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
On September 9, 2016, a drought level 1 response was issued by GEPD for 53 counties in northwest and central Georgia. Georgia’s drought management plan, as outlined by the Georgia Water Stewardship Act of 2010, establishes a three-tiered approach to water resource conservation and monitoring. The first tier of the system is called “Drought Level 1” and initiates a conservation and public awareness campaign by local water utilities in affected counties. Look for forthcoming information regarding the drought level 1 response from local water authorities in these counties to help citizens better understand drought, its impact on water supplies and the need for indoor and outdoor water conservation.
Outdoor watering: Is it okay to plant trees and irrigate turfgrass? Yes, normal outdoor watering is allowed between the hours of 4pm and 10am and new landscapes can be watered any day, any time for 30 days in accordance with the Georgia Water Stewardship Act. However, proper plant care and responsible watering practices should always be followed.
Contact your local University of Georgia Extension Agent for scientific publications, bulletins, and fact sheets regarding plant care and irrigation practices. Key practices include mulching, proper plant selection, raising mower heights, and proper irrigation. In addition, the Georgia Urban Ag Council and the Georgia Green Industry Association launched a website called Georgiawatersmart.com outlining best management practices for indoor and outdoor water conservation.
According to the 2012 Annual Report, the Metropolitan North Georgia Water Planning District estimates that the 15 County Metro Atlanta area reduced per capita water consumption by as much as 20% between 2000 to 2010 through local water stewardship and conservation efforts. Spread the word about water conservation and drought awareness and stay informed on the latest practices for managing drought stressed landscapes. For more information about the level 1, 2, and 3 drought responses, visit the Water Conservation page of the Georgia Environmental Protection Division website.
The Georgia Dept. of Agriculture will host a Pesticide Waste Collection (Clean Day) event on September 30, 2106 at the Cordele State Farmers Market in Crisp County from 9:00am to 3:00pm. The Georgia Department of Agriculture is excited to have the funding to support this excellent program as a benefit to all Georgia citizens and the environment. The collection day is open to all who would like to participate. Due to collection limits, pre-registration is required and must be completed by September 26, 2016. Additional information and registration forms can be found online at http://agr.georgia.gov/georgia-clean-day.aspx
Don’t leave pesticide waste sitting around in storage waiting for an accident or spill to happen, take advantage of this rare opportunity to dispose of pesticide waste safely and responsibly.
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 May through August. 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 2016 has delivered hot and dry weather with less than normal rainfall. With August approaching, now is the time to fine tune your turf management program to salvage an acceptable appearance while minimizing growth until environmental factors improve.
The first order of business is to recognize moisture stress in turfgrasses in the early stages. Look for areas with a dull bluish-gray cast. Additionally, take note of footprints and tire tracks in the turf that do not seem to rebound.
Dr. Clint Waltz, UGA Extension Turfgrass Specialist, suggests these tips for managing turfgrass during drought periods:
Raise the cutting height within the recommended mowing range
Reduce fertilizer applications until conditions improve
Modify herbicide programs during high temperatures and moisture stress
Water deeply & Infrequently
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.
Reduce Nitrogen Applications
Plant growth requires water. Without water, the benefits of nitrogen are not optimized and you may be wasting product. Promoting heavy top growth amidst drought conditions increases water demand. Reduce rates or postpone fertilizer applications until environmental conditions improve to fully realize the benefits of fertilizer while saving water and reducing turfgrass stress.
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. As of July 26, 2016 there are no official declarations of drought by state or local authorities in Georgia and responsible landscape and lawn watering may take place between the hours of 4:00pm and 10:00am in accordance with the Georgia Water Stewardship Act of 2010. In the event that water resources require a drought response level 2, watering programs would need to be adjusted for the odd-even schedule by address.
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 certified cultivars such as TifTuf bermuda. Visit www.GeorgiaTurf.com for more information on selecting turfgrasses.
