There's an outbreak of bacterial disease in wheat in South Dakota this year, says Lawrence Osborne, SDSU Extension plant pathologist
The main problems are black chaff and bacterial stripe.
"Infection occurs through wounds or natural openings in the leaf, which may develop into streaks and water-soaked tissue, usually accompanied by yellowish to whitish ooze," he says. "In dryer parts of the day, the ooze appears shiny or scaly on leaf surfaces on or near the dark, sunken streaks within the affected leaves."
Some leaves may have an orange cast, but this bacterial disease's appearance should not be confused with tan spot, a fungal disease.
"Tan spot typically produces small diamond- or lens-shaped, tan lesions on leaves, bordered with bright yellow halos," Osborne says. "Stagonospora blotch, another fungal leaf blight, may most closely resemble the bacterial symptoms. Neither fungal disease produces shiny or slimy ooze like the bacteria, and the fungicides used against tan spot will not help with bacterial disease."
Crop rotation, resistant cultivars, and proper nutrient management are the primary means for stopping black chaff.
"Residue removal or burial will help limit inoculum in a field, but for some areas, may be impractical or undesirable," he says. "Rainy weather, especially when high winds are involved, tends to favor plant wounding and thus, bacterial infection."
For confirmation of a bacterial wheat disease outbreak, submit samples to the SDSU Plant Diagnostic Clinic. Mail samples to the SDSU Plant Diagnostic Clinic, 153 SPB, Box 2108 Jackrabbit Drive, Brookings, SD, 57007.
Source: SDSU AgBio Communications