Invasive Cheatgrass (Bromus tectorum)

How do I Prevent it?

Original methods of controlling Cheatgrass included the use of herbicides, cattle grazing, tilling the land, and early season burning of fields to prevent the seeds from dispersing (Meyer et al. 2008). These methods, however, tend to be expensive and dangerous! Not only can perennial vegetation be harmed in these processes, but sometimes the method being used for controlling the grass gets out of control and the results are uncontrollable (Meyer et al. 2008).

Bromus tectorum is a hard species to regulate, but there are people out there doing research to try and find ways to get this invasive species under control. So far, it is known that there are other species similar to that of B. tectorum that limit the production and establishment of the invasive species. Native species tend not to be competitive with Cheatgrass, but other plants such as E. elymoides, E. multisetus, and P. secunda have a little fight in them and compete with Cheatgrass (Goergen et al. 2011). When competition occurs there is a decrease in the production of flowers. One study done shows that there has been a shift in other grass species ability to tolerate and live among B. tectorum (Goergen et al. 2011). This suggests that people might be able to use a mixture of these adapted grass species that can now live amongst Cheatgrass to begin restoring areas that are highly invaded (Goergen et al. 2011). For more information on the competitive nature of Cheatgrass, go to the Interactions page.
Another investigation is looking at the possibility of manipulating fungal pathogens that are already seen in B. tectorum but rather than using them for seedling restoration they want to use them as a biocontrol organism to slow the growth of the invasive grass (Meyer et al. 2008). Biocontrol is being looked at as a possibility because there is a major need of Cheatgrass being targeted and put in control. At this point in time there are three fungal pathogens being looked at: commonly known as head smut, chestnut bunt, and black-fingers-of-death, scientifically and respectively known as Ustilago bullata, Tilletia fusca, and Pyrenophora semeniperda (Meyer et al. 2008).

Infecting the Seedling  
Both the head smut and the chestnut bunt pathogens infect the plant when it is a seedling, and the black-fingers-of-death pathogen kills seeds that area already in the seed bank. The head smut pathogen, U. bullata, already infects a large genera of grasses. Unfortunately, this pathogens infection rate is highly determined by temperature, which can be a hard thing to control (Meyer et al. 2008). Successful infection tends to only happen when Cheatgrass seeds germinate at temperatures of ten to twenty-five degrees Celsius in the fall (Meyer et al. 2008). In order to produce the head smut pathogen in large quantities “farming” Cheatgrass would have to occur to create the spores needed for the fungal pathogen to become active (Meyer et al. 2008). Scientists are currently trying to figure out how to dehydrate the pathogen so it can be carried to the fields and be tested in larger quantities. Another pathogen being studied is the chestnut bunt, T. fusca. Unlike the head smut pathogen, the chestnut bunt pathogen can infect seedlings under snow cover (Meyer et al. 2008). It has also adapted and has a longer life expectancy in the field and will stay in a soil spore bank (Meyer et al. 2008). Problems are seen in this pathogen when it comes to infecting the Cheatgrass because the spore of the plant must be placed on the soil surface; direct contact with seeds does not tend to work as well (Meyer et al. 2008).

Infecting Mature Seeds
The third organism being looked at as a biocontrol agent for B. tectorum is the black-fingers-of-death pathogen, P. semeniperda. Unlike head smut and chestnut bunt pathogens, the black-fingers-of-death pathogen infects mature grass seeds, but has higher success rates for mortality when the seeds are in their second dormancy stage (Meyer et al. 2008). This pathogen also tends to attack mainly cool season grasses; though it is known for causing high mortality in Cheatgrass under natural conditions (Meyer et al. 2008). The main thing this organism would be used for is elimination of seed banks that are going to carry on into the next growing season.

Best Option
By combining all three fungal pathogens, and possibly in coordination with some of the original control methods, Cheatgrass should be able to be taken under near-complete control (Meyer et al. 2008).  The key to removing Cheatgrass, however, is persistence! Once a process is begun, the treatment must continue to happen for up to five years because that is how long Cheatgrass seeds can survive in the soil (Zouhar 2003). It may take longer though. If you are just a home owner with some of this invasive grass growing on your property you can remove it by pulling it out with your hands, mowing it, or weed whacking it (Zouhar 2003). However, the grass still needs to be removed before it can mature or produce seeds, so be sure to catch it before it turns brown. After you have removed it, till the soil and plant the area with desirable, native species. 


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