 lentil seeds.
An integrated disease management plan should include a well-planned fungicide program.
Virus patches in lentil. Note initial infection area (dead plants) and newer infections nearby.
Beet western yellows virus (BWYV) in lentil.
Lentils with CMV and AMV. Note the bare ground surrounding the plants.
Ascochyta blight is a potentially serious but manageable disease of lentil in Australia. Most current varieties are unlikely to have significant yield losses due to ascochyta blight. However, ascochyta blight does infect lentil pods and seed, causing a discolouration of grain that will significantly reduce the marketability and value of affected grain.
Symptoms of foliar infection
The disease (caused by Ascochyta lentis) appears on leaves and pods as round, whitish lesions with brown margins. Black fruiting bodies in the lesions distinguish the disease from spots caused by herbicide damage. Severe infections cause leaf yellowing. Tips of stems wilt, turn brown and die. Pod infection spreads to the seeds, which turn purple-brown and shrivel in whole or in part.
Ascochyta blight can be both seed and stubble borne. Wind borne spores from infected lentil stubbles can blow into adjacent paddocks and infect new lentil crops. Infection can occur at any stage of plant growth, but is more significant during late flowering and pod fill. Wet weather favours disease development and rain splash spreads spores onto new crop growth within the crop, including pods.
Ascochyta blight management begins with the use of disease-free seed. Test retained seed if there is any doubt about the disease status of the seed. Sow into paddocks that are free of infected lentil stubble and avoid close rotations of lentil in the same paddock. Sow a variety that is resistant (R) to AB seed infection such as PBA Jumbo2, PBA Herald XT and PBA Ace. Moderately resistant (MR) varieties are PBA Hurricane XT, PBA Blitz, PBA Bolt and PBA Giant. For other varieties, strategic fungicide sprays may be required during flowering and pod fill.
Fungicidal seed dressings help control seedling infection. Destruction of lentil stubble by burning, cultivation or grazing helps to minimise disease carry-over between seasons. Delay sowing until early June because early sowing increases the length of time the crop is exposed to disease. Ascochyta blights of field pea, chickpea and faba bean are specific to those crops and will not cause ascochyta blight on lentil.
See also 'Lentil: Integrated disease management'
Botrytis grey mould (Botrytis spp)
Botrytis grey mould (BGM) infects lentil seed and stubble but is generally only a problem in wet years, when it can cause crop devastation. A dense crop, lodging and rain in late spring provide ideal conditions for the disease to develop in the crop canopy. Wider row spacing, later sowing and reduced seeding rates will reduce crop canopy density and the likelihood of infection.
Symptoms of stem and pod rot
Botrytis grey mould (Botrytis fabae and B. cinerea) can infect any above-ground plant parts. Lesions on leaves and pods are initially dark green but turn greyish-brown as they mature. Grey mould also develops on flowers. If the canopy is wet for long periods the pathogen grows on the stems, which quickly become covered with a fuzzy layer of grey mould. This all occurs within the crop canopy, often unseen from above the canopy. When the weather turns dry, clouds of spores are released into the air when plants are disturbed. Severely infected leaves, flowers and pods wilt and fall to the ground. If wet conditions continue the stems become girdled, resulting in spreading patches of brown and dying plants within the crop.
Symptoms of seedling blight
Seed from severely infected crops is often discoloured and shrivelled. If infected seed is used for sowing, plant establishment is usually poor, due to low germination and seedling blight. Blighted seedlings emerge but are yellow and stunted, and usually die after one or two weeks. If germination takes place under wet conditions, mycelium from infected seedlings can grow through the s