When It Rains, It Pours June 2, 2015 By John Daniels, agronomist, Central Region

Figure 1 - Extended periods of cool, wet weather favor the growth of Poa annua and other weeds.

Much of the region has been inundated with frequent rains over past few weeks. In May, monthly rainfall records were broken for parts of Oklahoma and Texas. The rain has been a welcomed sight for several drought-impacted areas as it increased soil moisture and helped substantially raise reservoir levels. However, broad, heavy rain events have led to widespread flash flooding, some of which has caused damage to several golf courses. Recent rains on a course in southwest Missouri triggered the formation of a gaping sinkhole that swallowed up part of a practice area.

Even golf courses fortunate to avoid property damage have had to deal with a barrage of other challenges resulting from all the rain. Rapid turfgrass growth and the inability to mow without creating damage have created a domino effect of lanky rough. As mentioned in a previous update, incremental adjustments in height of cut may be necessary to avoid scalping and reduce clumps of grass.

A wet spring also has increased the prevalence of many troublesome weeds (Fig. 1). Excessive rain has reduced the efficacy of preemergence herbicides leading to weed breakthrough. Untimely rains have further complicated weed control by forcing spray rigs armed with postemergence herbicides to remain in the maintenance facility. More hand removal will most likely be required as weeds grow larger and are more tolerant to herbicides. 

Figure 2 - Plentiful moisture has triggered outbreaks of diseases like large

patch. Note the reddish-orange perimeters that are symptoms of an actively

growing patch.

Be on the lookout for disease outbreaks during long periods of wet weather. Dollar spot, large patch (Fig. 2) and leaf spot have been reported throughout the region.  Treatment with a penetrant fungicide is advised for active infections. Consider tank mixing fungicides to increase the spectrum of diseases controlled and reduce the likelihood of resistance. Make sure you are maintaining adequate nitrogen levels to accelerate recovery from infection. For those routinely affected by summer patch, preventative fungicide applications, based upon 65 degrees Fahrenheit soil temperatures at a 2-inch depth, most likely should have gone out by now. The key for controlling turfgrass diseases is to apply an effective fungicide when the pathogen is active and prior to damage.


Central Region Agronomists:

Bob Vavrek, agronomist –

John Daniels, agronomist –


Information on the USGA’s Course Consulting Service 

Contact the Green Section Staff

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