USGA - Regional Update

Warm And Wet

JULY 17, 2015

By Jim Skorulski, agronomist, Northeast Region

June and July have brought wet weather to the Northeast Region. Some parts of the region have been deluged with persistent rain and violent thunderstorms that caused flooding, saturated soil conditions and damage to trees. Needless to say, mowing has been a challenge. Some courses in western Pennsylvania have resorted to hand mowing rough in saturated areas. The wet conditions, increased humidity, and warm temperatures increase stress and disease pressure on cool-season grasses. Increased weed activity also can be expected, especially where spring herbicide programs were impacted by winter-recovery efforts. Weed growth and luxuriant growth are likely to be issues in naturalized roughs in the coming weeks.

However, wet weather and warm nights have had a positive effect on some golf courses where cold, dry weather hindered winter-recovery programs. Observations and reports from the field indicate that most damaged areas on greens have recovered, achieving reasonably good turf density. Decent root quality also has been observed at courses in central New England. Fairway damage that has been slower to recover also is filling with help from persistent seeding, sodding or plugging efforts.

Wet weather and summer heat still present challenges, especially for courses with cool-season turf and areas recovering from winter damage. The following are some thoughts as we proceed through mid-summer:

• Turfgrass plants subjected to wet weather and high humidity are more succulent and therefore more vulnerable to mechanical injury from mowers and traffic, especially where establishment or recovery programs have been in place. Raise mowing heights, utilize solid rollers, avoid mowing clean-up areas or skip mowing altogether when surfaces are soft and saturated.   
• Areas that have been reestablished are composed of juvenile plants that often are leggy. The natural tendency is to lower mowing heights and groom leggy turf to produce more upright, uniform surfaces.  While practices like low mowing heights and grooming are important for restoring surface quality, they should only be initiated when the weather is conducive. Do not jeopardize the hard work reestablishing damaged areas by being too aggressive. Take a conservative approach with adjusting mowing heights, grooming, brushing and topdressing.
• Turfgrass on newly constructed or regrassed playing surfaces also is more vulnerable to wear injury, resulting in thin or permanently damaged turf in high-traffic areas during wet weather. Golfers should be aware of the potential damage caused by the way they walk and the shoes they wear. Restricting play and even temporarily closing new greens following heavy or prolonged rain events can preserve the quality of new putting surfaces.    
• Make sure employees fully understand how to properly operate equipment during periods of wet, warm weather. Reemphasize the importance of mower and roller operation around green perimeters and collar/apron areas. Utilize turning boards to protect turf from wear damage.  
• Summer patch, anthracnose, dollar spot, brown patch and Pythium disease pressure will remain high with humid conditions and warm temperatures at night. Utilize a well-planned rotation of fungicides to control diseases when disease pressure is high. This may not be the time to experiment with new products or untested spray mixtures. Also, it may be necessary to shorten spray intervals when disease pressure is high. Keep it simple.
• Maintain plant growth regulator programs using trinexapac-ethyl on annual bluegrass surfaces through wet weather conditions. Application intervals also will need to be shortened to maintain desired growth regulation. The growing degree day model established at the University of Wisconsin is a helpful tool to schedule plant growth regulator applications.
• Now is not the time to sod slow-recovering fairway areas. Establishing commercial sod during summer is challenging, and warm soil temperatures negatively impact root establishment. Furthermore, shallow-rooted and often thatchy sod requires frequent irrigation and is easily damaged by mowing. A better strategy at this point is to continue spike seeding, leaving sod work for late summer when growing conditions are more favorable.

Finally, parts of the region are experiencing outbreaks of gypsy moth caterpillars that are defoliating many species of deciduous and coniferous trees.  Usually deciduous trees can tolerate a single defoliation and should put out another set of leaves. However, defoliation has a greater impact on coniferous trees. Many facilities have had to treat the unusually high population of gypsy moths.  Recently, gypsy moth populations have been held in check by a virus. Hopefully warmer temperatures and wet conditions will be more conducive to the spread of the virus. Caterpillars infected by the virus can be seen hanging on the trees while their body melts away, leaving some to call it the zombie virus.