Gardening with Gary

Gardening Advice from an Expert

Fungi

Q. I have some sort of fungus growing in small spots in my front garden. I've never had it before this year. First I thought some poor animal had vomited, and that's what it was, but now I know it's not that at all. It is like a pale flesh-tone in appearance and when pouring water on it, seems to not so much foam, but almost looks like it is. How do I get rid of it?

A. You definitely have a fungal problem going on here. It is severe but controllable, the sooner the better, so read this and get out to your local nursery or garden center and check their shelves for a treatment. If you encounter problems, ask an employee for help, but read the label before purchasing. Follow the directions exactly and as often as called for. Apply in the early morning hours before the sun is strong and shining brightly on the lawn areas.

Fungal infestations:
'Melting out' or pink snow mold are two common fungal diseases that cause dead spots in lawns. Now that the weather is drier, the fungal diseases are probably inactive, but the dead spots remain. You may overseed or patch with sod, but take care that the replacement seed or sod matches the existing turf type.

For future prevention of fungal disease, power-rake to remove thatch and allow the top portion of the lawn soil to dry between irrigations

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Fungal Turf Diseases by John and Jeri Cretti

Hot, dry summer weather stresses lawns, creating a perfect environment for fungal diseases. In our weekend plant diagnostic clinics lots of turf samples are showing up infected with dollar spot disease and ascochyta blight.

Identifying Diseases:
The term "dollar spot" refers to silver dollar-sized spots that appear throughout the lawn. With severe infections the spots will coalesce into large dead areas. It's not uncommon on bluegrass lawns for these dead, irregular patches to be 10 to 12 feet wide. Although the turf may appear scorched, increased watering may make the disease worse.

To identify this disease, get down on your hands and knees and look for yellow-green blotches or banding on grass blades. They eventually bleach to white or straw color.

One of the most common lawn diseases on cool-season turf grass lawns is ascochyta leaf blight. The height of summer is the time to be on the look for uniform areas where the lawn turns straw colored. In many instances, pockets of blight infection may cause your lawn to develop a patchy appearance. Check the leaf blades for signs of bleached areas on the tips. You'll also notice an abrupt margin between the diseased tissue and healthy tissue. We've even seen infection starting at the center of the leaf blade forming a straw-colored band across the leaf.

Underlying Causes:
These turf problems usually occur because of underlying stress. They may result from poor soil conditions, uneven water distribution, soil compaction, or using dull mower blades that create severe wounds for the fungal spores to enter. Preventive tactics are best, so manage your lawn properly. A healthy and vigorous-growing lawn can overcome these fungal diseases on its own, eliminating the need for fungicides.

Prevention and Recovery:
Don't mow the grass too short. Raise your mowing height to 2 to 3 inches tall, never removing more than 1/3rd of the grass blade at any one mowing. Also, make sure the mower blades are sharp.

Water the lawn to a depth of at least 6 inches as infrequently as possible without creating water stress. In our semiarid climate, water in the very early morning hours or late afternoon to take advantage of higher water pressure and reduced evaporation.

During the heat of summer, avoid the excessive applications of nitrogen fertilizer. Fast-release, high nitrogen lawn foods will induce tender, succulent growth that is susceptible to many lawn diseases. If your lawn needs nutrients, select a slow-release nitrogen formulation that contains iron and sulfur for our alkaline soils. Apply 1/2 to 1 pound of actual nitrogen per 1,000 square feet of lawn. Early fall is an ideal time to apply a slow-release lawn fertilizer. One of our favorites is one made in our region that contains DPW (dehydrated poultry waste). Local university studies show that slow release turf fertilizers help to reduce severe outbreaks of many lawn diseases.

Even with a severe outbreaks of ascochyta blight and dollar spot, the lawn can and will recover as weather conditions begin to cool down, bringing soft fall rain.

If soil in your lawn is becoming compacted from heavy use, core-aerate the lawn with a mechanical aerator. Aerators remove 3- to 4-inch long cores that allow water, air, and nutrients to get into the soil.

What About Fungicides?
We avoid spraying fungicides since the results are unpredictable. For example, a product that is very effective when used during this outbreak may not work when used again. Also, fungicides may spur future insect and disease problems because of their harmful effects on beneficial soil organisms.

With just a little help, your lawn will recover from the stresses of summer heat and drought.

Provided by NationalGardening.com, the online publisher of the National Gardening Association.