Diseases of fruit plantation medicinal and aromatic crops (2+1)

Leaf scorch disease

Causal Organism – Leptothyrium fragariae
Symptoms

• Leaf scorch lesions appear not only on leaf blades but also on the petioles, fruit pedicels, and sepals of the calyx.
• In early stage, leaf scorch lesions resemble those produced by the leaf spot organism as the small dark purple spots appear scattered over the upper surface of the leaflets.
• It is not difficult to distinguish the two after the spots have developed.
• In mature condition the leaf scorch spots are large and irregular in outline and never show the white central area which is characteristic of the leaf spot disease.
• On the contrary, black fruiting bodies which develop in the central area give the leaf scorch disease a “tar spot” appearance.
Disease cycle

• Strawberry leaves often survive the winter and diseased leaves in the early spring may bear both the perfect and imperfect stages of the leaf scorch organism.
• Ascospores are more important than the conidia in causing primary infection, since they are discharged in large numbers during the early spring months when the new leaves are developing.
• Under suitable moisture conditions the ascospores germinate within 24 hours and cause infection by direct penetration of the epidermal cells in contrast to the stomatal infection by Mycosphaerella fragariae.

Management

• Use healthy planting materials.
• Avoid creation of unnecessary injury and wounds
• Application of fertilizer should be delayed at least per day?
• Spraying with Copper oxy chloride (0.2 per cent) or Dyfolation (0.2 per cent) or Chlorothalonil (0.2 per cent) is effective.
• Use of resistant varieties like
• Spray the Bordeaux mixture 1%.