Important Seedborne Diseases of Pulse Crops
Below are seedborne diseases of pulse crops, their causal agents and economic
importance. Planting disease-free seeds is a smart way to minimize the possibility of the
diseases and losses associated with them. The Regional Pulse Crop Diagnostic
Laboratory (RPCDL) test your seed lots for the presence of these pathogens
Aster Yellow Phytoplasma
Aster yellows is caused by one or more strains of a bacterium with no cell wall and
difficult to culture. It is aster leafhopper transmitted during feeding. It can also be
seedborne and seed transmitted. Aster yellows causes severe reductions in yield and
quality. The most common symptoms include general yellowing, stunting, and rosetting.
This bacterium can infect many plants including field crops.
Our laboratory uses PCR to detect Aster yellows phytoplasma
Bacterial blight is a serious disease of field peas that is caused by the bacterial
Pseudomonas syringae pv. pisi and Pseudomonas syringae pv. syringae. Xanthomonas
campestris pv.Cassie is responsible for bacterial blight in chickpea. The disease first
appears on leaf as small, dark-green, water-soaked spots (lesions), which coalesce and
later turn yellowish to brown. Both pre-emergence and post emergence damping-off may
occur. Heavily infected seed may be discolored, resulting is poor seed grade. Severe
epidemics can occurs which can lead to crop failure.
The pathogens are seedborne. Infected and contaminated seeds are the most important
sources of inoculum for field epidemics. The pathogens also survive on stubble and in the
Bacterial blight disease management options are planting disease-free seeds, crop
rotation, varietal selection, and avoiding early sowing.
Our laboratory uses seed wash-dilution-plating out technique for detection of agents of
For all fungal screening, our laboratory uses morphological characteristics on growth
media to identify fungi and fungi-like agents.
Anthracnose of lentil and chickpea is caused by the fungus Colletotrichum truncatum.
has been reported in Canada, and United States in North Dakota and Montana. The
fungus infecting field pea is caused by C. pisi. Anthracnose of lentil is an economically
important disease, where it occurs. Anthracnose is an emerging problem of pea. The
disease symptoms include tan lesions which can lead to defoliation and girdling, causing
plants to wilt and lodge. Seeds from infected plants may be discolored and shriveled,
resulting in significant dockage. Also, low infection levels can cause significant yield
losses and provide additional inoculum for re-infection. In pea, anthracnose reduces
productivity and germination ability of seeds. The best way to prevent the disease is by
not introducing the pathogen through planting of disease-free seeds.
Alternaria blight is caused by a fungus, Alternaria alternata. It infects chickpea,
field pea. The pathogen is seedborne and it can be spread by planting infected seeds. It
causes lesions on leaf margins and tips; petioles, flowers and pods, similar to those
caused by Ascochyta. Affected leaflets drop off the plant. Alternaria can cause
germination loss, and severe losses later in the growing season.
Ascochyta blight is a disease complex caused by Ascochyta species (fungi), and other
pathogens in field pea. The species of Ascochyta are host-specific: Ascochyta rabiei only
infects chickpea and Ascochyta lentis only infects lentil. In field pea Asochyta blight is
caused by a complex of three pathogens: Asochyta pisi, Mycosphaerella pinodes
(asexual stage: Asochyta pinodes), and Phoma pinodella. The pathogens cause lesions
(diseased spots) on every parts of the pulse crop they infect and can easily spread on the
field. These lesions coalesce to form blight. The disease can reduce seed yield and seed
quality. This pathogen can be seedborne at high levels. Growers are advised to test their
seed lots and only plant those below the following thresholds: 0%, 5%, and 5% in
chickpea, pea, and lentil, respectively.
Gray mold (Botrytis) is caused by Botrytis cinerea in chickpea and lentil. The pathogen
causes symptoms, which at onset appears as water-soaked lesions on stems, branches,
leaves, flowers, and pods, then progress to gray/brown lesions, and are often covered
with a gray mass of fungal hyphae and spores. The pathogen prefers blossoms and pods
but can also attacks other aerial parts of the plant. The disease causes flowers to drop,
resulting in significant seed yield losses. Seedling soft-rot of chickpea can arise from
infected seeds. The fungus can survive on infected seed for up to five years. A test that
determines the amount of seed borne botrytis that is present in the seed is available in
This disease, caused by Fusarium oxysporum, was responsible for the decline of the
industry in many regions of the U.S. including Montana's Gallatin valley during the middle
Fusarium wilt is caused by subspecies of Fusarium oxysporum specific to crop. For
example, F. oxysporum f. sp. pisi infects pea, F. oxysporum f. sp. lentis infects lentil, and
F. oxysporum f. sp. ciceris infects chickpea. Existence of several different races within
each subspecies makes breeding for resistance challenging. However, there is resistance
to races 1 & 2 of Fusarium wilt in many pea varieties. The pathogen is very long-lived in
the soil (as chlamydospores) and can increase in a field each time you replant the
Resistance breakdown is a reoccurring phenomenon; thus, seeds needs to be tested for
Fusarium wilt agents.
