Imagine this: Your new crop has just been planted, and as a Greenhouse Grower, you have production targets that you need to achieve. But suddenly, your goals are threatened by tiny, barely visible invaders—thrips. These pests, if not managed early, can devastate your crops, causing frustration, financial loss, and a scramble to regain control. But fear not! By implementing 5 proactive strategies, you can prevent early thrips outbreaks, ensuring your crops thrive and your budget stays intact.
Most Growers know that early prevention is key, but certain key practices can often be overlooked as the busyness of growing a new crop gets underway. This blog post will provide you with five essential tips to protect your crops from early thrips outbreaks. By following these guidelines, you can reduce the risk of costly infestations, maintain your production targets, and keep your cost per square meter under control.
1. Monitoring thrips populations
Thrips populations can infest newly planted crops several different ways. If your last crop ended with thrips pressure, a portion of that population could have survived your clean out measures by hiding in the structure, in cracks and crevices, or under the ground cover – and you could see the first signs of infestation within a few weeks of planting. Your seedlings or cuttings can also arrive with thrips eggs, or other life stages present.
For many Growers, the question is not if thrips will infest the crop, but when that will happen. In order to stay one step ahead of this costly pest, implementing effective monitoring strategies is crucial for detecting and managing thrips populations early on., Here are three methods you can use to monitor thrips:
As an expert in integrated pest management (IPM) for greenhouse growers, it's crucial to implement effective monitoring strategies to detect and manage thrips populations early, especially in newly planted crops. Here are three methods growers can use to monitor thrips:
1. Blue and Yellow Sticky Traps
How They Work: Sticky traps are an essential tool for monitoring thrips populations. These traps are typically blue or yellow, as these colors are highly attractive to thrips. The sticky surface captures thrips adults as they fly towards the trap.
Placement: Place the traps just above the crop canopy, at regular intervals throughout the greenhouse, with a higher density in areas where thrips are more likely to enter or where there is a history of infestation.
Monitoring Frequency: Check the traps weekly, recording the number of thrips caught to assess population trends. An increase in numbers can indicate the need for further action, such as the release of Orius insidiosus nymphs and adults to target thrips adults, and Amblyseius swirskii or Amblyseius cucumeris to target thrips larvae.
2. Plant Sampling and Visual Inspection
How It Works: Directly inspecting the plants is another effective method for monitoring thrips. Scouts should examine the leaves, flowers, and other plant parts where thrips are known to feed or lay eggs. If you are growing in a soil-based substrate or coco coir, Scouts can also sample the growing media to monitor for thrips pupae and pre-pupae.
Procedure: Create a weekly monitoring plan. Use a hand lens to look for adult thrips, larvae, or signs of feeding damage, such as silvering or stippling on the leaves. Flag areas with where thrips are present.
Monitoring Frequency: Conduct visual inspections weekly, increasing the frequency in certain areas if thrips are detected early on. This method allows for the early detection of thrips before populations reach damaging levels.
3. Tap Sampling (Beat Method)
How It Works: Tap sampling involves physically dislodging thrips from the plants to assess their presence and population density, especially in crops with denser canopies such as strawberries where visual inspection may be more difficult.
Procedure: Gently tap or shake the foliage and flowers to dislodge thrips over a yellow sticky card. The yellow sticky card will trap the dislodged thrips, making it easier to see and count thrips adults and larvae.
Monitoring Frequency: Perform tap sampling at least once a week, especially in areas where visual inspection or sticky traps have indicated the presence of thrips, or where there is a history of early infestations. This method is particularly useful for detecting early infestations when thrips are still in low numbers.
2. Establish Preventative Populations of Amblyseius swirskii or Amblyseius cucumeris
Preventative biological control is your first line of defense against thrips. By introducing populations of predatory mites such as Amblyseius swirskii or Amblyseius cucumeris, you can effectively manage thrips before they become a problem.
Why Amblyseius swirskii and Amblyseius cucumeris?
These predatory mites target the larval stages of thrips, preventing them from developing further as pupal and adult stages. By establishing these mites early in the crop, you can create a standing army of beneficial mites that will be ready to counter early infestations.
How to Implement This Strategy
Timing: Begin introductions of predatory mites at the beginning of the crop, ideally at the time of planting. If possible, begin introductions at your propagator, to help counter thrips infestations which may occur there.
Distribution: Apply the mites evenly throughout the crop, and allocate higher rates in areas where early thrips infestations have historically occurred during previous crops.
Maintenance: Regularly monitor mite populations and reapply as necessary to ensure they remain effective. When thrips is not present, or if population numbers are low, your predatory mite populations can be sustained with supplementary feeding of feeder mites.
