Grass Issues......

Asked July 26, 2016, 1:51 PM EDT

Hi: I have a few problems with my lawn this season. First, we recently removed two large cottonwood trees. I filled the holes with new soil and planted Scotts EZSeed in the patches. The grass germinated and came in very well. However, recently those formerly nice growing patches have become brownish and seemed starved for water (See Pic Below). The confusing part is that when I water, I get a lot of mushrooms in those spots. I am assuming from the decomposition of the wood/stumps under the dirt. Any ideas on the new grass? Second, I have noticed that there are numerous small patches of dark green on the lawn too that look out of place (See Pic Below). Any ideas? Lastly, the removed Cottonwoods are throwing suckers up everywhere in the lawn. I have removed the larger roots where I can, but the clusters of suckers keep coming up every couple of days. I am now spraying them with Weed-B-Gon and waiting to pull them. The suckers have been wilting. Is there anything else that I can do? Thanks for your time. You provide a wonderful service. Regards, Greg

Scott County Minnesota

8 Responses

I am going to assume (correct me if I'm wrong) that you have had the stumps ground out and that you re-seeded in May/June. Did you treat the stump at all and if so with what? If you treated it with a chemical to increase decomposition, it may be causing problems for the grass plants.

However, the browning is likely due to the grass mix you used to repair / patch your lawn over the area where the stump was removed. Mixes may include grasses that will grow quickly to cover the soil and allow the slower perennial grasses to grow in. Also, some cooler season grasses go dormant and turn brownish in summer heat, then become revitalized temperatures cool. According to my colleague and turf expert, Sam Bauer, it is typical for rough bluegrass to turn brown in the middle of the summer due to heat stress. Here is a good article and a publication:

I took a look online at the Scotts EZSeed products, but there are several types and none had a seed analysis. Maybe check out your seed label and look for plants like rough bluegrass (poa trivialis) and/or creeping bentgrass. The EZSeed patch and repair product does mention tall fescue.

Re: the dark green areas - this looks like it is a tall fescue species (Festuca spp.), which can be a clumping, coarse grass species. You may want to kill off these spots and re-seed.

Re: the suckers / stump issue - yes, the mushrooms are growing from the decaying wood and they will continue to appear when moisture levels are high enough in the soil. There's no way to eliminate them until the wood is decayed. The suckers should be treated with a product specifically for suckers. Weed-B-Gone products are for lawn weeds such as chickweed, creeping charlie, dandelion, etc. You need a product specifically labeled to kill suckers from trees and shrubs. These products are typically growth regulators. NOTE: Labels on pesticides (includes herbicides, fungicides, miticides) are legal documents. Always follow the label directions attached to the pesticide container you are using. Pesticide labels may change frequently. Internet labels may not match the label on the container you are using. The site of use or plant to which the pesticide is to be applied must be listed on the label or the pesticide cannot be used. Remember, the label is the law.

Feel free to reply with additional questions, photos / comments.

Thank you for the quick and thorough response. However, I was not able to open the first url link you sent at purdue turf tips. It says it no longer exists.

Oh, and you are correct that the stumps were ground out and I did NOT apply any sort of chemical treatment to the area or stumps.

Here is the composition of the seed mixture I put down. Does this give you any clues as to the Summer browning/dormancy?

I am contacting our turf expert in Extension to see what his take is on this issue. I believe it will be related to a combination of new seed over a ground out stump (usually a shallow divot in the landscape), the seed selection and the recent heat wave. I will let you know what I hear!

Any news for me yet?

Yes! Here is the response from our turf expert, Sam Bauer:

The grass seed mixture looks fine.

His issue is likely to be related to the difference in soil type used over the stump and the fact the stump is beginning to decay. The decaying process uses oxygen in the soil and ties up nitrogen (needed by the grass), so often this will result in a decline in turf quality.

A good core aeration this fall will help to create channels for oxygen. He should continue on an aeration program over this area (consider aerating the entire lawn) for at least 3 years in the fall around Labor Day.

After aerating, overseed with a high quality mixture of Kentucky bluegrass following aeration. Good bluegrass mixtures may be purchased at garden centers and big box stores. I suggest avoiding the Kentucky bluegrass varieties "Park", "Kenblue", and "VNS" (Variety Not Stated). Most other Kentucky bluegrasses available should work well. Rake the seed into the aeration holes and the canopy of the grass, and apply a fertilizer at this time.

Water daily (up to 3 time lightly per day) to maintain a moist seedbed. Continue watering until good germination is visible. Monitor moisture in this area and be sure the seeded area doesn't dry out. Note this may require watering 2-3 times per week if there is little / no rainfall and temperatures are high. Be sure the ater soaks in and avoid saturating the site so much that water pools. If it gets too wet, just let the area dry out before watering again. Hand watering with a hose or a using small sprinkler on a timer would work fine.

Fertilizing now is advised. You can either fertilize the entire lawn or just this small area, but you will need to do it with a broadcast spreader, not by hand. Follow label directions on application rate, but generally you're looking for 1lb of nitrogen per 1000ft.sq.

For example, a fertilizer with the analysis 25-0-10 contains 25% nitrogen (N), 0% phosphorus (P), 10% potassium (K). To supply 1lb of nitrogen/1000 sq ft. with this product, he will need to apply 4lbs of total fertilizer per 1000 sq ft. (because the fertilizer is 25% N, 4lbs x 0.25 = 1lb N).

If the product analysis is 10-0-0, he will need to apply 10bs of total fertilizer per 1000 sq ft. If he has a quarter acre lawn (approx 11,000 sq ft.), he will need 110lbs of total fertilizer. I hope this makes sense. The fertilizer label and spreader settings noted on the label are helpful.

As for the blue-green clumps of grass, this appears to be perennial ryegrass. The only option for removing it is to cut it out by hand. A harsh winter may take it out as well. He should seed these areas with mostly Kentucky bluegrass and fine-leaved fescues in the future.