Lawn Disease Identification and Control
A lot of people believe that watering your grass, and keeping it constantly moist throughout the growing season, is one of the best things that you can do. But think about this. If you couple that overall moisture with summer heat, your lawn becomes hot and humid, which is the perfect growing medium for fungal growth and insect propagation. Even though these organisms are not related, they both need the same environment to grow. If you notice brown spots, if there is a milky deposit, like chalk dust on your grass, or if there are brown or purple stripes on the leaves, you may be faced with an insect or a fungal disease situation.
This disease is caused by several types of Helminthosporium fungi. Several common names such as melting out. crown rot and leaf blight are also used to describe this common turf problem. Leaf spot is probably the most widespread of all lawn diseases
The spores of the fungus are easily distributed by the wind and are present in nearly every lawn certain weather conditions trigger the spores into activity. In the spring, cool temperatures, high humidity and predominately cloudy weather are ideal for infestation. Helminthosporium leaf spot flourishes under these conditions. This state of the disease is not always damaging and lawns often recover without the homeowner knowing there was a problem. However, leaf spot can “shift gears” and continue to be damaging in the hotter weather of late spring and summer. At this time. the activity is mostly conﬁned to the roots and crowns of the plants — hence, the name “crown rot”. This is the most damaging form of the disease.
Turf infested with leaf spot or crown rot is thinned and oﬂen looks as though it is suffering from drought or is mistaken for insect damage. Many people water their lawns, thinking they are drying out. Actually, excessive moisture will accelerate the spread of the disease. In addition to too much moisture, close mowing and infrequent mowing also aggravate the disease. Letting the grass get very tall and then cutting it back, or mowing with a dull blade, weakens the plants and allows the leaf spot disease to enter the plant system. This is probably the most common homeowner mistake that leads to leaf spot activity.
In most cases, the ﬁrst step is to stop the spread of the disease with an effective disease control. Warner Landscape uses the most effective leaf spot control available. Water the lawn thoroughly once a week only – and let it dry out between waterings. Do not water aﬁer 3:00pm. It is important not to have wet grass blades as night falls. The disease is most active at night. Mow regularly — at least every 7 days. Use a sharp mower blade and cut the grass tall (2-1/2 to 3 inches). You may bag the clippings if you like, but if you don’t, do not let heavy patches smother the grass.
Many people wonder why their lawn was affected. when others nearby do not have the problem. The factors relating to a heavy outbreak of diseases are many. Too much thatch, a dull mower blade, close mowing and severe mowing aﬁer grass has gotten too tall can affect the rate of buildup of leaf spot activity. The main factor, however, is the species and variety of grass in your lawn There are over 40 varieties of bluegrass alone. Some are very resistant to leaf spot and some are very susceptible. Depending on how severe the disease is and the type of grass in your lawn, it may take 1-2 months or more for your lawn to recover. Proper maintenance practices will speed the lawn back to normal.
Dollar Spot Disease
The fungus SOLEROTINIA HOMECARPA causes dollar spots, a turf disease which can attack a number of different grass varieties. The outbreak of dollar spot is affected by soil moisture, nitrogen levels, grass variety, humidity, mowing practices, and temperature.
Dollar spot is more prevalent during periods of mild weather (60-80 degrees/F) primarily during the late spring and fall months; however, it can occur throughout the summer if proper conditions exist. Lawns with low moisture conditions and low nitrogen levels are more susceptible and favor disease development.
Mild cases of dollar spot generally recover or can be mowed out of your lawn. Sometimes applying extra fertilizer may help to grow it out. More severe cases may reguire a special fungicide treatment for proper control. Warner Landscape can discuss both control and prevention programs with you. Other helpful control practices include regular applications of fertilizer and watering. Your lawn needs about 1-1/2 inches of water per week from rainfall or irrigation. It is best to water at mid-day for this disease. Mow regularly, at least every 5-7 days. Use a sharp mower blade and cut the grass tall. Short mowings will aggravate this problem.
Many people wonder why their lawn was affected when other lawns nearby do not have the problem. The factors relating to a heavy outbreak of disease are many. The principle difference is often the grass variety! Some varieties offer much more resistance to diseases than others. In addition, too much thatch, a dull mower blade and poor watering practices will make your lawn more susceptible to problems.