“When soil temperatures consistently measure 65 degrees (F) at the 4″ depth and are trending upwards, it’s time to fertilize warm-season turf,” says Dr. Clint Waltz, UGA Turfgrass Extension Specialist. Resisting the temptation to fertilize warm-season turf too early in the season not only conserves valuable time and resources, but encourages a healthy competitive lawn. Spring season air temperatures often fluctuate from lows in the mid 40’s to highs in the mid 70’s, resulting in wide swings in soil temperature. The best time to fertilize warm-season turfgrasses such as bermudagrass, zoysiagrass, St. Augustinegrass, and centipedegrass is during the active growth season spanning May through August when air temperatures reach highs in the mid 80’s to 90’s and soil temperatures remain well above 65 degrees.
The Georgia Urban Ag. Council has released their twenty-second annual sod producer survey outlining the inventory levels and pricing data for spring 2016. The sod forecast provides the green industry with valuable insight when estimating expenses and availability for the upcoming season. Dr. Clint Waltz, Extension Turfgrass Specialist with the University of Georgia, notes that the inventory for all warm-season species is expected to improve marginally over the previous two years and half of the larger growers predict a poor supply of bermudagrass for early 2016. Sod prices for 2016 are expected to stabilize at 4% to 15% over 2015.
Looking ahead, 57% of growers have indicated an increase in production acreage for 2016 to meet the anticipated market demand for 2017 and 2018. According to Waltz, there are still 45% to 52% fewer acres in turfgrass production relative to pre-recession levels, but it appears that the total acres in turfgrass production are rebounding. His advice: “Don’t let sticker shock curtail projects, plan ahead.”
For the full report, refer to the January/February 2016 issue of Urban Ag Council Magazine or visit www.GeorgiaTurf.com.
Winter is the time to scout for lawn burweed (Soliva pterosperma), a broadleaf weed producing seed clusters in mid to late spring that delivers a rather irritating jab to bare feet. The tiny spines on the seeds are actually quite fragile and tend to break off in your skin during the removal process, leaving an itchy reminder of their presence. My children who love to run barefoot in the backyard can testify to the annual “de-spurring” event each spring.
December through February is the best time to manage this cool season annual because plants are juvenile and haven’t developed the seed burs. In addition, warm season turf species are dormant and have a better tolerance to certain herbicides. While control is possible in spring, spurs have already formed and will persist after treatment. If the spurs are not a concern, the weeds will take care of themselves by May as the hot weather sets in and concludes the annual life cycle of this bandit. A dense canopy of dormant or actively growing turf can deter weed establishment.
For broadleaf herbicide recommendations, reference the UGA Pest Management Handbook for your specific turf. Perform scouting several weeks after the application to determine if follow-up applications are necessary.
Late June through early July is a good time to treat for mole crickets in turf.
How do you know if a lawn has mole crickets?
Unfortunately, it is easier to scout for mole cricket injury earlier in the year. Mole crickets themselves are small and very hard to see in June and July.
Mole crickets tunnel underground, killing roots by feeding and tunneling and also come up to eat the leaves. Attacked grass begins to thin and then disappear. The ground will be softened as the soil is pulverized by the tunneling of the crickets. On bare ground you should see the tunnels, especially a day or so after a rain. Golf course managers can watch for the presence of mole crickets by looking for tunnels in sand traps.
Landscapers and home owners may mistake earthworm castings for mole cricket injury. Earthworms leave piles of granulated soil while mole crickets leave tunnels. Even dying grass is not proof you have mole crickets. Look for the small tunnels and thinning grass.
Use a soap drench to drive mole crickets to the surface where you can see them.
Prior to drenching, the soil should be moist. Irrigate 24 hours before drenching if the soil is dry. Mix one-half to one ounce of dishwashing detergent in a gallon of water. Soak the soil well in affected areas. Mole crickets should come to the surface within a few minutes.
Mole crickets have one generation a year. The adults fly, mate and lay eggs March through early June. Eggs generally hatch in May and June.
