122%
|
| Bloomington |
270
|
218
|
246
|
57 F
|
154%
|
| Carbondale |
467
|
300
|
378
|
62 F
|
106%
|
From the turf tip archives
A drop in temperatures on April 26 and 27
triggered a light to hard frost in Chicago area. This caused
the Poa annua leaf tips to appear bright red on the #3 tee at
Golf House's Sunshine Golf Course. The following article describes
the natural phenomena which is sometimes confused with fungal
leaf spot pathogens of turfgrass.
.jpg)
Reddish brown color and thinning of a clone of bentgrass
which is not very frost tolerant. |
What happened to the color of bentgrass?
We broke high temperature records that second week in
April and it seemed that we were going to miss spring
and jump into summer. However, reality hit soon thereafter.
It cooled off drastically, rains came and the sun went
away. So did the color of the bentgrass on my putting
greens! The annual bluegrass didn't seem to mind the swing
in temperatures, but the bentgrass looked like a Monet
up close, mottled and variable in color. I looked for
signs of a pathogen, was it a leaf spot of some sort?
I thought it could be possible until I consulted Dr. Randy
Kane of CDGA fame. Most of the time the chlorophyll masks
the presence of anthocyanins and the grass appears green.
When cooler temperatures prevail the anthocyanin pigments
remain in the leaf blade and stem. The cooler temperature
also causes the chlorophyll to become denatured in the
leaf blade and the masking effect is lessened. Some of
the blue-red-purple pigments become more prevalent in
the turfgrass blade and color the plant. (Luke
Cella - May, 2002 turf tip).
|
Figure 2. Red to yellow discoloration of Poa
annua in a non-uniform pattern at Sunshine Golf Course caused
by freezing temperatures following a warm, mild mid-April period
in Lemont, IL on April 26, 2006. Figure 3. (Mouse Rollover)
Closeup shows red discoloration (anthocyanin pigment) is localized
to the upper and outer edges of individual Poa annua leaf blades.
Diseases/Pests we've experienced
thus far…
Cool weather Rhizoctonia diseases
Yellow patch (or cool weather
brown patch)
Cool weather brown patch was the most consistent turfgrass pathogen
observed blighting creeping bentgrass greens and tees in Chicagoland
during March and April. The noted turfgrass pathologist Houston
Couch referred to this disease as Rhizoctonia yellow patch.
Yellow patch is caused by the soil-borne fungus Rhizoctonia
cerealis. R. cerealis is only active at low temperatures and
so damage to creeping bentgrass putting greens is limited to
non-dormant turfgrass from November to April. The fungus grows
within a narrow temperature range of 50 to 65 degrees, and is
not active above 75 degrees. Typically, yellowish patches develop
which can measure up to 3 feet in diameter and most damage occurs
at the outer edge where a narrow ring of necrotic (white to
tan) blighted leaf blades exist. We observed a significant yellow
patch outbreak in early April that was associated with an A-4
creeping bentgrass putting green that was covered during winter.
In this case patches were reddish in color and not yellow (Fig.
4). In many cases Rhizoctonia yellow patch can be difficult
to see, and most golfers will not notice the faint patches affecting
the creeping bentgrass/Poa annua playing surface (Fig. 5).
Figure 4. Lee Miller samples the outer-edge
of a patch symptom caused by Rhizoctonia yellow patch on an
A-4 creeping bentgrass putting green in Chicago, IL on April
10, 2006. Figure 5. (Mouse rollover) Rhizoctonia yellow patch
symptom with only the narrow outer ring visible on a PennLinks
creeping bentgrass tee in Chicago, IL on April 18, 2006.
| Large patch (or zoysia patch) |
|
 |
Rhizoctonia large patch also known as zoysia
patch is the most important disease of zoysiagrass grown
in northern regions of the U. S. such as southern Illinois.
Large patch is caused by the soil-borne fungus Rhizoctonia
solani that is active at temperatures between 50 to 86F.
The size of patches can be very large, up to 20 feet in
diameter, hence the common name. The fungus causes a lesion
at the leaf sheath and the emerging leave blades often appear
bright orange. Although closely related to warm season brown
patch, it is genetically distinct from Rhizoctonia brown
patch which occurs during summer when minimum temperatures
reach 68 F. Large patch disease of zoysia fairways and tees
can begin early fall (mid to late September) and continues
when thatch temperatures remain above 50 F. Very wet conditions
are usually associated with large patch outbreaks. In southern
Illinois this year the extended mild, cool spring together
with large rainfall events has caused patch symptoms to
reappear which is not uncommon. Spring outbreaks are typically
less severe and large patch is naturally suppressed as thatch
temperatures reach 86 F. |
Control strategies similar for cool weather
Rhizoctonia diseases
A cultural practice that can reduce both yellow patch and large
patch is to improve drainage by core aerification. Reduction
of areas with standing water following rain/deep irrigation
will reduce disease severity. It is also thought that excessive
N can increase disease severity of yellow patch, but this has
not yet been studied in detail. Fungicides such as flutolanil
and azoxystrobin are effective in suppressing both Rhizoctonia
diseases. One application before or as soon as symptoms begin
to develop in September to early November, will typically suppress
both Rhizoctonia patch diseases throughout the entire winter
and spring. During spring, a second application can be made
at the onset of patch symptoms.
