Origin and Breeding
SW 5512Y was developed from lodging tolerant germplasm typified by upright stem growth at the point where stems originate from the crown. SW 5512Y was selected for overall disease resistance to the major alfalfa diseases, resulting in a variety that is well suited to a broad range of US growing environments. Its high level of disease and nematode resistance makes SW 5512Y highly adaptable, a good choice wherever a 5 dormancy variety is desired.
SW 5512Y is a high yielding medium recovery type suited for hay and haylage production where moderate speed of regrowth initiation is desired after cutting. As a lodging tolerant variety, SW 5512Y is especially well-suited to growing situations that may lead to lodging. Compared to other varieties, SW5512Y can exhibit reduced lodging in situations of heavy manure application, irrigation from overhead sprinklers, or rain that leads to harvest delays and increased lodging potential, especially when accompanied by wind.
The first cut is the heaviest cutting of the year, and most susceptible to lodging. The lodging tolerant characteristic of SW 5512Y helps maintain yield of the heavy first cut, and can help maintain forage quality of second and later cuttings through the reduction of long trailing uncut stems that often remain after cutting a lodged crop. Such uncut stems become less digestible, leading to forage quality reduction if harvested in subsequent cuttings.
SW 5512Y has outstanding overall disease resistance, with HR (Highly Resistant) ratings for all six major alfalfa diseases common in the US. SW 5512Y has strong overall root rot resistance including high resistance to Phytophthora and multi-race Aphanomyces, important for stand persistence in variable soils with imperfect internal drainage. SW 5512Y also has an HR rating against stem nematode, important in irrigated production when the water source includes tail waters from infested upstream fields.