Lawn Doctors Turf Alert

Dry Conditions, Stressed Turf, & Ascochyta Blight

Extremes in Soil Temperatures

Our Spring this year has been one of extremes that is leading to stressed turf

• We had a relatively mild winter, which is actually MORE stressful on the grass plants- the snow cover can insulate the grass and provide winter protection.
• We had a very rapid warm up in early April with EXTREMELY hot and dry conditions. Our temperatures then cooled off again, so that many grass varieties were very slow to "wake up" and start active growing. These extremes of soil temperatures are causing additional stress to the grass plants.

Soil temperature graph for our area this spring (blue line)- Note the extremes. (Source: https://www.greencastonline.com/tools/soil-temperature)

Dry Conditions

We haven't seen a lot of rain in the forecast, so we are seeing dry conditions in our area.

• According to drought.gov, we are in drought conditions, most of our area is considered to be Moderate to Exceptional," with the 30-day precipitation totals at about 25%-50% of normal.
• Remember that grass cannot store water. Even if my lawn got 5 inches of rain last week, it would still need another inch of water this week to stay green! Grass does best with long soak waterings- less often. It is fine to let the rain take care of the grass, but grass without adequate water will go brown.

Lawn Watering Guidelines:

1. Water in the morning. 
2. Water DEEPLY (to soak the ground 3-4 inches deep) -generally 45-60 minutes, LESS OFTEN - (every 4-8 days, in most conditions)
3. Do NOT water at night if you can avoid it. This can lead to more fungal disease
4. Use a water timer if morning is a difficult time to water (ask us if you need suggestions)
5. Short watering of 15,20 to 30 minutes is generally more damaging than not watering at all. It is the equivalent of licking your lips on a hot windy day. It does not quench your thirst and it chaps your lip. Short watering does not reach the root zone and stresses the grass.

More information and the science behind these watering guidelines:

University of Georgia Turfgrass Water Management

USGA Turfgrass Water Requirements

University of Minnesota Water Saving Strategies for Lawns

Dormancy:

If you choose not to water, the grass will go dormant. This is a very natural process that helps the lawn protect itself from the heat. In dormancy, the grass will turn brown.

If you let the lawn go into dormancy, make sure that you:

1. DO NOT MOW when the lawn is dormant, or drought stressed.
2. Minimize all traffic on the lawn during this time. No jumpy things, no kiddie pools, no slip and slides (in fact most of these things amplify the heat underneath them so it makes the lawn stress even more).
3. Lawns in dormancy will still need at least 1/4 to ½ inch of water every 2-3 weeks to keep the crown of the plant alive and able to recover when conditions improve.
4. When a lawn suffers drought, some areas may thin out, which is natural as the plants are all fighting for soil moisture. Typically, when the rains return, most areas will recover depending on the severity of the conditions.

This information is CRITICAL for those with a sprinkler system too!!!

Every summer, we see drought stress, turf damage, fungal disease and in the past 3 years, chinch bug damage. We see significantly more issues in lawns that are improperly watered.

We frequently hear from customers.....

"but I have a sprinkler system."

• Unfortunately, we see MORE improper watering with sprinkler systems than in most other lawns.

• The zones and settings of many sprinkler systems are set up improperly and are doing MORE DAMAGE THAN GOOD!

• Short watering of 15,20 to 30 minutes is generally more damaging than not watering at all. Short watering is the equivalent of licking your lips on a hot windy day -it does not quench your thirst and it chaps your lip.

• Short watering does not reach the root zone and stresses the grass.

• We see significantly more incidence of chinch bug damage, stressed turf, fungal disease and die-back in lawns with too short and too frequent watering

Grass needs 1 inch of rain (or watering) PER WEEK to stay green... no matter how much water it had last week.

Ascochyta Blight Fungal Disease

Ascochyta Blight Fungal Disease

We are seeing stressed grass and Aschochyta fungal disease in the grass. We are also seeing some wilting and fungal disease in shrubs and ground cover

The conditions this spring have lead to stressed grass that we normally don't see until hot summer conditions. With stressed grass, we are seeing significant Aschochyta Blight spots and tracks in lawns in the last two weeks. Aschochyta damage is temporary and normally does NOT need any treatment.

The bad news: Ascochyta Blight can show up very quickly with straw-like grass almost overnight. Ascochyta Blight most of the time will show up as track marks in the lawn from mowers, our machinery, odd brown patches or even footprints. It is impossible to predict which lawns will react with the blighted grass.

The good news: With proper watering and mowing, lawns usually make a full recovery from Ascochyta Blight, once weather conditions improve. Fungicide treatments are NOT recommended to treat Ascochyta Blight. 

What is Ascochyta Blight & How does it affect the grass?:

Ascochyta Blight is a relatively minor fungal disease that can look very ugly in lawns. The fungal spores are common and prevalent in the thatch layer of most lawns. This is not something that we see being spread by wind or by contact with mower or other wheels.

When grass is stressed, the weight of wheels or footprints causes a microbreak in the grass blade and the fungal organism takes this opportunity to invade and cause “blighting” of the leaf blade which shows up very quickly as a straw-like color.

Many people will assume that the grass has been burned and is dead, but because this is a “foliar disease” only, the bight will only affect the grass blades and does NOT damage the crown of the plant or the roots. The grass blades and crown of the plant below the blight will be green and alive.

Damage from Ascochyta Blight is found more commonly in lawns that are improperly watered. It is critical that homeowners with sprinkler systems make sure that the times for their zones are set to water LONG and less often (-watering 10-15 minutes per zone every other day is detrimental and will be one cause of stressed lawns, more likely to lead to diseased conditions.)

For more information about Ascochyta Blight:   

Iowa State

https://www.extension.iastate.edu/turfgrass/blog/ascochyta-leaf-blight-scorches-iowa-lawns  (from 2010 in Iowa, but very applicable to our current conditions), 

University of Nebraska: https://extension.unl.edu/statewide/cass/Lawns%20Hit%20Hard%20by%20Ascochyta%20-%20Sarah%20Browning.pdf

Colorado State:

https://extension.colostate.edu/docs/pubs/garden/02901.pdf

University of Missouri:

http://extension.missouri.edu/publications/DisplayPrinterFriendlyPub.aspx?P=IPM1029-4 

North Carolina State:

https://turfpathology.ces.ncsu.edu/2020/04/ascochyta-leaf-blight-uncommon-sometimes-devastating/

Mowing Guidelines:

• The single greatest contributor to lawn stress (which also contributes to fungal disease) is mowing too short. 
• You should be mowing at the highest setting on your mower. 
• Mowing height should be at least 3.5 inches, but higher is better if possible (we prefer 4-4.5 inches). 
• You should never mow more than 1/3 of the grass blade per mowing. 
• Consistently mowing too short will cause your lawn to die! 

Under Stress Conditions - Stay Off/Don't Mow : If your lawn is showing signs of drought stress and growth has slowed or stopped, (brown spots, a silverish sheen, or it sounds crunchy when you walk on it) please stay off of it as much as you can. You do not need to mow your lawn if it is not growing! 

More information and the science behind these mowing guidelines:

North Carolina State:

https://www.turffiles.ncsu.edu/2015/04/mowing-height-impacts-weed-populations/

Michigan State:

https://www.canr.msu.edu/resources/mowing-lawn-turf

Penn State:

https://extension.psu.edu/the-impact-of-mowing-on-weed-pressure