Alternaria Leaf Blight of Parsley
Alternaria leaf blight was first found in Australia on parsley crops in Queensland and Victoria in 2005.
The disease is caused by the fungus Alternaria petroselini and commonly infects parsley overseas.
In Queensland, it caused significant damage to a single crop following extensive wet, humid weather.
In Victoria, the disease has been found only on one property, where it caused minor damage.
The disease is also known as leaf spot or scorch and can cause dark spots on leaves that may lead to leaf and petiole death.
Root and crown infections can cause damping-off of seedlings and chlorosis and collapse of older plants. Overseas, the disease typically occurs during or following wet winter weather.
The disease is seed-borne, so planting of infested seed causes the disease to spread to new production areas.
Since infested seed spreads the disease, control is primarily through planting high quality, pathogen-tested seed.
Fungicides may also assist in managing the disease; ask your chemical adviser for state regulations on approved products.
As the disease can also be soil-borne, rotation to non-umbelliferous crops for a period of 2-4 years is necessary to reduce carryover of the fungus to new parsley crops.
Alternaria leaf blight is unlikely to become a major issue for Victorian parsley producers except following heavy irrigation in hot weather.
To report suspected exotic or unusual pests or diseases, call the EXOTIC PLANT PEST HOTLINE 1800 084 881