Winter desiccation on a creeping bentgrass green that had significant thatch accumulation.
Winter desiccation is a form of “winter injury” that can often occur in February and March during extended periods of dry weather. Most susceptible are seedlings that were seeded late in autumn, and established turf that has excessive thatch. If you seeded in late October and turf is not yet mature, consider applying water if we get into an extended dry period. Lack of maturity means limited root growth and more frequent water is needed.
Creeping bentgrass is quite susceptible to desiccation, particularly when it accumulates some thatch. In fact, winter desiccation injury often more common on fairway height turf that has accumulated thatch compared to that growing on putting greens. Roots become elevated in the thatch and are unable to absorb water from soil. Creeping bentgrass growing on elevated sites that are most exposed to wind is most susceptible. Again, water application may be needed during extended dry periods to reduce the risk of desiccation. This may required methods of water application other than just irrigation. For example, sometimes boom sprayers are used to deliver water – multiple passes may be needed. In areas where desiccation is common on bentgrass greens, it not unusual for superintendents to topdress heavily in the fall, or provide some kind of cover on the surface through winter – sometimes synthetic cover or using branches from cedar trees or other evergreens – to help reduce wind effects. Click links below for more information.
Some grasses, such as bermuda, are susceptible to winter injury when crowns become elevated.
There are various ways to keep crowns covered, some are more practical than others. One excellent cover is snow. In 2021, air temperatures in Kansas reached -18 F in the eastern part of the state and low temperature extremes occurred in southern states too. For example, parts of southern Texas reached temperatures as low as 5 F in mid-February. A municipal park manager in southern Kansas had sodded Latitude 36 bermudagrass, a cultivar with good cold hardiness, on baseball fields and dog parks in late summer 2020 and was quite concerned about its survival following the February temperature plunge. When April arrived in our state, I visited the location to investigate the extent of winterkill, but it was minimal. About 4 inches of snow helped insulate the crowns. In other areas of the transition zone and upper South that had no snow cover, some extensive winterkill of bermudagrass and other warm-season grasses occurred.
There are other, more reliable ways to protect the crowns of warm-season grasses, as snow may not always be present when temperatures like this happen. Soil provides a warm blanket for crowns. When air temperatures drop below 0 F, it is common for temperatures just below the soil surface to be significantly higher. In Kansas in Februrary, 2021, lowest soil temperatures at a 2 inch depth were generally at least 40 F warmer than the lowest air temperature that occurred (e.g. air at -18F, soil at about 25 F). Soil provides a very nice blanket for crowns. It confirms that keeping crowns from rising above the soil by minimizing thatch accumulation is important, and removing thatch may be needed if it becomes excessive. For crowns that are above the surface, topdressing will help create a warmer environment during winter.
It’s that time of the year when it’s both very hot and, likely, very dry. While it’s important to water landscape ornamentals all year long, now is a critical time to make sure plants have all the resources they need.
We have several publications about best practices for watering:
Newly planted trees (within their first year) should be watered at least weekly but check the soil to make sure it’s draining well. Slow-release watering methods like micro-pore bags and 5-gallon buckets with small (1/8-inch) drainage holes are a good way to apply irrigation to trees and some shrubs. However, remember to remove the bags when they are empty to ensure good airflow around plant stems and reduce pests and diseases. Removing turfgrass and other ornamental plants to at least the tree dripline (or beyond) will help trees access more water and grow more quickly—make sure to mulch the turfgrass-free zone to help retain applied water.
Established trees will benefit from a thorough soaking (to a depth of 12 inches out to and beyond the drip line) every 3 to 4 weeks. Established shrubs need water every 2 to 3 weeks during this drought- and heat-prone time of year. Plants growing in raised beds and berms may need to be watered every 1 to 2 weeks. Soaker hoses work well for watering established trees and shrubs.
You may want to consider taking advantage of a light rainfall (if you get one in July and August) by watering immediately afterward to help moisture move deeper into the root zone.
Any way you slice it, watering is a good thing. There are many other factors to consider for successful planting, but right now watering is top of the list. Keep it up—plants are thirsty just like you!
The temperatures are reaching summer high’s this week, and it is more important than ever to be monitoring and increasing watering schedules. Adjusting irrigation settings to accomodate for extreme temperatures will be vital for the health and survival of new plantings, as well as established plantings.
Featured in the Horticulture e-Newsletter, Ward Upham discussed the importance of watering for trees and shurbs. The article is featured in the link here.
Here are some other timely blog posts about watering as well:
Fine fescues include multiple species: creeping red fescue; slender creeping red fescue; Chewings fescue; sheep fescue; and hard fescue. In our state, they have traditionally been used in seed mixtures targeted at shady sites. In general, fine fescues perform fairly well in shade. Decline of fine fescues has been observed in Kansas during midsummer under wet conditions.
Some fine fescue species are exhibiting good color and density in summer heat in Olathe, KS.
The 2020 NTEP Fine Fescue trial was planted in September at the Olathe Horticulture Research Center in full sun. It is a low-maintenance trial: no irrigation has been applied (other than during establishment) and the area only received starter fertilizer at the time of establishment. Many of these species and cultivars look very good in mid-July 2021. We will continue to evaluate their performance over the coming years. It’s quite possible that some of the fine fescues could provide an acceptable quality lawn with relatively low input.