Mole crickets are generally younger and smaller in late June and July and much easier to kill.
Areas with signs of adult mole cricket activity in April and May are most likely to have nymphs in July.
Not all turf needs to be treated for mole crickets.
Consider treating turf that has a history of mole cricket problems. Athletic fields that keep their lights on during May and June can be at greater risk because the lights attract the adults.
Mole cricket nymphs are small and easy to control in late June and early July. As these insects get larger they will require more chemical and more applications for control. Later chemical treatments may be less effective giving a lower kill rate. As the mole crickets get larger, they also do more damage to turf.
When using insecticides, you can increase control of mole crickets by allowing the soil to dry out for 3 or 4 days and then irrigate thoroughly in the evening. Apply the insecticide the next afternoon. Mole crickets are sensitive to soil moisture and will move down in the ground to find comfortable conditions if the surface is dry. Irrigation will bring them back up to resume feeding the following night, making them easier targets for control.
Timely treatment is the key to good mole cricket control. Read and follow all label recommendations when using any pesticide.
Patrick McCullough, Extension Turf Weed Scientist, University of Georgia
This is is a common question many turf managers will be asking before herbicide applications this summer. Responsible pesticide applicators will always read and follow label directions before applying any product. However, there is often confusion regarding the language on labels about this issue. Many herbicide labels will contain a statement such as “Do not apply when temperatures are above 90° F”. These disclaimers are usually included on labels to limit the liability of chemical companies when turf managers apply their products during summer heat. This disclaimer is often unaccompanied by anything else to explain or clarify the effects of temperature on potential herbicide injury on turfgrasses.
Turf managers who carefully follow label instructions will see these disclaimers and may hesitate before applying herbicides. Others will question the exact interpretation of these warnings. Examples of questions often asked include the following.
Is it safe to apply herbicides if:
temperatures are below 90° in the morning but above 90° in the afternoon?
temperatures are below 90° this week, but rise above 90° next week?
temperatures are above 90° now but are forecast to drop to the 80s?
the temperature is 89.9° and the label says do not apply at 90°or above?
Unfortunately, there are no correct (or incorrect) answers for these questions. Herbicide applicators must evaluate their turf and factors that may increase turf injury. Several factors turf managers should consider when applying herbicides in summer include:
Weed species and population
Past performance of herbicides
Turfgrass species is a major factor in determining tolerance to herbicide applications. The overall sensitivity level of a species should be evaluated before herbicide applications and closely monitored when temperatures are high. For example, bermudagrass and tall fescue are both labeled for treatments with sulfentrazone (Dismiss). Tall fescue is naturally more sensitive than bermudagrass to sulfentrazone and rates must be reduced to account for lower tolerance levels. Turfgrasses that are sensitive to herbicides under good growing conditions may be more susceptible to injury during periods of heat stress and other herbicide chemistries should be considered.
As temperatures exceed 90° F, cool-season grasses become stressed and consumption of carbohydrates exceeds production through photosynthesis. Thus, grasses such as tall fescue with good tolerance to herbicides during active growth may be naturally more susceptible to herbicide injury during periods of physiological stress. Warm-season grasses grow more efficiently than cool-season grasses under these temperatures and generally have minimal stress when water is not lacking. Uninhibited growth of warm-season grasses at higher temperatures may be attributed to better tolerance to herbicide applications in summer relative to cool-season grasses. However, herbicide tolerances for specific species are all dependent on the chemistry of the product applied.
Effects of temperature on herbicide activity
Turf managers must also understand potential effects of temperature on herbicide activity. Many herbicide chemistries, such as synthetic auxins, have greater activity at warm temperatures compared to use during cooler weather. For example, Trimec Classic (2,4-D + dicamba + MCPP) applications often have erratic activity in early spring but perform much more effectively in summer. Sensitive species to these herbicides, such as St. Augustinegrass, have a higher risk of injury due to greater activity under excessive heat. Switching to another chemistry, such as a sulfonylurea herbicide, may be a safer option especially at reduced label rates. Enhanced activity of herbicides during these periods may also allow end-users to reduce rates and applications required to achieve desirable weed control.
