Poa annua is the scourge of all golfers.

Poa annua, or annual meadow grass (known in America more commonly as annual bluegrass or simply poa), is a widespread low-growing turfgrass in temperate climates. It has a slightly creeping, fibrous, rootstock. The vivid green leaves are short and blunt at the tips. They are soft and drooping.
Not only does poa annua make playing the game more difficult, but it also takes away from golf courses‘ beauty with its uneven and bumpy greens. It makes reading a putt almost impossible and can turn even the best players into a shivering mess when they line up their shot. If you’re looking for a fast, unpredictable, and unreadable putting surface, poa annua is your go-to grass. But if you’d rather keep your sanity intact on the greens, it might be wise to steer clear.
If you’re struggling to get rid of poa annua, you’re not alone.
It’s the weed that just won’t die! But don’t worry – it can be defeated with the right strategy. Removing it from your lawn or a golf course can be a tricky task. But chemical control is often the most effective method for definitively resolving an infestation. There are two major types of herbicides you’ll need to employ: pre-emergent and post-emergent, with both offering unique benefits in controlling this stubborn weed species.
But don’t let its weaknesses discourage you – Poa annua has some great qualities too!
It’s one of the most resilient grasses, able to grow in a variety of climates and soil types. With its natural ability to adapt and thrive, it has become an integral part of nearly every golf course on the planet. So even though it can be pesky for players, this weed still plays an important role in keeping our courses lush and beautiful.
So the next time you’re out on the course, don’t forget about poa annua. It may cause some headaches, but it’s also a key part of our beloved game. And who knows – with a little practice and patience, you might even be able to use its unique characteristics to your advantage! Good luck out there.
Source: https://en.wikipedia.org/wiki/Poa_annua