drought

Landscape Alerts & Updates | September 2019

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Insufficient production and storage of photosynthates during the fall transition into dormancy can translate to issues during spring green-up.  Drought stressed turfgrass in August 2016 (Left) was able to recover prior to dormancy following appreciable rainfall (Right). However, we are seeing drought-stressed turfgrass in September of 2019 and the dormancy transition is quickly approaching.  Photo by Clint Waltz, UGA.

Tips for managing drought stressed turfgrass as dormancy approaches

by Clint Waltz

During periods of hot and dry weather, certain modifications to your lawn maintenance practices will help to carry your turfgrass through periods of inadequate rainfall and reduce losses. The height of the warm-season turfgrass growing season spans from May to October. Given average conditions (regular rainfall and moderate temperatures), bermudagrass, zoysiagrass, St. Augustinegrass, centipedegrass, and other warm-season species respond quickly to cultural and maintenance practices such as mowing, fertilizing, aerating, topdressing, and weed management.  However, the summer of 2019 has delivered hot and dry weather with sporadic rainfall.  With fall approaching, now is the time to adjust your turfgrass management program to promote a smooth transition into dormancy and green-up next spring.

From mid- through late-summer rainfall across Georgia has been variable with some areas receiving timely rain and other areas being droughty.  Moisture stress in turfgrasses can be recognized in the early stages by a dull bluish-gray cast.  Additionally, take note of footprints and tire tracks in the turf that do not seem to rebound.  If you are in an area that has lacked rain, consider applying some irrigation to get the grass growing.

Dr. Clint Waltz, UGA Extension Turfgrass Specialist, suggests these tips for managing turfgrass as it transitions into dormancy:

  1. Raise the cutting height within the recommended mowing range
  2. Do not apply nitrogen containing fertilizers
  3. Modify herbicide programs during high temperatures and moisture stress
  4. Water deeply & infrequently
  5. Grasscycle
  6. Use water conserving and drought tolerant turfgrasses

Raise the Cutting Height

Turfgrass stress can be reduced by using a sharp mower blade and raising the cutting height by 1/2″ or to the tallest allowable height of the recommended mowing range during drought.  A clean cut also reduces moisture loss through wounds and minimizes entry points for disease.  Taller shoots promote deeper roots and a dense canopy can help to reduce ground surface temperatures and conserve moisture.  Grasscycling (mulching clippings versus bagging) can also help to conserve moisture.

Avoid Nitrogen Applications

As grasses move into dormancy they need to “harden-off”.  Nitrogen fertilization encourages new shoot growth which directs plant sugars, and other metabolites, away from storage organs (e.g. rhizomes, stolons, and crown).  These storage organs and sugars provide the energy for the grass to green-up next spring. By allowing the plant to harden-off and accumulate sugars in the storage structures, the grass is better able to survive winter stresses and recover next year.

Modify Herbicide Programs During High Temperatures and Drought

Many herbicides act upon plant growth processes and can be less effective during periods of drought when weeds are not actively growing. In addition, certain herbicides may cause damage to drought-stressed turf or non-target landscape plants due to volatilization and drift during high temperatures. Review your pesticide labels for specific information regarding temperature requirements, watering requirements, and proper application.

Water Deeply and Infrequently

The optimum watering schedule can be roughly determined by observing the number of days that pass between signs of moisture stress. Apply sufficient water to saturate the root zone to a depth of 6-8 inches.  Clay soils and sloped areas may require staggered watering intervals to allow time for water infiltration between cycles and prevent runoff.  Irrigating in early morning conserves water by reducing evaporation and drift.  A good practice is to align watering schedules with drought management rules so that in the event of a declared drought, the appropriate watering program is already in place.  The 2010 Water Stewardship Act permits lawn watering between the hours of 4:00pm and 10:00am.

Use Water Conserving and Drought Tolerant Turfgrass Cultivars

The University of Georgia Turfgrass breeding programs continue to make excellent strides in developing improved cultivars with low water use and high drought tolerance. For new installations or where turfgrass replacement is needed, look for improved cultivars such as TifTuf bermudagrass.  Visit www.GeorgiaTurf.com for more information on selecting turfgrasses.

Aerification: Restoring Turfgrass Carbohydrate Reserves

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Dr. Clint Waltz, Extension Turfgrass Specialist with the University of Georgia, reports that hot temperatures and low rainfall in the fall of 2016 likely sent warm-season turfgrasses into winter dormancy with depleted carbohydrate reserves. During “normal” circumstances warm-season turfgrasses accumulate and store carbohydrates from late summer through early fall.  Last year, non-irrigated turfgrasses likely suffered drought-induced dormancy and transitioned to winter a weakened condition.  With insufficient energy accumulated in root systems, a thin canopy and a two- to four-week delay in the green-up of warm-season grasses might be common this spring.

