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Onion Thrips Activity Increasing in the Treasure Valley
All Crops Treasure Valley, Treasure Valley - Idaho, Treasure Valley Oregon
Onion Thrips (Thrips tabaci)
Posted on: June 18, 2025 by Jemila Chellappa
Pest Alert: Onion Thrips Activity Increasing in the Treasure Valley
Crop: Dry Bulb Onion
Pest: Onion Thrips (Thrips tabaci)
Region: Treasure Valley – Oregon and Idaho
Onion thrips populations are increasing across the region, with presence confirmed in over 97% of monitored onion fields. In many of those fields, more than 80% of plants are now infested. Fields with more mature, larger plants are showing particularly elevated activity. Smaller, early-stage fields (3-leaf stage or younger) remain largely unaffected, but this is expected to change as the season progresses.
Thrips Identification & Lifecycle
Adult onion thrips are tiny (1–1.3 mm), slender, pale yellow to brown insects with fringed wings. Immature stages (called larvae or nymphs) are wingless and lighter in color. Thrips thrive in hot, dry conditions and reproduce rapidly, often completing multiple generations per season. Eggs are laid within the leaf tissue, and nymphs feed on sap, developing through several instars before pupating in the soil or leaf axils.
What to Watch For
- Silvery streaks or flecking on leaves caused by feeding
- Black specks (excrement) near feeding sites
- Thrips concentrated in leaf folds, near the neck, or under tight canopies
- Reduced vigor or curling of young leaves
Thrips infestations can reduce onion yield by 20% or more. While no significant signs of Iris Yellow Spot Virus (IYSV) have been confirmed so far this season, continued vigilance is important, especially as thrips numbers build. IYSV lesions appear as oval to diamond-shaped chlorotic or necrotic spots on leaves, reducing photosynthetic efficiency and negatively affecting bulb storage.
Management Recommendations
Coverage is Key:
As canopy density increases, spray coverage becomes more challenging. Increase spray volumes to ensure deeper penetration into the neck and inner foliage, where thrips hide.
Insecticide Strategy:
- Systemic products (e.g., Movento) are effective by moving through plant tissues and targeting hidden feeding sites.
- Translaminar products (e.g., Radiant) enter the leaf surface and reach thrips feeding on the undersides or inside folds.
- Adjuvants: Use a penetrating adjuvant to enhance uptake and movement of active ingredients within plant tissue.
Cultural Practices:
- Avoid excessive nitrogen, which can promote lush growth and higher thrips populations.
- Monitor weed presence, as weeds can serve as alternate thrips hosts.
- Early planting and maintaining strong plant vigor can help plants tolerate feeding pressure better.
Resistance Management:
Rotate insecticides with different modes of action to delay resistance development. Always follow label directions and recommended thresholds.
Scouting Tips
- Start scouting early and continue weekly, especially as plants reach the 5–7 leaf stage.
- Sample at least five plants from four separate areas of the field.
- Use hand lenses or beat plants over a white surface to count individuals.
- Focus on inner leaves and the base of the neck.
- Threshold: Begin treatments when thrips exceed 1–3 per leaf, depending on crop stage and environmental conditions.
Stay vigilant. Early and consistent management of onion thrips helps protect yield potential and reduce the risk of IYSV later in the season.
More management information here https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/onion-thrips
This alert was prepared by Russell Smith Ollivierre, Oregon State University Malheur County Extension, with data contributions from Stuart Reitz, Oregon State University Malheur Experiment Station.
» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/onion-thrips
Strawberry Root Weevil Pupa
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho, Treasure Valley Oregon
Strawberry Root Weevil
Posted on: June 12, 2025 by Jemila Chellappa
Strawberry Root Weevil Alert – Be on the Lookout!
Found Strawberry Root Weevil pupae in Treasure Valley: The pupa of the strawberry root weevil (Otiorhynchus ovatus) is a transitional life stage between the larva and adult, typically found in the soil near the root zone of host plants. Here are the key characteristics:
Strawberry Root Weevil – Pupal Stage Characteristics:
- Color: Initially creamy white; may turn light tan as it matures.
- Shape: Soft-bodied, oblong, and slightly curved. The body is segmented and resembles the general adult form.
- Size: About 5–7 mm in length, depending on species and development stage.
- Visibility of adult features: The legs, antennae, and developing snout (rostrum) of the adult are visible but folded close to the body.
- Habitat: Pupates in an earthen cell or cavity in the soil, usually close to the roots of infested strawberry or other host plants.
- Duration: The Pupal stage generally lasts 2–3 weeks in spring (April–June), depending on temperature and soil conditions.
- Mobility: Pupae are non-feeding and immobile.
Since pupae are hidden in the soil, they are rarely observed unless the soil is carefully excavated near the crown and roots of the plant. Refer to the attached file for a visual reference of the Strawberry Root Weevil Pupa
Strawberry root weevils (Otiorhynchus spp.) are common pests in strawberry fields across the Pacific Northwest. While adult weevils cause minor notching on leaves, the real damage comes from their larvae feeding on roots through winter and spring, leading to stunted growth, reduced yields, or even plant death in severe cases.
What to Watch For:
- Notched leaves from adult feeding (visible in early summer)
- Wilting or stunted plants from root damage
- Adults hide under plant debris during the day or emerge at night
Now is the time to inspect your strawberry fields. Check for notched leaves, look under plant debris, or monitor at night for adult activity. Early detection is key to preventing egg-laying and larval root damage.
If you notice signs, consider control options including biological (entomopathogenic nematodes), cultural (soil cultivation), or chemical treatments applied at night for best results. More management information here https://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil
Stay alert and protect your berries!
» https://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil
Eastern Idaho Pest Alert June 6, 2025 | Vol. 6, Issue 4
All Crops Eastern Idaho
Pest Alerts from Bonneville County – Eastern Idaho
Posted on: June 10, 2025 by Jemila Chellappa
Eastern Idaho Pest Alert June 6, 2025 | Vol. 6, Issue 4
Coverage Areas: Bannock, Bingham, Bonneville, Cassia, Fremont, Jefferson, Madison, and Teton Counties
CURRENT PEST AND DISEASE ISSUES
Fire Blight Alert
Fire blight risk levels are Exceptional to Extreme across most of Eastern Idaho through mid-June.
