Conversion of Fairway‐Height Perennial Ryegrass Turf to Kentucky Bluegrass without Nonselective Herbicides

Abstract

Many golf course superintendents wish to convert perennial ryegrass (Lolium perenne L.) fairways to other cool‐season species such as Kentucky bluegrass (Poa pratensis L.) because of the former's high fungicide requirement. However, interseeding into a mature turfgrass stand often results in poor seedling survival because of competition from the existing stand. The objective of this research was to evaluate methods for enhancing Kentucky bluegrass (KB) establishment when interseeded into a mature perennial ryegrass fairway turf. Core aeration, scalping, plant growth regulators (PGRs), postseeding low mowing (PSLM), high seeding rates, and multiple seedings were used singly and in factorial combinations. Postseeding low mowing (0.6 cm twice weekly for 4 wk) and high seeding rates [196 kg pure live seed (PLS) ha−1] were most effective in enhancing KB establishment. Plots receiving PSLM averaged 31.9% KB 21 months after seeding (MAS) compared with 18.1% in non‐PSLM plots. Seeding KB at 196 kg PLS ha−1, both fall and spring, resulted in an average of 29.8% KB 21 MAS while seeding at 98 kg PLS ha−1, in the fall only, resulted in only 19.7% KB. A single preseeding core aeration or scalping treatment did not increase KB establishment, nor did preseeding applications of the PGR trinexapac‐ethyl [4‐(cyclopropyl‐α‐hydroxy‐methylene)‐3,5‐dioxo‐cyclohexane‐carboxylic acid ethyl ester]. Mefluidide {–[2,4‐dimethyl‐5‐[[(trifluoromethyl)‐sulfonyl]amino]phenyl] acetamide} increased KB establishment at 6 MAS, but the effect was gone by 21 MAS. Where nonselective herbicides are not used, fastest conversion to KB will occur with a combination of PSLM and high seeding rates.

Seeded Zoysiagrass Establishment in a Perennial Ryegrass Sward

“…siagrass spread the second year was attributed to phyto-Evaluation of irradiance and soil temperatures under toxicity that occurred after mefluidide application, as a perennial ryegrass canopy has indicated that scalping well as turf decline due to summer stresses. perennial ryegrass as performed herein results in ap- Kraft et al (2004) found that mefluidide enhanced proximately 35% shade exposure of zoysiagrass seed-Kentucky bluegrass establishment by about 13% 6 mo lings, and seedlings under an untreated, 1.4-cm-tall canafter seeding in September at 196 kg ha Ϫ1 into an existing opy are exposed to approximately 75% shade (Zuk et perennial ryegrass canopy. However, at 21 mo after al., 2005).…”

“…Zoysiagrass coverage in scalped perennial ryegrass by October of the third season of establishment was 75% in Study I and 40% in Study II. researchers who observed nominal effects of PGRs on Scalping perennial ryegrass resulted in an initial reducturfgrass conversion (Fry and Dernoeden, 1986;Kraft tion in turf quality of up to 5 points compared with et al, 2004), convinced us that more aggressive perennial untreated turf in our test, which would affect the golfer's ryegrass seedbed treatments were required to successperception of the course and would likely reduce play fully establish seeded zoysiagrass. Fry and Dernoeden should the course remain open.…”

“…Plant growth regulaperennial ryegrass was unsuccessful unless a high seedtors were applied in 401 L water ha Ϫ1 with a CO 2 sprayer at ing rate (196 kg ha Ϫ1 ) was employed in combination 241 kPa of pressure. Irrigation was applied through a hosewith suppressing the perennial ryegrass by scalping the end sprinkler two to three times daily for the first 4 wk after first few weeks after seeding (Kraft et al, 2004). seeding in 1999 to provide 2 mm of water in each session.…”

Flucarbazone–Sodium Absorption, Translocation, and Metabolism in Bermudagrass, Kentucky Bluegrass, and Perennial Ryegrass

“…However, there are limited POST herbicides available for controlling perennial ryegrass in Kentucky bluegrass lawns, golf courses, or sports turf. Cultural practices, such as low mowing and interseeding Kentucky bluegrass, have potential to reduce perennial ryegrass populations, but results are often inconsistent and warrant nonselective herbicide use (Kraft et al 2004).…”