UCCE Tulare/Kings Counties Master Gardener Program

July's Questions & Answers
By Carolyn Carpino, UC Master Gardener

Q. I have a fescue lawn and practically overnight it developed greasy looking spots that are wilting and dying fast. When I water it seems to get worse. Will these spots spread to the rest of my lawn? What can I do to remedy this problem?

A. The lawn disease you describe is "grease spot" caused by a fungus called Pythium that is extremely active in summer, according to Master Gardener Norm Phillips. It spreads by excessive water and the inability of the grass (especially near the soil surface) to dry out during the day. The problem usually starts in low spots where water collects and shows up when temperatures are warm to hot. To control this disease, reduce shading, improve soil aeration and water drainage. Do not water in the evenings or more than three times per week. Instead, water only when needed and water deeply to a depth of 4 to 6 inches in the early morning. Three fungicides: Subdue, Alliette and Fore are available, but need to be applied before the disease is too severe for best results. The lawn usually repairs itself if damage is minimal, but some spots may need reseeding in fall.

Q. Is there a way to get rid of snails and slugs without using a poison, which may harm my pets?

A. Snails and slugs are a perennial problem. The good news is they have just one generation a year, so if you can control them now you've solved the problem for the season. If your problem is a localized one, beer traps are quite effective for slugs. A butter tub sunk to ground level and filled
with an inch of beer lures the whole gang to a fatal party. Snails are tougher customers and need handpicking to bring their populations down. After watering go out in the early morning or at night with a flashlight for a search and destroy mission. Pay your kids by the snail! Then you can
either smash them or drown them in a bucket. There is also a new product on store shelves called Sluggo. It contains iron phosphate and is not harmful to pets.

Q. I'm seeing a lot of a flat, creeping weed with small, red-spotted leaves in my garden. What is it and how do I get rid of it?

A. You're describing spotted spurge, a very common annual weed that germinates in open spaces from March through October. Although it is an annual, its prolific seed production (several thousand per plant!) makes it a major pest. It's very important to hand-pull or hoe new spurge plants before they set seed. This means at least a weekly weed walk through the garden to keep on top of it.

The primary method of managing spotted spurge is prevention since it is difficult to control once established. Open areas encourage spurge infestations, since spurge seeds need light to germinate. Spot treat spurge in pathways and unplanted areas with Roundup, then apply several inches of mulch wherever spurge has gone to seed. Keep lawns thick and healthy. Set mowing height at 3 inches in fescue to shade out weed seedlings and be sure to regularly water and fertilize bermudagrass lawns to keep them vigorous. Preemergence herbicides (Dimension, Pre-M, and Weed Stopper) are helpful in reducing spotted spurge and work best if they are applied in late winter before seeds germinate. There are no selective herbicides that will control established spurge in turf or flowerbeds, so once again prevention and persistence are the keys to winning the war with this weed.

July 15, 1999

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