Onion Rust
Onion Rust  Onion Rust is a fungal disease that survives on crop debris and wild Alliaceae species. The disease may be worse in nitrogen rich soil or where potassium levels are low.. It is sometimes referred to as garlic rust, or leek rust as it is actually a more serious problem with these plant species than onions.Susceptible Plants- Garlic, onions, chives and other alliaceae species, ornamental allaceae are less susceptible. Symptoms- Onion rust is readily identified. Early symptoms consist of small yellow to white flecks, streaks, and spots on leaves. As these small areas expand, the leaf tissue covering them breaks and the orange spores (urediospores) of the fungus become visible as pustules. Severely infected leaves can be almost entirely covered with pustules, resulting in complete yellowing, wilting, and drying of the leaf. As the disease progresses, a second, darker Severe onion rust on garlic and other alliaceae can cause extensive loss of foliage and subsequent reduction in bulb size and quality. On infected onion and chives, symptoms consist of small (less than 1/8 inch in diameter), white to tan spots. The orange pustules often form concentric groups on the spot periphery. Disease severity on onion and chives is significantly less severe than on garlic. Life Cycle- The fungus probably survives as either urediospores or teliospores, with urediospores apparently being the more important source of inoculum. Urediospores are windborne and can be spread long distances. Infection and subsequent disease development are favored by cool temperatures and high humidity. Prevention and Control- Check nitrogen and potassium levels in the soil. Improve the drainage of the soil if necessary. Use a crop rotation- minimum 3 years but preferably 4 or 5 years. Clear away and destroy any diseased plant debris. Do not compost diseased plants. Fungicidal Controls-Concern Garden Defense Multi-Purpose Spray Concentrate. as a preventative measure for onion rust.
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