July 10, 2024
With the heat wave over the last few days, insect development has been moving quickly, and model predictions are a few days earlier than we expected as of a week ago. If you are planning to use an in-season Vantacor application on your mint, the best time to spray will be starting in the next few days. The growing degree model predicts that peak moth catch will be on July 15 near Imbler, and July 18 near Baker Valley. Try to complete your sprays before peak egg laying, which is predicted to occur on July 26 or July 30 in Imbler and Baker Valley, respectively. Check the app to stay up to date with any changes in these predictions.
Previous OSU studies suggest that the best time to apply Vantacor to get the best overall control of mint root borers, loopers and variegated cutworms is between peak moth catch and peak egg laying based on the mint root borer growing degree model. Vantacor is a systemic insecticide that is absorbed by the plant, and controls insects over an extended period. It works best on insects at the egg and early larval stages. Since insects lay eggs over a couple week period, you want to spay early enough that the earliest laid eggs are still vulnerable, but late enough that the product is still effective when the later eggs are laid.
Mint root borer moths have been captured in two of the six sites with traps this year. Last week, a total of 8 moths were caught between two sites. No moths were found in the other four fields. These moth counts are just slightly higher than last week. No variegated cutworms or loopers were caught in sweep net samples in the fields yet. The model for variegated cutworms predicts that first instar larvae peak on July 10 near Imbler and should peak on July 12 near Baker Valley. Third instar larvae should peak on July 19 and 22, respectively.
July 3, 2024
Hello and welcome to the Mint Pest Alert for 2024. This website is designed to help you control mint root borers, variegated cutworms, and loopers in mint fields. Over the next couple weeks, I will share the results from a trapping program in your region. I will also include information from growing degree models for mint root borers and variegated cutworms. These models predict when the insects will reach various growth stages, which can help you figure out the most effective time to spray.
A new addition to the Mint Pest Alert this year is a growing degree web app found at the top of this page. This means you can get updated model predictions any time. Select the weather station closest to you using the options on the left.
Traps were put out in mint fields last week. The growing degree model is predicting peak moth catch for mint root borer moths on July 17 near Imbler, and July 20 in Baker Valley. For variegated cutworms, first instar larvae are expected to peak on July 9 and 11 in Imbler and Baker Valley, respectively.
Previous research has shown that the optimal time to use Vantacor to control mint root borers, variegated cutworms and loopers is between peak moth catch for mint root borers, and peak egg laying. This timing can give you control of these pests with one spray. Keep in mind that model predictions might change depending on how much warm weather this upcoming heat wave brings.
Archived posts from 2023
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
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.
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.
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