As if the drought were not enough to reduce forage yields this year, some Sacramento Valley oat hay growers have been hit with a bad case of Barley Yellow Dwarf Virus (BYD) disease this spring, causing poor appearance and low yields.

Symptoms of BYD include reddening of the leaves, stunting of plants, and irregular and small or blank seed heads. The virus is only transmitted by aphids, which acquire the virus from wild grasses. The presence of the virus does not affect the feeding quality of the forage.

Controlling the aphids to prevent infection is possible, but not generally effective or cost efficient. Early planting favors aphid movement into fields, so later plantings (around 15 November in the Yolo County area) to...