Time To Start Treating For Lawn Disease

With all the rain we've been getting in the Northeast lately, and the warm weather that's coming in next week, conditions are prime for lawn fungus and other diseases to thrive. Before the damage is done it's a good idea to start treating your lawn and plants because it's easier to prevent lawn disease than it is to cure it. You may already be seeing mushrooms in your lawn.

There are a number of different organic treatments for lawn disease.

Corn Meal

Applying corn meal to your lawn at a rate of 10 lbs per 1,000 square feet every week or two before disease takes hold can minimize the chance of your lawn getting a disease. In addition to corn meal being a mild fertilizer that will green up and help your lawn grow out of some diseases, corn meal appears to stimulate the growth of trichoderma. Trichoderma is a beneficial fungus that doesn't harm other plants and actively kills a variety of pathogenic fungi that harm lawns.

If your lawn has already started showing signs of disease, apply at a rate of 20 lbs per 1,000 sq ft every week. 


A dilute solution of milk applied to lawns and plants helps control disease. In addition to calcium, milk contains amino acids and a number of beneficial microorganisms that help control disease including bacillus coagulans, bacillus subtilis and trichoderma.

Mixing a dilute milk spray for lawns and plants is simple. Mix 3 1/4 cups of milk in a 2 gallon pump sprayer  to treat 500-1,000 square feet of lawn and apply once every week or two before any signs of disease develop. I sometimes get the milk that comes in pouches that make 1 quart. I remove 3 1/2 teaspoons of the dry milk and mix it with water in a 32oz spray bottle. The rest goes into my 2 gallon sprayer. See my previous post for how much milk to add to water for spraying plants.

I've had success with milk on cucumbers that usually develop powdery mildew and tomato plants as well.

Neem Oil

Neem oil is extracted from the seeds of the Neem tree. It can be used as a pesticide and fungicide. It has a bit of an odd smell (that goes away after a few hours) but does a pretty good job. I've primarily been using it as in place of other insecticidal soaps but I've also seen neem kill powdery mildew effectively. For other types of diseases, I'm not too sure on it's effectiveness.

One issue with Neem oil, and some other foliar sprays, is you need to spray them early in the morning to give the spray time to dry before the sun comes up or it can burn the plant leaves. 

Serenade Fungicide

With corn meal and milk you are either trying to increase the population of beneficial fungi in your lawn or hoping that the milk you bought has the beneficial bacteria in it. In the past few years biofungicide products have hit the consumer market. Serenade Garden for example contains the QST 713 strain of Bacillus subtilis as the active ingredient. This strain of Bacillus subtilis has been shown to combat a number of different plant pathogens. Serenade is an EPA registered product that is also approved for organic gardening. It is listed by the Organic Material Review Institute (OMRI) as well as the EPA/USDA National Organic Program (NOP).

I started using it in the garden last year and have been pleased with the results. Unlike Neem oil, Serenade can be sprayed any time of the day according to the label but I still try to spray it early in the morning. Even water left on leaves can act as a little magnifying glass that might burn the leaves when the sun comes up.

If I start spraying before there are any signs of disease I mix up 4 oz (8 Tablespoons) per 2 gallons per 800 sq ft of lawn as well as hitting some susceptible plants as I make my way around. If disease is already present you can increase the concentration up to 8 oz (16 Tablespoons) per 2 gallon tank. Spray once a week, more frequently if there are heavy rains in the spring when temps are still around 65 degrees.

Compost Tea

Compost tea is made by "brewing" compost in a mesh bag submersed in water while air is pumped into the container to keep the mixture aerated. Other ingredients such as molasses and fish fertilizer may be added to help feed the beneficial microbes in the compost as they reproduce during the brewing. The compost tea then gets applied across the lawn and landscape. The beneficial organisms in the compost help to minimize the population of bad microbes.

There has been a lot of success reported with using compost tea. I haven't started using it myself.

More Lawn Disease Tips

  • Don't over fertilize you're lawn but do feed it to keep it healthy
  • Avoid cutting the lawn when it's wet or when it's going to rain later in the day
  • Make sure you're lawn mower blade is sharp
  • Keep your lawn mowed regularly as the grass grows fast in the spring. You can keep the grass mowed high but if you let it grow too much it reduces air circulation and increases humidity around the grass which can increase the potential for disease. While I normally mow once a week, in the spring and fall it gets closer to 2x every 3 weeks.
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