Poa Annua Controls in Couch Fairway

Published on 23rd May 2019 in Course News, Golf News, Local and Member News, Local News

It’s this time of year that poa annua starts to invade in the couch grass fairways. Poa is an undesirable grass variety and as the couch goes into winter dormancy the poa begins to thrive.

If not controlled, the poa will quickly infest the couch causing severe thinning.

Recent studies and investigations have revealed poa annua has developed an increasing resistance to the herbicides which have been approved to combat it. There is no easy solution.

This article explains the challenges controlling poa in the fairways at Flinders G C during the winter months.

Poa annua control in couch fairways

Poa annua (winter grass) can have an unpredictable and lengthy window of germination. No two seasons are the same, and it’s going to be a challenge to control the poa annua in the couch fairways this winter. Whilst there is a concentration of germination around the transition from summer to autumn, poa annua germination can continue for many months.

The most effective way to control poa annua is to target the weed before it germinates. The dry start to autumn has delayed the application of a pre emergent herbicide, as the fairways are suffering drought stress and the herbicide won’t bind with the dry soil. 

The pre emergent herbicide as the name suggests, has to be applied and washed in before the poa emerges. This provides a barrier on the soil surface to prevent weed seed germination. The predicament is we very nearly ran out of water and did not have the ability to activate the herbicide by irrigating into the soil.

In previous years pre emergent herbicides are applied in late summer / early autumn to cater for this broad poa annua germination window.

All applications must be made before poa germinates, because pre emergent herbicides will not control poa that has already emerged.

A pre emergent herbicide has been applied to the fairways this week and the rain showers forecast for the next few days will activate the herbicide.

Poa annua has started to appear in the fairways and whilst the pre emergent won’t control the germinated poa, it will restrict the spread of seed.

Flinders G C has three different couch grass types on the fairways; these being santa ana, winter green and common couch. These couches have different growth habits, tolerance to herbicides and tolerance to cold temperatures. Poa annua is hardest to control in the common couch fairways, as common couch has a more open growth habit, and enters winter dormancy sooner than santa ana or wintergreen couch.

Post emergent herbicides will be applied to fairways during winter to control the established poa annua. Over time poa annua has developed a resistance to post emergent herbicides, requiring strategic managed rotation of herbicides often with varying inconsistent results.


Colin Morrison

Course Superintendent


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