WREC Plant Pathology Updates
Dry Pea and Lentil Root Rot Management Guide (PP1960)
Root rots are an important yield-limiting factor in lentil and pea production in North Dakota and Montana. The primary causal agents of root rot of peas and lentils are the fungal pathogens Rhizoctonia solani and Fusarium species and the fungal-like water mold pathogens Aphanomyces euteiches and Pythium species. Identification of the causal agent of root rot will guide management strategies. Proactive management of root rots are important to maximize production of these important crops in our region.
The management guide is available online at the NDSU publication website:
https://www.ag.ndsu.edu/publications/crops/dry-pea-and-lentil-root-rot-management-guide
Print copies are also available from the Williston Research Extension Center.
Funding was provided by the North Central IPM Center (USDA-NIFA).
Growing Pulse Crops Podcast
Anyone interested in growing pulse crops (chickpeas, peas and lentils) will have an opportunity to learn more through a podcast series that North Dakota State University plant pathologist Audrey Kalil initiated in collaboration with Future of Ag, Soil Sense podcaster Tim Hammerich.
Th episodes of the Growing Pulse Crops series are available at https://www.growingpulsecrops.com/ or through cellphone podcast apps. Fifteen episodes were released this season.
The series follows pulse crop farmers through the growing season and dives into the research that’s helping them through some of the challenges they face. Topics include intercropping, fall sown peas, chickpeas, and pest management.
Presenters will include Brian Jenks, weed scientist at NDSU’s North Central Research Extension Center near Minot; Michael Wunsch, plant pathologist at NDSU’s Carrington Research Extension Center; Mary Burrows, professor of plant science and plant pathology at Montana State University; and Lyndon Porter, research plant pathologist at the U.S. Department of Agriculture’s Agricultural Research Service in Pullman, Washington and many others.
This series was developed by members by of the Pulse Crop Working Group in response to stakeholder interest in this format. The goal of the Pulse Crop Working Group is to foster collaborative relationships among researchers, Extension professionals and stakeholders through face-to-face meetings and virtual interaction to address integrated pest management priorities in pulse crops.
The group is funded by the North Central IPM Center. Visit https://www.ncipmc.org/projects/working-group-projects/ to learn more about the group.
To receive the podcast on a cellphone, subscribe to the series through Apple podcasts (iPhone), Google podcasts (Android) or any other pod catcher app. Once subscribed, the podcast will download to your phone automatically when each new episode is released.
Lentil Disease Diagnostic Series (PP1913)
The new lentil disease diagnostic series features high quality images of diseases along with descriptions to help identify symptoms.
The series can be viewed online here:
https://www.ag.ndsu.edu/publications/crops/lentil-disease-diagnostic-series
If you would like to obtain a hard copy a limited quantity are available. To order contact me at audrey.kalil@ndsu.edu
The book was produced as a collaborative effort of the Pulse Crop Working Group funded by the North Central IPM Center.
2018 Pulse Crop Survey – Insect Pest Report
NDSU pulse crop scouts (WREC: Shawn Postovit, NCREC: Graysyn Kitts) surveyed field pea, lentil and chickpea fields in northwest and north central North Dakota for insect pests from late May until early August. A total of 218 chickpea fields, 51 lentil fields, and 29 field pea fields were scouted. A summary of selected insect pests are discussed below.
Cutworms were observed in all three pulse crops surveyed but only present early in the crop growing season from late May to mid-June. The overall percentage of fields infested with cutworms was low – 8% of lentils fields, 3% of field pea fields and <1% of chickpea fields. The northwest area of ND had the highest densities of cutworms.
Pea aphids - Scouts collected aphids using 20 180-degree sweeps in each field at 5 spots. Pea aphids were most common later in the field season, usually late July into early August, and were only economic in 10% of the lentils scouted and <1% of the chickpea field scouted. Pea aphids were absent from the 29 field pea fields scouted. The hot spot for pea aphids was in Williams and Burke Counties. Otherwise, pea aphids were not a major problem in most of the pulse crop areas in 2018.
Pea leaf weevil (Sitona lineatus) is a new insect pest of field pea that was first discovered in the fall of 2016 near Beech, ND. In 2017, additional survey work found pea leaf weevils in field pea or faba beans fields the following areas: southwest (Dunn, Golden Valley and Stark counties), north-central (Mountrail and Ward counties) and northwest (Divide County). In 2018, pulse crop scouts and the IPM scout (Marc Michaelson from Dickinson REC) looked for feeding injury (leaf notching) of pea leaf weevil by examining 100 plants per field. Leaf notching was found over a wider range than previous years. Five new county records were documented in 2018 including Billings, Bowman, Hettinger and Slope Counties in southwest and Mercer County in west central. This survey focuses on number of leaf notches caused by adult feeding, and not the yield depriving larval feeding on the nitrogen-fixing root nodules. When the number of leaf notches are greater than 9 notches per plant (yellow square or red triangle on map), economic damage (yield loss) can be significant if conditions are favorable for pea leaf weevil in the spring of 2019 (warm springs >68F). Only Billings and Slope Counties had leaf notching greater than 9 notches per plant. Pulse producers should use this information along with field history of pea leaf weevil abundance to make decisions for the 2019 crop year. Research has demonstrated that insecticide seed treatments are more effective in reducing losses due to pea leaf weevil than foliar insecticides. Please see the new extension publication Integrated Pest Management of Pea Leaf Weevil in North Dakota E1879, April 2018, for more information.