High-risk management strategies:
- Prune infected twigs and branches on dry days.
- Disinfect tools between each cut using alcohol, bleach solution, or disinfectant wipes.
- Apply antibiotics within 24 hours of a wetting event (rain or heavy dew) when blossoms are open.
- Biological control products (e.g., Blossom Protect, Double Nickel) are recommended for resistance management and organic systems.
Codling Moth Management
Egg hatch timing is highly variable due to unusual weather patterns this spring. Spray timing depends on prior fruit damage and production system.
Conventional Orchards:
- High damage history: Apply 2 sprays per generation (start with oil or insecticide).
- Low damage history: Fewer sprays needed, often just 1 per generation.
Organic Orchards:
- High damage history: 3 sprays per generation, spaced 7–10 days apart.
- Low damage history: 2 sprays per generation.
Backyard Trees:
- Treatment options include conventional (e.g., Triazicide, Sevin) and organic (e.g., Cyd-X, Neem oil, Spinosad) products. See page 7 for efficacy and timing.
Leafhoppers
- Leafhoppers feed on plant sap, causing stippling and potential fruit damage.
- Regular scouting is advised for sensitive crops like apples, pears, and grapes.
- IPM strategies include monitoring populations and protecting beneficial insects.
FRUIT PRODUCTION NOTES
Alternate Bearing in Apples
Many apple varieties alternate between heavy and light production years.
- In heavy crop years, thin fruits to reduce strain and encourage consistent yields next season.
- Thinning also improves fruit size and reduces limb breakage.
PESTICIDE AND BIOLOGICAL OPTIONS FOR FIRE BLIGHT
Refer to the full table on page 5 for:
- Antibiotic options (e.g., Oxytetracycline, Kasugamycin)
- Biological products (e.g., Serenade, BlightBan, Regalia)
- Copper-based sprays for pre-bloom or dormant application
UPCOMING HOME GARDEN TIPS WEBINARS - Check the PDF attached
View full schedule in the attached PDF or join online at:
Beet Leafhopper Detected in Malheur County, Oregon
Sugarbeets Treasure Valley, Treasure Valley - Idaho, Treasure Valley Oregon
Beet leafhoppers (Circulifer tenellus)
Posted on: June 9, 2025 by Jemila Chellappa
Beet Leafhopper Detected in Malheur County
Treasure Valley – Malheur County, Oregon
June 4, 2025
Pest Detected:
Beet leafhoppers (Circulifer tenellus), the insect vectors responsible for transmitting both Beet Leafhopper-Transmitted Virescence Agent (BLTVA) and Beet Curly Top Virus (BCTV), were detected in all 12 fields surveyed during recent monitoring in Malheur County. These pathogens can cause significant yield and quality losses in potatoes and sugar, two economically important crops in the Treasure Valley:
- Beet Leafhopper-Transmitted Virescence Agent (BLTVA) – causes purple top disease in potatoes
- Beet Curly Top Virus (BCTV) – affects sugar beets and other broadleaf crops
Identification:
- Adults: Small (3.4–3.7 mm), wedge-shaped, pale green to yellowish, quick to fly when disturbed
- Nymphs: Wingless, flattened, yellow-green with visible wing pads
- Often found on broadleaf weeds and crop foliage
Symptoms of Infection:
Potatoes (BLTVA – Purple Top):
- Upright, stunted plant growth
- Rolling or curling of upper leaves
- Purpling or reddening of leaves
- Aerial tuber formation
- Early vine death and reduced tuber yield/quality
Sugar Beets (BCTV):
- Yellowing and thickening of leaves
- Leaf curling and brittleness
- Stunted plants; potential wilting or death in severe infections
Symptoms are most severe when infection occurs early in the growing season.
Scouting & Monitoring:
- Use sweep nets or yellow sticky traps to monitor populations. It is important to deploy more than one trap per field and check them regularly. When the average catch rate approaches 40–100 per week, action may be warranted.
- Begin scouting early, particularly during warm, dry spring conditions
- Focus on field borders and areas with broadleaf weeds (e.g., kochia, mustards, Russian thistle) that serve as host plants
Management Recommendations:
Cultural Control:
- Eliminate broadleaf weeds and volunteer crops along field edges and irrigation canals to reduce overwintering and early-season host sites
- Avoid planting near known beet leafhopper overwintering zones when possible
- Plant approved curly top-resistant varieties rather than relying solely on adult insect control
- Maintain good field sanitation and monitor surrounding non-crop vegetation
Chemical Control:
- Use neonicotinoid seed treatments for early-season protection
- Choose insecticides with translaminar or systemic activity for improved efficacy
- Group 4A and 3A products have shown the highest efficacy
- Rotate insecticide groups to mitigate resistance development
Integrated Pest Management (IPM):
- Combine cultural, chemical, and monitoring practices
- Track regional pest trends to support timely and informed intervention
Oregon State University
OSU Extension Service—Malheur County
710 SW 5th Avenue , Ontario, Oregon 97914
Tel:541-881-1417
Growing Degree Days Calculator
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho
Posted on: June 7, 2025 by Jemila Chellappa
New Feature Alert: Celebrate World Pest Awareness Day with PNW Pest Alert!
In honor of World Pest Awareness Day (June 6), we’re thrilled to announce a powerful new tool now available on www.pnw.pestalert.net
We’re excited to launch a brand-new tool on www.pestalert.net
Our Growing Degree Day (GDD) Calculator is now LIVE – designed to help you track pest development stages and make informed management decisions tailored to your location and crops. Check it out now: https://pnwpestalert.net/gdd/
Pest Alert – Codling Moth Activity Increasing in Apples
Apple Treasure Valley, Treasure Valley - Idaho
Codling Moth
Posted on: June 3, 2025 by Jemila Chellappa
Treasure Valley (Canyon County, Idaho)
June 2025
Moth captures confirmed from pheromone trap at local orchard (7 moths/trap/week)
Codling moth (Cydia pomonella) adult flight is active in the Treasure Valley region, with degree day (GDD) accumulations reaching ~680 (Base 50°F) as of June 2, 2025. Trap monitoring has confirmed moderate to high pressure, with 7 moths captured per trap this week.
