Diseases of Fruit Plantation Medicinal and Aromatic Crops

Verticilium wilt

Causal organism: Verticillium spp.
Symptoms

• Affected plants are stunted in growth and leaves develop dark green patches followed by interveinal and marginal yellowing.
• Leaves wilt, dry and eventually fall.
• A brown discoloration can be seen in the xylem vessel on cutting through the stem and roots .
• Low partial wilt but lower leaf yellowing, V shaped yellowing of leaf margine .No epinasty but lower leaf drys off.
Etiology

• Septate mycilia, V shaped conidiospores on which single celled conidia is formed.
• Mode of spread: The fungi survive in the soil on diseased plant debris and infect healthy plant by contact with root. Furrow irrigation, organic manure and tillage spread the pathogens.
• Primary Source of Inoculum: Dormant mycelia and chlamydospores in soil and crop debris.
• Secondary Source of Inoculum: Conidia
Epidemiology

• Disease spread at the temperature of 28 to290 C. Relative humidity 80 -85 %. Low soil moisture, alkaline pH, affected soil, susceptible host, black clay soil. Low nitrogen reduces disease severity.
Management

• Crop residues should be ploughed deep and clean seeds to be sown.
• Polyethylene mulching reduce wilt effectively .
• Neutralize pH by applying gypsum
• Destroy the affected plant parts by burning.
• Crop rotation with non host crop is to be followed.
• Biological agent such as Tricoderma viridae application.
• CHEMICAL: Carbendazim 0.1% as both soil drench and seedling dip.