I’m having an ongoing problem with what I’m told are grubs in my St. Augustin grass. Each summer I get these patches which turn yellow/ brown and die out, just as if I hadn’t watered them in ages, which is, of course, not the case. Apparently they eat the roots of the grass causing the tops to die. I have usually spread grub killer and that seems to take care of it. The problem is that the grub killer, called “Seven,” I believe, is super toxic, indicating the need to wear socks, long pants, gloves, respirator (my addition), etc. Do you know of any similar remedy for grubs that would not be so environmentally horrendous? I have three cats who live in this grass daily and I don’t want one of them to start growing an extra head or some other such gruesome mutation. Caroline, a Manx, already has all the extra toes she can handle.
Kathleen (a.k.a. Toxic Avenger)
I can think of three possible culprits for your St. Agustine grass problem, the likliest one being the chinch bug, Blissus insularis, small gray-black insects that suck plant juices from grass blades, especially St. Agustine grass, especially in hot weather. To confirm chinch bugs, according to the Western Garden Book , push a bottomless can into the soil just where the grass is beginning to turn brown. Fill can with water, If lawn is infested, chinch bugs will float to the surface. Diazinon and chlorpyrifos are chemical controls. According to Hogue, the Southern Chinch Bug feeds on several grasses, but Saint Augustine is by far the preferred host plant. The insect’s feeding may cause considerable damage: the grass becomes dwarfed, turns yellow and then brown, and dies. Because of the tendency of the species to form aggregations, the symptoms of attack are usually visible in scattered patches. The species is not a native. It first appeared in the Los Angeles area in the late 1960’s, having come from the southeastern states. It produces two generations per year and is most abundant in midsummer. Two additional possible culprits that require the same chemical control are Sod Webworms and beetle grubs. If you see whitish to buff colored moths flying around the lawn in a zigzag pattern at night, check for their larvae. To confirm Sod Webworms, drench area of lawn with a solution of 1 tablespoon dishwashing soap diluted in 1 gallon of water. Larvae will come to surface. Treat if there are 15 or more webworms per square yard.
Bugman, I love your web site but in a recent post (see below), you recommended some harsh chemicals to get rid of chinch bugs. Diazinon has been banned on golf courses because it kills birds. http://envirocancer.cornell.edu/FactSheet/Pesticide/fs28.diazinon.cfm Could you also recommend organic alternatives to bug control? Lots of lawn problems are caused by over fertilizing and overwatering the lawn rather than building up the soil itself. Here’s a web site with ideas for controlling chinch bugs without pesticides: http://versicolor.ca/lawns/ chinchNOW.html#action1 I live in a house built in 1908 in Massachusetts and I figure the lawn is an old pasture. The grass and clover lawn is deep rooted and survives even the longest droughts. I never water or fertilize. I just mow high with a mulching mower that basically chops up the grass blades and creates compost every time I mow. When friends complain about grubs, I don’t have a thing to add because the lawn is evidently so healthy that they don’t thrive. And if a drought is long enough to turn the grass brown, I still don’t worry, because the roots are healthy so the next rain brings back the green growth. Plus I see loads of butterflies, dragonflies, fireflies, interesting bugs, birds and other critters all summer long. Lots of builders strip the existing topsoil off a site (to sell to landscapers) and replace it with a shallow layer of topsoil, then seed it with grass that can never establish really deep roots in that thin layer. The homeowner is then stuck in a cycle of watering and fertilizing. If you dig into your lawn, you can figure out how deep the topsoil actually is. If it’s shallow, get a couple truckloads of topsoil laid down so you have a good 8-12 inches of soil, add a few inches of compost (which is often free from your city recycling center), re-establish the lawn with grasses that do well locally and then mow high with a mulching mower. You can save on your water bill while avoiding toxic chemicals that could hurt your kids, pets, birds and bugs. Thanks, Bugman, for a fantastic and fascinating site.