Submitted to- Dr VishwanathSubmitted by- Syed Danish

ALTERNARIA BLIGHT OF MUSTARD

INTRODUCTION

Rapeseed-mustard is group of crops contributes 32% of the total oilseed production in India

Alternaria blight disease caused by Alternaria brassicae.

Average yield losses in the range of 32-57 per cent due to Alternaria blight

Alternaria affects most cruciferous crops, including broccoli and cauliflower

The pathogens are greatly influenced by weather with the highest disease incidence reported in wet seasons and in areas with relatively high rainfall

Taxonomical Classification

Kingdom- Fungi Division - Deuteromycota Phylum- Ascomycota Class- Dothideomycetes Order – Pleosporales Family - Pleosporaceae Genus – Alternaria Species - Brassicae

ABOUT PATHOGEN

Alternaria brassicae is a plant pathogen able to infect most Brassica species including important crops such as broccoli, cabbage and oil seed.

It causes damping off if infection occurs in younger plants and less severe leaf spot symptoms on infections of older plants

Symptoms

The disease attacks on the lower leaves as small circular brown necrotic spots which slowly increase in size.

Many concentric spots coalesce to cover large patches showing blighting and defoliation in severe cases.

Circular to linear, dark brown lesions also develop on stems and pods, which are elongated at later stage.

Infected pods produce small, discolored and shriveled seeds.

SYMPTOMS

InstructorCourse

Survival and spread

The disease is externally and internally seed born.The pathogen survives through spores (conidia) or mycelium in diseased plant debris or weed.

Favorable conditions

Moist (more than 70% relative humidity) coupled with warm weather (12-25 °C ) and intermittent rains favors disease development

DISEASE CYCLE

CONTROL MEASURES:

1.CulturalUse of healthy seeds for sowing should be preferred.

Collect and burn the affected plant portions after the harvest of the crop.

Early sowing.

Deep ploughing.

Timely weeding and maintenance of optimum plant population.

Avoidance of irrigation at flowering and pod formation stages may help to manage the disease.

2. BIOLOGICAL

Spray of soil isolates of Trichoderma viride at 45 and 75 days after sowing.

3. CHEMICAL

The crop should be sprayed 3-4 times at 10 - 15 days interval.

Spray Mancozeb 75 WP at the rate of 2 kg in 1000 liters of water per hectare, as soon as the symptoms start appearing on the plants.