Mastering Clean Starts: Best Practices for Introducing Pest-Free Strawberry Plants

Most Growers and IPM Managers know that the first days after transplant are make-or-break for your crop’s success. A single infested plant can unleash aphids, mites, or thrips that can quickly wreak havoc in a greenhouse. The stakes are high: lost yield, costly interventions, and even the spread of devastating viruses. But you’re not powerless. With the right plan, you can start clean and stay clean. 

The Problem: Invisible Threats at Transplant 

At every replant, thousands of young strawberry plants arrive at your facility. But beneath the lush leaves and healthy roots, pests may be hitching a ride. Aphids, spider mites, and thrips are the usual suspects: tiny, hard to spot, and quick to reproduce. The worst part? They’re experts at slipping past even the most vigilant inspection. 

Why is this a crisis? 

Pests like the strawberry aphid don’t just sap plant vigor; they’re notorious for spreading viruses that can cripple your crop and your bottom line. Pest establishment can begin before your plants even arrive at your farm, and by the time you see symptoms like silvery patches, distorted leaves, or stunted growth, the damage is already done. The best defense? A clean start. 

The Guide: Crop Defenders’ Grower-Tested Approach 

At Crop Defenders, we have worked shoulder-to-shoulder with the largest greenhouse strawberry Growers in Canada and the United States with a sustainability-focused approach built on three pillars: inspection, immediate action, and biological prevention. 

1. Inspection: Spotting Trouble Before It Starts 

Aphids: 

• Look for clusters of pale green or yellow insects, especially on the undersides of new, uncurled leaves.  

• Use a hand lens to spot the distinctive knobbed hairs on strawberry aphids.  

• They are often concentrated near the crown and base of young foliage. Early infestations may also show sticky honeydew or black sooty mold. 

Western Flower Thrips (Adults and Larvae): 

• Adults are tiny, slender, tan to dark brown insects with fringed wings. They often hide in flowers, folded leaves, or deep crevices. Look for signs like silvering, leaf distortion, or bronzed petals. 

• Larvae are even smaller (0.5 mm), pale yellow to creamy-white, and wingless. They feed directly on plant tissue and are often missed in scouting. Focus on flower buds and new growth and use a fine brush or tap test to dislodge them onto a sticky card or paper for counting. 

Two-Spotted Spider Mites (TSSM): 

• Tiny webbing and stippling on the upper leaf surface are classic signs. These mites prefer dry conditions and quickly colonize under high heat or light stress.  

• Look for bronzing or crisping on older leaves and check near midribs or along major veins. 

Cyclamen Mites: 

• These microscopic mites hide deep in the crown and feed on the newest, still-folded leaves.  

• Symptoms include crinkled or brittle young leaves, tight or malformed flowers, greasy petioles, and a dull, cracked texture on developing fruit caps.  

• Unlike TSSM, cyclamen mites thrive in high humidity and low air movement, especially in propagation or shaded zones. 

Inspection Tips 

• Inspect every shipment, every time. Assume there could be a potential risk of infestation.  

• Focus on new growth and leaf undersides. Pests love these spots. 

• Use magnification. A simple hand lens can help with detection and identification. 

• Document everything. Record pest and plant conditions. 

2. Immediate Action: Plant Dip Protocols 

Why Dip? A plant dip is your first line of defense. It’s a proven way to knock down pest populations before they enter your greenhouse. Research shows that dipping plants for 2–5 minutes in an appropriate solution can significantly reduce pest loads.  

How to Dip:

• Prepare a dip solution recommended for strawberries (check with your consultant for the latest options). Consider a combination of contact-based insecticides (i.e. mineral oil, soap) for immediate mortality, and a microbial insecticide (i.e. Metarhizium, Beauveria) for additional mortality in the following 5-7 days.  

• Fully submerge plants for at least 2 minutes, but no more than 5. 

• Rinse thoroughly to remove excess dip and prevent phytotoxicity. 

• Plant promptly after treatment.  

Tip:  Always follow label instructions and safety guidelines. Over-dipping or using the wrong solution can stress plants and reduce transplant success. 

