Alfalfa Fall Management Tips and Tricks

Seeding:

Seeding by the end of August is the best for Southern MN because the alfalfa should be about 6-8” tall by the time we have a “hard frost”.  This is because the alfalfa plant needs to move from an “annual” to a “perennial” to be able to survive in the winter.  The best population for seeing is between 20-25 plants per square foot and make sure that the seed is going into the dirt, not on it. 

Fall Management:

Fungicide:

Fungicide in alfalfa is a great fall management technique if you want to keep plants healthy throughout the winter.  It helps reduce the total pathogen, like antracnose, in the soil which can increase the leaf percentage on the plant at harvest!  Who doesn’t want to have a larger yield?  Antracnose can cause high leaf loss, quality and stand density decrease and it will cause diamond-shaped lesions on the stem of the plant.  A classic shepherd hook shape is a typical sign as well.  Late summer applications of a fungicide may help reduce this even on following cuttings!  Call your UFC Field Sales Agronomist (FSA) to see if putting fungicide on your alfalfa field is right for your operation.  There are varieties of alfalfa that are resistant to anthracnose including HarvXtra MegaTron by CROPLAND.  If you need alfalfa seed, talk to your FSA!
Not sure if fall fungicide on your alfalfa field is right for you?  Try a split field or do a test plot!

Leafhopper Populations:

Leafhoppers can be present in August so make sure to have your FSA check your field early and often, especially on new seedings. If you want to check your self, the only way to get an accurate count of leafhoppers in a field is to use a sweep net.  Take the sweep net and quickly swipe it side to side 10 times and close the mouth of the net with your hands.  Then you can slowly bring the bottom up, opening it as you go.  Try not to let many bugs escape before you can count them.  Try to take 4-10 sweep samples per field to get an overview of the entire field.  Check out the table below for leafhopper economic thresholds, created by the University of Minnesota Extension.

Fertilizer:

Key nutrients for alfalfa are Sulfur(S) and Boron(B).  What’s the best way to monitor these nutrients? A tissue or soil test!  Contact your FSA to set up a sample for your alfalfa fields.   The best thing is to get Boron on the fields in the summer, plus you can add a glyphosate, to help with weed control, as well as a fungicide.  It is best to have a soil sample on a grid to make sure that we are putting fertilizer in the right areas, regardless if it is a good or bad area in the field.  Some things to talk to your FSA about is what exactly you need to put on your alfalfa.  Some programs may include Potash (K), Phosphorous (P), AMS (S) or Gypsum (S) and Boron (B). Use manure to supplement a good fertility program, but don’t let it be the only program you are using. 

Fall Harvest:

Forage Quality:

Leaf loss should not exceed 10-12%.  This can cause a big loss of not only yield, but quality as well.  Leaves have a relative feed quality of 400, while stems only have a relative feed quality of about 70.  Therefore, the more leaves you have, the better quality your hay will be.  There are many things that cause leaf loss like disease (like ancranose, see above), cutting, merging or ranking, chopping, and baling.  Every time you move the hay there will be leaf loss.  Try to move it as little as possible to keep the quality high! Another thing that will decrease the quality is the addition of ash, or dirt.  Ash in forages should only equal 8-10%, anything over 10% is just dirt getting into your hay during harvest. 

Remember to have your last cutting by September 5^th.  HarvXtra allows growers a little bit more flexibility with a final cutting, which can help increase the yield.  In late august, a dense stand (55 stems/ft2) is work about 100-125 pounds of dry matter per inch per day.  Pay attention, because if you cut too early it can equal to yield loss, but if you cut to late it will have a winter hardiness loss and will hurt your yield in the following years. If you are not able to cut by September 5^th, then wait until October 15^th.  The reason for this is because energy is stored during early fall and sunlight is converted to carbohydrates.  This is what helps the plant to live all winter and then start growing in early spring.  We don’t want more than 200 heat units to accumulate after the last cutting and if the October cutting needs to be taken then the goal is to have no regrowth after that cutting. 
 
If you have any questions regarding your alfalfa field, make sure you contact your UFC FSA or talk to one of our Nutritionists to make sure that the quality of your forage is good for the cows you are feeding it to.