Category : Fungal
Alternaria leaf blight
Alternaria petroselini
Symptoms
Brown-black necrotic lesions on leaves which may have chlorotic margins; lesions expand and coalesce causing the death of leaves and petioles; dark necrosis on crown and upper region of taproot; damping-off of seedlings
Cause
Fungus
Comments
Management
Plant only pathogen-free seed; apply appropriate foliar fungicide; rotate crops to non-umbelliferous varieties fro a period of 2-4 years if soil-borne fungi
Cercospora leaf blight
Cercosporidium punctum
Symptoms
Small, necrotic flecks on leaves which develop a chlorotic halo and expand into tan brown necrotic spots; lesions coalesce and cause leaves to wither, curl and die
Cause
Fungus
Comments
Management
Plant only pathogen-free seed; rotate crops; plow crop debris into soil ofter harvest; apply appropriate fungicide sprays
Crater spot
Rhizoctonia solani
Symptoms
Small, water-soaked lesions on crowns or petioles in contact with soil; collapse of petioles; petioles drying; lesions develop a sunken appearance and a dry, firm texture
Cause
Fungus
Comments
Management
Destroy crop debris or plow deeply into soil; avoid planting seeds too deep to prevent petioles coming into contact with soil; apply appropriate protective fungicides at plant bases; rotate crops with non-hosts such as grains to prevent disease building up in the soil
Damping-off
Pythium spp.
Rhizoctonia solani
Symptoms
Soft, rotting seeds which fail to germinate; rapid death of seedling prior to emergence from soil; collpase of seedlings after they have emerged from the soil caused by water-soaked reddish lesions girdling the stem at the soil line
Cause
Fungi
Comments
Management
Avoid planting parsley in poorly draining, cool, wet soil; planting in raised beds will help with soil drainage; plant high quality seed that germinates quickly; treat seeds with fungicide prior to planting to eliminate fungal pathogens
Powdery mildew
Erisyphe heraclei
Symptoms
Powdery growth on leaves, petioles flowers stalks and bracts; leaves becoming chlorotic; severe infections can cause flowers to become distorted
Cause
Fungus
Comments
Management
Plant tolerant varieties; avoid excess fertilization; protective fungicide applications provide adequate protection; sulfur application can be used in infection occurs early in season
Rust
Puccinia spp.
Uromyces spp.
Nyssopsora spp.
Symptoms
Light green discolored lesions on leaves which become chlorotic; yellow-orange pustules on underside of leaves; stems bend and become swollen or distorted; plants may be stunted
Cause
Fungi
Comments
Management
Plant in well-draining soils to reduce humidity around plants; apply appropriate systemic fungicide
Septoria leaf spot
Septoria petroselini
Close-up of Septoria lesion on parsley
Symptoms of Septoria leaf spot on parsley leaf
Septoria lesions on parsley leaves
Symptoms
Small, angular, gray-brown spots with defined red-brown margins on leaves; black fungal fruiting bodies may be visible on surface of lesions; leaves becoming chlorotic and necrotic
Cause
Fungus
Comments
Management
Control of disease is reliant on cultural control methods and good sanitation practices: use pathogen free seeds or treat seeds with fungicide prior to planting; rotate crops; plow plant debris into soil; if disease is present avoid working with infected plants when foliage is wet; apply appropriate protective fungicides