From the Fields 6/20/10
by Jim Morrison
The Pasture Walk held in Winnebago County on June 14 included many good questions and discussion on a variety of forage topics. This article will address some of that discussion.
There is no "silver bullet". Each forage species, legume and grass, has strengths and weaknesses. There is no "one best" species. Today, we need to go beyond just selecting species; attention needs to be given to variety selection for our forage program. For example, if selecting orchardgrass or tall fescue, select tested varieties that are winter hardy, late maturing, have consistent yield across the growing season, and have rust resistance.
Producers are encouraged to purchase certified seed, indicated by the "blue seed tag" on the bag. This tag gives reasonable assurance that the seed in the bag is the variety stated on the label. The tag also means standard minimum purity and germination has been met. Furthermore, other crop, inert matter and weed content are within the maximum tolerance. The "blue seed tag" does not guarantee performance, it does not mean seed is free from undesirable crop and weed seeds, and it does not mean that certified seed is "better" than uncertified seed.
As mentioned above, the certified seed tag will list the variety in addition to other information. Producers should avoid purchasing VNS seed or "variety not stated". In this
situation, the variety name is not known by the seed marketer, or it is not divulged. The seed may or may not be leading genetic material and the performance is not dependable year after year. In other words, one is buying a "pig in a poke".
Cool season grasses require vernalization, or exposure to a period of cold temperature, to produce a seed head. Thus, cool season grasses seeded in the spring will not typically initiate flowering or form a seed head until they go through winter. Another example of this condition is winter wheat seeded in the spring will not produce a seed head.
Pure live seed or PLS is a way to make "apples to apples" comparisons between seed lots by adjusting for germination and purity into a single number. To find the PLS, multiply the percent germination by the percent purity and divide by 100. The seeding rate can be expressed or calculated based on PLS. For example, if a lot of orchardgrass seed has an 85% germination rate and is 98% pure, the percent PLS is 83 (85% x 98%). If the recommendation was to seed 14 pounds PLS per acre of orchardgrass, we need to divide the recommended rate of 14 pounds PLS by the percent PLS. In other words, 14 pounds PLS divided by 83% x 100 is equal to 17. Thus we need to seed 17 pounds of bulk seed per acre to get the equivalent of 14 pounds PLS per acre.