Vol. 54—2000 - NorthEastern Weed Science Society

RE-ROOTING OF FOUR VARIETIES OF CREEPING BENTGRASS AFTER
APPLICATIONS OF BENSULIDE AND DITHIOPYR
T. L. Watschke and1. A. Borger'
INTRODUCTION
This study was conducted at Penn State University, University Park, Pa in the greenhouse
at theAgriculturalSciences and IndustriesBuilding to evaluate the re-rooting of 'Penncross',
'Seaside', 'Penneagle' and 'Pennlinks' creeping bentgrasses. Applications of bensulide and
dithiopyr were applied to the bentgrasses for two growing seasons. Samples were taken the
springfollowing the two yearsof applicationsforthe assessmentof re-rooting.
METHODS AND MATERlALS
This experiment was a completely random design with nine replications. On Feb. 27,
1999, two-inch diameter plugs were collected from the plots in the field thatreceived the
herbicideapplications.The soil was removedto a depthof 0.5 inch. The plugs were thenplanted
in a sandmediumin four-inchpots in a greenhouse.
Bensulide and dithiopyrwere appliedduringtwo of the threepreviousgrowing seasons.
All treatments were applied on May 3, 1996 and, with exception of dithiopyr again on May 3D,
and Aug 26, in 1996. In 1998, all treatments were applied on April 16 and with exception of
dithiopyr again on May 20, and Aug 19. All applications were applied using a three-foot hand
held CO, powered boom sprayer with two 6504 flat fan nozzles calibrated to deliver 80 GPA at
30 psi. Aftereach applicationthetest site receivedapproximately0.5 inch of water.
RESULTS AND DISCUSSION
Color(phytotoxicity)was ratedon five consecutivedays in Marchaftertheplugs were
placedin the greenhouse(Table1). No differenceswere foundin color regardlessof treatment
during the five day 'green-up' phase of the experiment. On March 18, topgrowth was harvested
and fresh weights of clippings was recorded (Table 2). No significant differences or trends were
found amoug the treatments. On March 23, roots were harvested, dried, and weighed as a means
of assessing re-rooting.No significantdifferencesin re-rootingwere foundfor Penncross,
Seaside or Pennlinks varieties. However, Penneagle that badbeen treated in 1996 and 1998 at the
high rate (40, 3D,and 30 ptslA) had significantly reduced re-rooting compared to untreated
Penneagle.Dithiopyrwas not foundto causeany significantdecreasein re-rootingon anyof the
varieties when applied at the label rate (0.5 lbs ailA) with a spring (April) application.
'ProfessorandResearchAssistant,respectively,Departmentof Agronomy,PennState
University,UniversityPark,Pa, 16802
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