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WREC Plant Pathology Updates

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Increasing Levels of Root Rot Observed in Lentils in NW ND (07/14/16)

Analysis of root rot samples collected during field scouting (Adam Carlson, NDSU & Kim Zitnick, NDSU) has revealed increasing incidence and severity of root rot in lentils across northwest ND (Fig 1). Root rotting and wilt-causing Fusarium pathogens have been most commonly isolated. The frequency of Pythium has increased recently, whereas Aphanomyces euteiches has only been detected from one field. Rhizoctonia solani thus far has not been observed. Frequent rain and resulting high soil moisture is most likely responsible for the observed increase, in combination with the seed treatment fungicides no longer being effective at this point in the season.

Determination of the casual organism is important in the case of root rot as not all seed treatment fungicides are effective against all pathogens. There are currently no seed treatments available for control of Aphanomyces in peas and lentils. Rotating out of peas and lentils for 4-6 years can help reduce the buildup of these pathogens, although note that some root rotting pathogens can infect other broadleaf crops.


For more information about root rot diseases of pulses see the new Pea Disease Diagnostic Series (NDSU), as well a publication from Canadian pulse growing associations, “Root Rot in Pea and Lentil in Western Canada”.


Audrey Kalil

Plant Pathologist

NDSU Williston Research Extension Center

 Julie Pasche

Assistant Professor, NDSU Plant Pathology

 Kim Zitnick-Anderson

Post-Doctoral Researcher, NDSU Plant Pathology


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Pea and Lentil Disease Update (07/28/16)

Pea and Lentil Disease Update

Scouting of peas and lentils in Burke, Williams, Divide, Mountrail and McKenzie Counties for foliar disease continues as earlier planted crops start to come off the field (Adam Carlson, Crop Scout NDSU). In pea, ascochyta blight is commonplace in fields, with the highest incidence found in Mountrail County, but severity levels remain low as they have for most of the season (Fig 1). We are beginning to see white mold in some fields in Williams and Divide Counties, and powdery mildew has been observed in McKenzie County (Fig 1). Bacterial blight has been identified in all pea fields scouted (Fig 1). kalil.1                                                                                                                                                                                    In lentils, ascochyta blight and anthracnose were almost universally present in Divide, Williams and McKenzie Counties but severity levels were low (Fig 2).



Audrey Kalil

Plant Pathologist

NDSU Williston Research Extension Center

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Incidence of Ascochyta Blight in Peas and Lentils in Northwest ND (06/23/16)

Incidence of Ascochyta Blight in Peas and Lentils in Northwest ND

Scouting of pea and lentil fields in NW ND has revealed low incidence of Ascochyta Blight in lentils (Fig 1), and low to moderate incidence in field pea (Fig 2) so far this season, however, cool and wet conditions in the forecast may lead to increased incidence of this disease. 


If timed appropriately, fungicides can be effective for management of Ascochyta Blight and Canadian researchers recommend using the following guidelines for making a treatment decision (Fig 3):

  • Scout the same 4 locations in your field every 3-5 days from V10 through bloom
  • Assign points to stand, leaf wetness, 5 day weather forecast and disease severity. 
  • If the total number of points exceed 65 AND disease symptoms are present, a fungicide treatment may be warranted.


Also available at this website: http://reducedtillage.ca/docs/Ascochyta_Scoring_System_2006.pdf

Note: These guidelines have not been specifically tested for conditions in North Dakota and should serve only as a reference. 

When scouting, remember that it is critical to distinguish this disease from Bacterial Blight, which will not respond to fungicide treatment. For information about distinguishing Ascochyta blight from bacterial blight of peas see the bulletin Mycosphaerella (Ascochyta) blight and bacterial blight of peas.  For more information about Ascochyta Blight refer to the June 2nd article published this year in the Crop & Pest Report: Field Pea Diseases Review: Ascochyta /Mycosphaerella Blight.