Thanks to the Northern Pulse Growers Association for funding this survey.
2018 Pulse Crop Disease Scouting Summary
NDSU pulse crop scouts (WREC: Shawn Postovit, NCREC: Graysyn Kitts) surveyed field pea, lentil and chickpea fields in northwest and north central North Dakota for diseases from late May until early August. Regular rainfall during the growing season led to environmental conditions suitable for disease development in all three crops.
Anthracnose and white mold were the primary foliar diseases observed in lentils this growing season. Anthracnose onset was in mid-July when the fields scouted were at the early pod growth stage. Incidence of diseased plants reached up to 18% in some fields (Figure 1). White mold was present in 60% of fields scouted from mid-July to early August with incidence ranging from 1-26% (Figure 1).
Bacterial blight symptoms were observed in field pea beginning in early June when the crop was at late vegetative to early reproductive growth stages. Incidence reached 40-50% in some fields (Figure 2) with 2-18% of the crop canopy exhibiting symptoms. White mold was not observed in pea fields.
Onset of Ascochyta blight in chickpea was in mid-June, when the crop was at mid to late vegetative growth stages. Fields varied greatly in incidence and severity of Ascochyta symptoms (Figure 3). In some fields, the percent of plants showing symptoms stayed below 4% throughout the survey, while in others incidence reached 100% by mid-July. The differences observed among fields were most likely due to the amount of the fungal pathogen present in fields (inoculum), rainfall and fungicide application timing.
Thank You to all the producers who participated in the pulse crop scouting effort!
The Northern Pulse Growers Association funded this work.
Pulse Crop Update (07/12/18)
Pea fields in the northwest part of the state have reached early to late reproductive growth stages (Figure 1). Lentils and chickpeas are a little behind the pea crop, but most fields in the northwest region have reached bloom.
Disease levels in lentil fields have remained low. Out of the eleven lentil fields scouted by the NDSU WREC pulse scout (Shawn Postovit) from June 18th – 29th, only one field was positive for foliar disease (Ascochyta Blight – Figure 2). With the crop having reached canopy closure in many fields and the weather remaining wet in this region, we will continue to scout for foliar diseases, as high humidity within the crop canopy will favor disease.
Bacterial blight has been identified in pea fields in Williams, Burke and Mountrail counties (Figure 3). Incidence ranges from 8 – 48% of plants exhibiting symptoms. Severity is generally low, with under 15% of the crop canopy showing symptoms. More information about bacterial blight can be found on a previous article in the crop and pest report from 6/2/16 titled Field Pea Diseases Review: Bacterial Blight and Brown Spot.
Scouting of chickpea fields in the northwest and north central region of the state for Ascochyta blight continues. In some fields incidence has reached up to 80% (Figure 4). The percent of the crop canopy exhibiting symptoms was on average 7% in the sixteen fields that were positive for disease. Many of these fields have been treated with fungicides in recent weeks.
More information about management of chickpea Ascochyta blight can be found on a previous article in the crop and pest report from 6/28/18 titled Management Recommendations for Ascochyta Blight on Chickpea.
Pulse Crop Disease Update (06/21/18)
Ascochyta blight has been found by an NDSU pulse crop scout (Shawn Postovit) in chickpea fields in Williams and Burke Counties at up to 50% incidence. Ascochyta first appears as scattered disease lesions on plants (Fig 1) but this disease can progress very quickly and thus foliar fungicides must be applied in a timely manner. Applications of systemic fungicides are advised as soon as trace levels of disease is detected. If weather remains cool and wet, applications of fungicides should continue every 10 to 14 days during bloom and early pod fill. Note that Strobilurin (FRAC 11) fungicides are not effective on Ascochyta blight on chickpeas as the pathogen, Ascochyta rabiei, has developed resistance. Further management recommendations can be found in the publication Management of Ascochyta Blight of Chickpea found on the Pulses: Tools for Growers webpage. Refer to the 2018 North Dakota Field Crop Plant Disease Management Guide for products currently registered on chickpea in ND.
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”.
Plant Pathologist
NDSU Williston Research Extension Center
Assistant Professor, NDSU Plant Pathology
Post-Doctoral Researcher, NDSU Plant Pathology
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). 
In lentils, ascochyta blight and anthracnose were almost universally present in Divide, Williams and McKenzie Counties but severity levels were low (Fig 2).
Plant Pathologist
NDSU Williston Research Extension Center
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.
Plant Pathologist, NDSU Williston Research Extension Center
