Preparing for plum curculio in apple orchards (conventional and organic methods)

Article written by Madeline Wimmer, UMN Extension Fruit Production Educator.

A close up image of a plum curculio insect on a leaf.

Plum curculio is one of many insect pests that impact apple production in Minnesota. Photo from the University of Minnesota website.

Plum curculio (Conotrachelus nenuphar) is a North American native, common pest of apples and other tree fruits in the Upper Midwest. Impact on apples tends to lead to scars (often looking like a crescent moon) since eggs are laid beneath the skin, but are usually crushed as the apple fruit grows; however apples can also drop early and are susceptible to feeding by adults, which also causes damage. The scars from egg-laying (i.e., ovipositing) are safe to eat, but it does affect fruit appearance and marketability. Fruit can additionally look somewhat dimpled or deformed.

Plum curculio adults are active and management is typically needed until around 308-340 DD (base 50 °F) have accumulated after petal fall, which can be monitored through a model like Cornell’s NEWA plum curculio model.

Life cycle

Plum curculio tends to overwinter in forest edges under debris. During petal fall, plum curculio adults can begin entering (walking with lower temperatures and flying when warmer) the orchard perimeters when temperatures are consistently above 60 °F and start ovipositing, or laying eggs underneath the fruit skin as soon as fruits reach 5 mm. Adults tend to be most active during the night with activity slowing down when temperatures dip below 50 °F. Because their activity is temperature dependent, egg-laying can be completed as quickly as two weeks during warm periods, or last four-to-six weeks during cooler conditions.

Monitoring: Scouting and trapping

Scouting

Growers can scout for plum curculio daily after petal fall since this is the most critical management period for plum curculio. Plum curculio adults are dark brown weevil beetles that are about ¼ inch long, with light patches and four humps located on their back (wing covers). Scout by looking for slit-like scars on fruitlets, especially on orchard perimeter rows. Beating trays can also be used to check for plum curculio within the tree canopies.

Growers who have had heavier plum curculio pressure during previous growing seasons may begin scouting earlier as plum curculio can show up as early as bloom. It’s additionally recommended to check earlier blooming varieties that will reach petal fall first.

Trapping

A tedder trap with a lure positioned above it with trees in the background.

This tedder, or pyramid style trap is positioned at the edge of the orchard at Door Creek Orchard in Cottage Grove, WI. Photo taken on April 27, 2026.

Several different styles of traps also exist for monitoring plum curculio populations. The main ones include circle trunk traps that wrap around trees, and pyramid traps, also known as tedders, which can be installed along orchard forest edges and checked multiple times a week.

I recently spoke to Liz Griffith of Door Creek Orchard in Cottage Grove Wisconsin, who primarily follows organic practices and prefers tedders, observing less success with circle trunk traps for trapping plum curculio. She also secures plum essence to her traps as a lure for plum curculio.

Notes about trapping:

The traps work well for detection, but are not a management method.
Benzaldehyde can also be used as a lure and alternative to plum essence.
Both styles of traps and the lure are available on the Great Lakes IPM website for purchase.
When using insecticides, the first application can be made when .1 adults are found per day (i.e., 1 adult in 1 trap within 10 days, 1 adult in 2 traps within 5 days, or 1 adult in 5 traps within 2 days). This decision is best made in conjunction of working with a prediction model like Cornell's NEWA program.

Management

Conventional

The Midwest Fruit Pest Management Guide (MFPMG) lists a number of chemical options for plum curculio management with a few caveats. Pyrethroids (e.g., Asana, Baythroid, Danitol, Mustang Maxx, Permethrin, and Warrior) can kill beneficial insects, as well as predatory mites when used during petal fall. When predatory mite and pest mite populations are out of balance, European red mite or two-spotted spider mite population outbreaks can occur when the conditions are right.

Additionally, the MFPMG also mentions carbaryl products (e.g., Sevin) can also be a knockdown insecticide for plum curculio, but additionally act as fruit thinners for apples and may lead to fruit drop when used at petal fall. Conventional alternatives to these products include Avaunt and Imidan.

Organic

Surround is a product that is made from kaolin clay and can be used to proactively deter plum curculio in an orchard. It is commonly used in organic orchards, but applications need to be carefully strategized to maintain continuous tank agitation and nozzle care to prevent damage to the sprayer. Surround works best when applied before periods of egg laying, and reapplied after rainfall if it washes off.

While the MFPMG lists Entrust SC (spinosad) as effective against oriental fruit moth during petal fall, it does not list it as an effective product for managing plum curculio during this time. This may be because it has a short residual window and any effectiveness may be based on ideal timing for when plum curculio is active. Pyganic, another organic approved product, is a knockdown product with even less residual activity than Entrust SC, and may not be a good substitute.

One other product that is OMRI approved and registered for plum curculio and apples is Venerate XC. It works by causing exoskeleton degradation through contact and/or ingestion of the product. Due to this mode of action and limited research done with Venerate XC specifically on plum curculio, it might be most helpful to trial its use in conjunction with another tactic like Surround to test its effectiveness in your orchard, while also applying it based on scouting and degree day models for good timing.

Notes about management:

Removing wild fruit trees, like wild plum, near orchard woodlands can reduce populations.
Small scale orchards that are aiming to go low-no spray can practice beating trees daily with something underneath to catch and dispose of adults.
Application timing is essential to managing plum curculio.

A note on apple curculio (Anthonomus quadrigibbus)

While plum curculio is a major pest of apples, there also exists a lesser-known pest commonly known as the apple curculio (Anthonomus quadrigibbus) that can become problematic for some orchards.

Apple curculio differs from plum curculio by the ovipositing wound they leave on fruits after egg laying, and those eggs/larvae that survive will continue to pupate within fallen apple fruits. This makes removing fallen fruits from the orchard floor a good management for apple curculio, in particular.

For more information on apple curculio in apple production, check out the article below: