You’re proud of your lawn; you mow regularly, fertilize frequently, but every summer it starts to develop large, unsightly dead spots and you’re not sure why. Some one tells you it’s insects, another person says you’re not watering enough. The truth is that a lot of lawn issues can have similar symptoms, but very different causes. Let’s look at four of the most common causes of spotty lawns and die-off in our yards, and ways we can address them in the short- and long-term.

Bugs

Insects, specifically ‘grubs’, are often the most commonly blamed for large patches of dead lawn. Savvy gardeners know that these larva come from the two species of European crane fly, Tipula oleraea and Tipula paludosa. The flying adults are often called ‘mosquito hawks’ or ‘skeeter eaters’, but they don’t actually eat mosquitos. Instead, after the adults have hatched and laid eggs in wet areas with plenty of foraging material (lawns, anyone?), the larvae chew on roots of their favorite plants, including turfgrass. Grubs start feeding starting in September, but damage might now show up until lawns start actively growing again in April and May.

Solution: First, confirm that you are dealing with crane fly larvae, so you’re not throwing money at a solution that won’t work. Even if you see crane flies, it doesn’t mean they’re causing your lawn damage. Heavy animal presence, such as birds, skunks, and raccoons digging into and pulling up your turf, is a good sign that your lawn has or recently had crane fly grubs. You can also pull back the turf in late Winter and do a head-count; any more than 25 grubs (also called ‘leatherjackets’) per square foot should require action.

Systemic insecticides such as imidacloprid, found in products like Bioadvanced Season Long Grub Control, will prevent further damage for several months. More natural solutions like Grub & Soil Nematodes let you treat effected areas without chemical insecticides, but may need to be applied multiple times.  

Crane flies thrive in poor-draining, wet soils – if you’re able, cutting back on your water during late Summer / early Fall will reduce the survivability of grubs, but since this is also the prime time for re-seeding, that may not be an option. Soil drainage is also key to another common issue:

Moss

If grubs win Gold for being blamed for lawn damage, moss takes silver. But many folks don’t know that moss doesn’t kill grass, it simply grows where grass struggles to thrive. Many turfgrasses have the capacity to grow roots up to a foot deep, but because of poor topsoil conditions, and compacted soils due to traffic, they are restricted to the first few inches of soil. Combined with our frequent watering, and trying to grow grasses in shady areas such as between buildings and under trees, grasses end up struggling while we’re unintentionally creating the perfect environment for mosses, which have no true roots and thrive on consistently moist surfaces. Grass grown in these problem areas, even when re-seeded or with new sod applied, will eventually struggle, thin, and die-out, while the moss just keeps on doing it’s thing.

Solution: Moss-killing products such as Moss Out (available in granules or liquid applications), will kill off moss, but unless the environmental issues above can be addressed, grass will still not thrive in those areas. If you’re determined to have grass in a problematic area, consider any way you can improve drainage, or increase available sunlight by thinning or moving trees. Alternatively, consider using the area for a garden with moisture- or shade-loving plants!

Disease

As gardeners, many of us are familiar with how damaging plant pathogens can be, and we recognize some of those same signs in our turf. But lawn diseases can vary wildly between environmental triggers, effected turf species, and areas of the country where they are more prevalent. This makes knowing when and what particularly difficult to treat. Some common lawn disease include Brown Patch, Necrotic Ring Spot, Dollar Spot, Summer Patch, and Snow Mold. If you are unsure which of these is the specific culprit in your lawn, consult with a local professional such as an Extension office, landscaper, and especially your local Grange Experts!

Solution: Broad-range lawn disease treatments are best applied according to manufacturer recommendations that relate to the disease you’re targeting. Environmental solutions will also help; many diseases thrive in damp, decaying plant matter. Make sure your soil drains well, and low-lying problem areas are addressed with extra drainage solutions if needed. Areas of lawn that have become compacted may need to be revitalized and replaced. Some turf species need semi-regular dethatching. Lawn aeriation and gypsum treatments (for clay soils) can be a short-term solution to increase water flow deeper into the soil, but they won’t be a permanent fix.

Soil

Did you catch a theme among these problems? Drainage is a huge contributing factor to many of the problems lawns face, whether that’s insects, disease, or competing plants. Several common weeds will also take advantage of poorer soils where grasses are struggling, increasing the amount of time and money you spend to correct them.

When it gets to the point that you decide to start over, on a portion or the entire lawn, there are some steps to consider that will ensure the spring and summers ahead are filled with more time enjoying a healthy lawn and less time trying to resuscitate it.

Simply re-seeding over struggling lawn, or pulling out dead patches and replacing it with sod, won’t address soil issues. Instead, when dealing with predominantly clay soils and areas that are heavily compacted, remove some soil volume and replace with some organic matter such as premium compost. Aim to have improved soil at least 2-3 inches deep. After gently rolling the soil (but not dramatically compacting it), you can add or remove more until it is level with the surrounding topsoil, or to the desired grade. Consider alternatives to a grass surface in areas with high foot traffic needs, such as paving stones, gravel paths, etc. French drains can assist with excess moisture and run-off, either alongside or under your lawn. Alternatively, you may decide that a turf lawn is more seasonal work than you want for the greenery around your house – if that’s the case, let our Grange Experts suggest some popular plants or hardscapes to create a beautiful yard that will still make the neighbors jealous!