- Track daily GDDs to prepare for second-generation sprays (expected at 1000–1100 GDD).
- Continue weekly trap monitoring to refine timing.
This timing coincides with peak first-generation egg hatch. Immediate action is advised to prevent worm damage to apples.
- Egg hatch typically begins at 250 GDD
- Peak egg hatch occurs between 650–750 GDD
- Now, in the critical larval emergence window
Recommended IPM Management Actions: Spray Immediately to Control Larvae
Apply a larvicide now to target newly hatched larvae. Follow label instructions and re-treatment intervals. Reapply if moth captures remain above the threshold.
Cultural & Mechanical Controls
- Thin fruit clusters to reduce entry points (leave one fruit per cluster, space ~6" apart).
- Remove and destroy infested or fallen fruit weekly.
- Bag fruit at quarter-size after spraying (brown paper bags or nylon footies with kaolin clay pre-soak).
- Keep trap records: If weekly trap catch exceeds 5–10 moths per trap, additional sprays may be needed.
Resistance Management
- Rotate modes of action (IRAC group) each generation to avoid resistance.
- Limit broad-spectrum insecticides that can flare up mites and reduce beneficial insects.
There are different management options to consider when controlling this pest.There are different management options to consider when controlling this pest.
https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth
Option A: Starting at 200 DD, apply a mixture of water and horticultural oil at 1% concentration to smother egg infestation. Follow with the first application of insecticide at 350 DD. Reapply insecticides based on the protection interval stated on the label.
Option B: Starting at 220-250 DD, apply insecticides that target newly hatched larvae. Reapply insecticides based on the protection interval stated on the label.
The reference publication links to view insecticide options for commercial or residential sites.
This pest needs prevention all season long for clean fruit.
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1879&context=extension_curall
https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/
To report pest activity in your area: https://pnwpestalert.net/submitalert/
Summer 2025 Heat Wave Forecast: Be Prepared for Heat Stress in the Field!
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho
Heat Wave Forecast
Posted on: June 2, 2025 by Jemila Chellappa
"Protect Yourself and Your Crew from Extreme Heat: Gear up and Stay Hydrated"
According to NOAA's Climate Prediction Center the 2025 summer forecast calls for 'overwhelmingly above normal' heat starting in June link: Please take a moment to familiarize yourself with the symptoms of heat related illnesses and what actions to take.
Environmental Health and Safety links:
Managing-heat-stress-with-faqs
CDC links:
HeatRisk | Tracking | NCEH | CDC
About Heat and Your Health | Heat Health | CDC
Heat-related Illnesses | Heat | CDC
Remember to drink plenty of fluids, wear appropriate clothing, sunscreen, and pace yourselves.
More Information: Beth Brune
Operations Manager
University of Idaho | Kimberly R&E Center, Kimberly, ID 83341
Email: bbrune@uidaho.edu
Eastern Idaho Pest Alert MAY 30, 2025 VOL. 6 ISS. 3
All Crops Eastern Idaho, Magic Valley
Pest Alerts from Bonneville County – Eastern Idaho
Posted on: June 1, 2025 by Jemila Chellappa
Coverage Areas: Bannock, Bingham, Bonneville, Cassia, Fremont, Jefferson, Madison, and Teton Counties
CURRENT PEST AND DISEASE ISSUES
Fire Blight Alert
- Fire blight risk levels are Exceptional to Extreme across most regions in Eastern Idaho through mid-June.
- High-risk management includes:
- Pruning out infections on dry days.
- Disinfecting tools between cuts.
- Applying antibiotics within 24 hours of a wetting event when blossoms are open.
- Consider biological control products for resistance management.
- A full table of risk periods by location is provided, with tailored spray guidance.
Codling Moth Management
- Egg hatch timing is highly variable due to weather.
- Management recommendations differ based on past fruit damage levels and whether growers use conventional or organic approaches.
- Conventional:
- Two sprays per generation recommended for high damage history.
- Fewer sprays for low-damage history, starting with oil or insecticide.
- Organic:
- Three sprays spaced 7–10 days apart for high-damage history.
- Two sprays per generation for low-damage history.
- Backyard tree treatment options include both conventional and organic products.
Leafhoppers
- Feeding causes stippling on leaf surfaces and can damage fruit.
- Monitoring and management are advised, especially for sensitive crops.
FRUIT PRODUCTION NOTES
Alternate Bearing in Apples
- Many apple varieties exhibit alternate bearing with heavy crops every other year.
- Best management is to thin fruits in heavy years to balance future yields.
PESTICIDE AND BIOLOGICAL OPTIONS FOR FIRE BLIGHT
UPCOMING HOME GARDEN TIPS WEBINARS: Check the PDF attached
Let’s work together to protect both our crops and our ecosystem. Reach out to your local Extension office for help with insect ID and integrated pest management (IPM) strategies tailored for your area https://www.uidaho.edu/extension/directory/counties
More Information, Contact:
Lena Allen
Horticulture Secretary
University of Idaho
Bonneville County Extension
208.529.1390
» Pest_Alert_May_30_2025_alternate_bearing_fruit,_leafhopper.pdf
Pest Alert: Found One Codling Moth in the Canyon County Apple Trees
Apple Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley
Apple Codling Moth
Posted on: May 28, 2025 by Jemila Chellappa
Codling moth is a key insect pest of apples and pears in Idaho. Left unmanaged, it can cause "wormy" fruit and significant crop loss.
