S5:E3 In-Season Management of Alfalfa

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Show Notes

Managing for high yielding, high quality alfalfa is an intensive process. From scouting for insects and foliar diseases to managing nutrition and cutting schedules, there is a lot to take into consideration. Leta Larsen, Forage Specialist with WinField United shares what it takes to get the most out of your stand year after year. 

Fertility 

Proper nutrition is the foundation of a quality alfalfa stand year after year. Some of the key nutrients to keep an eye on include potassium, boron and sulfur. Sulfur drives protein production for alfalfa. Boron can easily be tank mixed in the form of Max-In Boron when you're making another application. Tissue testing throughout the season can give you insights into what the plants need for foliar feeding.  

“Potassium is to alfalfa what nitrogen is to corn. Potash drives yield and stand longevity,” said Leta. “It’s recommended that per every 1 dry matter ton of alfalfa, growers apply 50 lbs of potash. So, if a farmer has a goal of 5 dry matter tons per acre, that would be 250 lbs of potash per acre.” 

Typically growers will make 2 applications of potash per season. After first cutting, it's beneficial to apply potash, boron, and sulfur. After 3rd cutting when growers are getting ready to “put the alfalfa to bed” for the winter, an applications of potash only because potash is critical for winter hardiness. For alfalfa, potassium needs to be around 150 ppm on soil tests. 

Soil pH is also crucial to stand longevity. For alfalfa soil pH needs to be between 6.8-7.2. Outside of that range, growers need to make applications of lime and these applications should be make 1-2 years ahead of seeding.  Soil pH has a lot to do with the longevity of the stand and stand persistence will go down if pH isn’t right despite good early season seeding results.  

Insects 

Insects can devastate an alfalfa stand. Timely scouting for insects and diseases can make a serious impact on yield. Using sweep nets in the field to see what insects are out there and understanding thresholds should be done throughout the growing season.  

Alfalfa Wevil hasn’t historically been a big deal in Michigan but lately there have been more issues with this insect. Typically in Michigan Wevil can be managed by cutting the alfalfa; however, in Indiana, growers may need to spray an insecticide to control Wevil. These insects leave pinwheel in the leaves.  

“Leaves are around 400% RFQ stems are around 70% so we want to keep as many leaves as we can,” shared Leta.  

Potato leaf hopper is one of the main insects that needs controlled in second and third crop. Piercing and sucking insect. As a rule of thumb, Leta shared that if you see one, it's time to spray, because once symptoms show up its too late. Leaf Hoppers don’t over winter in Michigan so they often show up later in the season and they have a very quick life cycle. Leaf hoppers can look a lot like an aphids, but aphids are not typically a threat in Michigan. Pre-harvest intervals are usually 7-10 days for insecticides which can impact your decision to spray for control.  

From nutrients to pests, executing on management plans its crucial to improving yield. Laying a good foundation is essential and to sum it up in three words it comes down to Potash, Boron and Bugs. To learn more abut management tactics for high yielding alfalfa, tune into our full episode of Field Points.