Common Diseases in Lentils

Common Diseases in Lentils

Botrytis Grey Mold

Botrytis cinerea and Botrytis fabae

Symptoms	Disease first appears as discrete cream colored lesions on lower leaves. Lesions girdle the stem and cover it with a furry layer of grey mold, eventually causing stem and whole plant death.

Factors favoring	High humidity and moderate temperatures with high moisture. Rain and sprinkler irrigation. Dense stands of lentils


	Botrytis injury	Botrytis pod injury

Anthracnose

Colletotrichum truncatum

Symptoms	Generally, symptoms appear later in the growing season. The disease kills lower leaves, causing defoliation and eventually premature plant death. Brown lesions with dark borders may be present on leaves and stems, sometimes with small black bristle-like fruiting bodies (pycnidia). Stem lesions could potentially grow to girdle the plants. Typical field symptoms include lodged plants with abnormal dark brown stems and pycnidia on the lower stem

Factors favoring	Infected fields nearby. Humid to moist weather conditions, rain splash, wind, and sprinkler irrigation. Leaf wetness for 18 to 24 hours. Moderate temperatures ranging between 20 to 25 °C (68 to 75 °C).Dense stands of lentils


	Early infection	Heavy Anthracnose infection showing black stems

Fusarium wilt

Fusarium oxysporum f.sp. lentis

Symptoms	Disease appears in patches at seedling and adult stages. Seedling wilt is shown by sudden drooping, followed by drying of leaves and the whole seedling. Symptoms are seen from flowering to pod filling stages. Stunting of the plant, wilting of top leaves, yellowing of foliage and death of the plant are the obvious symptoms on the infected plants. A slight reduction of lateral root growth is seen in a healthy root system.

Factors favoring	Soilborne disease Warm spring and hot, dry summer. Optimum temperature is around 25°C (75°F).


White Mold

Sclerotinia sclerotiorum

Symptoms	Leaves and stem turn brown to tan and die prematurely. Infected areas are covered with white fluffy mold. Dark brown to black scletotia develop inside and outside of the infected plants.

Factors favoring	Wet and cool weather conditions. Dense stands of lentils

Ascochyta _Blight

Causal Organism: Ascochyta lentis

Symptoms	Spot-like lesions can develop on leaves, stems, pods, and seeds. Small black pycnidia become visible with maturity. Premature leaflet drop, stem breakage, and stem dieback may occur. Affected crops under severe infection may be blighted and seed may become shriveled, reduced in size, and discolored. Flowers and pods could abort, leading to yield loss.

Factors favoring	Non-resistant cultivars grown and planting low quality seed will increase the chances of infection. This pathogen does best in cool, wet weather. If crop rotation is not used, the severity of infection may increase. Residue from previous crops provides high inoculum risk. Infection may be increased if protected seed treatments and fungicides are not used. Also, not taking advantage of helpful cultural controls such as deep plowing, harvesting early, desiccating crops before harvest, and growing a non-host barrier grown in-between lentil crops and residues are a sure way to increase inoculum carryover.


	Ascochyta lesions on leaflets	Affected crops may be severely blighted and seed becomes shriveled and discolored.	Ascochyta infected (on left) vs. clean seed (on right).


Root Rot Seedling Blight

Root rots and seedling blights in lentil are primarily caused by soil-borne fungi including Rhizoctonia, Fusarium, and Pythium species.


Causal Organism: Rhizoctonia sp.

Symptoms	Reddish to dark brown root lesions can develop on epicotyls and hypocotyls. Brown discoloration occurring near the soil line on the epicotyl could girdle the stem. Seeds may rot, or when growing, develop rot or pre and post-emergence damping-off. Lesions developing on roots that eventually progress enough to pinch them off can be observed. Stem lesions can develop at or below the soil line that may expand above the soil line to the lower branches in older plants. Leaves can turn yellow from the base of the plant up. Circular patches of stunted plants may be observed in the field. A plant that can be easily pulled out from the soil is indicative of rot.

Factors favoring	No-till or reduced-till and sandy soil favors infection, particularly when organic matter is high. Cool temperatures (11-18C) and root knot nematode presence make plants more susceptible to infection, although the pathogen tolerates a wide range of soil temperatures. Infection is more likely when paired with diseased seed, compacted soil, herbicide carryover, and non-rotation of crops.

