Poa Annua Control – Poa Annua Grass Treatment For Lawns
Poa annua is a perennial grass native to Australia and New Guinea. It grows up to 2 meters high and 10 cm wide with long taproots which are used for food or fiber. It produces seeds which can germinate within 6 months after being sown. Poa annua plants produce new shoots from their roots every year during spring, summer, autumn and winter seasons (depending on climate). These shoots grow into small bushes and eventually become tall fescues.
Poa Annua Control – Poa Annua Grass Treatment For Lawns
Poa annua is one of the most common weeds in Australia and New Guinea. It is not only found growing wild but also cultivated under certain conditions such as tropical rainforests, dry desert areas or agricultural fields. The leaves of poa annua have a distinctive green coloration and are very tough when compared to other grasses. They are usually smooth, oval shaped, dark green and hairy at the base. The flowers are white with pink centers and resemble tiny sunflowers.
The seeds of poa annua resemble the seeds of corn. These seeds are very hard but do not readily fall off as they are tightly held within a husk. The roots of poa annua are light brown in color and have a distinctive triangular shape at the base which looks like a three sided pyramid.
Poa annua grows in tropical and subtropical grasslands all over the world. It is mainly a pest in Australia and New Guinea but can also be found in the warmer parts of North and South America, Africa and Asia. In these places it is considered a noxious weed due to its tendency to quickly spread and choke out other species of grass. It is mainly spread through human activity but also by birds and grazing animals which eat the seeds. In temperate zones poa annua can be found growing as a “winter annual” meaning that it survives the winter and germinates in spring, grows all year then dies back again in winter, leaving just the rootstock to survive.
The noxious weed status of poa annua is mainly due to the fact that it crowds out native plant species and reduces the biodiversity of an area. It is also regarded as a serious pest for farmers and gardeners. Poa annua can grow in a wide range of soil types and is tolerant of a wide variety of soil conditions. It is also very drought resistant and will quickly colonize an area eliminating all other plants. It spreads mainly by seeds but also by creeping roots which can extend up to 90 cm from the parent plant.
Also it forms a strong turf that prevents other species from establishing themselves especially when there is heavy traffic.
Poa annua is regarded as a “bad” grass by most gardeners and landscapers because it has an undesirable habit of creeping in and taking over, especially when left uncared for. It is usually regarded as a weed with no real benefits to offset its invasive behavior. It is sometimes used as a cheap fodder crop for grazing animals but the leaves are not particularly nutritious. The small pink flowers that it produces are sometimes regarded as an attractive addition to ornamental gardens.
Poa annua is usually propagated by division of offshoots or by seed. It is an annual and will die back to the roots each year. It can also spread very quickly under the right conditions and can form a monoculture very easily. In subtropical and tropical areas poa annua can act as a perennial. The seeds are very small and can be carried by the wind for long distances.
Also if the seed lands in a suitable place it can quickly take root and begin growing so any area that it invades is very difficult to remove.
Poa annua is regarded as an economic pest in most of the world due to its rapid growth and tendency to crowd out slower growing species. It can quickly colonize areas left untended and take over completely if not controlled. it is also regarded as a food source in some poorer parts of the world but is generally low in nutrition. It is sometimes used for thatching in 3rd world countries but the large strong stems are better suited to basket weaving. It is sometimes used as an ornamental grass in gardens.
Poa annua can be controlled by repeated mowing but as it regrows from the roots this can become a time consuming task. Also many areas that poa annua invades are not accessible to machinery so it can only be controlled by hand. The best way to control an infestation is to prevent it in the first place which means keeping all human and animal waste cleared away to prevent the seeds from becoming established.
Poa annua is regarded as a weed in most parts of the world but it does have some positive uses especially as animal fodder. In some parts of the world it is very important as a nutritious fodder crop and allows farmers to maximize the land available for grazing. It is more nutritious than other common grasses and can grow very quickly when conditions are favorable making it a valuable resource in some areas. It is also high in protein and minerals and forms the basis of many animal feeds.
The seeds are also used as a nutritious human food and were a staple in many diets before more exotic foods became available. They can be eaten straight from the plant but are usually dried first. In large quantities however they can give a mild upset to the stomach. They can also be ground down and used in animal feeds.
Poa annua is sometimes regarded as a good honey source but this is not really the case due to the low nectar content of the flowers. However honey can be produced from the flowers if there are no better alternatives available.
Poa annua is sometimes regarded as an invasive species in some areas but this is not really true since it is native to most of the countries where it has been noted spreading. It can however out-compete slower growing native grasses in some areas and thus change the flora of the area. However it is usually kept in check by natural controls such as grazing mammals and native insects so it does not spread unchecked. In some areas the seeds are spread by humans and the increase in distribution may be at least partially man made.
Poa annua is generally regarded as a serious weed but its rapid growth rate, high nutrition value and usefulness as animal feed means that it is unlikely to disappear any time soon.
