Golfdom, January 2013

herbicide or growth regulator while the neighboring biotype is unafected As a winter annual most annual bluegrass seed will germinate in fall Tus PREs applied for annual bluegrass control should be applied in late summer Previous research at Cornell University and our current research on creeping bentgrass Kentucky bluegrass and or perennial ryegrass fairways clearly show that including a late summer application of a PRE in combination with a program of POST herbicides improves annual bluegrass control over the POST program alone If the PRE is not included the tremendous bank of annual bluegrass seed in the soil will germinate all fall and quickly reoccupy any of the openings left by annual bluegrass controlled by the POST applications Using multiple modes of action in an annual bluegrass control program also can minimize the chances of developing a population resistant to a single mode of action approach During summers like 2011 or 2012 turf stands of desired turf and or annual bluegrass thin and die Te immediate response is to interseed the desired turf but annual bluegrass germinates at the same time and starts to out compete the desired turf again Figure 3 Options for using PREs in overseeding are limited to applications after the seedlings have matured Initial research results at UNL investigating the use of PREs applied prior to seeding to control the annual bluegrass between the overseeder slits and preliminary results are surprisingly positive Our other research partly funded by the USGA is evaluating POSTs applied shortly afer emergence of the desired turf to help minimize annual bluegrass Simply overseeding into thin turf without aggressive annual bluegrass control will continue the cycle of annual bluegrass infesting the stand PRE EMERGENt HERBICIDES FIgure 3 After summer thinning of fairways containing annual bluegrass overseeding desired turf the dark green lines of perennial ryegrass in this case is done to improve playability However annual bluegrass germinates quickly in the fall re occupying bare areas and likely out competing the desired turf over the winter Current research is evaluating the aggressive use of pre and or post emergent herbicides to limit annual bluegrass reinfestation Preliminary results are promising Yellow nutsedge control Yellow nutsedge has long been controlled with POST applications but PRE control has been documented from both Echelon prodiamine plus sulfentrazone and Tenacity Applications of Echelon to established turf need to be at the typical PRE application timing for crabgrass of mid spring and are most efective with sequential applications Tenacity can control yellow nutsedge PRE in a new seeding on bare soils Tough neither of these products provide 100 percent control of yellow nutsedge every time their typical 70 to 90 percent control is far better than we ever expected from previous PRE applications Though few major changes have occurred in pre emergent herbicides over the last 20 years researchers continue to advance our understanding of these products resulting in improved weed control and expanded uses in golf turf Zac Reicher Ph D is a professor in the Department of Agronomy and Horticulture at the University of Nebraska Lincoln He can be reached at zreicher2@ unl edu Ad Index January 2013 golfdom 53 Golfdom com photo courtesy zac reicher Companies featured in this issue Advertiser PAge Agrium Adv Tech 5 AMVAC Environmental Products 3 The Andersons 31 Arysta LifeScience 21 BASF Corp 1 Bayer CV4 Control Solutions 19 CourseVision 15 Dow AgroSciences 59 Earthway Products 43 FMC Professional 23 Floratine Products Group 27 Hunter Industries 29 J2 Golf Marketing 6 Jacobsen 9 Nufarm 33 PBI Gordon 35 Smithco CV2 Spectrum Technologies 17 Standard Golf 48 Staples Golf Design 10 Syngenta CV3 Trojan Battery 7 Turfco 13 This index is provided as an additional service The publisher does not assume any liability for errors or omissions