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For as long as I can remember, golf course superintendents have sought the holy grail of Poa annua control. It seems like every few years a new product comes to market with claims of selective removal of this highly adaptable turf species. Meanwhile, perpetual whispers of even better products waft through the air at industry events.

Poa annua combat in the 21st century has a newly registered weapon. Methiozolin has been tested at numerous facilities for more than 10 years. Now that it has received registration in most states, superintendents are eager to put it through its paces. The usual program consists of making anywhere from three to five applications during the year. Post-application watering is key to moving this root-absorbed active ingredient down into the rootzone. The best outcome when using this product is to have all the Poa annua “melt” away while the desirable turf fills in the voids left behind.

During recent Course Consulting Service visits, I have seen varying levels of success at courses using this new product. Some courses are seeing excellent results while others are still waiting to see if anything is going to happen. Here are some important points to consider when incorporating methiozolin into your Poa annua control strategy:

Have patience: While heavier rates of this herbicide will absolutely kill most, if not all, biotypes of Poa annua, a slow transition should allow healthy surrounding turf to fill in the voids.

Be careful what you wish for: Be ready for dead turf. Methiozolin kills Poa annua. If you have 10% Poa annua in your greens, make sure you’re willing to have 10% of your green surface area dead. Warning: we all typically underestimate how much Poa annua we really have.

Communicate: Golfers may not fully appreciate seeing Poa annua carnage on the putting surfaces. Communicating the plan and explaining what to expect will help assuage golfer concerns.

Follow the label: Many years of research and trials went into the development of methiozolin for Poa annua control. Label instructions are written for good reasons. Resist the urge to go rogue with this stuff.

Temper expectations: Methiozolin is another tool in the ongoing battle against Poa annua invasion. Expecting it to be the silver bullet is unrealistic.

Stay the course: Continuing to utilize proven strategies to limit Poa annua invasion is still a good thing. Preemergence herbicides, plant growth regulators, well-timed aerification and hand-picking should continue to be part of your Poa annua control program.

While methiozolin may not turn out to be the holy grail we’ve always looked for, it is proving to be a good tool in your quiver of arrows aimed at pesky Poa annua.

West Region Agronomists:

Brian  Whitlark, senior consulting agronomist –

Cory Isom, agronomist –

Information on the USGA’s Course Consulting Service

Contact the Green Section Staff