First Cutting Project is being conducted by Cornell Cooperative Extension of Chenango, Herkimer, Madison, Otsego and Schoharie Counties and the Central New York Dairy and Field Crops Team.
This is our third week of monitoring of 1st cutting for quality in 2012. Grass maturity has increased unbelievably since last week. Orchardgrass is heading out at a much shorter height than we would have anticipated. With that tested NDF values are higher than we would have predicted. All pure and mostly grass stands should be harvested at this point. There may be some grass stands at lower elevations that are beyond the maximum desired 55% NDF for milk production and may be better harvested for lower quality dry hay. Mixed alfalfa/grass at mid to lower elevations should be harvested and we urge that you err on the side of harvesting early if you have any doubts. Begin harvesting alfalfa and mostly alfalfa stands over the next few days at lower elevations. Again this is an easy check for alfalfa height before you start.
Another reason to harvest mixed stands in particular is that we are beginning to see considerable alfalfa weevil damage in these stands. Although there is some damage in more pure stands the greater damage seems to come with the more limited number of alfalfa plants for the weevil to feed on in mixed stands. The warm weather of March has moved the development of these insects along as they are also affected by growing degree days (GDD) and there were enough GDDs between late March and the present for them to develop and cause injury. You will notice feeding on upper leaves and you may notice there are only the veins of the leaves left; the leaves appear skeletonized. Best control is to harvest. Break off a few stems and beat them lightly against the sides of a container and the small green larvae with a white stripe and black head will drop to the bottom of a container. It may be good to check alfalfa regrowth for weevil feeding.
As always use information in the attached table as a guide to know when to harvest by checking your fields! Next and last report will be May 22!
Here are numbers that are helpful when using alfalfa and grass height as an indicator of NDF content: Begin cutting 100% grass stands when nearby alfalfa is 14 inches tall to achieve the desired 50% NDF. Begin cutting 50/50 mixed alfalfa and grass stands when nearby alfalfa is 22 inches tall for the desired 44% NDF. Begin cutting 100% alfalfa stands when alfalfa is 28 inches tall for the desired 40% NDF.
The desired NDF for all grass fields is 50%, 50/50 mixed alfalfa and grass fields is 44%, and pure alfalfa stands is 40%. Predicted days to cut are based on daily NDF increases for grasses of 1% point, 50/50 mixed stands of .8% points and alfalfa of .5% point. Typically NDF increases about 0.8 to 1.2/day for grasses expecting the lower end of that range in cooler weather and the higher end in warm. Alfalfa NDF increases about 0.4 to 0.7/day again figuring the lower end of that range with cool temperatures and the higher in warm. Predictions are adjusted for the coming week’s weather and right now we are assuming normal growth.