 

 

 

 

 

 

What can be done to improve the green-up and growth of warm-season turfgrasses this spring?

1) AERIFICATION – Core aerification in late April to mid-May.  This will improve air exchange and water infiltration to stimulate root and shoot growth.  Performing hollow-tine aerification that removes 1/2 inch diameter soil cores to a 3 or 4 inch depth is the recommended approach.

2) TIMING OF FERTILIZER – Withhold the application of nitrogen fertilizer until soil temperatures at the 4-inch depth are consistently 65 degrees and rising.  Visit www.Georgiaturf.com to find lawn calendars that include fertility recommendations for each species.  Soil temperature data from the Georgia Automated Environmental Monitoring System can be found at www.Georgiaweather.net.

3) SOIL TESTING – Collect a soil sample and submit for testing to ensure that soil Ph, phosphorous, and potassium levels are within the recommended ranges for optimum growth.  Contact your local UGA Extension Agent about submitting a soils sample to the UGA Agriculture and Environmental Services Laboratory or call 1-800-ASK-UGA1.

Restoring carbohydrate reserves this spring is an important step in preparing turfgrasses for a healthy growing season.  Read the full article by Dr. Clint Waltz at www.Georgiaturf.com.

A Rough End to the Season for Warm-season Turfgrasses

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The lack of rainfall in the second half of the growing season has hindered the production and storage of energy that normally takes place in warm-season turfgrasses from late summer through fall.  In effect, warm-season turfgrasses could enter winter dormancy with depleted carbohydrate reserves.  Dr. Clint Waltz, Extension Turfgrass Specialist with the University of Georgia, is concerned that winter hardiness and spring green-up issues could result from a rough end to the growing season.  The weather over the next few weeks will decide how warm-season turfgrasses cross the finish line into dormancy.

“The limiting factor is water,” said Waltz. The biological activity that is necessary to gather and store carbohydrates requires water and we need some rain.  With soil temperatures at the 4″ depth holding in the 60’s for October and the forecast through the end of the month calling for high temperatures near 80 degrees for much of the state, there may be some opportunity for growth where irrigation is available.  However, gains will be marginal as the day length, temperatures, and radiant heat levels continue to drop.  Applying 1/2″ inch of irrigation per week may be sufficient to help mitigate spring green-up issues and prevent crown desiccation if dry weather continues.  Fertilizer is NOT recommended for warm-season grasses at this point in the season, especially nitrogen.  Applications of potassium are generally recommended to promote winter hardiness, but without adequate water, the benefits of these applications may not be fully realized.

What can turf managers do to prepare?  Irrigate if you can, do not fertilize, minimize mowing and wear damage, and avoid practices such as aeration that would induce additional plant stress as the turfgrass enters dormancy.  When using irrigation systems, be sure to follow the parameters of the Georgia Water Stewardship Act of 2010 and stay informed on the latest drought information at www.georgiawatersmart.com. For more information on landscape watering visit www.Georgiaturf.com and download the publication “Best Management Practices for Landscape Water Conservation.” Most importantly, contact your local UGA County Extension Agent at http://extension.uga.edu/about/county/index.cfm or call 1-800-ASK-UGA1

Level 1 Drought Declared in Georgia

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Level 1 Drought Declared in Georgia

Level 1 Drought Declared on September 9th

On September 9th the Georgia Environmental Protection Division declared a Level 1 drought for 53 Georgia counties.  This includes the Northwest part of Georgia which is experiencing severe and extreme drought conditions.

A Level 1 Drought Response declaration means you will be hearing more from your local water authority about water conservation.

What does this mean to community and school gardens?

At this point, not much.  As always, we need to use best management practices in watering our gardens.  According to the Georgia Water Stewardship Act of 2010 irrigation of personal food gardens is allowed at anytime.  It allows daily outdoor watering for “purposes of planting, growing, managing, or maintaining ground cover, trees, shrubs, or other plants only between the hours of 4 p.m. and 10 a.m. by anyone whose water is supplied by a water system permitted by the Environmental Protection Division.”

You may want to make sure your irrigation system, hoses, and faucets are not leaking.  Does your garden have a rain barrel?  Find additional watering tips below:

Happy gardening!