UGA Cooperative Extension
Paulding County Extension Office:
Agriculture & Natural Resources
Urban Agriculture Updates
Fall is the Time to Control Spring Dead Spot in Bermudagrass
Elizabeth Little,
Homeowner IPM Specialist with the UGA College of Agricultural and Environmental Sciences
Spring dead spot, or SDS, is one of the most common and important diseases on bermudagrass in Georgia. It is difficult to manage Spring Dead Spot without an integrated approach. This fungus disease is most common on intensively maintained turf like golf courses or lawns.
SDS causes dead patches
The characteristic dead patches appear in the spring when the grass is breaking dormancy, and the problem can persist well into summer. The fungus that causes the disease attacks the roots and stolons in the fall and winter. This makes the grass more vulnerable to winter freeze damage, which leads to the dead patches of grass.
Late September through October is the best time to apply preventative fungicide applications if SDS has been a problem this past season. But this won’t provide complete control. Most infections can be eventually eliminated over a period of years by combining fall fungicide applications with sound cultural practices.
Maintaining a disease free lawn in the coming years can only be accomplished by eliminating the stress that allowed the disease organisms to attack the lawn in the first place. Lawns are stressed by poor soil conditions combined with an imbalance of nutrients. Compaction, poor drainage and thatch thicker than one inch are also linked to SDS outbreaks.
Follow these tips
Applying nitrogen late in the season or excess nitrogen, especially with a potassium deficiency, can encourage the development of disease. An integrated management program to improve the lawn’s health includes the following steps:
• When planting new lawns, use cold tolerant cultivars.
• Aerate and remove thatch regularly.
• Irrigate deeply and less frequently. (Once per week in the absence of adequate rain.)
• Mow at the recommended height. Low-mowing height stresses lawns.
• Monitor pH and nutrient levels on a regular basis with soil tests. Keep potassium and phosphorus in balance with nitrogen.
• Maintain a pH between 5.5 and 6.0 if disease has been a problem. The pH can be lowered by using ammonium sulfate as a nitrogen source.
• Apply moderate levels of potassium in September and October to increase cold hardiness. If a deficiency of potassium is indicated on a soil test, two applications of potassium sulfate or potassium chloride can be applied at a 3 to 4 week interval for a total of 1 lb. of K2O per 1,000 sq. ft. Excess potassium should be avoided as it can also encourage disease.
• Do not apply nitrogen after August. Nitrogen should be added in recommended amounts in late spring and early summer. Use moderate amounts of nitrogen during the summer so that excess nitrogen is not carried over into the fall.
• Apply fungicides in late September or October if SDS was a problem the previous spring. These fungicide recommendations are for commercial turf managers and are provided by Dr. Lee Burpee, UGA Plant Pathologist. Homeowners can find fungicide recommendations in the Pest Management Handbook or though their local Extension Office.
“Rubigan (fenarimol) continues to be the standard for control of SDS. In the Piedmont region of Georgia, apply Rubigan at 6 oz./1000 sq.ft. in late September or early October. A split application of 4 oz. in late September/early October followed by 4 oz. in late October/early November is also effective.
The Rubigan label advises applying irrigation after spraying. However, effective control has been achieved by applying Rubigan in at least 2 gallons of water per 1000 sq.ft. with no follow-up irrigation.” 1
Other warm-season grasses, such as zoysia, centipede and St. Augustine, will also benefit from these general recommendations to prevent diseases like take-all and Rhizoctonia large patch. Follow recommendations for fertilizer applications for the particular grass species. A pH of approximately 5.5 to 6 is generally optimum for warm-season grasses.
See these sites for more help
For more information on maintaining turfgrass in Georgia, see the website www.Georgiaturf.com. For fungicide recommendations, contact your local University of Georgia Cooperative Extension agent or consult the Georgia Pest Management Handbook at www.ent.uga.edu/pmh/.
Lee Burpee, UGA Professor of Plant Pathology, Warm Season Disease Management in 2010 Turfgrass Field Day Guide page 12.
