Vol. 54—2000 - NorthEastern Weed Science Society

RESPONSE OF KENTUCKY BLUEGRASS AND PERENNIAL RYEGRASS TO TIffi
APPLICATIONS OF ETIffiPHON UNDER REDUCED LIGHT CONDITIONS
T. L. Watschke and J. A. Borger'
INTRODUCTION
Little is known about the effects that ethephon might have on the turf quality of perennial
ryegrass and Kentucky hluegrass grown underdifferent levels of shade. Six studies were
conducted on a mature stand of perennial ryegrass (three studies) and Kentucky hluegrass (three
studies) at the Landscape Management Research Center, Penn State University, University Park,
Po. The objective of the studies was to determine whether ethephon treated turf would have
improved quality under varying levels of shade.
METHODS AND MATERIALS
Each study was a randomized complete block design with three replications. All of the
treatments (ethephon at 3,5, and 10 ozlM) were applied on June 21,1999 using a three foot CO,
powered boom sprayer calibrated to deliver 40 gpa using two, flat fan, 6504 nozzles at 40 psi.
Each study area was covered with a shade cloth (kept twenty inches above the turf canopy
with a wooden rack) to simulate shade. Shade was imposed at three levels (30, 55 and 73 pereent
light filtering). The racks with shade cloth were removed each week to record data and mow and
thenreturned.
All test sites were maintainedat two andone halfincheswith a rotarymower with
clippingsremoved.Thetest site was irrigatedas neededfor thedurationof the study. Color
ratingsweretakenapproximatelyevery seven days for six weeks. Freshweights (g) were
harvestedusing a twenty inchrotarymowermakingone pass perplot on Aug 3.
RESULTS AND DISCUSSION
On July 20, (approximately one month aflertreatment) the color ratings for Kentucky
bluegrass tended to produce a trend whereby a slight increase in color was observed as the rate of
ethephon increased from 3 to 10 ozIM across all three levels of shade (Table 1). On July 27,
Kentucky bluegrass treated with ethephon at the lowest level of shade (30"10)had a slightly better
color than untreated turf. This trend was not found on the final rating date (Aug 3).\
Kentucky bluegrass shaded at the 55% level tended to have improved color on July 27
compared to untreated turf. By the final rating date (Aug 3) all ethephon treated Kentucky
bluegrass was rated below the acceptable level of 7. Only untreated turf was rated as acceptable.
On July 20, Kentucky bluegrass treated with ethephon at the 10 ozIM rate and exposed to
73% shade was rated above the level of acceptably (7). At 73% shade, all treated and untreated
'Professor andResearchAssistant,respectively.Departmentof Agronomy.PennState
University, University Park, Po, 16802
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