Dr. Ross Braun is a former K-Stater (M.S. and Ph.D. degrees in turf at K-State) is now a lead research scholar at Purdue University, and is working diligently with these species. The Purdue research team is working with that at the Univ. of Minnesota on fine fescues (low-input turf). To learn more about fine fescues, development of new cultivars, and management, check out the article and video below by Ross and explore the web site on which these are posted.
The dreaded check engine light popped on this past month. Bound to happen to a 15-year-old vehicle, pushing a quarter of a million miles. I immediately stopped by a local auto parts store and connected a diagnostic scanner to find a faulty fuel level sensor. Not the worst diagnostic error, but I knew I had to be more aware of the miles I drive between refueling. It reminded me of a quote by Dr. Dana Lonn, former managing director for technology at Toro Company, in which he states, “controlling an irrigation system without soil moisture data, is like driving a car without a gas gauge.” I realized more than ever what he meant as I found myself making more frequent stops at the gas station to refuel this past month, just to be sure.
The rootzone profile is much like a fuel tank, where adequate water, or “fuel”, is needed in the profile to maintain a healthy turfgrass stand. How do you know when to refill your soil profile? Setting irrigation clocks to specific days of the week to water is prone to lead to overwatering, like myself now, making more stops than necessary to refuel the vehicle. Even calculating daily evapotranspiration rates (which are estimates of the water used by turfgrass) fail to accurately account for moisture in the soil profile. Utilizing technology and devices to determine soil moisture is much like a fuel level sensor that can aid in determining when the plant needs water. This is where implementing technology in the landscape has advantages. The greater period you can stretch between irrigation applications, the greater chance a rainfall event will occur which will serve as “free water”, though I do not anticipate free gas events.
Soil water sensors are like a fuel gauge – necessary! Both wired and wireless are available.
For the past three years, I have been working to determine how to best employ technology in the turf landscape. Soil moisture sensors are one of many tools we can use to precisely determine when irrigation is needed to maximize water savings, increase turfgrass quality, provide consistent playing conditions, and minimize overwatering. Research results from 2020 indicated soil moisture sensor-based irrigation yielded 84% water savings compared to frequency-based irrigation (2x week-1) and 72% savings compared to deficit evapotranspiration (60% ET) irrigation. These significant water savings were achieved by simply monitoring soil moisture and watering only when necessary to “refuel the tank.” For more information as reference to this project, see this past article (Development of Irrigation Scheduling Techniques that Conserve Water in Turfgrass Landscapes using Soil Moisture Sensors and Weather Data. Kansas Turfgrass Foundation Newsletter, September 2019).
Throughout my turfgrass management career, I have had the opportunity to work with many great golf course and athletic field facilities across the United States. Many of those managers took on the philosophy to be data-driven because it removes the guesswork. The more data available at one’s fingertips the better decisions one can make. The key is not to become overwhelmed with the data, however, but to use the data to aid in improving your decisions or as a “tool in the toolbox”. Regarding irrigation, automated systems may become more widespread in the future and use sophisticated technology to control irrigation. Until then, we can use the current technology to establish our own automated irrigation decisions. I often like to think about two or three simple questions before I choose to irrigate. Specific questions and thresholds center around soil moisture data, turf canopy conditions, and future precipitation forecasts. Certain criteria must be met before the irrigation is turned on which has achieved significant water savings while maintaining turfgrass quality. As my research nears an end, I think it is time to schedule that service on my fuel level sensor.
Green up of Latitude 36 bermuda in mid-April in the Wichita area.
After severe cold, warm-season grasses have responded well and are generally experiencing good green up this spring. I have had no information regarding winter injury on bermudagrass or zoysiagrass. If you noticed any significant injury this spring, please reach out to me – I’d like to know. Air temperatures were very cold throughout the state between February 6 and 19th, reaching a low of -18 F in the eastern part of the state and in the Wichita area. There were differences in snow cover, however, and that can impact the level of insulation provided to the grasses. The lowest soil temperature at a 2-inch depth at the Olathe Horticulture Center was 29 F on February 15th. Winter injury becomes a greater concern if turfgrass crowns are elevated above the soil in thatch, or if there is no snow cover at all during extreme cold. The Wichita area had several inches of snow on the ground when the extreme cold occurred. I recently visited a new sports complex on which Latitude 36 bermudagrass was sodded late last summer, and no play occurred on the fields last year. Green up of those fields is looking very good (see picture above). Likewise, Northbridge and Latitude 36 bermudagrass in the Kansas City area have greened up well this spring. I have noticed some slow green up on an area of Riviera bermuda (seeded type) at our research center. Good green up of warm-season grasses may be due the fact that grasses were at the peak of acclimation (defined as the plant being physiologically prepared to tolerate extreme cold) when the cold temperatures arrived. There is greater risk of injury if grasses are not fully acclimated. This could occur with a late fall freeze, or when a short period of warmth in winter or early spring leads to some deacclimation (loss of tolerance), and then severe cold temperatures return when a front passes through.
