YELLOW PATCH ON SEEDLING TURF

Nick Christians and Spencer Nelson
November 16, 2012

Last week, Spencer Nelson, one of our undergraduates, brought a picture to me of a disease on creeping bentgrass seedlings from the new Iowa State University Golf Performance Center south of Ames, IA.  The bent had been seeded approximately a month before the picture was taken.  The disease looked like Yellow Patch, a cool temperature disease caused by Rhizoctonia cerealis.   He took a sample to the Iowa State Plant Disease Clinic and had pathologist Erica Saalau-Rojas grow it out on agar plates. 

Erica was able to confirm that it was a Rhizoctonia organism, but was not able to confirm that it was cerealis.  It is highly likely that it is cerealis, given the time of year and the appearance of the patches on the turf.

I was in Chicago this week for a golf course superintendent's meeting at Medinah Country Club.  One of the subjects that came up at the meeting was that they are also seeing Yellow Patch on seedling bentgrass in the Chicago area.

Here is some information from Spencer on what he saw and what was applied to control the disease.

A patch disease has developed on seedling creeping bentgrass at the new Iowa State Golf Performance Center just south of Ames. The patches are showing up in bentgrass seedlings of four different cultivars in both USGA greens and native soil fairways. The 4 bentgrass cultivars are V-8, L-93, 007, and an Alpha/T-1 blend.  The patches are between six and twelve inches in diameter with a yellow border. The foliage inside the ring is mostly purple.

Initially the patches were small and yellow with little to no purple and were believed to be a fertility problem. As the patches grew a fungal problem became a more evident diagnosis. The second assumption was Yellow Patch, Rhizoctonia cerealis. Samples were taken to the ISU Pathology lab for identification. Before the results were back from the lab, the area was treated with Instrata(chlorothalonil, fludioxonil, and propiconazole). The pathology lab confirmed the diagnosis of Rhizoctonia spp.  

Figure 1.  Is the Yellow Patch symptoms as they appeared on November 7, 2012.

Figures 2 and 3 are microscopic pictures of the organism that was grown on agar media at the ISU Plant Disease Clinic.  The hyphae show the septa and the classic right angle branching with the pinched appearance at the right angle of a Rhizoctonia.

QUACKGRASS WAS THE BIG WINNER IN DROUGHT

Nick Christians
November 13, 2012

Quackgrass (Elymus repens) is known for its long clasping auricles and its extensive rhizome system.  It is one of the most persistent and difficult to control weeds in cool-season lawns.  Rhizomes give this species an ecological advantage over other grasses during extended dry periods.  While Kentucky bluegrass also has a rhizome system, quackgrass has a more extensive system and will out compete Kentucky bluegrass in dry years.

This was the case in this year's drought in the Midwest.  Lawns went through an extended period of dormancy that in many areas lasted for months.  This fall, we are seeing Kentucky bluegrass lawns recover. But wherever there was quackgrass in the lawn, it has gained an even bigger foothold.

Last week, I was asked to look at a lawn that one of my students cares for through his lawn care service.  It had been a mostly Kentucky bluegrass lawn up to this year, but following the drought, nearly everything that is recovering is quackgrass from the rhizome system.

Roundup will kill it, but the problem is that Roundup generally does not translocate through the entire rhizome system.  When you reseed, there is always some living rhizome tissue and quackgrass returns.  I generally recommend repeated applications of Roundup, followed by sodding.  Even that extreme treatment generally fails, however, and the quackgrass returns.

Figure 1.  Long clasping auricles of quackgrass.

 Figure 2.   Quackgrass rhizomes.

Figure 3.  Lawn in central Iowa that is nearly all quackgrass following the drought of 2012.

GRUBS FEEDING IN NOVEMBER IN CENTRAL IOWA

Nick Christians
November 11, 2010
nchris@iastate.edu

Here is another post from Larry Ginger of "American Lawn Care" in Des Moines.  Larry has been keeping us updated on late grub damage and fall seeding on lawns that he manages.  Below are some pictures from Pleasant Hill, Ia showing active grubs on November 9.  I am going to have to change my teaching notes on this.  Generally the grubs have burrowed deep underground by this time, but here they are in November.