Identification – Know the Signs & Symptoms
Stage | Identification |
Adult Moth | Grayish-brown, 1/2 inch long, with a coppery-brown band at wing tips. |
Egg | Tiny, flat, and translucent – laid singly on fruit or leaves. |
Larva | Creamy white to pink caterpillar with a dark brown head – this is the “worm.” |
Pupa | Formed in bark crevices or leaf litter in silken cocoons. |
Symptoms on Fruit:
- Small, dark entry holes ("sting") on the apple surface.
- Frass (sawdust-like excrement) near the hole.
- Tunnels inside the fruit leading to the core.
- Premature fruit drop in severe infestations.
Current Monitoring & Degree Days
- Biofix (first moth detected): Mid-May
- Current Degree Days (base 50°F): 206 DD as of May 18
- Egg hatch begins: 220–250 DD – NOW is the time for action!
Management Options
Option A: Early Prevention (Egg Smothering)
- When: At 200 DD
- Action: Apply horticultural oil (1% concentration) to suffocate eggs.
- Follow-Up: Insecticide at 350 DD.
Option B: Target Larvae
- When: 220–250 DD
- Action: Apply insecticides to kill newly hatched larvae before they burrow into fruit.
Insecticide Options: Refer https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth
Always read and follow the label directions for safety and effectiveness.
Non-Chemical Options
- Fruit Bagging: Bag individual fruitlets to block larvae entry.
- Sanitation: Remove dropped fruit and prune trees to reduce overwintering sites.
- Trapping: Use pheromone traps to monitor moth flights and guide sprays.
Season-Long Strategy: Codling moth has multiple generations per season. Continue monitoring traps and tracking degree days to time follow-up sprays or control measures.
Helpful Resources
https://climate.usu.edu/includes/pestFactSheets/Codling-Moth.pdf
https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/
For more assistance, contact your local University of Idaho Extension office https://www.uidaho.edu/extension/directory/counties
Keep your fruit clean and healthy – act now!
Eastern Idaho Pest Alert – May 23, 2025 | Vol. 6, Iss. 2
All Crops Eastern Idaho, Magic Valley
Eastrern Idaho Pest Alert
Posted on: May 23, 2025 by Jemila Chellappa
Pest Alerts from Bonneville County – Eastern Idaho
As temperatures begin to rise across, many of us are starting to notice increased insect activity in our fields, gardens, and landscapes. It’s natural to feel the urge to reach for an insecticide at the first sign of bugs—but we encourage you to pause and take a closer look. Not all insects are harmful, and many play important roles in pollination, natural pest control, and maintaining ecological balance.
Spraying too early or without proper identification can unintentionally harm beneficial insects and disrupt the natural balance of your growing environment. Whenever possible:
- Identify the insect first—Is it a pest, a predator, or a pollinator?
- Monitor populations—Are the numbers high enough to justify treatment?
- Consider non-chemical options, such as biological or cultural controls.
Let’s work together to protect both our crops and our ecosystem. Reach out to your local Extension office for help with insect ID and integrated pest management (IPM) strategies tailored for your area. https://www.uidaho.edu/extension/directory/counties
Stay informed, and spray smarter! Find more information in the attached newsletter -Temperature Watch: Recent warm days may be misleading—nighttime temps below 40°F can damage tender plants such as tomatoes, peppers, cucumbers, squash, beans, and zinnias. Be ready to protect your plants!
Garden Tip – Hardening Off Transplants: Give new plants time to adjust outdoors.
Weed Alert – Quackgrass: Spreading aggressively by rhizomes and seeds, quackgrass is hard to control in lawns and flower beds.
Fire Blight Update: Cool temps have kept fire blight risk low, but risk will increase as temperatures rise and trees bloom. Monitor forecasts and prune infected tissue early.
Fire blight risk levels vary across locations—some areas entering High to Extreme Risk by late May.
Codling Moth Monitoring: Moths detected in warmer locations, but no spray timing yet for Eastern Idaho. Continue monitoring traps. Spray dates TBD.
Backyard Control Options Listed – Both conventional and organic sprays outlined for codling moth. Be sure to rotate products each generation. Full list available in the alert bulletin.
Upcoming UI Extension Events: Check the PDF attached
More Information, contact:
Lena Allen
Horticulture Secretary
University of Idaho
Bonneville County Extension
208.529.1390
Potato Growing Degree Days
Potato All Locations
Posted on: May 22, 2025 by Nora Olsen
Calculating growing degree days (GDD) or heat units is one method to look at the effect of temperature on the potato crop. Plant growth and development is greatly influenced by temperature, and we use GDD to get an idea of how the plant is developing throughout the season. It also gives a great perspective of how the current season compares to previous seasons.
To quantify this period of cold temperatures, we collated the cumulative GDDs for Parma, Kimberly and Shelley. The source of the GDD was AgriMet (www.usbr.gov/pn/agrimet/wxdata.html) weather stations located at the three sites. Daily GDD is calculated by adding the maximum temperature and the minimum temperature, dividing by 2 and subtracting a base temperature. The base temperature is used to define the temperature at which potato growth is diminished. The AgriMet calculation of GDD uses 50F as a minimum and 86F as a maximum. There are limitations to the use of these minimum and maximums since potatoes will grow outside of this range, but these calculations can still provide a reasonable prediction of the temperatures impacting potato growth.
To help provide a picture of the relationship between temperature and plant development, we will continue to update the GDD graphs weekly for the three locations and post at www.uidaho.edu/cals/potatoes/storage.
The graphs may look a little different this year than in the past. Click on the arrow near the top to toggle between the three growing locations. Also, use the dropdown menu to add or subtract the years you want to compare. The black line is 2025. The graphs will be updated weekly.
