Conversion of Kentucky Bluegrass Rough to No-Mow, Low-Input Grasses.

The primary grass used for golf course rough in the North Central United States is Kentucky bluegrass (Poa pratensis L.).  Kentucky bluegrass requires large inputs of water, fertilizer, chemicals, and cultural management to provide a quality turfgrass stand and performs poorly under no-mow, low-input situations.  The objective of this study was to compare several methods for converting Kentucky bluegrass roughs to low-input grasses.  A 5x5 factorial randomized complete block design with 4 replications was planted at 2 locations in Minnesota (St. Paul and the Rush Creek Golf Club in Maple Grove).  Five conversion treatments were included:  (1) existing rough sprayed with glyphosate, followed by core aerification and seeding; (2) core aerification of existing rough, seeding, and glyphosate 5 d after seeding; (3) core aerification followed by soil fumigation, and seeding 14 d after fumigation; (4) removal of exisiting turf with a sod cutter followed by tillage and seeding; and (5) method 4 with the newly established grass being mowed at 5.7 cm for the first growing season.  Five grass species were included; strong creeping red fescue (Festuca rubra L. ssp. rubra), sheep fescue (Festuca ovina L.), hard fescue (Festuca brevipila Tracey), Chewings fescue (Festuca rubra L. ssp. commutata Gaudin), and tufted hairgrass (Deschampsia cespitosa (L.) P. Beauv.).  During the first year of the study, treatment 3 was the most effective at reducing Kentucky bluegrass regrowth and broadleaf weed infestations.  Treatment 2 was least effective at reducing Kentucky bluegrass regrowth and broadleaf weed infestations.  Treatment 1 provided the best overall stand quality.  Strong creeping red fescue provided the best overall stand quality while sheep fescue provided the lowest quality rating.  The best treatment-species combination was hard fescue and treatment 3 while sheep fescue and treatment 4 was the lowest-performing combination.