3. Biological Prevention: The Right Bios at the Right Time 

Biological control isn’t one-size-fits-all. The best strategy depends on your pest pressure and greenhouse conditions. 

Aphids: 

• Release the parasitic wasp Aphidius colemani (for Green Peach Aphids and Cotton-Melon Aphids) at a low, preventative rates on wheatgrass banker plants or in distribution boxes. Note that parasitic wasps like Aphidius colemani are not effective against Strawberry Aphids.  

• Use Green Lacewing larvae (Chrysoperla carnea) or Brown Lacewing adults (Micromus variegatus) to target emerging Strawberry Aphid hotspots.   

Thrips: 

• Introduce predatory mites like Amblyseius cucumeris in sachets at transplant. Optionally a release of prey mites one week after sachet placement can support predatory mite egg laying and establishment.   

• Release Orius insidiosus adults at higher rates for the first several weeks to establish a population. Sweet Alyssum banker plants with Orius insidiosus can also be used, however they are known to attract thrips.  

• Release soil-dwelling predators such as Dalotia coriaria and Stratiolaelaps scimitus to predate thrips pupae and prevent their development into adults.  

Why Does It Seem That Some Bios Fail? 

• Timing: Introducing beneficials after pest populations explode is too late. Preventative releases are crucial for establishing bio populations adapted to your crop and climate in anticipation of pest influxes.  

• Environment: Excessively high or low temperatures, low humidity, or chemical residues can reduce biocontrol establishment and effectiveness. 

• Pesticide Use: Even “soft” chemicals can harm beneficials. Always check compatibility before spraying or drenching.  

4. Monitoring & Reporting: Sticky Tools and Scouting Rhythm 

While bios are your first line of defence, monitoring is your early warning system. A clean start isn't just about what you do on Day 1, it's about what you track every day after. Thrips, mites, and aphids can establish quickly if the signs are missed or not communicated and acted upon. 

Use Sticky Cards and Tape Strategically 

• Yellow sticky cards catch flying pests like adult thrips and whiteflies. 

• Blue cards are better for western flower thrips specifically. 

• Place sticky cards below the troughs, not just at canopy level. This helps capture thrips adults that can develop from pupae on the floor.  

• Consider sticky tape across walkways or at lower crop zones to intercept early fliers before they move upward. 

  
  

Establish a Scouting Rhythm 

• Set standard scouting intervals with more focus on sections with a historical record of higher pest pressure.  

• Ensure Scouts are trained with pest and symptom identification, and set accountabilities to manage their performance.  

• Use a consistent scouting form or app that records: pest type, life stage, counts per flower and trap, plant symptoms, and environmental conditions.   

  
  

Build a Clear Reporting System 

• Create a workflow where Scouts submit reports to IPM Managers same day. 

• Use colour-coded dashboards or maps to flag hotspots for immediate action. 

• Correlate pest data with bios release schedules to adjust your IPM plan dynamically. 

The Stakes: What Happens If You Don’t Act? 

If critical preventative actions are skipped or rushed-through: 

• Pest outbreaks can make costly, reactive chemical interventions necessary. 

• Virus transmission can devastate your crop. 

• Yield and quality losses can strain margins. 

If you start clean and stay vigilant: 

• Lower pest pressure means fewer interventions and healthier plants. 

• Sustainable production protects your growing investment. 

• Peace of mind knowing you’re staying one step ahead.   

How Crop Defenders Supports Growers Like You 

At Crop Defenders, we’re more than a supplier – we help Strawberry Growers protect their margins through sustainable pest management. We do this with: 

• Locally Reared, Fresher Bios including Amblyseius swirskii, Amblyseius cucumeris, Orius indisiosus adults and nymphs, Aphidius colemani, and more with quick availability.  

• Expert Consultants that work with Growers to design and implement effective strategies that are designed to reduce costs.  

• Ongoing Support: From scouting training to developing customized solutions, we’re here to help you every step of the way. 

Take control with a clean start for your next crop, and schedule a free consultation: 

• Get tailored strategic guidance for your operation 

• Identify gaps in your pest management system 

• Optimize your budget 

Schedule a Call