Crook County Weed and Pest Monthly Update

Although summer took its time to arrive, it seems to be flying by at a rapid pace. Weeds grew thick and fast, and with the abundant moisture they continue to do so.

Leafy spurge is having a great year of growth around the county, as well as all species of thistles but most notably Scotch thistle. Grasshoppers and Mormon crickets seem to be prevalent in many places throughout the county, but the consistent rains seem to be keeping them at bay. The district has kept very busy both in the office and in the field spraying leafy spurge.

The “Medusa-nata” tour was attended by two employees and two board members, and was very informative. Both grasses seem to be extremely invasive, and control options seem to be very minimal at this point.

Neither grass is susceptible to grazing due to their high silica content and brittle growth, and the herbicides that work best have very strict grazing restrictions. More studies and data will be collected in coming years to hopefully come up with a viable option to control both species.

Unfortunately, a small population of Ventenata grass was found within Crook County as well as sizeable populations just into Campbell County, all found in close proximity the Crook/Campbell county border. With the size of populations found, there is much speculation to the actual scope of invasion, and possibility of it being far more widespread than previously thought. The small patch in Crook County will be treated immediately, and we will continue to keep a sharp eye out for any other infestations.

Weed and Pest has been busy treating weeds all around the county. Two district employees have been out spraying every day, and commercial applicators contracted to treat county roads and highways have started treating along the roadways.

Although whitetop was late to grow, there were sizeable populations that have grown from previous years. The county borders seem to be where the worst infestations are coming. Notable populations are increasing in many areas: along Hwy 16 east of Moorcroft on the Weston County line, the Colony area, along the north end of the Little Missouri River and the Oshoto area towards the Campbell County line. There have been ongoing conversations about designating whitetop as the secondary species on the special management program (which is currently spotted knapweed), and we would appreciate any input from the public concerning this change.

Black henbane is another concerning weed was found in Crook County that is not yet established with large populations. A single plant was found along Inyan Kara Creek Road about five miles north of I-90.

Black henbane is a bushy plant growing up to three feet tall with greasy hairs covering the plant. Leaves are fairly large, up to six inches wide and eight inches long. The flowers are creamy white with dark purple in the center and along the veins.

Multiple seed pods form and are urn shaped and can hold several thousand seeds per pod, and up to 500,000 seeds per plant. This plant is avoided by livestock and can be toxic as well. Black henbane tends to invade more in disturbed areas, but due to the seed production it can spread very rapidly.

Weed and Pest has a two-man crew treating leafy spurge around the county. Continual rainfall, wind, high river levels and lack of hours in a day have made control efforts difficult.

To date, the district has treated for 15 different landowners, and on six different sections of state land. These treatments total 235 actual treated acres which have covered and protected roughly 7200 acres of lands within the county. The district will continue to treat leafy spurge the remainder of the summer and into the fall.

The District would like to extend an apology to all landowners who were planning on getting leafy spurge bio-control beetles from us this year. Our beetle suppliers had other matters to attend during collection time, and were not able to provide any beetles this year.

We have not been able to find any other suppliers at this point, which likely means there will not be any. Once again we are very sorry for this inconvenience, and will have the bio-control beetles again next year.

Lastly, the district would like to invite everyone to a “Leafy Spurge Field Day” on August 16 starting at 9 a.m. and running through the afternoon. This field day will be an opportunity to take a look at herbicide plot work that was done on leafy spurge.

Further, it is a chance for the public to talk about potential changes or “upgrades” to the special management program. The field day will be held right across from Devil’s Tower up Lytle Creek County Road, just below the reservoir. Food and drinks will be provided.

Submitted by Andrew Litzel