Lawns

Look in the links above for a specific topic or scan the questions below. Questions are arranged by date so you may want to jump down to the month when you are experiencing trouble. Follow the links within the answers for a complete description of the insect/disease cycle and discussion on causes and control.

Moss on Lawns

5/01 Moss on lawns is found in ANY soil where turf is thin and moist throughout the spring and/or fall. Once established moss will tolerate very dry conditions. Most moss control products (potassium salts of fatty acids) will provide fair control. Begin in September. After several applications (as many as five), remove dead moss and reseed with a species that will thrive. In shade plant fine fescues and full sun on droughty areas consider tall fescue or perennial ryegrass. Alternatively, consider starting a moss garden in areas that do not get 6 hours of sunlight or are consistently moist.

Moles and meadow mice
Q. 5/1 Our lawn has a lot of moles in the upper section and the grass is sparse. I was told that they are feeding on the grubs. What can we do to kill the grubs?

A. First, determine whether the damage is from moles or voles (meadow mice). Moles create tunnels under the soil. Some moles also create little mounds of soil outside of their holes. Moles are not necessarily an indication that there are grubs in the lawn. They will feed on many things including beetles and worms. The best treatment is trapping or just raking down the hills they leave behind. There are many different types of traps for moles including the harpoon trap. To determine if there is a problem with grubs, wait until September, when grubs do most damage, and roll back a one square foot piece of sod. If you find more than 5 grubs / sq ft, then you may need an insecticide to prevent damage to the lawn. Mice differ from moles in a few ways. They create trails through the grass and are mostly responsible for damage over the winter, when they have the benefit of snow cover. Mice feed on vegetation, not insects. If control for meadow mice is necessary, set snap back traps along runways. Bait with peanut butter or an apple slice and cover with a shingle bent like a tent.

Grubs
Q. 6/2 My lawn is looking kind of sparse and the guy at the garden center said I need to treat for grubs. He suggested Grub-B-Gone or milky spore. What should I get?

A. Grubs feed on roots of grasses causing brown patches noticeable from September to the following June. To determine if grubs are causing the damage you should monitor the turf for white grubs beginning mid-August: Lift 1'x1' sections of turf every 30' or so and inspect the roots for C-shaped grubs, which will be quite small(1/4") at this time. More than 5-8 grubs per section suggests a potential for noticeable damage. If you see many Japanese beetles or European chafers this summer, consider sampling for grubs as directed above. Treat the lawn if necessary in mid-late August with insecticides or Beneficial nematodes. A relatively new pesticide, Imidacloprid, must be applied in June to be effective for the fall brood of grubs. Choose this product if you consistently have damage from high grub populations. Milky spore needs warm soil temperatures for long periods of time, and high grub populations to spread from one grub to another. Our soils (Cattaraugus Co. NY) just do not stay warm enough for long enough, plus you may have to tolerate significant turf damage before the grubs would die.

Dog urine
Q. 6/17 I have a German Shepard and it is killing my lawn with urine. It creates about a square foot of dead grass. Is there any way to prevent this? Someone said feed the dog tomato juice or add lime to the soil.

A. Dog spots are yellow or brown patches of grass that result after your dog urinates on the lawn. Salts in urine can burn the grass. It is not the pH of the urine that is the problem. Re seeding bare spots is the only remedy. Repair small spots in the lawn before weeds move in. There are some grasses more resistant to dog urine: Festuca sp. var. Kentucky 31 (fescue) and Lolium perrene (perennial ryegrass). But besides replacing the lawn, you could train the dog to go somewhere else (like a gravel or mulched bed) or water the area every time the dog does its business. Lawn that is fertilized is more susceptible since the salt content is already higher. Replacing dogs with cats is also effective.

Perennial weeds
Q. 6/27 I have a weedy vine in my lawn. How do I get rid of it?

A. Perennial weeds may be best controlled in fall. Follow herbicide applications with fall fertilization to help grass fill in those bare areas. Also look at the under lying reason that may be stressing the turf. For example, ground ivy prefers part shade and moist soil. Plantain is common in compacted soil. Reduce compaction by adding a compost top dressing. Choose the best grass seed for the site (or modify the site to suit the grass) and many weeds will not be able to compete with the grass. A dense lawn is your best defense.

Ground ivy may be controlled after the first frost. Triclopyr, 2,4-D, and fluroxypyr are some of the better herbicides for controlling ground ivy. It is important to alternate herbicides when attempting ground ivy control. Also, fertilizing twice a year decreases the spread of ground ivy.
For veronica, repeated applications of triclopyr (Ortho's Weed B Gone for difficult to control weeds) is recommended. The best alternative is to hire a certified pesticide applicators that has access to stronger products.
Plantain is common in compacted soil. Reduce compaction by adding a compost top dressing. 2,4-D in early fall will control plantain. Always read the pesticide label.

Testing soil
9/18 Q. How many times per year should I test the soil in my grass?

A. Soil can be tested for nutrient analysis and pH. The nutrient analysis test is performed at a laboratory and measures the amount of nutrients such as phosphorous and potassium in the soil. This is useful when establishing or renovating a lawn. Testing pH can be done in our office and will give you the acidity or alkalinity of the soil. This should be done every one to three years. If after your first test the pH is acceptable (6.0 to 7.0) then you can wait 3 years before testing again. If it is very acidic and you need to add lime, you should test it every year until it reaches the desired range.

Using Pesticides Safely
Indiscriminate use of pesticides introduces unneeded chemicals into the environment, puts yourself at risk of contamination, possibly kills beneficial insects and could lead to pesticide resistance in pest insects. Before choosing an insecticide, ask yourself how much damage you can withstand. If the damage to the plant is only aesthetic, your first option is always to do nothing. To choose the appropriate insecticide, look for the name of the pest and the host plant on the label. Always read the label and follow the directions for application methods.

This publication may contain pesticide recommendations that are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator's responsibility, by law, to read and follow all current label directions for the specific pesticide being used. Due to constantly changing labels and product registrations, some of the suggestions given in this writing may no longer be legal by the time you read them. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The author and Cornell Cooperative Extension assume no liability resulting form the use of these guidelines.