Albert Lea Seed House Oat Production Guide - Page 18

Barley Yellow Dwarf Virus Barley yellow dwarf (BYDV) also known as “red leaf” is a prominent virus that can affect oats. This virus is usually vectored by the Cherry Oat Aphid. Plants are usually infected early in the season when aphid populations are highest. Damp and dense canopies can aid in the survival of the aphids, enhancing the potential of an infection Symptoms An infected leaf of a plant will start to change color and start to yellow and usually become red and necrotic. The leaf will become upright or stiff. Infected leaves margins will roll inward on themselves. Examples of oats infected with BYDV can be observed in Fig x7. and x8. Control A management plan for this disease consists of genetic resistance and/or chemical control of the Cherry Oat Aphid, which is a vector for the disease. Fig x8. Oat plants infected with BYDV Fig x9. Oat leaf infected with BYDV (From Oklahoma State University Digital Diagnostics ) Chemical Disease Control Grain Millers recommends weekly scouting of an oat crop. IF a grower determines the need and elects to apply a fungicide, they should do so at or before flag leaf stage. Trade names of some of the most commonly used fungicide are Stratego, Headline, or Tilt. SDSU Pathologist, Emmanuel Byamukama recommends the use of Tilt fungicide (triazole fungicide) for Fusarium head blight management. All three of the compounds listed above are approved and have residue tolerances in the US and Canada. Stratego is a mix of 2 modes of action, and tends to be a bit longer-lasting. Under stress conditions, Headline has been known to burn the crop or set it back. Tilt is an older compound (propiconazole) and has a shorter active period, but is available in several strengths and trade names, including generics. It is important that producers recognize that none of these compounds are preventatives. Fungicides attack and kill the fungi that form the pustules. In the case of fungal diseases like fusarium, they can slow or eliminate the formation of DON and other mycotoxins. This is only exhibited at certain stages of the plant growth and the fungal growth. Many fungicides may also delay the maturity of the plant – 3 to 5 days normally. This is not normally a problem in the US, but can create issues in later planted crops or in some areas of Canada. Scout the field for the first few pustules of rust, or for symptoms of Septoria or other fungal diseases. Warm, humid conditions with lots of dew in late mornings are ideal for most of the fungal disease formation. Spraying too late after the disease has fully attacked the plant will not yield a positive economic response. Fungicides only work if applied at the onset of the diseases. 18