Golfdom, August 2010

CASE STUDY Superintendents say herbicide eradicates pesky weed during fairway renovations to Poa B Y L A R R Y A Y L W A R D E D I T O R I N C H I E F w w w g o l f d o m c o m Golfdom 55 M ike Hart has been working as a golf course superintendent since 1975 and the 63 yearold says hes never seen anything to rid Poa annua annual bluegrass on bentgrass fairways Until now Hart the superintendent of Danville Ill Country Club recently renovated his courses 18 fairways the front nine in 2008 and the back nine in 2009 and converted them from Kentucky bluegrass to bentgrass Working with turfgrass professor Bruce Branham from the University of Illinois Hart applied Velocity herbicide on the turfgrass three weeks after seeding to keep Poa from growing in with the bentgrass We had a bad Poa problem here before Hart says It drove me crazy Hart believes the old low mow bluegrass on the fairways grew weak and the Poa kept getting stronger until it overtook the bluegrass Every year Id watch the Poa get more dominant he says So we decided to switch to bentgrass Hart had been through such conversions before and many of them were unsuccessful in his mind because the Poa grew back so strongly To Hart a successful conversion was limiting Poa to a 10 to 20 percent grow back range so it was more manageable Velocity from Valent Professional Products features bispyribac sodium as its active ingredient Valent says the herbicide can gradually eliminate Poa annua and Poa trivialis from creeping bentgrass and effectively transition a Poa dominated mixed stand of turf to pure bentgrass Hart began renovation of the front nine holes in the fall of 2007 He renovated the back nine a year later He closed the holes in August in both cases Hart slit seeded the fairways as carefully as possible Four weeks after seeding Hart sprayed the fairways with 6 ounces 30 grams per acre of Velocity He couldnt believe he was applying a herbicide at such a high rate to such young turf It scared the bejesus out of me when I did it Hart admits Three days later the bentgrass displayed some yellow and began to thin It went from new lush fairways to a yellow thin stand of grass in one week Hart says I was expecting that to happen but it didnt do my heart any good to see it But Hart felt much better when he saw the Poa in the mix also turn to yellow and begin to die Then the green returned to the bentgrass in about a week minus the Poa Hart was impressed After the projects were completed on both nines Hart estimates the turfgrass was 85 to 90 percent bentgrass Two and three years later Hart remains impressed with the healthy stand of bentgrass fairways And he didnt have to spend a million dollars to get the renovation done The fairways look absolutely fantastic he says We did the project for under 40000 and did everything in house Hart continues to battle the low percentage of Poa annua in the fairways and he wants to be sure to keep it in check He applies light rates of Velocity about 2 ounces 10 grams per acre three times a year to keep the Poa weak Its the only thing Ive seen that works against Poa he says of Velocity William Sharp a research specialist from the University of Illinois who has studied the herbicides effect on Poa recommends 30 grams of active ingredient per acre sprayed at two weeks apart for a fairway renovation Sharp advises the first application be Continued on page 56