Biocontrol: How Strawberry Growers are leading the way

According to Dr. Surendra Dara of the University of California Cooperative Extension, 90-95% of strawberry growers in California use predatory mites to manage two-spotted spider mites. But how did this pest control method get so widely adopted? What can growers of other crops learn from this experience? 

To discuss this topic, I reached out to Lane Stoeckle, a certified crop advisor and pest control advisor (PCA) based in Southern California. Together with his father Lee, Lane owns an independent consulting business that provides field scouting, plant protection, fertility and irrigation recommendation to both conventional and organic strawberry growers as well as to a growing number of blackberry growers.

According to Dr. Surendra Dara of the University of California Cooperative Extension, 90-95% of strawberry growers in California use predatory mites to manage two-spotted spider mites. But how did this pest control method get so widely adopted? What can growers of other crops learn from this experience? 

To discuss this topic, I reached out to Lane Stoeckle, a certified crop advisor and pest control advisor (PCA) based in Southern California. Together with his father Lee, Lane owns an independent consulting business that provides field scouting, plant protection, fertility and irrigation recommendation to both conventional and organic strawberry growers as well as to a growing number of blackberry growers.

Lane points out that the benefits of drone applications don’t stop there. “If you need to release persimilis and it just rained, workers do not like to go into a muddy field. Nobody does. But how easy is it to just fly over with a drone right after a rain to get the persimilis out without having anybody in the field? It’s very convenient.”

Lane believes that cost savings could be another advantage of biocontrol by drone, “Right now the cost of a crew to release persimilis and the cost of a drone release is neck and neck. But as labor wages go up and overtime goes up, the cost of a drone application could become cheaper over time compared to hand release.

Getting ready to tackle upcoming regulations 

As miticides have lost their effectiveness with the build-up of resistant mite populations, strawberry growers have almost completely replaced them by the release of predatory mites. Some other more environmentally friendly solutions are also being used for pest control, such as the use of vacuums for the management of the Lygus bugs. That said, even though the strawberry industry has found these reliable practices which also improve “sustainability’, it is still struggling to find solutions for other challenges such as finding alternatives to its long time criticized use of pre-plant soil fumigants to avoid soilborne diseases such as Verticillium wilt, Fusarium wilt and charcoal rot.  

Finding sustainable alternatives “is the question of our time right now,” according to Lane. “It’s such a huge and important question at this moment. I really think that we’re at a crossroads in the industry to address this issue hand on.”  

Lane comments that the industry is really starting to see the after effects of the phase out of Methyl Bromide, a very effective soil fumigant which was definitely banned in 2016 for its proven toxic impact on human health and the environment. 

“I see more soilborne diseases popping up on fields every single year. I now see it to the point where you have two land tiers. The premium disease-free land, and the second tier are lands with a known disease issue.”

Lane believes that regulation on fumigation will keep getting stricter, which might drastically increase soil diseases. “The future of berry production and farming in California in general, will be without any fumigation. How do you combat that? It is the question of our time, I don’t have the answer to that.” 

But what Lane knows for sure is that, “The way that we’ve done things in the last 50 years is starting to not work. I think it’s gonna be baby steps to implement a more environmentally friendly sustainable approach to strawberry farming without the use of soil fumigant. For better or worse, growers will have to adapt to that. Some have gone to hydroponics, some have transitioned their field to organic and are using cover crops or Anaerobic Soil Disinfestation (ASD) to suppress diseases. But I don’t think enough progress has been made on that.” 

ASD is a strategy that has been studied for over a decade by University of California researchers like Carol Shennan and Joji Muramoto. 

Experimenting environmentally sustainable practices 

Lane has observed the adoption of some additional promising practices. He relates that “some growers now transition to barley as a cover crop because it is not a lygus host, and therefore it decreases the overall lygus population in the spring and summer. So I would say the species of cover crop is important to decrease the pest pressure as well”.

He explains that the barley stays on the field for about three to four months before being mowed down and then disked. “If a grower is moving to a new land, he will plant barley as well rather than another crop that would flower. It enhances soil health, increases the carbon and nitrogen ratio and organic matter, decreases weed growth…” 

In recent years, there’s been a lot of improvements in fertigation with microbiology to enhance the soil microbes to combat diseases and enhance soil health. “The rise of bio-stimulants has been instrumental in our personal fertility program. And it’s been critical in organic production.”

To conclude our conversation, Lane encourages all growers and PCAs to try new things on a small scale. “Don’t be afraid to fail. Partner with forward thinking companies and innovation, automation technologies. It’s going to take a massive group effort from the breeders and growers, to the experts in IPM, artificial intelligence (AI) and robotics, to name a few. Come together as an industry to tackle challenges of our time.”

The same way drone-as-a-service providers offer scalable, proven augmentative biocontrol protocols in various crops, Lane believes that, “If as a grower you could figure a way to make something work on a small scale, make it more affordable and more sustainable, chances are that someone out there in the industry will have an idea of how to make it work on a larger scale.”

Reader, we’d love to learn from you as well… What agricultural practices do you think require further research and experimentation to evolve towards more environmentally sustainable alternatives? Have you experimented with new plant health and soil health strategies in the past few years? Reach out to us and help shape our industry with your experience!

UAV-IQ is helping organic and conventional growers implement biocontrol in an efficient and cost-effective manner by using drones to release beneficial insects and mites exactly when and where they’re needed to suppress pests.a