You Are Here: Management Updates 2002 Archive June 21, 2002

Date: June 21, 2002
Category: Diseases
Subject: Fusarium Patch, Yellow Patch, Take-All Patch, Stripe Smut

It's the first day of summer, but the past week still had environmental conditions of spring. Several samples of Fusarium patch (pink snow mold) were submitted. The fungus responsible can be active in any cool, wet weather no matter what day it is on the calendar. As conditions get warmer, symptoms often become less typical but still usually include some kind of greasy/coppery small spots that can coalesce into larger areas with mowing or water movement. High foliar N makes plants more susceptible. Yellow patch (cool season brown patch) has also continued to be active in many areas.

Take-all patch of bentgrass is another disease that is active in cool, wet weather, so we are seeing much more than usual this year- even in older bentgrass, especially where pH is high. Where infections were less severe, symptoms may appear with the hotter weather if the infected roots cannot deliver enough water to the leaves.

A fairway sample that had received no fungicide treatments was infected with stripe smut, a first for the diagnostic lab. Luckily, this disease responds very well to the DMI fungicides which is why it is rarely seen any more.

Fungicides can be very effective but only if they reach the fungus that is causing the problem. In the case of root diseases such as Pythium root rot, summer patch, necrotic ring spot, and take-all patch, the fungi are on the roots. In basal rot anthracnose, the fungus is in the crown and can move into the roots. For these diseases, fungicides must be watered-in while still wet on the leaves. Once they have dried on the leaves, they will have penetrated the tissue and cannot be washed into the soil. Except for fosetyl-Al (Signature, Prodigy, etc.) which moves downward in the plant, most penetrant/systemic fungicides move upward in the plant.

Where no obvious fungal disease could be found in suffering Poa annua, nematode counts have been found to be extremely high, probably due to the mild winter which usually kills off many of them. A couple of samples also contained very well fed Hyperodes even where insecticides had been applied.

Summery weather next week is likely to bring summer patch and brown patch and continued problems with anthracnose.

- Submitted by: Dr. Gail Schumann