Most greenhouse strawberry Growers want a strong, reliable thrips management program that defends their yields as the season shifts from winter to spring. But cooler nighttime temperatures make it challenging for most biological control agents to keep up with the spread of thrips, especially Amblyseius cucumeris. Below 15°C (59°F), this predatory mite can struggle to establish and predate thrips larvae. Without the right adjustments, gaps in control can lead to costly infestations.
However, there are practical ways to work around these temperature limitations. This article will walk you through effective strategies to get the most performance out of Amblyseius cucumeris in cooler conditions, helping you stay ahead of thrips pressure before it becomes a problem.
Understanding how Cold Temperatures in Greenhouse Strawberry Production Impact Amblyseius cucumeris
Amblyseius cucumeris mites face a significant performance hurdle in early spring: temperature sensitivity. When temperatures dip below 15°C (59°F) , these predatory mites slow down considerably, limiting their ability to effectively control thrips larvae. This creates a dangerous mismatch, as thrips can continue to reproduce at these lower temperatures, potentially leading to a population explosion as warmer weather arrives.
Amblyseius cucumeris completes its life cycle in about 6 days at 25°C (77°F), but this can become longer than 12 days when ambient temperatures fall below 20°C (68°F). Apart from slower reproduction and establishment, these predatory mites generally become less mobile. To overcome this challenge, it's crucial to adapt your release strategies based on current and projected thrips infestation levels.
Optimizing Amblyseius cucumeris Release Strategies in Cold Conditions
Loose Applications vs. Sachets:
Use loose applications of Amblyseius cucumeris when thrips pressure is moderate-to-high, to ensure immediate dispersal of more predatory mites to target thrips larvae.
Prioritize loose applications for treating rows or houses which have relatively higher thrips population numbers than others.
Use sachets if thrips pressure is low, to ensure a steady release of predatory mites over time and maintain a consistent preventative population in the crop.
Application Frequency:
If thrips pressure is moderate-high, considering smaller applications of loose Amblyseius cucumeris several times per week, rather than a large application done only once per week. There are several crucial advantages that come with increasingly the frequency of applications:
Improved Establishment: Helps ensure a consistent presence of predatory mites throughout the crop.
Accelerated Population Growth: Support the development of multiple overlapping generations of predatory mites, leading to faster population buildup to counter thrips' reproductive speed.
Compensation for Mortality: Helps offset any losses of predatory mites due to unfavorable conditions.
While more frequent, smaller applications per week may seem more labor-intensive with higher upfront costs compared to a single application, they can actually help save more costs throughout the remainder of the crop cycle by preventing larger outbreaks that could result in larger yield losses, and require more extensive spray interventions.
How to Monitor and Assess Amblyseius Cucumeris Activity and Establishment
Implement a robust monitoring program to monitor Amblyseius cucumeris population levels and activity in your crop, and adjust applications accordingly in order to reduce the risk of unintentional population gaps which can let thrips populations surge.
Using a hand lens with 40X magnification, regularly examine leaves and flowers for active predatory mites, which look small, pear-shaped, and move quickly across the plant surface.
Check for the presence of eggs on the underside of leaves, around the axil of veins. They are oval, white and are approximately 0.14 mm in diameter.
Conclusion
By adjusting how and when you apply Amblyseius cucumeris, increasing release frequency in higher-pressure situations, and closely monitoring establishment, you can increase the impact this predatory mite will have against thrips. Cooler temperatures may slow things down, but with the right approach, you can keep your biological control program running efficiently and protect your yields as the season transitions.
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Learn more about our locally reared Amblyseius cucumeris today!