Scouting Report: October 8th

CDGATurfgrassProgram
6 min readOct 7, 2017
A little bit of morning fog was observed on Friday.

Periods of heavy rain to the south and more of a spitting rain to the north was welcomed throughout the region. For the first time since September 21st, it started to feel like fall. Drizzling rain, short days, fallen leaves, and heavy dew formation was pretty common as we ended the week.

7-day precipitation totals. Courtesy of NOAA.

Not many folks are saying ‘no’ to rain right now. Most of us have been able to squeeze in a few cultural practices ahead of the rain. The rain has probably had a more detrimental effects on farmers during harvest season. At the golf house, the recent rain has been helpful in establishing new research areas.

‘Crystal BlueLinks’ was seeded 23 days ago at the Midwest Golf House.

The drought in Chicago began in early September. The National Weather Service provided a few fun facts on this brief dry spell.

Not so fun facts about the drought in September. Courtesy of the NWS of Chicago.

Further south and west, the drought began much earlier and the recent rains haven’t really put a dent into it. The National Weather Service in the Quad-Cities areas created this graphic that demonstrates the lack of much needed rainfall.

Many areas of Illinois only received 25% of normal rainfall. Courtesy of the NWS of Quad Cities.

The folks at Michigan State University have recently published a new extension article that focuses on turfgrass management in a warm dry fall.

Weeds:

The recent rain may help in broadleaf control strategies.

Many broad leaf weeds are storing carbohydrates in the root system this time of year. During this time, herbicide efficacy may be improved and control of these pesky weeds can be more easily achieved. The recent rainfall should also help these herbicides translocate through the plant.

Insects:

Skunk digging is an indication that white grubs are present.

White grub related damage was observed again this week. This mild temperatures in the forecast for next week, these grubs may be hanging around in the top portion of the soil profile for a little longer. I have seen little to no grub related damage on courses that have applied Chlorantraniliprole earliler in the year. There has also been a lot less grub related damage on properties that have a high population of coyotes.

Cutworms present on a few putting greens this week.

I have also seen more cutworm activity on putting green surfaces.

Diseases

Dollar spot keeps growing in size.

Dollar spot has been pretty aggressive lately. I’ve been nurturing these spots on one of our tee boxes to see how big they can get (sickening huh?). These spots grew about a half inch in diameter this week. There are many fungicides that work well on dollar spot. Additionally, there are several fungicides that solely target dollar spot. However, we are getting closer to Microdochium patch weather. Perhaps it may be wise to start thinking about using materials that may also offer a little protection against Microdochium patch in addition to dollar spot.

Bipolaris leaf spot was active on a few creeping bentgrass putting greens this week.

Bipolaris leaf spot has popped back up again. This disease was active in early summer, mid summer, and now again in early fall. Once again I am observing this disease on the creeping bentgrass cultivars A1, A4, and Penncross. If I really think about it, Bipolaris has been the most common disease I have noticed on treated putting green surfaces.

There could be a few reasons why I am seeing this on treated putting greens.

  1. There are many commonly used fungicides that may not work very well against this disease. For instance, chlorothalonil and iprodione have not demonstrated strong efficacy against this disease.
  2. This disease can easily be misdiagnosed as other leaf spots or anthracnose. Not all fungicides that control anthracnose will control Bipolaris (and vice versa).
  3. The site of pathogen infection is not fully understood. I see fruiting structures of this pathogen all over the plant, from the base of the sheath up to the leaf. We still don’t know the most appropriate application procedures to tackle this disease. This includes customization of spray rate volume and nozzle selection.

White spots

White spotting was observed this week in Chicago. Picture courtesy of Dan Tully

White spots on fairway and putting green surfaces have popped up this week at several golf courses. These small spots appear bleached. Individual blades can be pale green to completely white in appearance. Damage from these spots appears to be negligible. Some have observed very minor thinning and everyone I have spoken with has indicated that the spots tend to disappear with time.

I indicated last week that I thought this malady may be ‘Yellow spot’.

Example of Yellow spot on creeping bentgrass. Picture taken in July 2011 in Tennessee.

However, as I continue to gather more observations of this disorder, it may be something a little different. Yellow spot expresses itself during or immediately after hot weather conditions (>90 degrees) in mid-summer. To date, these current white spots have ramped up under much cooler weather.

Another difference is the color of the affected grasses. Creeping bentgrass associated with Yellow spot were lime green to color. Rarely did yellow spot turn individual leaves completely white. Additionally, I don’t remember seeing Yellow spot on fairway height creeping bentgrass.

White spots on a creeping bentgrass fairway in the Chicago area.

What this malady may actually be is ‘White leaf’ disease. This disease is frequently diagnosed in other grass families such as sugarcane. On turfgrasses, White leaf disease has been diagnosed on annual bluegrass and creeping bentgrass in California. It has also been diagnosed on creeping bentgrass in Wisconsin the past two years.

Dr. Larry Stowell of PACE Turf has on ongoing collection of images that show White leaf disease on an array of different grasses.

www.paceturf.org/photo/search.php?keywords=white%20leaf

So, why it is so difficult to confirm a diagnosis on either yellow spot or white leaf disease? With yellow spot, researchers have not been able to confirm the casual agent. In some instances, researchers have made associations of yellow spot with cyanobacteria (algae) production. With White leaf disease, the casual agent may vectored in by insects. A high powered electron microscope may be required to see the pathogen. In essence, it is very difficult to see the ‘smoking gun’ with this malady.

The take-home message is that this malady can go away on its’ own as quickly as it appeared.

Rust

Rust disease was developing underneath a tree. This grass hasn’t been trimmed in weeks.

This is the time of year that many tree leaves begin changing color. Thanks to rust disease, grass leaves get to join the fun too. Rust is becoming more pronounced on slowly growing turf that is not being frequently mowed.

Looking ahead

Temperature anomalies through next Friday. Warm temperatures seem likely. Courtesy of tropical tidbits.

Above average temperatures seem likely throughout next week. This is great news for folks establishing new turf areas this fall. Increased warmth should also aid in recovery from aeration practices. However, as mentioned earlier, this warmth may keep many harmful insects in the top few inches of the soil profile.

Twitter: CDGATurfgrassProgram

Email: jbenelli@CDGA.org

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CDGATurfgrassProgram

Written by Derek Settle, PhD & Shehbaz Singh, MS. Mission: Provide science-based turfgrass research and diagnostics to 400+ member golf courses/superintendents.