We are under attack!
Armyworms continue to march and eat pasture and lawn grasses. I thought they would be about through by now, but evidently they are not. I've had people call me and bring worms to my office this past week.
An entomologist with the University of Georgia said this week that this summer is the worst he has seen for armyworms and other caterpillars in 20 years. What a summer experience we've had. Makes you want to go through another one, doesn't it?
Anyhow, fall armyworms are the caterpillars stage of a nondescript, small gray moth that winters in Florida and the tropics. Each year, storms bring the adult moths north. The females lay up to 700 eggs on just about everything. During a recent test, 15 small flags were put on a turf plot. Just 24 hours later, each flag had at least one egg mass. Some had more than a dozen.
The eggs are cream-colored at first but turn darker as caterpillars get ready to hatch. They are covered with gray fuzz from the female's body. Young armyworms are [1/4]- to [3/4]-inch long. Mature ones are 1[1/2] inches. They are dark with several light stripes down the length of the body. The head or face has an inverted "Y" on it.
One sign that armyworms are near might be birds clustered on your lawn. But if the worms are bad, don't think the birds will take care of all of them. You should treat your lawn with an insecticide if you find five or more caterpillars per square foot. Left unchecked, armyworms will eat the blades off the grass.
Sevin, Dursban, and Orthene are good insecticides to use. For pasture owners or others with grass close to ponds, Sevin and Orthene will not kill fish because of runoff. Bacterial insecticides like Thuricide are effective but only on little ([1/2]-inch or smaller) worms. As always, follow labeled rates for the insecticides.
Irrigate before treating, to move the caterpillars out of the thatch. Treat lawns in the afternoon when the caterpillars are likely to begin feeding. If possible, mow before you treat and then don't mow for three days after the treatment.
Winter Weeds - It is time to put out pre-emergence herbicides to prevent winter weeds in your lawn. By the calendar we say late September or early October, or when temperatures get between 55 and 60 degrees. A couple of weeks ago we had already reached those temperatures. A few winter weeds may have already germinated, but you'll still get most of them. Remember you should put pre-emergence herbicides only on turf that has been established for at least a year.
This always brings up a dilemma to the homeowner who has recently sprigged or seeded grass and doesn't have a complete lawn. Naturally, you are going to have more weeds because you have less grass, but you can't use the herbicide. Many times you have to live with the weeds to a certain extent until you grass becomes established. You can hand pull weeds or use post emergence sprays after they are up and growing.
Several pre-emergence herbicides are available. Some of the more common ones are Surflan, Balan, Crabgrass Preventer, XL, Pendamethalin and Atrazine. You can choose granular or liquids, but more people prefer the granular for its ease of application.
If you are planning on overseeding your lawn with annual ryegrass, a pre-emergence herbicide will prevent your grass from coming up.
Other September Tips - Diseases have continued to be a problem on lawns. Most are secondary because of the stress this summer. Avoid over-application of nitrogen fertilizer at this time of year. If you want to put out a winterizer fertilizer, make sure it is low in nitrogen and high in potassium. Also monitor your irrigation carefully. Watering too often promotes diseases. Once a week this time of year is plenty for an established lawn.
If you plant ornamental shrubbery around your house this fall, leave enough room behind the plants to paint, put up screens, etc. Most shrubs should be a least 3 feet from the house. A one-gallon shrub looks far way from a house when it's first planted, but remember the size it will grow.
Sid Mullis is an agent with the University of Georgia Extension Service office for Augusta-Richmond County.