COURSE CARE
Henry Wadsworth Longfellow and … Poa annua? June 19, 2012 By Bob Vavrek

Encouraged by a mild winter and an unusually warm March, a bumper crop ofPoa annua seedheads has been a nuisance at many courses this spring.  Alternating periods of cold and warm weather combined with droughty conditions through June seem to have produced another flush of seedheads just when you thought they were gone for the season.

Was your golf facility affected by a double whammy ofPoa annuaproblems this spring? Many courses noticed a bumper crop of small, dime-sizedPoa annuaplants in bentgrass playing surfaces this spring, even those that were relatively clean last fall. No doubt, the exceptionally mild winter weather was the primary reason for the high survival rate of so muchPoa annua.To the disdain of turf managers and players alike , the new Poa annua tends to be the biotype that produces an abundance of seedheads.   

However, both old and new Poa annua plants appear to be seeding for an extended period of time this spring. Attempts to suppress seedhead development with plant growth regulators (PGRs) have been, at best, marginally successful. This should come as no surprise when 10 days of temperatures in the 80’s occurred during mid-March to jump start Poa annua growth and reinforce the suspicion that degree-day models used to predict seedhead development and timing of PGR treatments become practically worthless when a significant spike in soil temperatures occurs in early spring.  

Heavy seeding will limit green speed and disrupt smoothness of putting surfaces. Old school management practices such as grooming, vertical mowing and brushing can be effective options for removing some of the troublesome seedheads from the greens, but these techniques have become a lost art at many courses that now rely solely on mowing and rolling to prepare a putting surface for play.   

Seedhead issues will subside when, and if, the weather patterns stabilize this summer. Perhaps the less obvious, but more important, issue to consider is the surprising amount of new Poa annua that has become well established in greens this spring at courses that were, up to now, making considerable progress increasing the ratio of bentgrass to Poa annua through cultural and chemical  programs.   

Certainly, a spring like this has many superintendents wondering if attempts at Poa annua control are really worth all the effort and aggravation in a climate that can, at times, be so favorable to this grass. Yet, these same superintendents will try almost anything to rid the course of annual bluegrass after struggling with extensive losses of Poa annua caused by winterkill or heat stress.  

Perhaps long-term Poa annua control is a goal we will never achieve throughout the upper Midwest. Perhaps we are resigned to accept Poa annua as a permanent component of the playing surfaces, knowing full well that it will forever be much like Longfellow’s little girl with the curl… 

When she was good, 

She was very good indeed, 

But when she was bad she was horrid.   

Source: Bob Vavrek ( rvavrek@usga.org) or 262.797.8743

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