Next week I’m going to tell you about the giant hogweed.
Thanks for the post Bill. Well my least favorite plant has to be the Hogweeds (Heracleum spp.) and the Giant Hogweed (Heracleum mantegazzianum) is the king of them all! These plants have been spreading through out the states and have become a huge problem. Ingestion of the plant causes severe burns and blisters and even blindness.
It also has a tendency to grow where it is mowed often.
My father in-law has gotten huge blisters on his hands after cutting this stuff (he was only using a string trimmer too). He has had to be hospitalized twice due to the injuries he got from this plant. Many people think that the stuff you get from these plants are good for you and make a tea out of them. DON’T DO IT!
The stuff you get from this plant is so caustic that it will burn off your skin and just touching it can cause a severe rash not to mention the damage it does if ingested. This stuff isn’t just found in the wild either, it is spreading through out people’s gardens and lawns too.
There is currently a movement to get this plant added to the Federal Noxious List so hopefully that will keep it under control, but until then it is up to all of us to make sure it doesn’t escape our attention and get out of hand. By swatting these plants as soon as you see them you are not only doing a service for yourself and your family, but for everyone around you too. So be proactive and don’t let this nasty stuff take root in your area.
The GBB (Garden Bloggers Brigade) has written an excellent piece about this plant too. Check it out here: The Ugly Truth About the Giant Hogweed.
P.S. Thanks for the post Bill, sorry you had to go through that!
Thanks for the great post Bill. I have never heard of this plant before and find it absolutely fascinating that such a thing exists. It almost reminds me of the movie Little Shop of Horrors where they had the plant that ate meat. 🙂
Quite a villainous plant indeed.
Everyone make sure you take care when working with this plant. Take a lesson from Bill and don’t let it get the best of you!
Just to let everyone know, there’s talk about getting all these poisonous plants and weeds listed in California on the controlled hazardous list so that it makes it much harder for people to obtain them. It would also carry harsher punishments to those who spread them.
Bill sent this in a while ago, but I just came across it again. I don’t know if anything was ever done about this or not, but it’s possible this could happen again so everyone needs to be prepared.
Thanks for the heads up Bill!
Bouvardia racemosa) bloom. This is a picture of the Yellow Bouvardia (
I love seeing pictures of plants in full bloom. This one is a beauty!
Thanks for the post, I can almost smell the fragrance from here!
Thanks for the great post! I love seeing these posts as it really gives you an appreciation for all the different plants out there and how they can effect emotions. Thanks again!
Wow, this plant is beautiful. Water Lily’s are one of my favorite flowers. Thanks for the great post and thanks for all the information on this plant it’s a real eye opener!
And that folks concludes this edition of From the Garden. If you grow any of these plants, or if you’re just curious about them, now you know a little more about them and can appreciate them a little more. Remember, knowledge is power!
Sources & references used in this article:
… LAWN WEEDS: II. EVIDENCE FOR DISRUPTIVE SELECTION IN POA ANNUA L. IN A MOSAIC ENVIRONMENT OF BOWLING GREEN LAWNS AND FLOWER BEDS by SI Warwick, D Briggs – New Phytologist, 1978 – Wiley Online Library
THE GENECOLOGY OF LAWN WEEDS: VII. THE RESPONSE OF DIFFERENT GROWTH FORMS OF PLANTAGO MAJOR L. AND POA ANNUA L. TO SIMULATED … by SI Warwick – New phytologist, 1980 – Wiley Online Library
THE GENECOLOGY OF LAWN WEEDS: I. POPULATION DIFFERENTIATION IN POA ANNUA L. IN A MOSAIC ENVIRONMENT OF BOWLING GREEN LAWNS AND … by SI Warwick, D Briggs – New phytologist, 1978 – Wiley Online Library
Effectiveness of herbicide programs for annual bluegrass (Poa annua) control in bermudagrass (Cynodon dactylon) by SW Bingham, RL Shaver – Weed Science, 1979 – JSTOR
Effect of paclobutrazol and flurprimidol on suppression of Poa annua spp. reptans in creeping bentgrass (Agrostis stolonifera) greens by BJ Johnson, TR Murphy – Weed technology, 1995 – JSTOR
THE BIOLOGY OF CANADIAN WEEDS.: 37 Poa annua L. by SI Warwick – Canadian Journal of Plant Science, 1979 – NRC Research Press
Herbicidal properties of sethoxydim for the control of gramineous weeds by 石川尚雄， 山田正三， 保坂秀夫， 川名貴… – Journal of Pesticide …, 1985 – jlc.jst.go.jp
Efficacy of different herbicides for controlling weeds in wheat crop-II. Weed dynamics and herbicides by I Khan, G Hassan, KB Marwat – Pakistan Journal of Weed Science …, 2002 – agris.fao.org