dying lawn

Asked July 30, 2013, 3:24 PM EDT

Hi, I'm not sure if I should do this here or on the Garden Line, but here goes. I live in a townhome and have a small lawn out front (about 10'X 10' roughly) that dies out every summer. It's in sunlight 100% of the day, is bordered on two sides by my asphalt driveway, on a third side by my concrete walkway, and the fourth side is landscaping and mulch. I had grubs. This was easy to see. I used nematodes on them and they worked like a charm. No more grubs, but the lawn died anyway. Someone suggested I may have sod webworms so I applied the sc nematodes for the surface dwellers, in addition to the other nematodes, and that didn't work. I noticed tiny cobwebs on the lawn early in the morning last summer and researched this. I determined, correctly or not, that the problem might be the Dollar Spot fungus. So I sprayed with a fungicide this year but here it is, not even August, and the lawn is about 90% dead. I should mention that I also started using lime and gypsum, in addition to fertilizing ( I use Milorganite), which has done wonders for the larger backyard that had similar problems, but obviously hasn't helped out front. This year I noticed a lot of very tiny insects when I was picking some weeds, that "bounded" away as I knelt down, like really tiny grasshoppers. They were no larger than the business end of a pin so I couldn't see them, I only felt them and was aware of their movement. I don't know if they might have been the problem or not. I also only experienced them the one time. I'm also noticing the cobwebs again on the dead grass. I apologize for the length of this but I wanted to be as complete as possible. I'm completely out of ideas. I appreciate any suggestions you can give me at your convenience. This is driving me nuts. Also, can you suggest a good pre-emergent fertilizer for weeds that I can apply this fall? Thanks very much for your time, Joe

New Castle County Delaware

2 Responses

I have forwarded your question to our extension IPM specialist to answer the insect portion, but I can provide some information on other parts of your question. I assume you mean you lawn turns brown and goes dormant, rather than completely dies. If it greens back up in the fall or following spring, it has just gone dormant. If you have to reseed it, then it has died. We have certainly had plenty of rainfall this summer, but your lawn does sound like it is in an extremely stressful location. If it is slightly sloped, you may be getting pretty rapid runoff of rainfall and drought may still be the reason your lawn goes dormant. Check the soil moisture by digging down a few inches. Also check how deeply the turf is rooted into the soil. Shallow rooting may mean the lawn is not getting enough water. You can supplement with weekly irrigation, or just accept the dormancy and enjoy when it greens up again. I am not sure what you mean by a pre-emergent fertilizer (there is no such thing). A pre-emergent herbicide is used for summer annuals and that should be applied in the spring. We don't usually apply pre-emergent herbicide in the fall because winter annuals germinate over a long period of time and aren't much of a problem in lawns. You should apply fertilizer in the fall. You a product that contains slow release nitrogen and apply up to 2 lbs of actual N/1000 square feet. It may be helpful to bring a sample of the lawn (include both dead and living tissue) to the county extension office (on Wyoming Road) or diagnostic clinic (in Townsend Hall).

I second Susan's response that a sample brought into the extension office or diagnostic clinic would be helpful to try and resolve your problem. There are a number of possibilities for your situation including insects, disease, environmental, or cultural. A sample would allow us to get a better idea of what was occurring in your situation.

The insects 'bounding' away this spring were likely a type of leafhopper and rarely cause any injury to lawns. They are very common and this spring may have been great conditions for an increase in their populations. However, it is still doubtful they are the cause of your problem. The cobwebs seen on the lawn are most likely from a variety of small spiders you have in your lawn (quite natural and beneficial) and are not the source of the problem. Sod webworms can be problematic in lawns in the summer (usually end of June) or in September and usually if frequent applications of broad spectrum insecticides have been applied to the lawn. Sod webworms are often problematic when the natural enemies (ants, spiders, ground beetles, etc...) are removed by frequent insecticide applications.

Nematodes are great biological options for controlling both white grubs and sod webworms. White grub damage may be found from the middle of August until sometime in October if the grubs are present. The grass may appear greasy to drought stressed as the crown of the plant is unable to get sufficient water due to grubs eating the roots. Rainfall can mask some of the damage by keeping the crown of the plant in contact with water. This damage can also be masked by weekly watering as Susan suggested in her response.

Heavy fertilizer applications in the spring encourages shoot growth at the expense of root growth. Grass without healthy root structure will struggle during hot dry summers. This summer has not been too hot or too dry, so I do not think this is as much of a concern as in past years. Susan's other comments of fertilization are great.