Saturday, March 15, 2008

Turf - Hybrid Bluegrasses

Dr. Mike Goatley, turf specialist at Virginia Tech spoke at a turf session held at the University of Delaware Carvel Research and Education Center on 3/14. In his first talk, he gave information on new turfgrasses that are coming on the market. One group are the hybrid bluegrasses which have some desirable traits that warrant consideration in Delaware. The following is some information from Dr. Goatley from the Virginia Tech Turf and Garden Tips website.

There are some new grasses on the market that warrant attention in Virginia (and Delaware). One of those grasses is hybrid bluegrass, a cross between our long-time standard Kentucky bluegrass with Texas bluegrass. The result of this cross is touted to be a seeded turf with the great looks and recuperative potential of Kentucky bluegrass and the added heat and drought tolerance of Texas bluegrass. So what is the take of Virginia Tech’s Turfgrass Team on hybrid bluegrass to date? We believe this grass certainly has merit, but most cultivars still have not been around long enough in our field research trials to be added to our “promising” or “recommended” cultivar list.

Some early observations of hybrid bluegrass.

1) Hybrid bluegrasses germinate from seed slightly faster than Kentucky bluegrass, but the differences in overall establishment rate have not been significant. Hybrid bluegrass germinates and establishes slower than tall fescue.

2) These grasses survive prolonged heat and drought periods, but their performance has not been significantly different from most Kentucky bluegrasses or turf-type tall fescues to date. Hybrid bluegrasses enter dormancy in these stressful periods, a survival feature already well documented for Kentucky bluegrass. Don’t interpret hybrid bluegrass’ claims as being heat and drought tolerant to mean it maintains a lush green color throughout a prolonged dry period.

3) Perhaps the most promising characteristics of hybrid bluegrass to date is its tolerance to one of the major summer diseases in Virginia’s lawns: Rhizoctonia blight (often referred to as “brown patch”). Research by Dr. Jeff Derr and Dr. Brandon Horvath at the Hampton Roads AREC is indicating hybrid blue has much lower brown patch pressure than tall fescue in the Tidewater climate.

4) The other characteristic noted in our trials is that hybrid bluegrass really responds to nitrogen fertilization, similar to Kentucky bluegrass. Under low N fertility programs (say 0.5 to 1 lb N/1000 sq ft/yr), this grass has a tendency to develop diseases noted for their occurrence in low fertility situations: leaf rust, dollar spot, pink patch, and red thread. It appears that in order to maintain the best quality hybrid bluegrass turf possible, it is going to require 3-4 lbs N/1000 sq ft/yr, with 75% of the seasonal N being applied in the recommended September to November period.

5) Spring greening and regrowth is still very slow (similar to Kentucky bluegrass) as compared to tall fescue and perennial ryegrass.

What about the commercially available mixtures of hybrid bluegrasses and tall fescues? Tall fescue continues to be the best adapted cool-season turfgrass for most of Virginia (and Delaware) because of its tolerance to heat and drought stress primarily because of its deep root system. It is only logical that two grasses touting heat and drought tolerance would be combined as a seed mixture for Virginia’s (and Delaware's) lawns. However, there are not a lot of university research trials to date to document the success and/or failure of these mixtures. The best we can do is to hypothesize what these combinations might provide if the mixtures perform up to expectations:

1) Hybrid blue/tall fescue combinations seem reasonable based on expectations in turf quality. Most hybrid bluegrasses currently on the market have a slightly wider leaf blade than Kentucky bluegrass and are very similar in appearance to the turf-type tall fescues. The clumping problems associated with mixtures of Kentucky bluegrass and older, forage-variety tall fescues in years past are not likely an issue with this new combination.

2) Hybrid bluegrasses possess a strong creeping growth habit due to rhizomes (underground stems). This creeping growth potential is something that most tall fescues do not possess. This should further improve turf density and provide for recuperative potential if a turf stand is damaged.

3) The brown patch tolerance will likely improve turf quality during periods when disease pressure is high, possibly reducing the need for fungicide applications.

4) The tall fescue component in the mix will enhance spring greening and regrowth.

At this time, it seems probable that the hybrid bluegrasses are viable alternatives and/or partners to turf-type tall fescue for much of the Tidewater and Piedmont regions (and for Delaware). The ideal time to establish any cool-season turf (including hybrid bluegrass) continues to be in late summer and early fall. Though most hybrid bluegrass seed is sold in the busy spring planting season, successful establishments are much harder to achieve from spring plantings. Virginia Tech researchers will continue to evaluate the latest offerings in turfgrasses to hit the store shelves and keep you abreast of our findings as the data become available.

Reprinted from "Can You Cure Your Lawn Woes by Singin’ the Hybrid Blues?" by Mike Goatley, Extension Turf Specialist, Virginia Tech in Turf and Garden Tips from Virgina Cooperative Extension

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