		Rhizoctonia injured seedlings

Causal Organism: Fusarium sp.

Symptoms	Patches are found in the field, usually occurring during flowering and on to the fruiting stage; however, infection may occur at any stage of the plant cycle. Plants may be stunted overall and the leaves often curl from the top to the bottom of the plant. Top leaves in the plant may wilt and droop. They can also shrink and curl without defoliating early. Some other symptoms include yellowing, reduced root system with discoloration, poorly developed nodules, and damage at the taproot tip. Seeds may rot, pre-emergence damping off can occur, and the plant may die.

Factors favoring	The pathogen is favored by high soil temperature and dry conditions. Presence of nematodes can increase severity of the infection. Also, using non-resistant seed or infected seed and having low levels of saprophytic microflora in the soil can increase infection.



Causal Organism: Pythium sp.

Symptoms	Plants may show stunting, yellowing or purpling of the leaves, and discoloration of the main tap root and feeder roots. Seeds may rot, damping-off can occur, and the lateral roots may develop poorly. If the environment becomes warm and dry, the plants may die. From a distance, the stands look unfavorable and the plants may turn beige to light brown in color and eventually die.

Factors favoring	Planting early in wet, cool soils may increase infection along with using low quality seed or nonresistant plants, infested debris from previous seasons, and planting on clay soils.



Stem Rot of Lentil (White Mold)

Causal Organism: Sclerotinia sclerotiorum.

Symptoms	A plant infected with Sclerotinia can develop bleached lesions on stems, leaves, pedicels and pods. The tissues that have stem lesions may turn yellow and wilt. Patches of dead plants may be observed. The plant parts are often covered in white, cottony mold. Dark brown to black sclerotia may be found on the plant or on the soil under its canopy.

Factors favoring	Conditions that favor the disease include humid environment, cool conditions, and dense canopies. Infested seed and susceptible host debris from previous seasons increase infection.

		Crop destruction by Sclerotinia


Anthracnose

Causal Organism: Colletotricum truncatum

Symptoms	The disease usually appears in the lower leaves first as necrotic and tan to creamy brown lesions, leading to leaf drop occurring in severe cases. Stems can develop tan to brown lesions which may have a defined black border and create indents along the stem that can even coalesce and girdle the stems, resulting in wilting. From a distance, brown patches and lodged lentil plants are formed in the crop resulting in lower seed yields. Pods may turn brown and necrotic. Seeds that are affected may have brown discolored spots and become shriveled, although not all infected seeds show symptoms.

Factors favoring	Conditions conducive for infection include warm, humid, and wet environments, especially late in the season. Having a dense canopy, infested seed, and leaving crop debris infested from previous years are all ways to increase inoculum. Moderate temperatures of 20-24 °C (68 to 75 °F) are optimal. Tillage of anthracnose infested fields increase survival of the pathogen in areas with cold winters.


	Early infection	Heavy Anthracnose infection showing black stems.



Links to other websites with information about lentil diseases some of which have been included here:
http://www.agriculture.gov.sk.ca/lentil http://www1.agric.gov.ab.ca/$department/deptdocs.nsf/all/prm7830 http://www.icarda.org/Publications/Field_Guides/Lentil/Lent1.Html http://www.apsnet.org/publications/commonnames/Pages/DiseasesofLentil.aspx http://www.ag.ndsu.edu/procrop/lnt/disease.htm http://www.icarda.org/Publications/Field_Guides/Lentil/Lent7.Html http://www.ars.usda.gov/Research/docs.htm?docid=20122 http://msuextension.org/publications/AgandNaturalResources/MT199615AG.pdf


Books:
Weidong Chen, Hari C. Sharma, Fred J. Muehlbauer, 2011. Compendium of Chickpea and Lentil Diseases and Pests. The American Phytopathological Society.
K.L. Bailey, B.D. Gossen, R.K. Gugel, R.A.A. Morrall, 2003. Diseases of Field Crops in Canada. The Canadian Phytopathological Society.

Common Diseases in Lentils

Common Diseases in Lentils

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