Seedhead Suppression of Poa annua on a Putting Green
Dr. Thomas Watschke and Jeffrey A. Borger (Penn State), 2000
INTRODUCTION, MATERIALS AND METHODS
This study was conducted on a mixed stand of creeping bentgrass and Poa annua at the Penn State Blue Golf Course in State College, PA. The objective of this study was to evaluate the effect of Embark T&O in combination MACRO-SORB foliar on the seedhead suppression of Poa annua.
All treatments were applied on April 14, 2000 using a three-foot CO2 powered boom sprayer calibrated to deliver 40 GPA with two flat fan nozzles at 40 psi. The turf was maintained using cultural practices for irrigation, mowing, and fertilization that would be typical for a green. The green did not receive any aerification/topdressing prior to or during the study.
RESULTS AND DISCUSSION
The addition of MACRO-SORB foliar improved seedhead suppression without increasing phytotoxicity. Embark T&O at 40 oz/A was the only treatment that caused an unacceptable phytotoxicity (rating 6.5). The addition of Ferromec (5 oz/1000 ft2) to Embark T&O (40 oz/A) decreased phytotoxicity (rating 8.0), but also decreased seedhead suppression (from 87% to 82%). Lowering the Embark T&O rate to 35 oz/A decreased phytotoxicity to an acceptable level (rating 7.6), but also decreased seedhead suppression more than desired (78%). The addition of Ferromec to Embark T&O (35 oz/A), although it did not appear to be needed to decrease phytotoxicity, did not appreciably improved seedhead suppression. By adding MACRO-SORB foliar at 2 oz/1000 ft2 to Embark T&O at the rate of 35 oz/A, seedhead suppression was increased from 78% to 92%.
Results from this study and other similar studies in previous years indicate that MACRO-SORB foliar enhances the effect of Embark T&O to suppress seedhead of Poa annua without increasing phytotoxicity.