Annual bluegrass invades desirable turfgrasses each fall in the sourthern states.
Annual bluegrass is a particularly serious weed problem in closely mowed areas such as golf greens and fairways. The upright type is a prolific seed producer and is an annual. The decumbent type produces very little seed and is perennial in nature although it dies during the summer in the deep South. Annual bluegrass begins to emerge in late summer and early fall when night temperatures are in the 60's and moisture is abundant. Annual bluegrass seeds continue to germinate through the fall, winter and spring - a characteristic that makes chemical control more difficult.