There is something peaceful about a calm, dewy summer morning on a golf course and staff members often appreciate some dew when mowing so they can see their lines. However, there are playability and agronomic downsides to dew that may leave superintendents looking for ways to minimize its impact.
How does dew form?
Several conditions need to be met for dew to form. There needs to be an adequate amount of water vapor in the air, and the temperature of the turf canopy must drop to the dew point. Clear nights with low wind often produce heavier dew because the turf surface will be cooler. Lower-lying areas also commonly see heavier dew formation as denser, more-humid air will migrate to lower areas and increase relative humidity and dew point temperature in these microclimates. If the dewpoint temperature is low and/or it is cloudy and windy overnight, that may lead to lighter dew formation or no dew at all.
What challenges does it create?
Extended dew cover leads to prolonged leaf wetness, which in turn can create an environment favorable to fungal disease. Diseases like dollar spot, brown patch, leaf spots and pythium blight all thrive with prolonged leaf wetness. Dew also interferes with playability on unmown surfaces, it may re-form on surfaces mown early in the morning, and it can cause clippings to pile up during mowing, which may necessitate dragging or blowing surfaces ahead of play.
How can you deal with dew?
Preventing dew is not feasible in an outdoor environment like a golf course, but minimizing its effects is possible and can improve turf health, overall playability and maintenance efficiency. I commonly see mechanical means of dew removal used to shorten the period of leaf wetness. Mowing, rolling, dragging, brushing and using a dew whip are all effective ways to remove dew, but they take time. Products advertised to suppress dew – like some surfactants – can also be used to help reduce the surface tension of the leaf blades and create a coating that prevents condensation from forming dew. It is important to understand that these products are meant to be applied to a dry turf canopy and aren’t recommended to be watered-in like other surfactants that are used as wetting agents.
During periods of high disease pressure, I think dragging fairways on non-mowing days is worthwhile. Greens will be mown or rolled on most days, but if they are given a day off it’s certainly worth using a dew whip or brush to clear the surface for playability purposes and to lessen prolonged leaf wetness. In terms of product applications, using dew-related surfactants like DewCure biweekly can control dew during periods of active growth. The use of many other wetting agents intended for soil applications can also provide short-term dew suppression, often lasting around five days. Overall, applications designed to reduce dew are not long lasting, and consistent dew management is necessary to ensure disease pressure is limited and playing surfaces are ready for golfers. If you have any questions regarding dealing with dew at your golf course, reach out to your local USGA agronomist.
Central Region Agronomists:
Zach Nicoludis, regional director, Central Region – znicoludis@usga.org
Tom Gould, agronomist – tgould@usga.org
Steve Wilson, agronomist - swilson@usga.org