Onion Thrips Activity Increasing in the Treasure Valley
All Crops Treasure Valley, Treasure Valley - Idaho, Treasure Valley Oregon
Onion Thrips (Thrips tabaci)
Posted on: June 18, 2025 by Jemila Chellappa
Pest Alert: Onion Thrips Activity Increasing in the Treasure Valley
Crop: Dry Bulb Onion
Pest: Onion Thrips (Thrips tabaci)
Region: Treasure Valley – Oregon and Idaho
Onion thrips populations are increasing across the region, with presence confirmed in over 97% of monitored onion fields. In many of those fields, more than 80% of plants are now infested. Fields with more mature, larger plants are showing particularly elevated activity. Smaller, early-stage fields (3-leaf stage or younger) remain largely unaffected, but this is expected to change as the season progresses.
Thrips Identification & Lifecycle
Adult onion thrips are tiny (1–1.3 mm), slender, pale yellow to brown insects with fringed wings. Immature stages (called larvae or nymphs) are wingless and lighter in color. Thrips thrive in hot, dry conditions and reproduce rapidly, often completing multiple generations per season. Eggs are laid within the leaf tissue, and nymphs feed on sap, developing through several instars before pupating in the soil or leaf axils.
What to Watch For
- Silvery streaks or flecking on leaves caused by feeding
- Black specks (excrement) near feeding sites
- Thrips concentrated in leaf folds, near the neck, or under tight canopies
- Reduced vigor or curling of young leaves
Thrips infestations can reduce onion yield by 20% or more. While no significant signs of Iris Yellow Spot Virus (IYSV) have been confirmed so far this season, continued vigilance is important, especially as thrips numbers build. IYSV lesions appear as oval to diamond-shaped chlorotic or necrotic spots on leaves, reducing photosynthetic efficiency and negatively affecting bulb storage.
Management Recommendations
Coverage is Key:
As canopy density increases, spray coverage becomes more challenging. Increase spray volumes to ensure deeper penetration into the neck and inner foliage, where thrips hide.
Insecticide Strategy:
- Systemic products (e.g., Movento) are effective by moving through plant tissues and targeting hidden feeding sites.
- Translaminar products (e.g., Radiant) enter the leaf surface and reach thrips feeding on the undersides or inside folds.
- Adjuvants: Use a penetrating adjuvant to enhance uptake and movement of active ingredients within plant tissue.
Cultural Practices:
- Avoid excessive nitrogen, which can promote lush growth and higher thrips populations.
- Monitor weed presence, as weeds can serve as alternate thrips hosts.
- Early planting and maintaining strong plant vigor can help plants tolerate feeding pressure better.
Resistance Management:
Rotate insecticides with different modes of action to delay resistance development. Always follow label directions and recommended thresholds.
Scouting Tips
- Start scouting early and continue weekly, especially as plants reach the 5–7 leaf stage.
- Sample at least five plants from four separate areas of the field.
- Use hand lenses or beat plants over a white surface to count individuals.
- Focus on inner leaves and the base of the neck.
- Threshold: Begin treatments when thrips exceed 1–3 per leaf, depending on crop stage and environmental conditions.
Stay vigilant. Early and consistent management of onion thrips helps protect yield potential and reduce the risk of IYSV later in the season.
More management information here https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/onion-thrips
This alert was prepared by Russell Smith Ollivierre, Oregon State University Malheur County Extension, with data contributions from Stuart Reitz, Oregon State University Malheur Experiment Station.
» https://pnwhandbooks.org/insect/vegetable/vegetable-pests/hosts-pests/onion-thrips
Strawberry Root Weevil Pupa
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho, Treasure Valley Oregon
Strawberry Root Weevil
Posted on: June 12, 2025 by Jemila Chellappa
Strawberry Root Weevil Alert – Be on the Lookout!
Found Strawberry Root Weevil pupae in Treasure Valley: The pupa of the strawberry root weevil (Otiorhynchus ovatus) is a transitional life stage between the larva and adult, typically found in the soil near the root zone of host plants. Here are the key characteristics:
Strawberry Root Weevil – Pupal Stage Characteristics:
- Color: Initially creamy white; may turn light tan as it matures.
- Shape: Soft-bodied, oblong, and slightly curved. The body is segmented and resembles the general adult form.
- Size: About 5–7 mm in length, depending on species and development stage.
- Visibility of adult features: The legs, antennae, and developing snout (rostrum) of the adult are visible but folded close to the body.
- Habitat: Pupates in an earthen cell or cavity in the soil, usually close to the roots of infested strawberry or other host plants.
- Duration: The Pupal stage generally lasts 2–3 weeks in spring (April–June), depending on temperature and soil conditions.
- Mobility: Pupae are non-feeding and immobile.
Since pupae are hidden in the soil, they are rarely observed unless the soil is carefully excavated near the crown and roots of the plant. Refer to the attached file for a visual reference of the Strawberry Root Weevil Pupa
Strawberry root weevils (Otiorhynchus spp.) are common pests in strawberry fields across the Pacific Northwest. While adult weevils cause minor notching on leaves, the real damage comes from their larvae feeding on roots through winter and spring, leading to stunted growth, reduced yields, or even plant death in severe cases.
What to Watch For:
- Notched leaves from adult feeding (visible in early summer)
- Wilting or stunted plants from root damage
- Adults hide under plant debris during the day or emerge at night
Now is the time to inspect your strawberry fields. Check for notched leaves, look under plant debris, or monitor at night for adult activity. Early detection is key to preventing egg-laying and larval root damage.
If you notice signs, consider control options including biological (entomopathogenic nematodes), cultural (soil cultivation), or chemical treatments applied at night for best results. More management information here https://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil
Stay alert and protect your berries!
» https://pnwhandbooks.org/insect/small-fruit/strawberry/strawberry-root-weevil
Eastern Idaho Pest Alert June 6, 2025 | Vol. 6, Issue 4
All Crops Eastern Idaho
Pest Alerts from Bonneville County – Eastern Idaho
Posted on: June 10, 2025 by Jemila Chellappa
Eastern Idaho Pest Alert June 6, 2025 | Vol. 6, Issue 4
Coverage Areas: Bannock, Bingham, Bonneville, Cassia, Fremont, Jefferson, Madison, and Teton Counties
CURRENT PEST AND DISEASE ISSUES
Fire Blight Alert
Fire blight risk levels are Exceptional to Extreme across most of Eastern Idaho through mid-June.
