ASCOCHYTA LEAF BLIGHT FREE
Plant in pasteurized soil or soilless mix free of the pathogen. Stems turn dark brown to black at the soil line. Golovinomyces cichoracearum (formerly Erysiphe)Īpply a fungicide to protect healthy plants. Leaves have white, dry fungal growth on their surfaces. Apply a fungicide to protect healthy plants. Use nitrate rather than ammonium forms of fertilizer. Management: Purchase culture-indexed cuttings free of the pathogen. Yellowing of leaves, wilting, and discoloration of the vascular tissue develops up one side of the plant.
Symptoms vary with the cultivar infected. Do not handle healthy chrysanthemums after handling infected plants. Destroy infected plants and disinfest tools used to handle them. Purchase virus-indexed plants that are free of the pathogen. Infected plants grown under low light conditions and when temperatures average less than 20° C (69° F) exhibit no symptoms. Leaves, at first mottled, become completely yellow. Maintain greenhouse humidity below 98% at all times. Infected tissues become covered with dusty gray spores. Protect plants grown outdoors from splashing. Water in a manner that keeps leaf surfaces dry at all times. The disease often spreads up plants in one side of the pot, eventually to the flowers.ĭo not plant infected cuttings. When infected leaves dry, the spots become brittle and crack. Small dark brown to black spots on lower leaves enlarge and become irregular in shape. Disinfect propagation beds between crops. Purchase culture-indexed cuttings that are free of the pathogen. Established plants wilt during the day when infected and recover at night. Surviving cuttings may be infected but have no symptoms. Apply a fungicide to protect healthy plants.Ĭuttings turn dark brown and collapse. If enough spots are present, the entire flower dies.Īvoid overhead irrigation.
Brown to black irregularly shaped spots develop on leaves.Īvoid overhead irrigation. Browning and blackening extends down the stem, causing the flower to droop. Yield loss is rarely reported, but is possible under conditions such as prolonged cloudy weather with cooler temperatures and rainfall.Flower development is retarded on one side of the bud. However, Ascochyta Blight typically occurs early in the season and small black fruiting structures are observed in the lesions.Īscochyta Blight has been reported in most major cotton producing regions. Small, black fruiting structures are likely to be embedded in symptomatic tissue.ĭiagnostics Note: Margins of necrotic regions on leaves and cotyledons will have dark borders. Elongated can-kers on the stem are reddish-purple to black or ash gray in color. Lesions on the cotyledons and leaves approach 2 mm (<0.1 in) in diameter, are white to light brown and circular in shape. Note dark border and also small, embedded fruiting struc-tures in the spots.Ĭaused by: Ascochyta gossypii (Phoma exigua)įoliar Symptoms: Ascochyta Blight forms lesions on cotyledons, leaves, stems, and bolls. Symptoms of Asochyta Blight on cotton leaf.
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