As spring sets in and temperatures warm up, don’t forget to check for those biennial weeds. Our SDSU Extension Weeds Field Specialist Eric Jones and other Extension professionals recently released an article on biennial weeds; I’ve summarized the information.

So far, our SDSU weeds crew has reported seeing thistle and common mullein; poison hemlock and wild parsnip often make the list of commonly spotted biennials as well. By the time you read this, there will likely be many species popping up. Biennial weeds have a two-year life cycle, the first year the plant grows as a rosette, and the second year it elongates (bolts) to produce a flower and seeds.

For best control, herbicide applications should be made at the rosette stage, before the stalk bolts. When spraying at the rosette stage, keep in mind that cold spring temperatures (below freezing) are not desirable as plant growth will be less active. You may treat after bolting, but it will likely not be as effective. Mowing after bolting, followed by fall herbicide application may be an effective option if you missed the first application window; however, timing is important as some plants will set seed quickly after flowering.

Of course, integrated pest management should always be used when considering pest control. Scout areas that are typically an issue, determine if a new or reoccurring infestation is present, and decide if previous management efforts should be adjusted. Keep in mind that other non-biennial species may germinate later, making application timing important. For more in depth information on this topic visit extension.sdstate.edu and search “biennial weed species.”

New tool for fertilizers

Recently, I wrote about planting recommendations, including how to determine fertilizer application rates. Recently, a new tool has become available to Midwest growers that can assist in making fertilizer applications. The following information is originally credited to our SDSU Extension Soil Fertility Specialist, Jason Clark.

Fertilizer recommendations can vary widely across state lines, which is a management challenge for producers working in multiple areas. To meet that need, South Dakota State University Extension and project partners released the “Fertilizer Recommendation Support Tool” (FRST). This decision aid provides an unbiased, science-based interpretation of soil phosphorus and potassium values for crop fertilization.

The new web-based FRST tool provides critical phosphorus and potassium soil test values to indicate where applying P or K fertilizers likely wouldn’t improve crop yields. Using data from 40 states in the U.S. and Puerto Rico, the tool has the potential to save fertilizer costs for farmers while reducing excess nutrient losses to the environment.

According to Clark, FRST was developed in response to the pressing need to harmonize soil testing across state boundaries and represents an improvement in our ability to evaluate soil test correlation.

Constantly updated, FRST’s database includes data from nearly 2,500 phosphorus and potassium trials for 21 major agricultural crops, primarily corn and soybeans.

The team plans to expand to other crops and nutrients, such as sulfur.

For more information about FRST (FRST v1.0), visit https://soiltestfrst.org/ and click on “Tool” in the navigation menu at the top of the page.

Funding for the project has been provided by the USDA-Natural Resources Conservation Service including the Conservation Innovation Grants, USDA-Agricultural Research Service, and USDA-National Institute of Food and Agriculture, and OCP North America. For more information about this project visit extension.sdsate.edu.