A species of the Ascochyta fungus called Ascochyta lentis, also known as Didymella lentis, causes this disease.
Why Does it Matter?
- Ascochyta blight of lentils is wide spread and can cause severe yield and grade losses.
- Yield loss. Under the right conditions yield losses can be as high as 50% in susceptible varieties.
- Grade loss. Ascochyta can cause shriveling and significant seed discolouration leading to grade loss.
What are the Symptoms?
- Lesions begin as small brown spots on leaflets, petioles, stems and pods, which enlarge and fade to a tan color with a darker margin.
- Even though lesions may girdle the stems, plant growth above the lesions doesn’t usually wilt.
- Tiny reddish-brown to black fruiting bodies (pycnidia) can be found in the lesions.
- Heavily infected leaves usually turn brown and fall off (premature leaf drop).
- Pod lesions are common and can result in infected seed that is shriveled, spotted and/or darkly discolored.
What is the Disease Cycle?
- Emerging plants become infected from infected seed or from spores growing on debris near the plants, especially when seed is planted into cold (8o C), wet soil.
- Lesions appear on the plants within 7 to 9 days of infection.
- Within 10 to 14 days, fruiting bodies in the lesions start to produce spores, which are spread by rain splash to new infection sites on the plant or to adjacent plants.
- The disease develops and spreads most rapidly during cool (15o C), wet weather.
- Seed infection can increase rapidly when lentils are left in the swath during wet or humid weather conditions.
How is it Controlled?
- Planting clean, disease-free seed is the safest method of control, although seed with up to 5% Ascochyta lentis infection will not significantly affect yield as long as soil and weather conditions favor quick germination and good plant vigor.
- Use a seed treatment registered for ascochyta control.
- Choose resistant varieties.
- Observe a 4 to 5 year crop rotation and do not plant lentils near fields that were infected during the previous season.
How Does 20/20 Seed Labs Inc. Test for Ascochyta in Lentils?
- 400 seeds are surface sterilized to remove contaminants on the seed coat then placed on culture agar and incubated for 7 days.
- A qualified staff member examines the plates for the presence of Colletotrichum truncatum, which is identified by the type and color of mycelium and spore bearing structures.
- This test gives the percentage of infected seeds to 0.25%.
- This test takes one week to complete.
Combined tests for botrytis, ascochyta, anthracnose, stemphylium and sclerotinia are available at reduced rates, depending on the number of disease tests requested.
Please contact us for more information.