Necrotic Ring Spot
Necrotic Ring Spot is a disease which attacks and kills the root system of bluegrass sodded lawns. This problem usually starts within 2-5 years of establishment of new sodded lawns and heavy clay sub soils seem to have earlier outbreaks than sandy or loam soils.
The disease is active throughout the growing season. Normally we don’t see damage in the spring or fall because of cool, wet, good growing conditions. Actually the disease is probably active and injuring the root system but is capable of withstanding this stress because of such good growing conditions. These good growing conditions are masking the activity and presence of the disease. As summer conditions arrive and air temperature increase to near 80 degrees. circular. plate-sized dead areas begin to develop. The root. system can no longer withstand the stress of the disease and the heat. The root system begins to die, causing the circular dead areas.
If your lawn has developed Necrotic Ring Spots, there is no quick ﬁx or easy cure for this unfortunate problem This is the only disease which attacks the root system. All other diseases attack the leaf growth of grass and are usually easily controlled. The following list of things must be followed in order to try and minimize the injury from NRS.
- Use only slow release, dry granular fertilizers (Warner Landscape uses only this material). Never apply any liquid fertilizers, as they are hotter and heat up soil temperatures!
- Mow as tall as possible! This helps shade the soil, reducing heat stress and allows for more water retention. Also, keep the mower blade sharp and mow regularly (every 5 to 7 days)
- Watering — this is the most important thing to do for prevention and recovery for this disease. Short daily waterings when temperatures are near 80 degrees or above during the honest part of the day is a MUST! Try to water between noon and 4:00pm. This will reduce soil temperatures and allow for continued root growth.
- Turf aeration — annual turf aerating will help stimulate root growth, allow deeper root penetration and let more air, water and nutrients reach the root zone.
- Fungicide treatment (yes or no)? Many times, by simply changing your cultural practices, such as mowing, watering, etc. may help to control NRS disease activity. The only thing left to try is a special fungicide treatment. Fungicides are quite expensive, but if they work, it is well worth the cost of this treatment.
This disease may occur any time from late fall until early spring when temperatures range from 28 to 45 degrees. An excessive amount of moisture or melting snow must be present. Snow mold is more likely to occur on grass that was too tall as it entered the winter. The long. matted down blades of grass provide an ideal environment. Damage is most severe when snow covers the grass for a long period.
Gray snow mold is more common on home lawns. Pink snow mold is usually conﬁned to golf course putting greens. Gray snow mold can spread to form large diseased areas. Grass within these areas become matted. closely pressed to the ground and often is completely destroyed
The matted areas of grass should be loosened to improve air circulation. A good raking with a ﬂexible leaf rake will fluff the grass to allow this. If you ﬁnd the grass so long that it will not stand up (3 or more inches) you can mow it to remove the extra-long blades which are contributing to the problem. In severe cases, a disease control should be applied immediately to help arrest the disease. Warner Landscape will recommend this treatment when necessary. With proper fertilization and follow-up maintenance, the lawn may recover without needing reseeding.
PREVENTION NEXT YEAR
Mow your lawn short in the fall and keep mowing it as long as it needs it. (This may be until almost Thanksgiving.)
The name Fairy Ring comes from the shape of the rings you may have noticed on your lawn, circular or half moon shape.
Unfortunately, there is no real cure for this problem unless you were to dig out the rotting material. You may have periods of no activity during drier periods. Turf Core aeration will help improve air and root stimulation and keeping the lawn fertalized properly and will make the fairy ring less noticeable.
Mushroom growth on our lawns is a very common occurrence with all turf varieties.
Mushrooms appearing for no reason
Aﬁer periods of high humidity and heavy rainfall organic material deep in the soil starts to decompose, i.e. Tree roots, stumps, building material, usually wood. As this material decomposes it releases nitrogen gases up through the soil and the fruiting bodies
(mushrooms) start to form.
Mushroom growth can be raked out or broomed away but can always reappear with the proper weather conditions. Take note; certain mushroom growth can be poisonous to children and pets, removal of them is advised.
If you have any questions about insect or disease prevention and control, please contact Warner Landscape and Sod. We are a professional turf care and management company, proudly serving the Clinton Twp, MI. area. For all of your landscape, sod and lawn care needs.
Warner Landscape GOLD Program
Here is what you get:
Pre-paid discount of 10% off
5 Visits of Granular Lawn Fertilizer
1 Fall Grub Prevention Treatment
1 Fall Turf Core Aeration