Sclerotinia (White Mold)
White mold is caused by any of these fungi: Sclerotinia sclerotiorum, S. trifoliorum,
minor. The pathogens infect a broad host range, including pulse crops and is often
introduced into field through planting of infected seed lots or equipment. They survive as
a mass of fungal hyphae enclosed in protective cases known as sclerotia. The fungi will
kill tissue and fill the stem with white hyphae and sclerotia, which then survive in the soil
for many years. Yield loss due this disease has been as high as 50%. It lowers sees
quality if any of the fungi form sclerotia on seeds.
Stemphylium blight (chickpea, lentil) is caused by Stemphylium botryosum. It is a
of increasing importance of lentil in Canada. It occurs in Montana and North Dakota. The
fungus also infects field pea. It causes leaf spots which coalesce causing defoliation of
the plant. The pathogen can be seed-borne and infected seeds have low germination
rate. There are no fungicides registered for control of this disease. Seed testing is a smart
and cost-effective way to measure, detect this disease, and avoid losses due to the
Our laboratory test for viruses by ELISA.
Alfalfa Mosaic Virus
Alfalfa mosaic virus (AMV) survives in infected seed or plant hosts. It typically
bright yellow mottle or mosaic symptom. In field pea and chickpea, it causes chlorosis
and necrosis of the new shoots. Pods may be malformed and fail to develop peas. Lentils
may develop necrotic tip growth, twisting and deformation of leaves and stunting when
infected with the virus. The virus is seedborne.
Bean Yellow Mosaic Virus
Bean yellow mosaic virus (BYMV) is distributed worldwide with a wide host range which
includes the temperate pulses. The virus is spread by a number of aphid species non-
persistently as well as being seed and mechanically transmitted. Symptoms on field peas
are variable. The virus may be symptomless or may induce bright mosaic, mottling of
leaves and clearance of veins. Necrosis may occur on tips, in stems and veins. Desi and
Kabuli chickpeas develop apical necrosis, reddening or yellowing, plant stunting and
premature senescence. Lentils develop mild mosaic, light green or yellow leaves. A
reduction in leaf size and stunting may occur. Infected plants produce very little seed.
Cucumber Mosaic Virus
Cucumber mosaic virus (CMV) causes severe disease in lentils, chickpeas and lupins.
also infects field pea. In areas where large aphid populations occur, crop losses can be
high due to reduced herbage production and grain yield. The virus is transmitted by a
number of aphid species, and it is seed-transmitted in many pulse species. CMV has the
widest host range of any known plant virus and is distributed worldwide. The host range
includes a large number of agricultural and horticultural crops including temperate pulses.
Pea Seed-Borne Mosaic Virus
Pea seed-borne mosaic virus (PSbMV) is distributed worldwide. The virus may be
symptomless, or show as mild mosaic symptoms on field peas and other legumes. Early
infections may cause considerable yield loses. PSbMV also affects seed quality by
causing brown ring patterns and spots on the seeds of field pea, faba bean, lentil,
chickpea, lathyrus and other legumes. The virus is believed to have spread worldwide
through the exchange of infected seed.
Pea Enation Mosaic Virus
Pea enation mosaic disease is caused by two symbiotic viruses: Pea enation mosaic
virus-1 (PEMV-1; an Enamovirus) and Pea enation mosaic virus-2 (PEMV-2; an
Umbravirus). Symptoms in peas typically include, in sequence, vein-clearing, mosaics,
plant growth malformations, stunting, and enations (outgrowths) on the veins of the
underside of the leaves. Infected pods are usually malformed, look warty, and contain
few, if they have seeds. Symptoms in lentils include stunting, rolling of leaves, mottling,
and tip wilting or necrosis. They can infect also infect chickpea. PEMV is seed-borne and
could be seed transmissible.
We use seed-wash and microscopy to extract and identify the nematode respectively
Stem and Bulb Nematode
Stem Nematode (Ditylenchus dipsaci) is one of the most devastating plant parasitic
nematodes and is widely distributed mainly in temperate areas. It is of great economic
significance worldwide and on the list of quarantine organisms of many countries. D.
dipsaci is an endoparasite that feeds in parenchymatous tissues in stems and bulbs. It is
a recognized pest of a wide range of root crops, ornamental and nursery plants, oat, pulse
and some pasture crops. Avoiding spread of stem nematode by infested seed.
NOTE: The seed test does not guarantee a disease-free crop! It only helps to
identify healthy seeds so that you can start healthy. Our test result is only
representative of the sample you send for testing! So, send us seed samples that
accurately represent your seed lots.
- Diseases of Cool Season Legumes (Pulse Crops: Dry Pea, Lentil & Chickpea) (USA)
- Seed Health Testing in Pulse Crops (Australia)
- • Guidelines for Seedborne Diseases of Pulse Crops (Canada)