You Are Here: Management Updates 2000 Archive April 18, 2000

Date: April 18, 2000
Category: Diseases
Subject: Turf Response to Cold, Moss and Algae

COLD TEMPERATURE RESPONSES: Most of the turf complaints in recent days are from golf course turf. The lawn grasses seem to be tolerating the extreme temperature variations better, and the rain has not been so long-lasting as to trigger major fungal disease problems. On golf courses, the Poa annua - as usual, is the source of most of the complaints. Some patches of annual bluegrass seem to be developing unusual coloration- either yellowish or reddish-purple in response to the very cold temperatures that returned in the past week or so. Some yellow patch (cool-weather brown patch) is active, but it should be eliminated by the warmer weather to come without causing lasting injury.

MOSS AND ALGAE: There seem to be more questions about these two "weeds" than usual each year. This may be because a lot of turf thinned out during the drought last summer. Although moss and algae do not really qualify as diseases, they certainly trigger a lot of questions at the diagnostic lab. It's important to remember that these are green plants that actually compete with the turf for space. Under good conditions, they should have not be able to compete with grass, but once established, they can be a persistent problem.

Even though most people don't want to hear it, moss encroachment is commonly associated with mowing heights that are too low. There are a number of "home remedies" which may or may not work, depending on the circumstances. A thick mat of moss may need to be physically removed when overseeding. Raising the mowing heights temporarily may allow the turf to get established and outcompete any new moss growth. In lawns, moss usually occurs in moist, shady and acidic areas. If the shade is too dense for good turf growth, it might be best to substitute woodchips or shade-loving groundcovers such as pachysandra- or even allow moss to dominate in the shady areas.

Algae is another green plant that should not be outcompeting turf. It too is a sign that the turf is not growing well because of thinning by disease or low mowing heights during stress conditions. Overwatering can help algae get established. DMI fungicides (such as Banner, Bayleton, Eagle, or Rubigan) can enhance algae problems, perhaps because of their growth-regulator effects. Chlorothalonil (e.g. Daconil) and mancozeb are often helpful at reducing algae, especially when accompanied by cultural practices that favor turfgrass growth.

- Submitted by: Dr. Gail Schumann