If you have a pasture of common tall fescue, chances are you also have the endophyte. Chances also are that your steers are 60 to 100 lbs. lighter than they should be at time of selling. Here’s why.

The tall fescue endophyte is a fungus that grows inside (endo) the plant (phyte). It produces toxins that cause fescue toxicosis, the most serious forage-livestock disorder in Missouri. The symptoms of fescue toxicosis are not always noticeable. For example, it is hard to tell when steers are gaining 1.3 lb/day rather than 1.8 lb/day. But when steers go to the sale barn, the cost is felt. According to research in Georgia and other places, a steer on highly infected tall fescue will go to the feedlot 100 lbs lighter than a steer on non-toxic tall fescue.

Some producers are electing to replace their old tall fescue with new cultivars. Others are learning how to manage the Kentucky 31. In either case, producers must first test for endophyte level. If the endophyte level is 20 percent or less, producers should manage what they have. If endophyte level is 55 percent or higher, they should consider replanting or seriously improving the management. It is critical to know the level of endophyte.

How do we test for the endophyte? This time of year, it is best to test the growing tillers. The testing process involves clipping each tiller at the soil surface, where it joins the root, then sending it to a good lab. Details about sampling, shipping and costs are provided by the private lab. A good lab is NOT a certified lab; certified labs test for fiber and protein. There is no certification for the endophyte, so a good lab is one with a good record of analysis.

Many labs test for the tall fescue endophyte. Some test with the microscope. As your samples arrive, the microscopic labs unpack the sample, stain it, and look for the endphyte growing between the cell walls. These labs are accurate only if the technician is well-trained.

Other labs use a chemical procedure. The chemical labs treat your sample with reagents that eventually give a color; this color indicates the presence or absence of endophyte. The chemical lab most often used by MU researchers and extension specialists is Agrinostics, a private lab located in Georgia. The Agrinostics lab has never given an inaccurate reading to our researchers or extension specialists. And they have a quick turnaround time. For more information about testing, check out the Agrinostics website at www.agrinostics.com.

Craig Roberts
573-882-2801