August Q & A
by Michelle Le Strange, UC Master Gardener Advisor

Q.How can I get rid of bermudagrass in my fescue lawn and flowerbeds?

A. Bermudagrass is difficult to eliminate because of its extensive underground root system. It also spreads by stem sections, so rototilling just spreads it farther. If you have tons of time and patience to hand pull the rhizomes (creeping roots) and stolons (creeping stems), you might be able to get rid of it in your flowerbeds and lawn. However these areas will be visibly disturbed and you will still need to prevent the seeds in the soil from germinating.

There are a few postemergence herbicides that work on bermudagrass, but what's used in the lawn can't be used in the flowerbeds and vice versa. These products might seem expensive at first, but they are concentrated so many applications can be made from a small container. Read and follow label directions and cautions carefully to insure the best control without damage.

In fescue lawns, a product called Turflon® containing triclopyr can be used to suppress bermuda while it is actively growing and keep it from taking over. A few monthly applications will be needed. Turflon is also effective on most broadleaf weeds including some tough ones like oxalis, so be sure to avoid drift onto flowerbeds and ornamentals or damage will occur. Also avoid spraying Turflon on exposed roots of shallow rooted trees.

In flowerbeds, use Grass Getter or Grass-b-Gon to kill any grasses (except annual blue grass) around broadleaf plants. We've used it around many cherished trees and ornamentals with great success. The bermuda turns a reddish color and dies within one to two weeks. It works better in warmer temperatures during the summer and is less effective in the early spring and fall. Be careful not to allow drift onto your lawn.

Follow up with a preemergence herbicide like Dimension, pendimethalin, or Weed Stopper to control bermudagrass seedlings in both the lawn and the flowerbeds.

Q. I have a fescue lawn and practically overnight it developed spots that are wilting and dying fast. When I water it seems to get worse. 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. 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 hot and muggy. To control this disease, improve soil aeration and water drainage. Do not water in the evenings or more than three times per week. Instead, water only when needed 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.There is a weed in my garden that looks like a grass, but when I hoe it, a bunch more comes up?

A.You're describing nutsedge, which is a tough perennial weed worldwide and in our area we have two kinds: yellow and purple. Both produce an extensive system of underground tubers from which they generate. The tubers of yellow nutsedge are smooth and round and have a pleasant almond taste, while the tubers of purple nutsedge are rough and scaly and taste bitter.

The best solution is to not let either yellow or purple nutsedge get established. They thrive in waterlogged soil and their presence often indicates that drainage is poor, irrigation is too frequent, or sprinklers are leaky. Once you notice the problem, get on it and keep after it. Carefully hand pull plants before they develop five leaves and they won't have a chance to form new tubers and eventually the old tubers will run out of energy to resprout.

If your nutsedge problem is widespread in a lawn consider two applications of Manage® and you'll see a dramatic reduction in population. Also available are several products containing MSMA or CMA. Nutgrass 'Nihilator® is effective against yellow, but not purple nutsedge. Pennant® is a preemergence herbicide that can be used in flowerbeds in the spring and early summer to keep nutsedge from sprouting, but has no effect on actively growing plants. Spot treatments of Roundup, Scythe, and Finale can also be used.

August 7, 2003