Current Alerts

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

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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

More Information 

Contact: Russell Smith-Ollivierre | Agriculture Outreach Program Coordinator

Oregon State University

OSU Extension Service—Malheur County

710 SW 5th Avenue , Ontario, Oregon 97914 

Tel:541-881-1417