1. Field Observations

Not much activity in the fields these days, though I have seen a few folks spreading and tilling where possible, in-between downpours. Rain is forecast to continue through this week as I'm sure everyone is well aware, so pay close attention to your winter forage crops and their development. Harvest your best fields first to capture peak quality, and don't try and chase quality in fields that are already past. Some of us may be ready to harvest alfalfa/grass mixed stands as soon as the ground is dry enough!! And some winter forages may unfortunately be heifer feed.

But while winter forages like triticale might be moving quickly, the same may not be true for the grasses in your alfalfa fields. Here is a recent note from Joe Lawrence, Dairy Forage System Mgmt Specialist with Cornell PRO-DAIRY:

"Based on my observations and the reports of alfalfa heights coming in, alfalfa is progressing quickly and grass progress seems to be a bit slower.  As happens every few years, this sets up a scenario where alfalfa heights suggest it is time to cut grass; however, grass will still be pretty immature with seedheads still very low in the stem. To avoid negative consequences to 2nd cutting (rapid head emergence, stunted regrowth) the grass seed head needs to be cut off with mowing of first cutting. i.e. 4" above soil surface if following the recommended 4" cutting height is being followed. See some information and a picture [below]. Also [pictured below] is just a quick summary of data many of the CCE teams have been sharing with me the last few years…."

Assuring the seed head is above cutting height (4"):

In springs where alfalfa development seems to outpace grass development, alfalfa height measurements can indicate it is time to cut grass (see graph) before the grass seedhead has progressed up to the stem to a point where it will be removed during mowing (4" above soil surface).  If the seedhead is not removed with cutting it will have negative consequences of grass regrowth.  The intact seedhead will emerge shortly after mowing and stunt regrowth.  When this occurs, it is better to wait for the seedhead to elongate above the cutting height even if this is slightly past the harvest timing suggested by the alfalfa height.  Grass progress can be rapid at this time so the delay needed will not be long and it is important to track progress frequently during this time.

2. First Cutting Forage Quality

Alfalfa height is a reliable indicator of NDF values in the field, so we use alfalfa height to predict Neutral Detergent Fiber (NDF) for alfalfa, mixed alfalfa/grass, and pure grass stands. When using alfalfa and grass height as an indicator of NDF content, in general:

Begin cutting 100% grass stands when nearby alfalfa is 14" tall to achieve the desired 50% NDF.
Begin cutting 50/50 alfalfa/grass stands when nearby alfalfa is 22" tall for the desired 44% NDF.
Begin cutting 100% alfalfa stands when alfalfa is 28" tall for the desired 40% NDF.

To achieve the desired NDF it is necessary to begin cutting at NDF values slightly lower than the desired value assuming some harvest and storage losses (which the above alfalfa height values reflect). For example 28 inch tall alfalfa is closer to 38% NDF but you will need to start then to end up at 40% NDF.

Predicted days to cut are based on daily NDF increases for grasses (1%), 50/50 mixed stands of (0.8%), and alfalfa (0.5%). Typically, NDF increases about 0.8 to 1.2/day for grasses and 0.4 to 0.7/day in alfalfa, expecting the lower end of that range in cooler weather and the higher end in warm. See the following fact sheet for more details: Predicting Spring Fiber Content of Forages.

Always check your fields to verify your heights and conditions! Remember that these predicted harvest dates are not set in stone, and will fluctuate as we go along. And they may creep up on us - especially since the fields are getting a lot of moisture now, and the temperature is only going up!

If your location is not listed but you know the height of your alfalfa, this chart is for you.  As of May 6, 2025:

3. Growing Degree Days (GDD) (See: Climate Smart Farming Growing Degree Day Calculator)

Growing degree days (GDD) are calculated by taking the average daily temperature and subtracting the base temperature for development of a given organism ((High + Low)/2 - base temp = GDD). For corn silage, we are using base 50/86, as corn development starts at 50 degrees F and ceases above 86. Check your location and planting date (more planting dates to come):

4. Pest Monitoring

This year we will again monitor for several field crop pests, including black cutworm, western bean cutworm, true armyworm, fall armyworm, and potato leafhopper. In the coming weeks, I'll deploy my traps at the locations below. We will have more of this information as the weeks progress.

BCW = Black Cutworm
TAW = True Armyworm

See you in the field!