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In the Field

May 14, 2010

This week there have been a number of reports of “yellow rings” appearing on annual bluegrass putting greens.  These rings are likely cool season brown patch or brown ring patch (formerly known as Waitea patch).  Differentiating between these two diseases can be difficult based on symptoms alone since they look very similar.  However, identifying which disease you are dealing with can be important when considering whether to treat for the disease, particularly during late spring—early summer.  Cool season brown patch will become inactive at temperatures greater than 70F, but will re-activate under cooler temps; whereas brown ring patch will continue to cause disease at temps up to 90F.  Therefore, if you have brown ring patch repeat fungicide applications may be necessary since favorable conditions will likely persist for several weeks.  Also, benzimidazoles (e.g., thiophanate-methyl) are not effective against brown ring patch.  Incubating a sample overnight in a sealed plastic container with a couple of wet paper towels can be a method to differentiate between these diseases.  If significant mycelium it is produced, particularly from the thatch, it is likely brown ring patch, not cool season brown patch.  A more definitive identification can be made by sending a sample to the UCONN Turfgrass Disease Diagnostic Center. More information on brown ring patch.

Misery Loves Company:  Annual Bluegrass Weevil in North Carolina

For those of you managing ABW here in New England you may find it interesting to know this pest is spreading.  A sample containing >20 larvae in a single cup cutter was received today from a golf course in the mountains of North Carolina.  Identification of the larvae was confirmed by Steve Rackliffe and Dr. Pat Vittum.  This report would appear to be the furthest south ABW has been found causing damage.


April 28, 2010
The cool, wet weather facing the region over the past couple days has provided favorable conditions for the development of Microdochium patch (aka., pink snow mold).  The development of new infections now is evidence to the fact that snow cover is not required for this disease.  Rather, temperatures in the mid-30’s to mid 60’s F and extended moisture or high humidity are sufficient to cause outbreaks.  Microdochium patch symptoms observed in the field at this time often appear as 2 to 3-inch patches with thinning turf in the center and orange to pink margins.  Under high humidity, it is also likely to see a halo of water-soaked tissue and mycelium at the leading edge of the patch.  In addition to patch-like symptoms, diffuse colorosis in linear patterns (streaking) originating from patches can be observed.  This is due to the movement of Microdochium spores by mowers or carried downhill by water. 

Fortunately, the forecasted temperatures for the end of the week are in the 70’s and 80’s and sunny; conditions which are sufficient to prevent further infection.  For severe outbreaks, particularly on putting surfaces, an application of iprodione, fludioxonil, pyraclostrobin, trifloxystrobin, or propiconizole will all provide effective control of Microdochium patch.


April 26, 2010
After a rapid start to the growing season with above average temperatures in March and April the recent weather pattern has been a return to normalcy.  For the most part this early spring has had a positive effect on turf growth.  Dr. Bill Dest reported observing strong root development in Kentucky bluegrass and perennial ryegrass turfs this spring.  This is a welcome change from this time last year when root growth appeared to be poor due to the cool/wet spring. 

While this spring appears to have favored early turf growth, it also favored an earlier than normal development of some turfgrass pests such as annual bluegrass weevil and basal rot anthracnose.  Additionally, soil temperatures increased earlier than normal this year potentially resulting in early colonization and infection of bentgrass roots by the take-all pathogen, Gaeumannomyces graminis var. avanae.  The UCONN Turf Diagnostic Center has diagnosed samples this year already showing take-all patch symptoms.  Symptoms at this time may appear as patches of wilted turf; however once soil conditions become dry these patches will likely collapse.  Frequent hand watering and fertilization of take-all patches expressing wilted symptoms may prevent further turf decline. Furthermore, acidifying fertilizers such as ammonium sulfate and applications of manganese sulfate (2 to 6 lbs Mn/A/yr) can help reduce take-all severity.  Repeat applications of strobilurin or DMI fungicides every 21 to 28 days until soil temperatures exceed 65 F may be required to control take-all patch, particularly on sites with a history of this disease. factsheet.

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