Fall Armyworms in Turf
Will Hudson, UGA Entomologist
|
In late summer, almost every year, caterpillars invade turfgrass throughout the state. The damage to established turf is mostly aesthetic, but newly sodded or sprigged areas can be more severely damaged or even killed. While there are several caterpillars that can damage turfgrass, in late summer most of the problems are from fall armyworms. Their favorite turf to feed upon is Bermuda grass. Adult armyworm moths are active at night and females lay eggs in masses of 50 to several hundred. Eggs hatch in a few days, and the young larvae begin to feed on leaf tissue. Damage from small larvae may at first look like skeletonizing, but as the worms grow, the entire leaf is consumed. Armyworms are most active early and late in the day, spending the hotter hours down near the soil in the shade. Larvae feed for 2 to 3 weeks before pupating in the soil. Moths emerge 10 - 14 days later. The entire life cycle from egg to adult moth takes about 28 days in the warm weather of August and September. If there is any doubt about whether worms are present, pouring soapy water on the grass (1/2 oz. dishwashing soap/gallon water) will bring them up very quickly. |
Control of armyworms and other turf caterpillars is relatively simple once the problem is identified. There are several pesticides from which to choose depending upon the site you are treating. Consult the UGA Pest Management Handbook or your local Extension Agent for recommendations. See the links below for contact information. Read and follow all label directions when using pesticides. Armyworms are most active late in the day and at night, so pesticide applications should be made as late as practical for best results. It is not necessary to water after application but an application rate of 20 - 25 gallons of solution per acre as a minimum will ensure good coverage. Do not cut grass for 1 –3 days after application.
Please share this information with others in the landscape & turf industry. For more information: Call your local Extension Agent at (800) ASK-UGA1 or locate your local Extension Office at http://www.caes.uga.edu/extension/statewide.cfm Pest Management Handbook (Follow all label recommendations when using any pesticide) - www.ent.uga.edu/pmh/ |
|
Controlling Moss and Algae in Turf
Edited from a publication by Gil Landry and Tim Murphy, Extension Crop & Soil Sciences
Occasionally turfgrass begins to thin and moss and algae begin to grow. These primitive plants develop because conditions for growing dense, healthy turf have declined. Neither moss nor algae are thought to be parasitic and both are spread by wind blown spores. Moss and algae can both form crusts on the soil surface which reduces air and water movement into the soil. Factors that favor the development of moss and algae include wet and humid conditions and compacted soils with thin turf.
Mosses are branched, threadlike green plants which form a tangled, thick mat over the soil. Moss is more common in shady areas with infertile, acidic soils and excessive thatch.
Algae are thread-like green plants which form a dense, green scum over the soil surface. Algae is common in full sun conditions and fertile soils.
Cultural practices that favor growth of turfgrasses will reduce the competition from moss and algae:
Maintain good soil fertility and pH - Have the soil tested to determine proper lime and fertilizer needs. For most turfgrasses, the soil pH should be between 5.5 and 6.5.
Improve drainage - Soils which stay moist because of poor drainage should be contoured so that water will drain off the area. In some cases, underground drainage may be necessary to correct wet conditions.
Increase light penetration and air circulation - Pruning tree limbs below 10 feet and removing selected limbs in the crown will improve light penetration and air movement. Also removing some of the least desirable trees and thinning and/or removing shrubs will help. Areas surrounded by buildings and vegetation with limbs close to the ground may require considerable work to provide adequate air circulation and light penetration.
Use a shade tolerant grass - Use St. Augustinegrass, zoysiagrass or tall fescue. If direct sunlight does not reach the ground during the day, an ornamental ground cover or mulch may be better for the site.
Cultivate compacted soils - Aerify with a machine that removes plugs of soil to reduce compaction. Drainage in fine textured soils (clay) can be improved by cultivation and adding organic matter.
Irrigate deeply and infrequently - Avoid light frequent irrigations. Wait for signs of moisture stress such as the development of a bluish-gray, dull color before irrigating. Then irrigate to wet the soil at least 6 inches deep. Most healthy turfgrasses need about 1 inch of water per week during active growth. If puddling occurs, stop irrigating and wait two to three hours for the water to soak into the soil before irrigating again. Repeat the cycle as needed until the soil is wet to the desired depth.
