Estimating alfalfa populations in the fall and spring provides an indication of potential field productivity. In each of these locations, select an area at random, and count the number of alfalfa crowns observed per square foot. Refer to the following chart. Alfalfa fields should also be assessed for disease, insect, and weed problems prior to a hard freeze. Yellow to brown plants may indicate disease problems.
Check leaves and stems for discolored areas indicating possible fungal diseases.
If no above ground symptoms are obvious, dig plants up to examine their root system. Yellow, reddish-brown to black discolored or damaged roots may indicate disease problems such as Phytopthora Root Rot or Verticillium Wilt. If significant amounts of a field are affected, correct disease diagnosis is critical. Disease resistant alfalfa varieties are available for many common diseases. Root feeding by certain insects may also affect alfalfa health.