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Pulse Crop Survey – Insect Pest Report (09/13/18)

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.

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.

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Thanks to the Northern Pulse Growers Association for funding this survey.

 

Janet J. Knodel

Extension Entomologist

This site is supported in part by the Crop Protection and Pest Management Program [grant no. 2017-70006-27144/accession 1013592] from the USDA National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed are those of the website author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture.

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