Pink snow mold
 |
Pink snow mold was reported to occur in Chicago during
the end of March, but the disease has not been severe this
year based on superintendent reports. Formerly known as
Fusarium patch, the fungus responsible for this disease
was later assigned a name change and is now known as Microdochium
nivale. Microscopic Identification relies on seeing
crescent or boat-shaped spores which are profuse. This is
an important pathogen of all our important cool-season turfgrasses,
especially creeping bentgrass, Poa annua, and Kentucky
bluegrass. This disease forms smaller patches than gray
snow mold. Pink snow mold patches are 1 to 3 inches in diameter
and have whitish centers with pink or copper to red margins.
The disease is favored by higher temperatures than gray
snow mold (>40 F) and is often a late winter/early spring
disease. Additionally, in Chicago Randy Kane has observed
gray snow mold infrequently (once every five years), whereas
pink snow mold is an annual event. Pink snow mold is capable
of severe infection of turfgrass crown and stolons and multiple
fungicide treatments can be required at 2- to 8- week intervals
to prevent damage. |
Poa Seedheads
Observations of Poa annua seedhead production
began at about March 25th for southern Illinois, whereas in
Chicago we observed development beginning about April 19th.
The weather model that utilizes air temperature degree days
accurately predicted Poa seedhead emergence throughout Illinois.
Additionally other indicators such as forsythia bloom continue
to be useful predictors in timing initial applications of Proxy/Primo
or Embark. Currently the Poa annua tee here at golf house is
covered with about 50% seedheads (Fig. 6). For the most part,
Proxy/Primo applications have worked well this year for suprressing
seedhead production. However, for the second year in a row,
one site has reported inadequate control of Poa seedheads with
Proxy/Primo, and the reasons are unknown. We do know that bluegrasses
are a genetically diverse group, and it is possible that control
efficacy of seedhead suppression varies among the different
genetic biotypes of Poa annua.
Fig. 6. Current seedhead development of Poa
annua on a tee at Sunshine Golf Course in Lemont, IL on May
1, 2006.
Diseases/Pests on the horizon…
Scouting of highly maintained turfgrass becomes
even more important as we enter the month of May. The warmer
temperatures bring us enjoyable outdoor weather as well as our
more familiar and chronic diseases capable of rapid development
given wet and humid conditions.
The Top 5 Pest List for May
1. Dollar spot (Sclerotinia homoeocarpa).
Although Pythium blight is considered the most important turfgrass
pathogen by most golf course superintendents, more time and
money is spent to prevent and control dollar spot than any other
turfgrass disease. Dollar spot is active at temperatures of
60-90 F, and can potentially damage most warm- and cool-season
turfgrass from spring until late fall. It is a disease of nearly
all cool season turfgrasses except tall fescue. Relatively easy
to identify as spots develop with fluffy white mycelium, and
the resulting infection centers have a bleached white center.
Foliar lesions are a bleached white color and may have an hourglass
appearance at mid-blade. Lower nitrogen fertility levels exacerbate
dollar spot, and might explain its increasing importance on
golf putting greens where fertility is tightly managed to allow
consistent golf ball roll speed.
Early $ Spot Applications
Last year, the first dollar spot outbreaks occurred
in Chicago around June 6th, whereas in 2004 initial outbreaks
occurred on May 6th. So, which is it going to be? As you can
see in the
table above, the Spring of 2006 is evolving much
closer to that of 2004, which was noted as a very BAD and early
dollar spot year. Base 50 degree days (DD50) are
running ahead of last year's schedule for most of Chicago, and
are well ahead in central and southern Illinois. This along
with the ample rainfall we just had, and the warm temperatures
forecasted for the next 10 days should kick the dollar spot
metabolism (and hopefully bentgrass too) into gear.
Research was done last year and is ongoing to
find the best timing for early preventative fungicide applications
for dollar spot control. Preliminary results from last year
indicate timing from 125-175 DD50 works best for
these applications. Most areas of northern IL are currently
in or around this degree day window, and if the warm forecast
pans out, it should push most squarely in this range. Therefore,
we are thinking early applications should be made in the middle
of this week into early next week for most areas of south and
west Chicago. Those cooler and closer to the lake will probably
have a few days after that. On the other hand, the clock could
be really ticking for central and southern Illinois, and we
would expect reports of dollar spot activity to start coming
from that region at any time now.
So what to apply? High rates of Emerald and the
DMIs Banner and Bayleton worked best in our first year of trials.
When tested on a DMI resistant dollar spot population however,
Emerald was by far the best performer, and should be considered
the tool of choice in this situation.