Targeted weed species and the benefits of control should also be considered before risking turf injury from herbicide use in hot weather. Warm-season weeds that spread laterally, such as spotted spurge or knotweed, will continue to grow during hot temperatures and out-compete turfgrasses for light, water, and nutrients. If continued growth of weeds may result in loss of the overall turf stand, practitioners should consider applying herbicides. Preventing annual weeds from taking over a turf area during summer may help reduce voids in early fall that may allow winter annual weeds to establish. Thus, turf managers must evaluate the risk of turf injury at the expense of weed control and potential implications in long-term management.
Previous turf injury from herbicide applications during moderate temperatures may indicate risk of greater injury during excessive heat. Similarly, past reports of turf safety under high temperatures may suggest a specific product has potential for use under local conditions. It is recommended for turf managers to record air temperatures, soil temperatures, relative humidity, turf health, and other environmental factors that may influence turf tolerance to herbicides. These records can be referenced to plan future spray programs for mid to late summer in subsequent years.
Other environmental factors influence turf injury from herbicides in summer. While temperature is an important factor, high humidity increases absorption of many herbicides compared to low humidity levels. Herbicide applications in early evening when humidity and temperatures decline may help reduce injury potential compared to midday when these levels are higher. However, subsequent heat and humidity may influence turfgrass translocation and metabolism of herbicides that could also limit tolerance levels after applications.
Unfortunately there are no perfect application programs or predictive models to determine safety of herbicides on labeled turfgrass species. It is recommended to spray a test area and evaluate turf injury before making broadcast treatments during periods of excessive heat. Furthermore, if there is uncertainty over making herbicide applications turf managers should wait and assess the benefits of potential weed control. Applicators may wish to consult local extension agents for further information regarding herbicide applications during summer months.
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The weed in question is most commonly lawn burweed (Soliva pterosperma), a.k.a. spurweed, stickerweed, sandbur, sanbur and sandspur. Lawn burweed is a winter annual member of the Aster family. The weed germinates in the early fall months as temperatures cool and remains small or inconspicuous during the cold winter months. However, as temperatures warm in the early spring, or about the same time as spring sports activities, lawn burweed initiates a period of rapid growth and begins to form spine-tipped burs in the leaf axils. The sharp-tipped spiny burs of this weed can irritate the skin.
Key identification characteristics of lawn burweed are:
opposite, sparsely hairy leaves that are divided into numerous segments, or lobes
small, inconspicuous flowers, and c) spine tipped burs that are found in the leaf axils (junction of leaf and stem).
attains an overall diameter of up to 6 inches and a height of about 3 to 4 inches.
It is commonly found in the Coastal Plain and Piedmont regions of Georgia.
Lawn burweed is easily controlled during the winter months.
December, January and February are ideal months to apply herbicides to control this weed. Lawn burweed is small and easier to control at this time of the year than in April and May. Also, turfgrasses are not actively-growing during the winter months and have better tolerance to some herbicides.
See the UGA Pest Management Handbook for pesticide recommendations for your turf type. Two to three weeks after the initial application, lawn burweed control should be evaluated. If control is not acceptable, an additional application may be necessary.
Lawn burweed can be controlled in late-March, April and early May, however, two main facts should be considered.
Lawn burweed begins to die as late spring temperatures approach 90° F and the plant is harder to control once the spiny burs or stickers have formed. Multiple herbicide applications are usually necessary, which increases the risk of temporary injury to the turfgrass.
Additionally, it takes time for the herbicide to control lawn burweed, and after death, it takes time for the dead lawn burweed plants to decompose. Therein lies one of the main problems with late treatments. Dead lawn burweed plants contain dead, or brown spine-tipped burs. Dead or alive, the spiny burs still present a problem. The only recourse at this point is to allow time for the plant to naturally decompose.