Renovate - Generally, turf may be renovated if at least 50 percent of the area has the desired turf. If turf cover is less than 50 percent, then reestablishment will be necessary. Refer to information on lawn renovation found on page 14 of Lawns in Georgia - http://pubs.caes.uga.edu/caespubs/pubs/PDF/b773.pdf. Under heavily shaded conditions, sodding is the recommended means of reestablishing turf.
Chemical suppression of moss and algae is temporary unless the growing conditions are improved. For both mosses and algae, raking or vertical mowing to break up the layer prior to and after chemical treatment and topdressing after will be helpful.
The key to algae control is to allow it to dry then break-up, or disturb, the algal mat allowing turf stolons to root into the soil. Typically the algae is associated with over irrigation or high rainfall and low mowing heights, so turning off the irrigation and raising the mowing height can reduce algal growth.
Chemical Suppression:
For Algae control see page 9 of this publication - http://www.ent.uga.edu/pmh/Com_Turf.pdf
For Moss control:
Hydrated lime -Apply 2 to 3 pounds of hydrated lime in 3 gallons of water per 1,000 sq. ft.
Ferrous sulfate -Apply 4 to 7 ounces or 10 ounces of ferrous ammonium sulfate in 3 to 5 gallons of water per 1,000 sq. ft. Other forms of iron are available alone (Scotts Moss Control Granules) or in combination with fertilizer for moss control (Scotts Lawn Fertilizer Plus Moss Control and Fertilome Classic Lawn Food Plus Moss Control).
Certain herbicides can be used to control moss and algae. However, as with the chemicals previously discussed, control is temporary unless growing conditions are improved.
Quicksilver (carfentrazone) selectively controls moss. It is labeled for most major warm season grasses. Follow labeled rates and directions closely.
Nonselective herbicides, such as glyphosate (Roundup, other trade names) will kill moss, but will also kill, or severely injure turfgrasses. The use of glyphosate should be limited to spots completely covered by moss when renovation of the site is planned. Allow 10 to 14 days following the application of glyphosate before seeding or sodding the site.
Research shows that oxadiazon, the active ingredient in Ronstar, reduced moss infestations on golf course putting greens. This research was not conducted in Georgia so it is not known if oxadiazon containing herbicides would control the various moss species here. Also, herbicides that contain oxadiazon are registered for use only on turfgrasses located on commercial properties (golf courses, commercial buildings, athletic fields, etc.). Oxadiazon containing herbicides are not registered for use on home lawns; therefore, their use is not recommended for lawn care companies that maintain home lawns.
Various products that contain potassium salts of fatty acids (Lesco Moss and Algae Eraser, Safer Demoss and Algaecide, Safer Moss Killer for Lawns) may be used to control moss and algae in turfgrasses. These products kill moss or algae through a contact mode of action. Use varies according to the specific product. Unless directions on the label are carefully followed, these products can injure desirable turfgrasses.
Acknowledgement: The authors acknowledge the University of Tennessee publication entitled Algae and Mosses in Turfgrasses by T. Samples and A. Windham from which the original circular was patterned.
Please share this information with others in the landscape & turf industry. For more information:
Pest Management Handbook (Follow all label recommendations when using any pesticide) - www.ent.uga.edu/pmh/
If you have any questions/comments, please contact Mary Carol Sheffield, County Extension Agent, Agriculture & Natural Resources
Related Links
- News and Events
- Extension Publications
- Georgia Department of Ag - Commercial Pesticide License Certification Information
- International Society of Arboriculture - Find a certified arborist
- Paulding County Gardening Newsletter
- Soil and Water Testing
- Walter Reeves - The Georgia Gardener
- Warnell School of Forestry and Natural Resources
Sign up for regular updates from Paulding County Extension by emailing msheff@uga.edu and requesting to be added to the Bulldog Bytes E-Newsletter!
