Current & Potential Impacts of the 2015 Wet Weather Pattern on the Turfgrass Industry

Published: July 27, 2015

The Missouri turfgrass industry is being adversely affected by the persistent wet weather, but not nearly to the extent as the annually planted row crop industry in the state. As we experience what could be the wettest May – July period in Missouri history, below are a few bullet points that point out some of the hardships this current pattern has brought to the turfgrass industry.

Turfgrass Establishment/Sod Farms

• If spring seeding was attempted to establish lawns, sports fields, or golf courses, the majority of that seeding failed. Spring seeding of cool-season turfgrasses is discouraged in Missouri because the establishment period is short and is followed by stressful environmental conditions that are conducive for abiotic stresses (i.e. heat, drought, flooding) and disease occurrence (Rhizoctonia/Pythium damping off, melting out). The conditions this year drove home this point.
• Most warm season turfgrasses (bermudagrass and zoysiagrass) used in Missouri are established vegetatively with sod, sprigs, or plugs. As opposed to cool-season species, early June is the most effective time for establishment of these species because warm summer temperatures will encourage rooting and spread before cool fall temperatures induce dormancy and growth cessation. The weather pattern has caused several problems for those attempting to establish warm-season turfgrasses.
• Getting into the field with heavy equipment necessary for sprigging or cutting sod has been nearly impossible. Sod farms have had particular hardships with timely delivery of sod of either cool-season or warm-season species. o If planted, cool nighttime temperatures associated with jet stream dips and cool fronts have severely limited the spread and establishment of new warm-season turfgrass areas.
• Similarly, low light conditions from frequent cloud cover have reduced the growth potential of turfgrasses. This impacts warm-season turfgrass species more severely than cool-season.
• Roots of newly established warm-season areas are stuck in a saturated, anaerobic environment that is not allowing soil penetration or proper establishment. If a dry down does occur, the plant will not be able to take up enough water to sustain itself and dieback may occur. The saturated environment will also play a role in subsequent tolerance of next year’s winter conditions, as juvenile plants with limited root systems are more prone to winterkill and cold dessication.
• Sod producers have had limited time to harvest sod or sprigs, particularly on fields prone to flooding.
• Due to intense demand, seed companies may sell out of many types of grass seed and face shortages. Buying seed now and storing in a cool, dry place may be wise if planning on cool-season turfgrass establishment this fall.

Home Lawns

• Due to the frequent rains, disease pressure has been very high. Brown patch of tall fescue has caused severe blighting on home lawns in some urban areas. A related disease on zoysiagrass, large patch, is still actively causing decline in St. Louis in early July, whereas in most years, large patch activity steeply declines in early or mid June. Fungicides bought over the counter are ineffective, particularly when applied curatively. Frequent, costly fungicide applications have been applied to high amenity lawns for disease control. On many regular or low maintenance lawns, reseeding of tall fescue this fall will be necessary, and weed control will be more difficult due to reduced stand density.
• Yellow nutsedge is a prevalent, troublesome weed species that commonly infests turfgrass areas during the summer months in Missouri. Nutsedge also grows well in saturated, wet soils, and has been a prominent weed issue this year. The weed is difficult to control, as rhizomes and nutlets are underground and simply pulling the plants often results in fast regrowth. Also, no pre-emergent herbicide is available to control this weed. Control relies on the use of specialized post-emergent herbicides (i.e. halosulfuron, sulfentrazone, bentazon) that may require addition of a non-ionic surfactant and may require more than one application for control. Also, these herbicides may impact reseeding efforts in the fall, so its important to read and adhere to the label carefully before using.
• Most home lawns in Missouri (~85-90%) are comprised of cool-season turfgrass species, mostly tall fescue. Cool temperatures and frequent rains have caused significant foliar growth of these species. On the surface all may seem fine, but a lush foliage without a sustaining root system has significant caveats.
• If any sustained period of drought and heat does follow this wet weather pattern, many home lawns may not have the root development necessary to keep up with the transpiration needs of the plant. Tall fescue has a good adaptive mechanism to go into drought dormancy when this occurs, but losses of Kentucky bluegrass, fine fescues, or perennial ryegrass stands may occur quickly.
• Homeowners and lawn care operators alike are required to mow in the brief instances when the sun does shine. Oftentimes the underlying soil is still saturated, and the equipment and traffic may cause considerable compaction. Aerification practices in the fall will be necessary to remediate. Additionally, mowing is not being conducted as frequently as necessary, resulting in unsightly clippings that if left on the turf surface provide a ripe environment for disease issues.
• Profitability of lawn care companies, particularly full-service operations, may increase due to this weather. Many pre-emergent herbicides applied for weed control will break down with the continued rainfall, meaning post-emergent products may be applied. Fungicide applications for disease control are also near or at a record high.

Golf/Sports Turf

• Similar to the farming community, golf superintendents and sports turf managers have had significant trouble finding dry times to get into their fields. Necessary fertilization, chemical applications and cultivation practices have suffered. Along with this, lost revenue will be realized due to cancelled sporting events and less rounds of golf across the state.
• Since golf putting greens are the most intensively managed (mowing heights 1/10” or less), they have been most adversely affected thus far. In the last six weeks, 3 - 8 samples of declining creeping bentgrass putting greens have been submitted to the Clinic per week. Various problems have been observed related to consistently waterlogged soils.
• Many bentgrass putting greens are beginning to go into physiological decline, with a particular condition known as wet wilt. During even brief periods of high temperatures and high humidity, bentgrass roots in saturated, anaerobic soils can not sustain the transpirational needs of the foliage. A rapid decline of the putting green subsequently occurs, and very little can be done to avoid it.
• Roots may also in fact “cook” in saturated soils during high temperature periods. Bentgrass putting greens have a low amount of verdure and are prone to rapid increases in soil temperature. If drainage is compromised or too much organic matter is present to hold water, soil temperatures may remain high for extended amounts of time due to water’s high heat capacity. This is starting to be witnessed in southern areas of MO. Cooler temperatures have negated most of this stress in early summer for urban areas, but it could become a considerable issue as the season progresses.
• Foliar diseases such as dollar spot and brown patch have been issues on putting greens, but these diseases pale in comparison to the impact of soilborne diseases. Pythium root rot, which is spurred by saturated soils, has caused considerable damage on golf putting greens in the region, and has been observed in most sample submissions. Take-all patch and also summer patch have also been observed infecting most roots of declining putting greens. Routine summer aerification or venting of putting greens can reduce the incidence of these diseases, but the frequent rains have limited opportunities to use the heavy machinery necessary. Most superintendents do not apply preventive controls effectively for these diseases, since Pythium fungicides are in different chemical classes than most other fungicides, and fungicides must be applied in high water volumes or immediately watered-in to the root zone for effective soilborne disease control.
• Turfgrass used for athletic fields has also observed hardships akin to those in the golf industry. Summer patch on Kentucky bluegrass has been an issue on several sports fields in the state. Once this disease sets in, turfgrass recovery is difficult, and weed encroachment can become an issue.