Northeastern Oregon

Fall Chemical Management

Late Aug/early Sep is the time to scout for Mint Root Borer (MRB) larvae in the soil if fall control is being considered. MRB larvae drop from the foliage to the ground in August and tunnel into rhizomes, where they will feed into the fall.

Larvae are generally too small to see in August, while sampling in late September is too late as damage is done.

Control treatments must be applied before larvae form hibernacula (overwintering, soil-based cocoons). Based on the insect development model, 5% hibernacula formation is expected September 11 in the Baker Valley, and occurred on August 29 near Imbler.

Sampling Recommendations for MRB larvae:

  • Sample 1ft2 of soil to a depth of 2-3” (include rhizomes)
  • 2 samples taken every 2-3 acres
  • Minimum 25 samples per field
  • Screen samples in the field or with Berlese funnels in the laboratory

Treatment threshold = average of 2-3 larvae/ft2 sample

Northeastern Oregon – August 25

Northeastern Oregon – August 3

Northeastern Oregon – July 26

Northeastern Oregon – July 20

Northeastern Oregon – July 12

Northeastern Oregon – July 5

Northeastern Oregon – June 30

Northeastern Oregon – June 23

Archived posts from 2022

Northeastern Oregon Mint Pest Alert Newsletter – August 31

Northeastern Oregon Mint Pest Alert Newsletter – August 10

Northeastern Oregon Mint Pest Alert Newsletter – August 4

Northeastern Oregon Mint Pest Alert Newsletter – July 28

Northeastern Oregon Mint Pest Alert Newsletter – July 20

Northeastern Oregon Mint Pest Alert Newsletter – July 15

Northeastern Oregon Mint Pest Alert Newsletter – July 6

Northeastern Oregon Mint Pest Alert Newsletter – June 29

Archived posts from 2021

Northeastern Oregon Mint Pest Alert Newsletter – August 28

Time for fall treatment.

Northeastern Oregon Mint Pest Alert Newsletter – July 30

Plan to sample early for larvae in soil.

Northeastern Oregon Mint Pest Alert Newsletter – July 23

MRB captures continue to decline

Northeastern Oregon Mint Pest Alert Newsletter – July 16

Optimum application window closed/ closing.

Northeastern Oregon Mint Pest Alert Newsletter – July 10

The optimum application window for MRB and VC control with Coragen or Vantacor is ending soon.

Northeastern Oregon Mint Pest Alert Newsletter – July 3

The optimum application window for MRB and VC control with Coragen or Vantacor is now

Eastern Oregon Mint Pest Alert Newsletter – June 18

Archived posts from 2020

Northeastern Oregon Mint Pest Alert Newsletter-September 11

Sampling Recommendations for MRB larvae:
•Sample 1ft2of soil to a depth of 2-3” (include rhizomes)
•2 samples taken every 2-3 acres
•Minimum 25 samples per field
•Screen samples in the field or recover larvae with Berlesefunnel in the laboratory
•Treatment threshold = average of 2-3 larvae/ft2sample

Northeastern Oregon Mint Pest Alert Newsletter- September 3

Late Aug/early Sep is the time to scout for Mint Root Borer (MRB) larvae in the soil if fall control is being considered (i.e. Lorsban, Mocap, nematodes). MRB larvae drop from the foliage to the ground in August and tunnel into rhizomes, where they will feed into the fall.

Larvae are generally too small to see in August, while sampling in late September is too late as the damage is done.

Control treatments must be applied before larvae form hibernacula (overwintering, soil-based cocoons). Based on the insect development model, hibernacula formation in Grande Ronde Valley should be 5% by September 11th and will reach 50% by October 14th. Baker Valley should expect 5% hibernacula by Sept 26th.

Northeastern Oregon Mint Pest Alert Newsletter- August 5

Recently, a new invasive leafhopper species, known as Ligurian leafhopper (Eupteryx decemnotata Rey, Hemiptera: Cicadellidae) was reported by Bill Gerth, OSU Plant Clinic and this prompted us to look out for this insect while sampling the commercial mint field in Western Oregon. This insect species is of Mediterranean origin and is a pest of many plants in the family Lamiaceae which include peppermint, sage, basil, oregano, rosemary, lemon balm, and other culinary herbs.

