A leatherleaf fern grower (Jeff) described chlorotic/necrotic water-soaked lesions on immature fronds in field production under 50% shade. Lab results suggested Cercospora or Rhizoctonia, but symptoms didn't match. He suspected Calonectria/Cylindrocladium.
Symptoms strongly point to Fern Anthracnose (Colletotrichum)—difficult to control. Lab tests often identify secondary pathogens. Rhizoctonia is possible but usually shows as crown/stem rot, not tip damage. Copper sprays have given temporary relief for some growers (suggesting bacterial involvement), but no empirical support. Physiological factors (heat stress, calcium deficiency) may contribute.
Jeff confirmed Anthracnose via independent research and MREC resources.
Heritage (Azoxystrobin) is labeled for this crop/pathogen but is very expensive and causes leaf greening/deformation. Cost-effectiveness in field use is uncertain. MREC links provide full integrated management methodology.
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