2. Basal-rot anthracnose (Colletotrichum
cereale). Poa annua golf fairways and greens are susceptible
to damage by anthracnose (formerly known as C. graminicola)
during spring through summer anytime temperatures are 60 to
95 degrees. Two types of anthracnose exist, a foliar phase and
a basal-rot phase of the plant crown. According to Randy Kane,
it is the basal-rot phase that prevails here in Illinois and
symptoms appear as irregular shaped yellowing patches. Lower
leaf blades are initially infected and so turfgrass thinning
is also a symptom. Plant stress is the predominant cause of
basal-rot anthracnose, and is associated with stressful cultural
practices or warm temperature stress of Poa annua. Leaf blades
yellow, but the actual site of infection is the crown region
which can appear completely black. Multiple black, round spore
producing structures (acervuli) as well as associated hair-like
structures (setae) can be seen using a low magnification hand
lens. Positive diagnosis requires a microscope to visualize
the presence of crescent shaped spores. Preventive fungicide
applications are crucial because post-infection applications
do not provide adequate control.
3. Crabgrass (smooth = Digitaria ischaemum,
and large = D. sanguinalis). Weed management usually
begins with a pre-emergent application to prevent crabgrass
seed germination at about late spring. A great problem of turfgrass
mowed at low clipping heights. Crabgrass has a rapid spreading
growth habit during summer that allows it to easily out-compete
most desirable turfgrass species. A prolific seed producer during
summer which germinate anytime warm soil temperatures and moist
soil conditions exist. The crabgrass seed germination prediction
model to time pre-emergent herbicide applications has already
moved up the state and by the third week of April reached Chicago.
Applications can also be timed by scouting for initial germination
of juvenile plants, which we have not yet observed in most Chicago
locations.
4. Black cutworm (Agrostis ipsilon).
Black cutworm presence is often signaled by birds feeding on
golf putting green surfaces or what can be called avian-aerification.
Cutworms feed during the evening (predawn) and will consume
all green plant material to expose stolons, thatch or soil.
Damage occurs in a ~1 inch circular radius from a central hole,
or as random pattern of shallow, surface tunnels. Greenish frass
may also be present at the feeding sites. Here at Golf House
we use a pheromone trap to capture moths, and report for integrated
pest management of black cutworms. Approximately 7-10 days after
initial moth flight cutworm larvae can be found feeding. Application
of insecticides at pre-dawn is timed to coincide with nighttime
larval feeding and may also prevent photodegredation of the
material. Additionally, mowing prior to dawn, clipping removal
and timely topdressing can also reduce black cutworm larvae
numbers.
5. Black Turfgrass Ataenius. The black
turfgrass ataenius is a relatively new insect pest. The larval
grub was first found damaging turfgrass at a golf course in
Minneapolis, MN in 1932. Since 1973 the damaging effects of
the beetle larva has been found on golf courses in nearly all
the northern states. The black adult beetle is very small measuring
¼ inch in length. In spring, the beetles fly from hibernating
sites which is beneath the soil of wooded areas. The adults
begin flight in May, and will lay eggs late May to early June;
soon thereafter the grubs begin feeding on turfgrass roots.
Annual bluegrass appears to be the favorite host. Nevertheless,
at Kansas State University black turfgrass ataenius grubs regularly
damaged our creeping bentgrass putting green which was Poa annua-free.
In fact, a superintendent who removed creeping bentgrass sod
from our green suddenly found he had a black turfgrass ataenius
problem; something we forgot to mention. The grubs are small
relative to the adult size, but because numbers can reach up
to 500 larva per square foot their damaging potential should
not be underestimated. During May, scout for the black beetle
adults which commonly fly over golf fairways or look for them
crawling around on the greens.
Research on the Sunshine Course
Moss control study
Fig. 7. Application of water soluble materials
to remove moss from a L-93/G-2 creeping bentgrass putting green
at Sunshine golf course in Lemont, IL on April 27, 2006.
An experiment to control/reduce moss (Leucobryum
sp.) on Illinois putting greens has been initiated on our #1
green with support by USGA funding (Fig 7). Typically mosses
live at the soil surface in shaded environments and survive
as spores. Today, moss is a continual problem that golf course
superintendents must manage to insure a consistent putting surface.
Recently, at many Chicago golf courses increasing problems with
moss infestation of creeping bentgrass/Poa annua putting greens
has been observed. Reasons for the upsurge of moss in greens
are speculative. On theory is that older fungicide chemistries
(now banned) were directly toxic to moss and prevented its establishment.
Additionally, any putting green cultural practice that reduces
canopy density can create a competitive advantage for moss growth
relative to Poa annua and creeping bentgrass. Environmental
conditions such as shade can also predispose individual putting
greens to moss infestations. Future research is needed to understand
how cultural practices may interact with moss to exacerbate
its infestation of golf putting greens.
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
