2012 alfalfa: A few more factors to keep in mind

By Dr. John Goeser
In my last article, we discussed 2012 alfalfa and the frost damage that occurred in some areas.  Now that it’s warming up, many of you are already in the fields cutting first crop – or maybe you’ve already finished.  As we look to the rest of the season, we have a few more factors to carefully evaluate as we put up high quality forages.  Again, thanks to Dr. Dan Undersander, University of Wisconsin-Madison agronomy professor, for offering his insight on these topics.

Pest and fungal pressure
Chances are we’ll see increased pest pressure this year as we didn’t have a strong winter kill to eliminate the bugs.  That said, this pressure will still be erratic and vary from one area to the next.  Work with your agronomist to customize the best pest management program for your fields. You’ve probably heard a lot of talk about Headline® lately.  Many agronomists are pushing the fungicide while university opinion is mixed.  The one thing you need to keep in mind is that you have to apply it early – at least 14 days prior to harvest.  If historically you’ve had issues that would warrant use of the fungicide, it may be a good idea to apply Headline to your alfalfa crop.  However, don’t blanket it across all of your fields or think you need to use Headline because the farm down the road did.  Carefully consider where you need it and where you can save yourself some money.

Nutrients
Due to lower amounts of acid rain, we’re seeing sulfur deficiencies in some areas.  At the same time, low boron content in the soil is leading to deficiency of that micronutrient in some alfalfa fields.  Symptoms of these deficiencies include yellowing of the leaves or wilting.  Note that because boron and sulfur deficiencies display similar symptoms, tissue sampling is your best tool for diagnosing the issue.  Again, handle treatments on a case-by-case basis to make the wisest investment. With this winter’s drought, we may be looking at potassium deficiencies as well.  This macronutrient is important in helping the plant resist disease, increase yield and boost stand longevity.  Recovery may be slow.  Work with your agronomist and do what you can to boost stand health.

Molds and mycotoxins
The good news is that we have no data or reason to suspect mold and mycotoxin issues at this point.  We’ll see what the summer holds in store for us.

Bacterial inoculants
I mentioned this before, but I want to reiterate the fact that bacterial inoculants are especially important this year.  The low temperatures we saw last month caused a low natural population of Lactobacillus bacteria in the field.  Using a proven Lactobacillus bacteria when putting up your haylage will allow for a more rapid fermentation and improved digestibility and palatability.

Looking ahead
A big challenge this year is that we’ll see a lot of variation between fields and crops.  That means we’ll have to make our decisions on a case-by-case basis.  Work with your agronomist and forage consultant to make sure you have all the information you need to make a good decision and put up the best forages for your herd.

About the author: Dr. John Goeser, formerly with Vita Plus, works with Rock River Laboratory, Inc.  He grew up on his family’s 1,200-cow dairy in eastern Wisconsin.  He earned master’s degrees at the University of Wisconsin-Madison in both plant breeding and genetics and dairy nutrition.  His researched produced a better understanding of how corn silage genetics influence dairy cattle productivity.  He went on to earn his PhD in dairy nutrition and spent five years in research at the university.  His doctorate research developed an improved method for measuring fiber digestibility, which UW-Madison patented and is now being used commercially.