High-risk management strategies:
- Prune infected twigs and branches on dry days.
- Disinfect tools between each cut using alcohol, bleach solution, or disinfectant wipes.
- Apply antibiotics within 24 hours of a wetting event (rain or heavy dew) when blossoms are open.
- Biological control products (e.g., Blossom Protect, Double Nickel) are recommended for resistance management and organic systems.
Codling Moth Management
Egg hatch timing is highly variable due to unusual weather patterns this spring. Spray timing depends on prior fruit damage and production system.
Conventional Orchards:
- High damage history: Apply 2 sprays per generation (start with oil or insecticide).
- Low damage history: Fewer sprays needed, often just 1 per generation.
Organic Orchards:
- High damage history: 3 sprays per generation, spaced 7–10 days apart.
- Low damage history: 2 sprays per generation.
Backyard Trees:
- Treatment options include conventional (e.g., Triazicide, Sevin) and organic (e.g., Cyd-X, Neem oil, Spinosad) products. See page 7 for efficacy and timing.
Leafhoppers
- Leafhoppers feed on plant sap, causing stippling and potential fruit damage.
- Regular scouting is advised for sensitive crops like apples, pears, and grapes.
- IPM strategies include monitoring populations and protecting beneficial insects.
FRUIT PRODUCTION NOTES
Alternate Bearing in Apples
Many apple varieties alternate between heavy and light production years.
- In heavy crop years, thin fruits to reduce strain and encourage consistent yields next season.
- Thinning also improves fruit size and reduces limb breakage.
PESTICIDE AND BIOLOGICAL OPTIONS FOR FIRE BLIGHT
Refer to the full table on page 5 for:
- Antibiotic options (e.g., Oxytetracycline, Kasugamycin)
- Biological products (e.g., Serenade, BlightBan, Regalia)
- Copper-based sprays for pre-bloom or dormant application
UPCOMING HOME GARDEN TIPS WEBINARS - Check the PDF attached
View full schedule in the attached PDF or join online at:
» Pest_Alert_June_6_apple_wooly_aphid,_snake_fly.pdf
Beet Leafhopper Detected in Malheur County, Oregon
Sugarbeets Treasure Valley, Treasure Valley - Idaho, Treasure Valley Oregon
Beet leafhoppers (Circulifer tenellus)
Posted on: June 9, 2025 by Jemila Chellappa
Beet Leafhopper Detected in Malheur County
Treasure Valley – Malheur County, Oregon
June 4, 2025
Pest Detected:
Beet leafhoppers (Circulifer tenellus), the insect vectors responsible for transmitting both Beet Leafhopper-Transmitted Virescence Agent (BLTVA) and Beet Curly Top Virus (BCTV), were detected in all 12 fields surveyed during recent monitoring in Malheur County. These pathogens can cause significant yield and quality losses in potatoes and sugar, two economically important crops in the Treasure Valley:
- Beet Leafhopper-Transmitted Virescence Agent (BLTVA) – causes purple top disease in potatoes
- Beet Curly Top Virus (BCTV) – affects sugar beets and other broadleaf crops
Identification:
- Adults: Small (3.4–3.7 mm), wedge-shaped, pale green to yellowish, quick to fly when disturbed
- Nymphs: Wingless, flattened, yellow-green with visible wing pads
- Often found on broadleaf weeds and crop foliage
Symptoms of Infection:
Potatoes (BLTVA – Purple Top):
- Upright, stunted plant growth
- Rolling or curling of upper leaves
- Purpling or reddening of leaves
- Aerial tuber formation
- Early vine death and reduced tuber yield/quality
Sugar Beets (BCTV):
- Yellowing and thickening of leaves
- Leaf curling and brittleness
- Stunted plants; potential wilting or death in severe infections
Symptoms are most severe when infection occurs early in the growing season.
Scouting & Monitoring:
- Use sweep nets or yellow sticky traps to monitor populations. It is important to deploy more than one trap per field and check them regularly. When the average catch rate approaches 40–100 per week, action may be warranted.
- Begin scouting early, particularly during warm, dry spring conditions
- Focus on field borders and areas with broadleaf weeds (e.g., kochia, mustards, Russian thistle) that serve as host plants
Management Recommendations:
Cultural Control:
- Eliminate broadleaf weeds and volunteer crops along field edges and irrigation canals to reduce overwintering and early-season host sites
- Avoid planting near known beet leafhopper overwintering zones when possible
- Plant approved curly top-resistant varieties rather than relying solely on adult insect control
- Maintain good field sanitation and monitor surrounding non-crop vegetation
Chemical Control:
- Use neonicotinoid seed treatments for early-season protection
- Choose insecticides with translaminar or systemic activity for improved efficacy
- Group 4A and 3A products have shown the highest efficacy
- Rotate insecticide groups to mitigate resistance development
Integrated Pest Management (IPM):
- Combine cultural, chemical, and monitoring practices
- Track regional pest trends to support timely and informed intervention
Oregon State University
OSU Extension Service—Malheur County
710 SW 5th Avenue , Ontario, Oregon 97914
Tel:541-881-1417
Growing Degree Days Calculator
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho
Posted on: June 7, 2025 by Jemila Chellappa
New Feature Alert: Celebrate World Pest Awareness Day with PNW Pest Alert!
In honor of World Pest Awareness Day (June 6), we’re thrilled to announce a powerful new tool now available on www.pnw.pestalert.net
We’re excited to launch a brand-new tool on www.pestalert.net
Our Growing Degree Day (GDD) Calculator is now LIVE – designed to help you track pest development stages and make informed management decisions tailored to your location and crops. Check it out now: https://pnwpestalert.net/gdd/
Pest Alert – Codling Moth Activity Increasing in Apples
Apple Treasure Valley, Treasure Valley - Idaho
Codling Moth
Posted on: June 3, 2025 by Jemila Chellappa
Treasure Valley (Canyon County, Idaho)
June 2025
Moth captures confirmed from pheromone trap at local orchard (7 moths/trap/week)
Codling moth (Cydia pomonella) adult flight is active in the Treasure Valley region, with degree day (GDD) accumulations reaching ~680 (Base 50°F) as of June 2, 2025. Trap monitoring has confirmed moderate to high pressure, with 7 moths captured per trap this week.
