Thrips and botrytis online resource library By Laura Barth

AFE launches new solutions for pest and disease management in floriculture

Flowers play a vital role in our lives. For your customers, it’s the vibrant bouquets gracing their homes to the blossoms and baskets that adorn special occasions. For you as a grower, it’s your livelihood. However, behind the visual splendor that your customers see lies an ongoing battle against the pests and diseases that threaten the health and beauty of their beloved blooms. The American Floral Endowment (AFE) has been at the forefront of this battle, spearheading 16 research projects to uncover innovative strategies for managing two of the most formidable adversaries in floriculture production: thrips and botrytis.

This article delves into some of the groundbreaking results of AFE’s Thrips and Botrytis Campaign, which is the direct result of six years of industry input and support. You can find all of the practical results, key takeaways, webinars and more on our newly released Thrips and Botrytis Online Resource Library: endowment.org/tb.

Western flower thrips. Photo courtesy of AFE.

THRIPS: A TINY TROUBLEMAKER

Thrips are minuscule insects with a colossal appetite for destruction. Growers have long understood that managing thrips is a multifaceted process that should utilize all available chemical, biological and cultural tools; however, thrips management programs continue to rely heavily on insecticide application. AFE’s Thrips and Botrytis Campaign has unearthed noteworthy findings in the quest to build a more robust IPM program for thrips and minimize insecticide resistance.

SCOUTING: KEEPING A WATCHFUL EYE ON THRIPS

In the battle against thrips, scouting is the way to begin the offensive. Scouting is the linchpin of thrips management and AFE offers resources that you and your employees can use to improve your scouting, sanitation and IPM program. Regular monitoring and early detection of thrips populations are essential for effective control no matter what management tactics you’re using. By identifying the correct species, infestation hotspots and preferred plant species early on, growers can deploy targeted interventions.

CUTTING DIPS: A PRECISE APPROACH

It’s one thing to use biocontrols to manage pests in a greenhouse, but it’s even better to use them to keep them out of your greenhouse in the first place. Cutting dips are a great way to do this. By dipping unrooted cuttings in an oil, soap, or biocontrol product that works on contact with pests, growers can effectively reduce thrips populations before they hitch a ride onto your other crops.

HARNESSING UV LIGHT: SHEDDING LIGHT ON THRIPS MANAGEMENT

One of the most intriguing discoveries from the campaign revolves around the use of UV light to manage thrips. Preliminary results indicate that exposure to UV light affects the survival and reproductive success of thrips adults and larvae. This study is ongoing and more results will be available soon on our Thrips and Botrytis Research Library.

UV-C light has shown to be an effective management tool against thrips without any significant plant damage. Greenhouse trials are currently underway. Photo courtesy of Bruce Parker, Ph.D., University of Vermont.

MARIGOLDS AS GUARDIAN PLANTS: A NATURAL SOLUTION

The campaign also highlighted the effectiveness of marigolds, particularly yellow-flowered cultivars, as guardian plants. The yellow blooms serve as ideal decoys, similar to yellow sticky traps. Strategically placed marigolds lure thrips away from the main crop, where they can then be managed using a slow-release sachet of predatory mites in the foliage to kill the adults and insect-killing fungus Beauveria bassiana mixed in the potting media to kill the juveniles. This technique can provide prolonged suppression of thrips for at least 2-3 months, all while minimizing the need for insecticides.

Yellow marigolds can be used early in the season to lure thrips out of crop plants, here they can be managed with biocontrol products. Photo courtesy of Margaret Skinner, Ph.D., University of Vermont.

BOTRYTIS: THE FUNGAL FOE

While thrips present a formidable challenge, Botrytis cinerea is another problem continually threatening growers, one that you have undoubtedly encountered. This destructive fungus can quickly turn beautiful blossoms into an unmarketable liability. Much like thrips, a multifaceted approach should be used for botrytis management instead of relying on fungicides alone. AFE’s Thrips and Botrytis Campaign has unveiled innovative strategies to combat this persistent pest.

FUNGICIDE USE: A BALANCING ACT

While fungicides can be effective against Botrytis, the results of this campaign underscore the rapid development of fungicide resistance, highlighting the need for a strategic approach to fungicide use. AFE offers resources to help you properly rotate your fungicides, sanitize your operation, scout for botrytis and manage botrytis in both greenhouse and postharvest environments so fungicide efficacy is maintained for when you need it most.

BIORATIONAL PRODUCTS: STRENGTHENING FLORAL DEFENSES

Our research has revealed several biorational products that when combined, may provide botrytis control on petunia and roses similar to that of leading commercial fungicides. One of these products is calcium chloride. Calcium strengthens and stabilizes the cell wall, making the penetration of Botrytis cinerea more difficult.

Another is natamycin, which is a natural fermentation product and food preservative that has antifungal properties. The combination of natamycin and calcium was very effective as both a greenhouse spray and postharvest dip. We will be having a special Grow Pro Webinar on Jan. 16 where you can learn more about biorational products for botrytis management. Visit endowment.org/growpro to register.

Botrytis blight damage on cut roses seven days after inoculation. Roses treated with dip application of biorational products used alone or in tank mixes. Photo courtesy of Jim Faust, Ph.D., Clemson University.

BENEFICIAL BACTERIA: EVALUATING NEW STRAINS AND APPLICATION TECHNIQUES FOR BIOCONTROL PRODUCTS

In addition to resources on effectively using biocontrols, AFE’s Thrips and Botrytis Campaign also supported research to help develop new biocontrol products. A team of researchers at Ohio State University screened a collection of bacteria for their ability to control botrytis blight on petunia and identified key lab assays to evaluate bacteria strains alone and in combination. This research will help provide information on the best way to develop testing protocols and bacteria combinations for new biocontrol product formulations.

Evaluation of bacterial strains for botrytis control. Bacteria (upper left) is grown and whole plants or cut flowers are treated. Botrytis spores (bottom left) are sprayed onto the plants and flowers are rated daily for disease severity. Photo courtesy of Michelle Jones, Ph.D., Ohio State University.

A PARADIGM SHIFT IN PEST AND DISEASE MANAGEMENT

The insights gleaned from AFE’s Thrips and Botrytis Campaign promise to further drive innovation and sustainability in pest and disease management. Growers are now armed with a diverse array of tools and strategies to combat thrips and botrytis, ensuring the health, beauty, and marketability of your floral crops. And we’re not done, either — we have two ongoing thrips and botrytis research projects and are currently seeking out new research to address the growing threat posed by Thrips parvispinus. Visit endowment.org/growpro to register for our Feb. 27 Grow Pro webinar, Preparing for Parvispinus.

Our Thrips and Botrytis Research Library would not be possible without industry input and support. We would love to speak to you directly about any questions you have and how you can put our resources to use in your operation. If you are interested in getting more involved with these programs or have research you would like to see AFE fund, reach out so we can work together to create a more vibrant and profitable industry.

Laura Barth

Laura Barth is the research coordinator at the American Floral Endowment. She can be reached at lbarth@ afeendowment.org.