Diseases of Fruit Plantation Medicinal and Aromatic Crops

Heart rot of pineapple

Causal organism: Phytopthora cinnamomi and Phytopthora parasitica.

Symptoms

• In the field, heart rot disease of young plants can be suspected where there is a change in the colour of leaves from normal green to yellowish green and browning of the leaf tips.
• The bases of the leaves shown yellowish white rotten area bordered by distinct and characteristic brown margin.
• The chlorophyll region commences?
• The affected area gives a odour due to secondary bacterial invasion.
• The rot extends the stem of the plant producing a soft cheese-like rotting condition.
• The roots of plants are largely destroyed with the result that the plants remain stunted and fruit formation is delayed or dose not form at all.
Etiology

• Aseptate mycelia, inter & intra cellular haustoria.
• Sexual spores – Oospores (oogonium).
• asexual spores – Zoospores and sporangium
Primary source of inoculum – Oospores & chlamydospores present in debris.
Secondary source of inoculum – Air & water splash borne zoospores.
Mode of spread

• The fungus inhabits and survive in the soil in the form of oospores.
• The spores spread through irrigation water and rain splash.
Epidemiology

• Heart rot under warmer and dry conditions is frequently associated with alkaline soils and poor drainage.
• It is severe in cool, wet soil.
• Temperatute:250C, heavy rains soon after planting leads to heavy disease incidence.
• Plants of one or two year age are more susceptible.
Management
• Deep planting should be avoided.
• Soil should not be allowed to enter the hearts during planting.
• Diseased plants should be removed and burnt
• Bordeaux mixture(1%) spray reduces the disease