- Track daily GDDs to prepare for second-generation sprays (expected at 1000–1100 GDD).
- Continue weekly trap monitoring to refine timing.
This timing coincides with peak first-generation egg hatch. Immediate action is advised to prevent worm damage to apples.
- Egg hatch typically begins at 250 GDD
- Peak egg hatch occurs between 650–750 GDD
- Now, in the critical larval emergence window
Recommended IPM Management Actions: Spray Immediately to Control Larvae
Apply a larvicide now to target newly hatched larvae. Follow label instructions and re-treatment intervals. Reapply if moth captures remain above the threshold.
Cultural & Mechanical Controls
- Thin fruit clusters to reduce entry points (leave one fruit per cluster, space ~6" apart).
- Remove and destroy infested or fallen fruit weekly.
- Bag fruit at quarter-size after spraying (brown paper bags or nylon footies with kaolin clay pre-soak).
- Keep trap records: If weekly trap catch exceeds 5–10 moths per trap, additional sprays may be needed.
Resistance Management
- Rotate modes of action (IRAC group) each generation to avoid resistance.
- Limit broad-spectrum insecticides that can flare up mites and reduce beneficial insects.
There are different management options to consider when controlling this pest.There are different management options to consider when controlling this pest.
https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth
Option A: Starting at 200 DD, apply a mixture of water and horticultural oil at 1% concentration to smother egg infestation. Follow with the first application of insecticide at 350 DD. Reapply insecticides based on the protection interval stated on the label.
Option B: Starting at 220-250 DD, apply insecticides that target newly hatched larvae. Reapply insecticides based on the protection interval stated on the label.
The reference publication links to view insecticide options for commercial or residential sites.
This pest needs prevention all season long for clean fruit.
https://digitalcommons.usu.edu/cgi/viewcontent.cgi?article=1879&context=extension_curall
https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/
To report pest activity in your area: https://pnwpestalert.net/submitalert/
Summer 2025 Heat Wave Forecast: Be Prepared for Heat Stress in the Field!
All Crops Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley, Northern Idaho
Heat Wave Forecast
Posted on: June 2, 2025 by Jemila Chellappa
"Protect Yourself and Your Crew from Extreme Heat: Gear up and Stay Hydrated"
According to NOAA's Climate Prediction Center the 2025 summer forecast calls for 'overwhelmingly above normal' heat starting in June link: Please take a moment to familiarize yourself with the symptoms of heat related illnesses and what actions to take.
Environmental Health and Safety links:
Managing-heat-stress-with-faqs
CDC links:
HeatRisk | Tracking | NCEH | CDC
About Heat and Your Health | Heat Health | CDC
Heat-related Illnesses | Heat | CDC
Remember to drink plenty of fluids, wear appropriate clothing, sunscreen, and pace yourselves.
More Information: Beth Brune
Operations Manager
University of Idaho | Kimberly R&E Center, Kimberly, ID 83341
Email: bbrune@uidaho.edu
Eastern Idaho Pest Alert MAY 30, 2025 VOL. 6 ISS. 3
All Crops Eastern Idaho, Magic Valley
Pest Alerts from Bonneville County – Eastern Idaho
Posted on: June 1, 2025 by Jemila Chellappa
Coverage Areas: Bannock, Bingham, Bonneville, Cassia, Fremont, Jefferson, Madison, and Teton Counties
CURRENT PEST AND DISEASE ISSUES
Fire Blight Alert
- Fire blight risk levels are Exceptional to Extreme across most regions in Eastern Idaho through mid-June.
- High-risk management includes:
- Pruning out infections on dry days.
- Disinfecting tools between cuts.
- Applying antibiotics within 24 hours of a wetting event when blossoms are open.
- Consider biological control products for resistance management.
- A full table of risk periods by location is provided, with tailored spray guidance.
Codling Moth Management
- Egg hatch timing is highly variable due to weather.
- Management recommendations differ based on past fruit damage levels and whether growers use conventional or organic approaches.
- Conventional:
- Two sprays per generation recommended for high damage history.
- Fewer sprays for low-damage history, starting with oil or insecticide.
- Organic:
- Three sprays spaced 7–10 days apart for high-damage history.
- Two sprays per generation for low-damage history.
- Backyard tree treatment options include both conventional and organic products.
Leafhoppers
- Feeding causes stippling on leaf surfaces and can damage fruit.
- Monitoring and management are advised, especially for sensitive crops.
FRUIT PRODUCTION NOTES
Alternate Bearing in Apples
- Many apple varieties exhibit alternate bearing with heavy crops every other year.
- Best management is to thin fruits in heavy years to balance future yields.
PESTICIDE AND BIOLOGICAL OPTIONS FOR FIRE BLIGHT
UPCOMING HOME GARDEN TIPS WEBINARS: Check the PDF attached
Let’s work together to protect both our crops and our ecosystem. Reach out to your local Extension office for help with insect ID and integrated pest management (IPM) strategies tailored for your area https://www.uidaho.edu/extension/directory/counties
More Information, Contact:
Lena Allen
Horticulture Secretary
University of Idaho
Bonneville County Extension
208.529.1390
» Pest_Alert_May_30_2025_alternate_bearing_fruit,_leafhopper.pdf
Pest Alert: Found One Codling Moth in the Canyon County Apple Trees
Apple Treasure Valley, Treasure Valley - Idaho, Eastern Idaho, Magic Valley
Apple Codling Moth
Posted on: May 28, 2025 by Jemila Chellappa
Codling moth is a key insect pest of apples and pears in Idaho. Left unmanaged, it can cause "wormy" fruit and significant crop loss.
