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.
