SportsTurf provides current, practical and technical content on issues relevant to sports turf managers, including facilities managers. Most readers are athletic field managers from the professional level through parks and recreation, universities.
Issue link: http://read.dmtmag.com/i/448298
Field Science 16 SportsTurf | February 2015 www.sportsturfonline.com e very year many turf manag- ers make preemergence (PRE) herbicides an integral part of weed management programs. By in large, PRE herbicides are used to control summer annual weeds such as crabgrass, goosegrass in addi- tion to small-seeded broadleaf weeds. Numerous options are available for use in warm- and cool-season turf at vari- able price points. Regardless of product selected, turf managers should consider four things to improve efficacy of PRE herbicide programs in 2015. CheCk for potential winter injury Many turfgrass managers lost areas of warm or cool-season turfgrasses fol- lowing the extreme winter conditions of 2013-2014. Losses occurred from winter desiccation, exposure to lethal temperatures, or a combination thereof. Characteristics of affected sites included: turf with shallow root systems; turf sub- jected to winter traffic; turf in areas of heavy shade (particularly during morn- ing hours); as well as poorly drained areas of turf. In many cases the extent of winter damage was not fully apparent until early summer, several weeks after PRE herbicides are commonly applied. This was problematic in that many PRE her- bicides have soil residual activity that can compromise rooting from stolon growth or prevent establishment of new seed altogether. It is highly recom- mended that turf managers check sites for potential winter injury before apply- ing a PRE herbicide in 2015. The basic process of evaluating potential winter injury is simple: remove a core of turf from the field, place it in a south fac- ing window, and keep it watered. If new leaf growth initiates, that is a sign that winter conditions have not harmed the turf and PRE herbicides can be used. If no new leaf growth forms, that should be a signal that winter conditions may have harmed the turf to the extent that re-establishment could be required; thus, PRE herbicide use in these areas should be avoided (see photo). explore labels Many think of PRE herbicides as tools only used for grassy weed control. Exploring product labels will reveal that many PRE herbicides are labeled for control of dozens of small seeded broadleaf weeds, as well as sedge and kyllinga species. For example, dithiopyr (e.g., Dimension) and pendimethalin (e.g., Pendulum AquaCap) labels claim control of more than 25 different broad- leaf weed species. Moreover, prodiamine + sulfentrazone (e.g., Echelon) and pendimethalin + dimethenamid (e.g., FreeHand) labels claim PRE control of numerous broadleaf weeds as well as yellow nutsedge and green kyllinga. To maximize the efficacy of PRE herbicide programs in 2015, turf managers can review the diversity of weeds across their fields and select a product that helps manage as many weeds as possible. Manage turf to reduCe weed pressure Another step that can be implemented to improve the efficacy of PRE herbicide programs in 2015 is to manage turf with an eye on reducing weed pressure during the summer season. Annual weeds such four Considerations for pre herbiCide use in 2015 ■ By Dr. Jim Brosnan anD GreG BreeDen Research has shown that increases in mowing height as small as 1/64 of an inch can increase photosynthesis as much as 13%