Degree Name

Master of Science (MS)

Semester of Degree Completion

1992

Thesis Director

Roger Darding

Abstract

Three plant growth regulators (Embark, Event and Oust) and two surfactants (crop oil and non-ionic surfactant) were evaluated for their effectiveness in controlling the growth of rough turf at Coles County Airport. The PGRs were evaluated for control of turf height, suppression of seedheads, phytotoxicity and weed control at two, four, six and eight weeks after spraying. Embark and Event were applied at a rate of 0.43, 0.64 and 0.86 kg/ha and Oust was applied at a rate of 0.01 and 0.02 kg/ha. The surfactants were applied at 1% of solution. All PGRs were more effective with a surfactant, but there were no significant differences between the two surfactants. Embark was the least effective PGR and by the eighth week no regulatory effects remained. Event with a surfactant at 0.64 kg/ha showed the best control of turf height and seedhead suppression, while exhibiting minor phytotoxic effects. Oust with a surfactant at 0.02 kg/ha also showed good control of turf height and seedhead suppression, however phytotoxic effects were more severe. One application of either of these treatments could eliminate mowing for four weeks, and it is estimated that five applications could eliminate mowing for the entire growing season. Five applications of Event with crop oil and Oust with crop oil would cost $49,495 and $16,350 respectively. The Coles County Administrative Board currently spends $30,000 a year to maintain turf height. Although Event with crop oil could reduce the number of mowings it would not be an economical way to control the height of the vegetation. If five applications of Oust could effectively control vegetation height for an entire growing season, the savings would be $13,650.

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