Larry also reports an 800% increase in his fall seeding business.  He is using a three-way blend of Falcon IV, Five Point and Six Point turf-type tall fescues.  He will send us some pictures of newly seeded lawns next week.

I have also been seeding areas that had been established to Kentucky bluegrass in the past, but were lost to the drought this summer.  I have tried turf-type tall fescues as well in some areas and will report the success with this next season.  My main concern is how well they will blend with the Kentucky bluegrass remaining on the area.


Figure 1.  Active grub on November 9 in central Iowa.

Figure 2.  Grub damage.

Nick Christians
Nov. 11, 2012
nchris@iastate.edu

Dr. David Minner from the ISU Horticulture department has been missing two Clegg Impact testers for the last 3 years.  They are used to measure the hardness of surfaces, such as sports fields.  They were likely lent to someone out there who still has them on the shelf and has forgotten where they came from.  If anyone has seen them, please let Dave or myself know.  

Here is a statement from Dr. Minner:

I am looking for a missing yellow or red Clegg Impact Tester that is used to determine athletic field hardness.  The device is shown below and will have either a 0.5 lb plastic hammer or a 1 or 5 lb steel hammer.  A hammer is just a cylinder that is dropped through the PVC tube and may be attached to a wire or metal “T” handle. The digital read out box may be in a separate padded box and both may be in a canvas carry bag.  They are pictured below.

David D. Minner, Professor

Extension Turfgrass Specialist

EARTH Program Co–coordinator, USVI

Horticulture Department

Ames, IA 50011

(o) 515.294.5726

(c) 515.231.1741

(f) 515.294.0730

SURFACTANT APPLICATIONS TO PREVENT LOCALIZED DRY SPOTS ON T-1 SAND-BASED GREEN

Drs. Andrew Hoiberg & Nick Christians

November 2, 2012

We were approached at the Iowa Turfgrass Institute (ITI) field day this summer by Jim Turner of Numerator Technologies of Sarasota, Fl. to perform a surfactant trial evaluating the prevention of Localized Dry Spot (LDS) on a California-style pure sand (no organic matter) T-1 creeping bentgrass putting green. What a perfect year to investigate!

The trial started on August 9, 2012, and continued through mid-October. An experimental surfactant  from Numerator Technologies called NT 6001 L was used at three different rates (6, 12, 18 oz/1000 sq. ft.) and applied every two weeks throughout the study period at a total volume of 2 gal/1000 ft. sq. The first application was allowed to dry on the turf for 24 hrs to evaluate potential phytotoxicity, of which there was none at any of the rates applied. Thereafter, treatments were watered in to facilitate movement into the soil, where the product needs to be to perform correctly.  Two weeks after the initial application on August 23, irrigation was stopped to generate LDS.  We were very effective at developing dry spots.  Once the dry spots were present, we resumed irrigation to prevent stress.

We found that the product performed well throughout the season at preventing formation of LDS, and especially shined at the end of the season after another prolonged period of drought. Plots treated at the rate of 18 oz/1000 ft. sq. had significantly less LDS in them when compared to the other rates and the control. The lesser rates of 6 and 12 oz/1000 ft. sq. also ended the season with less LDS than the control plots.

Figure 1.   

Graphical representation of LDS evolution between 9 August and 16 October 2012. Treatment 1 is control, treatment 2 is 6 oz NT 6001 L/1000 ft² , treatment 3 is 12 oz/1000 ft², and treatment 4 is 18 oz/1000 ft². You can see that treatment 4 had the least amount of LDS throughout the study and had significantly less LDS than any other treatment by the end. Treatments 2 and 3 also had less LDS than the control at the end of the study.

 

 Figure 2. 

8-22-12: You can see relatively little LDS on the plots early in the trial.

 Figure 3.

8-23-12: You can easily see where surfactants have been applied. Treatment S4 (18 oz/1000 ft. sq.), nearest the bottom center of the photo, performed the best of any rate throughout the study.

Figure 4.  

10-16-12: By the end of the study, the control plots are clearly evident. In the left column on the top and on the bottom for the middle and right columns.