Despite the hot, dry conditions, levels of asparagus rust are increasing in young plantings. Foliar disease management is important in all asparagus plantings. However, fields are particularly susceptible to infections during the first few years of establishment, causing a reduction in productive crown development.
Even in established asparagus fields, rust can have a significant impact on both the spear weight and spear number.
Warm weather with heavy dew, fog, or light rainfall enhances rust development. Infection can occur with as few as 3-9 hours of leaf wetness.
All foliar fungicides are most effective when they are applied before symptoms begin to move into the upper crop canopy. Thorough coverage is essential for good control.