Audrey Kalil

Plant Pathologist, NDSU Williston Research Extension Center

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Pea Enation Mosaic Virus Detected in Divide County (06/16/16)

Pea Enation Mosaic Virus Detected in Divide County

Be on the lookout for Pea ppth.kalil.1Enation Mosaic virus (PEMV). A pea plant exhibiting interveinal chlorosis was found by a crop scout in a field in southern Divide County (Fig 1). Genetic based lab testing by the MSU Regional Pulse Crop Diagnostic Laboratory found that the plant was infected with PEMV. PEMV is a viral disease that can infect many legumes including pea, chickpea, faba bean and lentil and is transmitted by pea aphid and green peach aphid, in addition to several other aphid species. Symptoms can vary based on host and environment, but infected plants will typically develop yellow or translucent flecks on the leaf (Fig 2A), vein clearing and later on “enations” or leaf blisters may appear (Fig 2B). Leaves might also be twisted or edges may have a downward roll. These early symptoms can easily be confused with herbicide damage, nutrient deficiency or other viruses, so laboratory diagnoses is important. PEMV may also cause stunting and a reduction in internode length. Pods may be twisted, deformed or develop a “warty” appearance (Fig 2C). If the plant is infected prior to bloom, pods may not fill normally and yield may be impacted.

ppth.kalil.2Few management options exist for PEMV. Reducing aphid populations with an insecticide application may reduce the secondary spread of the virus. However, it is unclear if that application would be cost-effective. In planning for next year resistance could be an option. Hampton, a PEMV resistant green field pea variety was released, and although it was developed for conditions in the Pacific Northwest, it may be a good option for growers who have problems with this disease.

Audrey Kalil

Plant Pathologist, NDSU Williston Research Extension Center

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Pea Seed-borne Mosaic Virus Detected in One Seed Lot from Mountrail County (05/19/16)

Pea Seed-borne Mosaic Virus (PSbMV) is a viral disease that can cause substantial yield and quality losses in lentils and peas and can also infect chickpeas, faba beans and vetches.

Pea Seed-borne Mosaic Virus (PSbMV) is appth.kalil.pea viral disease that can cause substantial yield and quality losses in lentils and peas and can also infect chickpeas, faba beans and vetches.  Plant symptoms include stunting, pod and leaf deformation, and delayed maturation (Fig 1. top). Seeds may be smaller, and discolored with split seed coats (Fig. 1 bottom). As the name implies the virus can infect the seed and when this seed is planted the virus can spread into the plant.  The transmission rate from seed to plant is on average 30% in peas and 44% in lentils. Aphid feeding transmits the virus from infected plants to new hosts during the growing season. Therefore, planting infected seed and high aphid populations put you at the greatest risk for PSbMV.

As part of a NW ND pulse scouting project funded by the Northern Pulse Growers Association, Taheni Jbir (Crop Scout, NDSU WREC) and Dr. Audrey Kalil (Plant Pathologist, NDSU WREC) collected pea and lentil samples from growers in Williams, Divide, Mountrail, McKenzie and Burke Counties.

A total of 10 lentil and 18 pea samplesppth.kalil.pea.2 were collected and analyzed by the NDSU Plant Diagnostic Lab for PSbMV (Fig 2). Low levels of PSbMV were detected in a single pea seed lot from Mountrail County, all other lots were negative for the virus. These results, from a limited number of seed lots, suggest that overall levels of PSbMV in planted seed may be low in NW ND; however, it remains important to scout for aphids weekly up through pod development as this virus can be transmitted very rapidly under high aphid pressure.

Remember that PSbMV infected seed should not be saved and as infected seed may be symptomless, it is recommended to get seed tested for this disease. To submit your seed for testing contact the NDSU Plant Diagnostic Lab https://www.ag.ndsu.edu/pdl

For more information on PSbMV and management options see the NDSU publication Pea Seed-borne Mosaic Virus (PSbMV) in Field Peas and Lentils (PP1704).

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2015 Wheat Midge Survey Results

The results of the 2015 survey for Wheat Midge Larvae have been reported. Samples were collected in harvested wheat fields in the fall of 2015 and results predict wheat midge populations for the 2016 growing season. According to Dr. Janet Knodel, NDSU Extension Entomologist, "No soil samples were found with economic population densities of wheat midge (greater than 500 midge larvae per square meter) this past year."  The majority of the samples, in fact, did not contain any wheat midge cocoons. This is good news for wheat growers and should reduce insecticide costs in the 2016 season. 


2015 Wheat Midge Survey Results

For more information about the results of this survey see the article below:


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