By establishing a preventative population of Amblyseius swirskii or Amblyseius cucumeris, you create a living barrier that reduces the likelihood of thrips outbreaks.
3. Trap Plants
Trap plants are crops that are particularly attractive to thrips, often more attractive than the crop you are growing. By placing these strategically throughout the crop, you can lure thrips away from your main crops to monitor their presence, and then remove them from your farm by bagging and replacing infested trap plants.
Selection: Choose trap plants that are known to attract thrips, and which are suitable for your greenhouse operations to use. Vegetable and soft fruit Growers can utilize potted bush bean plants as trap plants, and ornamental Growers may use crops that are more attractive, and less expensive to grow than your cash crop. Yellow flowering chrysanthemum plants, particularly the Vykron variety, are highly attractive.
Placement: Place trap plants in areas where thrips are likely to enter or congregate, such as near doors or vents, and they can be placed in even distribution patterns throughout the crop.
Enhancement: Yellow sticky cards can be placed in holders with trap plants, to increase trapping and detection.
Monitoring: Regularly inspect trap plants for signs of thrips, and bag and replace infested plants.Using sticky cards and trap plants for early detection allows you to catch thrips before they become a major issue, enabling you to respond quickly and effectively.
4. Establish Measures to Mitigate the Spread of Thrips on People, Equipment, and Tools
Thrips can spread rapidly through a greenhouse by hitchhiking on people, equipment, and tools. Implementing measures to mitigate this spread is essential for maintaining a thrips outbreak-free environment.
Personal Hygiene
Clothing: Encourage workers to change their PPE when moving from one section to another, such as disposable coveralls, gloves, booties, and hairnets to reduce the risk of spreading thrips.
Hand Washing: Install handwashing stations and require workers to wash their hands before entering and exiting the greenhouse.
Equipment and Tools
Cleaning: Regularly clean and disinfect equipment and tools to remove any thrips.
Dedicated Tools: Use dedicated tools for different sections of the greenhouse to prevent cross-contamination.
Movement Restrictions
Pathways: Designate specific pathways for workers to minimize unnecessary movement through crop areas. Have workers go through clean areas first, before moving into areas with thrips infestation.
Zones: Create zones within the greenhouse and restrict movement between them if possible, especially if thrips are detected in one area.
By establishing these measures, you can significantly reduce the spread of thrips and avoid the costs associated with controlling thrips over larger areas.
5. Allocate More of the Biocontrol Budget Towards the First 3-5 Weeks of the Crop to Front-Load the Populations of Biological Controls Used
Allocating more of your budget in the early stages of the crop cycle can yield substantial long-term benefits. By front-loading the populations of biological controls, you can establish a strong defense against thrips from the outset.
Budget Allocation
Initial Investment: Allocate a larger portion of your budget to biological controls in the first 3-5 weeks of the crop cycle.
Continuous Support: While the initial investment is higher, ensure continuous monitoring and reapplication of biological controls as needed which may often require lower, maintenance rates.
Benefits of Front-Loading
Early Establishment: Establishing a robust population of predatory mites and other beneficial insects early on reduces the likelihood of thrips outbreaks.
Disruption of Thrips Reproductive Cycle: By introducing different biological controls which target different life stages of thrips, you can disrupt their reproductive cycle and cost-effectively prevent outbreaks. Here is a simple formula you can follow:
Introduce Orius insidiosus to target thrips adults
Introduce Amblyseius swirskii or Amblyseius cucumeris to target thrips larvae
Introduce Dalotia coriaria (Atheta), Stratiolaelaps scimitus (Hypoaspis), and Steinernema feltiae (if you are growing in soil-based media or coco coir) to target thrips pre-pupae and pupae.
By prioritizing early investment in biological controls, you create a proactive approach that pays off in the long run.
Conclusion: A Holistic Approach to Thrips Prevention
Preventing early thrips infestations in greenhouse crops requires a holistic and proactive approach. The 5 strategies shared in this blog post will not only help you reach your production targets with minimal losses, but also keep your cost per square meter within budget. When there are gaps in preventative measures, the consequences can be costly, leading to early thrips infestations that require excessive spending on biocontrols and insecticides to control.
These are general guidelines for preventative measures, but how they are applied at your farm will be unique to your operations and the crops your greenhouse grows. Figuring out what works best at your farm, and how much money needs to be invested doesn’t have to be confusing. Schedule a call with our team of thrips control specialists to discuss how you can implement these strategies in your greenhouse, and protect your crops from costly thrips outbreaks. You deserve to achieve your production targets without having to worry about staying within your biocontrol budget.
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