Identification – Know the Signs & Symptoms
Stage | Identification |
Adult Moth | Grayish-brown, 1/2 inch long, with a coppery-brown band at wing tips. |
Egg | Tiny, flat, and translucent – laid singly on fruit or leaves. |
Larva | Creamy white to pink caterpillar with a dark brown head – this is the “worm.” |
Pupa | Formed in bark crevices or leaf litter in silken cocoons. |
Symptoms on Fruit:
- Small, dark entry holes ("sting") on the apple surface.
- Frass (sawdust-like excrement) near the hole.
- Tunnels inside the fruit leading to the core.
- Premature fruit drop in severe infestations.
Current Monitoring & Degree Days
- Biofix (first moth detected): Mid-May
- Current Degree Days (base 50°F): 206 DD as of May 18
- Egg hatch begins: 220–250 DD – NOW is the time for action!
Management Options
Option A: Early Prevention (Egg Smothering)
- When: At 200 DD
- Action: Apply horticultural oil (1% concentration) to suffocate eggs.
- Follow-Up: Insecticide at 350 DD.
Option B: Target Larvae
- When: 220–250 DD
- Action: Apply insecticides to kill newly hatched larvae before they burrow into fruit.
Insecticide Options: Refer https://pnwhandbooks.org/insect/tree-fruit/apple/apple-codling-moth
Always read and follow the label directions for safety and effectiveness.
Non-Chemical Options
- Fruit Bagging: Bag individual fruitlets to block larvae entry.
- Sanitation: Remove dropped fruit and prune trees to reduce overwintering sites.
- Trapping: Use pheromone traps to monitor moth flights and guide sprays.
Season-Long Strategy: Codling moth has multiple generations per season. Continue monitoring traps and tracking degree days to time follow-up sprays or control measures.
Helpful Resources
https://climate.usu.edu/includes/pestFactSheets/Codling-Moth.pdf
https://extension.colostate.edu/topic-areas/insects/codling-moth-control-in-home-plantings-5-613/
For more assistance, contact your local University of Idaho Extension office https://www.uidaho.edu/extension/directory/counties
Keep your fruit clean and healthy – act now!
Eastern Idaho Pest Alert – May 23, 2025 | Vol. 6, Iss. 2
All Crops Eastern Idaho, Magic Valley
Eastrern Idaho Pest Alert
Posted on: May 23, 2025 by Jemila Chellappa
Pest Alerts from Bonneville County – Eastern Idaho
As temperatures begin to rise across, many of us are starting to notice increased insect activity in our fields, gardens, and landscapes. It’s natural to feel the urge to reach for an insecticide at the first sign of bugs—but we encourage you to pause and take a closer look. Not all insects are harmful, and many play important roles in pollination, natural pest control, and maintaining ecological balance.
Spraying too early or without proper identification can unintentionally harm beneficial insects and disrupt the natural balance of your growing environment. Whenever possible:
- Identify the insect first—Is it a pest, a predator, or a pollinator?
- Monitor populations—Are the numbers high enough to justify treatment?
- Consider non-chemical options, such as biological or cultural controls.
Let’s work together to protect both our crops and our ecosystem. Reach out to your local Extension office for help with insect ID and integrated pest management (IPM) strategies tailored for your area. https://www.uidaho.edu/extension/directory/counties
Stay informed, and spray smarter! Find more information in the attached newsletter -Temperature Watch: Recent warm days may be misleading—nighttime temps below 40°F can damage tender plants such as tomatoes, peppers, cucumbers, squash, beans, and zinnias. Be ready to protect your plants!
Garden Tip – Hardening Off Transplants: Give new plants time to adjust outdoors.
Weed Alert – Quackgrass: Spreading aggressively by rhizomes and seeds, quackgrass is hard to control in lawns and flower beds.
Fire Blight Update: Cool temps have kept fire blight risk low, but risk will increase as temperatures rise and trees bloom. Monitor forecasts and prune infected tissue early.
Fire blight risk levels vary across locations—some areas entering High to Extreme Risk by late May.
Codling Moth Monitoring: Moths detected in warmer locations, but no spray timing yet for Eastern Idaho. Continue monitoring traps. Spray dates TBD.
Backyard Control Options Listed – Both conventional and organic sprays outlined for codling moth. Be sure to rotate products each generation. Full list available in the alert bulletin.
Upcoming UI Extension Events: Check the PDF attached
More Information, contact:
Lena Allen
Horticulture Secretary
University of Idaho
Bonneville County Extension
208.529.1390
» Pest_Alert_May_23_2025_quackgrass_hardening_off.pdf
Potato Growing Degree Days
Potato All Locations
Posted on: May 22, 2025 by Nora Olsen
Calculating growing degree days (GDD) or heat units is one method to look at the effect of temperature on the potato crop. Plant growth and development is greatly influenced by temperature, and we use GDD to get an idea of how the plant is developing throughout the season. It also gives a great perspective of how the current season compares to previous seasons.
To quantify this period of cold temperatures, we collated the cumulative GDDs for Parma, Kimberly and Shelley. The source of the GDD was AgriMet (www.usbr.gov/pn/agrimet/wxdata.html) weather stations located at the three sites. Daily GDD is calculated by adding the maximum temperature and the minimum temperature, dividing by 2 and subtracting a base temperature. The base temperature is used to define the temperature at which potato growth is diminished. The AgriMet calculation of GDD uses 50F as a minimum and 86F as a maximum. There are limitations to the use of these minimum and maximums since potatoes will grow outside of this range, but these calculations can still provide a reasonable prediction of the temperatures impacting potato growth.
To help provide a picture of the relationship between temperature and plant development, we will continue to update the GDD graphs weekly for the three locations and post at www.uidaho.edu/cals/potatoes/storage.
The graphs may look a little different this year than in the past. Click on the arrow near the top to toggle between the three growing locations. Also, use the dropdown menu to add or subtract the years you want to compare. The black line is 2025. The graphs will be updated weekly.
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