Lawn Diseases

Of all the pests that damage lawns, fungus diseases are one of the most difficult to tame.

Sooner or later, just about every turfgrass area will develop various disease problems. Some are harmless, while others can destroy areas in your lawn.

Fungi, microscopic organisms that are found everywhere and are spread by water, air, animals, etc, usually cause plant diseases. Certain varieties of turf are more susceptible to certain diseases than others, and they are under different cultural practices. That is why one lawn may have a disease problem, while another next door may be fine.

Most diseases we see are warm-weather diseases that are more severe during high rainfall and high humidity. May and June are the months when most damaging turf diseases do their damage. During summer months, the humidities are generally lower, unless a homeowner is irrigating excessively. Fall provides another opportunity for fungi to infect turf during rainy periods

Spring Dead Spot

Spring Dead Spot is one of the most troublesome diseases of bermudagrass. It is caused by a fungus, which infects the turf in the fall, but symptoms do not appear until the following spring with large circular dead spots, which do, not green-up with the rest of the Bermuda grass. As the season progresses, Bermuda from the outer edges will fill in, but it sometimes takes well into the summer to do so.

Spring Dead Spot seems to be most severe on lawns that have been sodded 3-8 years ago. Certain varieties of bermudagrass, such as tiff varieties, are more susceptible also. As the lawn matures after about 10 years, it seems that often Spring Dead Spot is not much of a problem. The severity of the winter also plays an important role, with more spots present after hard winters.  IF Bermuda is over-fertilized with Nitrogen late in the fall, the disease will increase.  At LawnAmerica, we gradually cut back on the Nitrogen level in September to help with this, and to send the turf into winter dormancy in a fairly lean state, which is the proper thing to do.

Control of the disease is inconsistent.

Oklahoma State University now recommends that two fall fungicide treatments be done for best control.  We can apply a special fungicide in the fall to help prevent the disease, with a follow-up about 4 weeks later with a different type of fungicide.  This should help, but it is not a sure cure in all situations.  We have experienced a decrease in the number and severity of the spots the following spring, with a faster fill-in of healthy bermuda.  Fungicides are expensive.  But if your problem is severe, we do recommend this service.  We can provide this special treatment for 1.9x your normal treatment cost, which will be invoiced with your initial treatment in late Sept. or early Oct.  The followup treatment is included, so you’ll not be invoiced with the 2nd treatment.

Maintaining good soil fertility, irrigation, and aeration are cultural practices with will help dead spots fill in faster during the summer. You can also rake a thin layer of black topsoil into the areas in spring to help speed up the fill in. Or, you can even just dig the dead area out and replace the soil and sod for an instant fix. Only do this if you have a free weekend and a lot of energy though!

There are many other diseases, which can infect turf. Look to our links pages for more information. There are cultural practices, which you can do to lessen the chance and severity of turfgrass disease.

Brown Patch

Brown Patch is a problem disease we see, which can especially do damage to Fescue and St. Augustine lawns. Look for brown spots a few inches to several feet in diameter, with a yellowish “smoke ring” around the perimeter of the patch especially early in the morning. It is recommended to apply a turf fungicide if conditions merit to avoid loosing turf.

Dollar Spot

Dollar Spot is a summer disease of bermudagrass and zoysia grass. Small silver dollar-shaped brown spots appear, sometimes coalescing together to form larger brown patches. The disease is favored under low soil fertility and low soil moisture conditions, along with excessive dew or frequent irrigation. Fungicides are usually not recommended for this disease, as a good nitrogen fertilization will eliminate the problem.

Winter Kill

Winter Kill refers to any severe damage or death sustained by the turf during the winter months. For the most part, well cared for turf is resilient and strong, but winter weather can be unforgiving to even the best lawns. The University of Arkansas has two helpful links about this: link 1 | link 2

Maintain Proper Soil Fertility

As long as you are on one of our full programs, preferably the 6 or 7-Step, we’ll take care of that. Inadequate nitrogen and potassium especially can increase disease problems. Too much nitrogen fertilization can also lead to disease problems. That’s why we only apply the proper amount of fertilizer each time-not too much or not too little-in order to green-up your lawn.

On some types of grass that are more susceptible to diseases in the summertime, we apply slow-release organic fertilizers, which are safer and better to use during periods of high disease pressure.

Irrigate Properly

Disease problems are more severe when the turf stays constantly moist. Sometimes, Mother Nature takes care of that for us, especially during spring. Sometimes homeowners can make the problem more severe by watering every day and at the wrong time of day. We recommend deep, infrequent irrigation, so that the water can get down deep into the root zone. We want the topsoil to dry out a little in between waterings. Do not water every day. Do not water in the evenings, so that the turf stays damp all night. Finish your irrigation as the sun comes up early in the morning so that the grass blades will dry out quickly.

Mow Properly

Mowing with a dull blade will damage the grass blade, leading to more infestation from fungus pathogens. Not mowing frequently enough and leaving excessive clippings on the turf can also lead to more disease problems.

We do offer a turf disease service with applications of certain turf fungicides. These are liquid applications, which not only kill the disease pathogens, but also will provide about 3 weeks of systemic control of re-infestation. We can do this on an as-needed basis, or we can set you up on a semi-preventative program with 1 or 2 treatments of fungicide every year during the peak disease periods from about April through early July.

For more information on these and other lawn diseases, visit:

http://aggie-turf.tamu.edu/
http://www.libraries.psu.edu/
http://turf.ufl.edu/