Golfdom, December 2016

WARM SEASON GRASS SEEDHEAD MANAGEMENT at 133 hours for non mowed plots Seedheads emerged later in spring of 2014 and 2015 compared with 2013 which may have resulted from bermudagrass maturity after establishment The initial seedhead emergence was consistent across mowing regimens in subsequent years In 2014 and 2015 the non mowed bermudagrass had initial seedhead emergence at 140 hours and 138 hours respectively All plots that received mowing programs had seedheads emerge at 142 to 143 hour photoperiods These timings were approximately three to four weeks later than the plots that were not mowed Seedhead production Although photoperiod was more inf luential on the initial emergence of bermudagrass seedheads calendar date week number and temperature growing degree day had greater associations with seedhead production from January until August Bermudagrass maintained at the lowest height evaluated 025 inch two days per week averaged about 50 percent less seedhead coverage than the other mowing programs at peak emergence in August Results suggest that TifGrand bermudagrass seedhead production can partially be suppressed by regular mowing at 025 inch compared to higher mowing heights Bermudagrass seedheads declined by late August from peak levels noted at all mowing heights This decline in seedhead cover was consistent with the decline in turf quality reductions in photoperiod and cooler temperatures in fall Bermudagrass shoot growth is highly dependent on photoperiod light intensity and temperatures Researchers have noted that bermudagrass exhibits reductions in biomass shoot height and tiller density as temperature and photoperiod are decreased These physiological responses to changes in temperature and photoperiod in fall likely are associated with the decline of seedhead production of TifGrand bermudagrass FIGURE 2 TifGrand bermudagrass seedhead coverage in plots maintained at the various mowing regimens evaluated SEA ISLE 1 SEASHORE PASPALUM Seedhead emergence Seashore paspalum quality and seedhead emergence had similar seasonal trends at all mowing heights Seedheads emerged in spring reached peak cover in late summer of all years and declined in fall Photoperiod was more influential on the initial seedhead emergence of seashore paspalum at all mowing heights than temperature growing degree day estimates In 2013 the photoperiods measured 135 hours at all mowing heights on the day seedheads were initially observed Seedheads emerged later in spring of 2014 and 2015 compared with 2013 In 2014 the initial seedhead emergence of non mowed plots was observed at a 138 hour photoperiod while mowed plots had initial emergence at 142 hours The initial observation of seedhead emergence for seashore paspalum was at a 138 hour photoperiod in 2015 at all mowing regimens The growing degree day estimates over years were erratic when initial seedhead emergence was noted on seashore paspalum These results suggest photoperiod has a greater value for predicting seashore paspalum seedhead emergence than temperatures Seedhead production Calendar date week number and temperature growing degree day were more influential than photoperiod on seedhead production from January until August for seashore paspalum maintained at 05 inch two days per week 15 inches once per week or not mowed during the experiment Seashore paspalum maintained at the lowest mowing height averaged about 30 percent to 40 percent less seedhead coverage from other mowing programs at peak emergence Turf that was mowed at 05 inch two days per week and 15 inches once per week had comparable seedhead cover to the non mowed plots in 2013 and 2014 Peak seedhead coverage ranged about 20 percent to 30 percent less in 2015 for these mowing regimens than previous years Seashore Continued on page 36 December 2016 Golfdom 35 Golfdom com