Ligurian leafhoppers are tiny, less than 3mm long or 0.12 inches, yellowish-green leafhopper (see image) with a characteristic pattern of spots on the head and the wings.

Ligurian leafhopper - Eupteryx decemnotata

The Ligurian leafhopper is an important pest in cultivations of plants from the family Lamiaceae. Just like other leafhoppers, they are sap-feeding insects causing damage by puncturing cells and removing their contents. The characteristic stippling is produced (see image) when pest density is high. The damage can be mistaken for thrips or mite injury. The occurrence of this insect pest in Northeastern mint production systems and damage potential in commercial fields is still unknown.

Ligurian leafhopper - Eupteryx decemnotata

Northeastern Oregon Mint Pest Alert Newsletter- July 31st

We are now at the optimal in-season application window at both Agrimet sites (the optimal window for Grande Ronde Valley will be closing soon).

Northeastern Oregon Mint Pest Alert Newsletter -July 24th

Peak moth flight of Mint root borer adults was reached July 21st in the Grande Ronde Valley, optimal control extends from this time through peak egg-laying (Aug 1st). The NMME forecast still puts peak moth flight for Baker Valley on July 26th. Good control can be achieved with Coragen® from peak moth catch through peak egg-laying.

Variegated Cutworm larvae should be controlled before 5th instar when they drop to ground and become difficult to control. Treatment threshold is 0.6 larva/sweep or 1.3 larvae/sq ft.

If applying Coragen, follow the label: http://www.cdms.net/ldat/ld8KF045.pdf

Northeastern Oregon Mint Pest Alert Newsletter- July 17th

Mint root borer capture rates in the pheromone traps were low and have yet to reach peak moth flight in Baker Valley.  No variegated cutworms were found.  Only one mint cutworm (See image below) was discovered during crop inspections and they are not generally considered a pest of economic concern as other cutworm species.

Northeastern Oregon Mint Pest Alert Newsletter- July 10th 

Recent cooler weather has pushed back the predicted peak flight activity by a couple of days.

Northeastern Oregon Mint Pest Alert Newsletter- July 2nd

The peak flight activity is approaching in the coming weeks.

Northeastern Oregon Mint Pest Alert Newsletter- June 26

This week’s newsletter presents “PAMS” – Prevention, Avoidance, Monitoring, and Suppression framework for mint IPM ranging from proactive to reactive approaches in bio-intensive to conventional settings.

Northeastern Oregon Mint Pest Alert Newsletter- June 19th

Regular scouting and monitoring determine the presence and potential insect pest damage to mint fields in Oregon. Management practices, such as crop rotation, tillage practices, varieties used, etc., reduce the occurrence of many of these pests. This newsletter is a decision support system that utilizes resources such as Online phenology and degree-day models (http://pnwpest.org/dd/model), and the Pacific Northwest Pest Management Handbooks (https://pnwhandbooks.org/insect/crop-pests?combine=mint ) to facilitate the efficient use of chemical control options.


Archived Reports – 2019

NE Oregon

Northeastern Oregon Mint Pest Alert Newsletter – August 29th


Northeastern Oregon Mint Pest Alert Newsletter – August 7th


Northeastern Oregon Mint Pest Alert Newsletter – August 1st


Northeastern Oregon Mint Pest Alert Newsletter – July 24th


Northeastern Oregon Mint Pest Alert Newsletter – July 17th


Northeastern Oregon Mint Pest Alert Newsletter – July 10th


Northeastern Oregon Mint Pest Alert Newsletter – July 5th


Northeastern Oregon Mint Pest Alert Newsletter – June 27th

We just finished the second week of trapping for MRB adults in Baker County and the numbers are very low so far.  A total five (5) MRB moths have been capture over the two week period.  We are not doing any area-wide monitoring in the Grande Ronde Valley but we are providing the phenology development updates based on predictive models for the GRV.  As expected, GDD accumulation is running behind a few days compared to last year.


Northeastern Oregon Mint Pest Alert Newsletter – June 19th


Northeastern Oregon Mint Pest Alert Newsletter – Factsheet