Nursery Management spoke to Dr. Norman C. Leppla, professor and program director, IPM at the University of Florida’s Entomology and Nematology Department about questions to ponder when considering biocontrol options.

Nursery Management: What is the one of the main points that growers should consider before beginning a biocontrol program?

Norman Leppla: Choosing a well-established supplier with a solid track record of serving customers is of utmost importance. Excellent customer service will be key as you begin and go through a biocontrol program. A good supplier will make sure you’re using their products appropriately. They’ll be upfront about availability and cost. And they’ll provide descriptions of target pests and their biology, as well as recommendations for applying and evaluating their products. They should provide the habitats and seasons in which the pests are encountered, developmental stages that are susceptible to parasitism or predation and relevant behavior of the natural enemies. 

NM: What is the first step when considering or adopting a biocontrol program?

NL: The first step is commitment and trying it one season is not enough. That’s another reason you need good-quality customer service from your suppliers. You must commit to a different system that involves cultural practices; sanitation (you must control the movement of things in and out of the greenhouse, including people); scouting; and being very careful of the source of your plants. You must commit to a system that’s biologically based and integrated.

NM: What are some common mistakes that growers make when adopting a biocontrol program?

NL: There are two mistakes that often occur – growers only conduct short-term trials. Like I said, trying it only one season is not enough. The other is when a grower takes the DIY approach and doesn’t enlist the help and expertise of their suppliers or when they try to rear their own natural enemies. I know a few growers who rear their own natural enemies, but it takes time to gain the experience.

Another common mistake is when a grower thinks of biocontrol as the same system as chemical control. They may think they’ll just remove the chemical and just add the biological, which is not the case whatsoever.

NM: Once a grower receives natural enemies from a supplier, what should they do first?

NL: Sometimes temperature extremes or other problems occur during shipping, so growers should open packages immediately to detect any potential issues and to provide a more hospitable environment for the natural enemies. Look for condensation or a fermenting smell, and the number of living and dead organisms should be estimated.

NM: What else would you like growers to understand about biocontrol programs?

NL: First, it works. It’s not a myth or something for odd characters. It’s mainstream and it can work for you. In an IPM program, there are times and a place when you need to use a chemical intervention. I’m not opposed to pesticides at all but be aware of their impact on natural enemies.

There are market advantages to using biocontrol including health benefits, no regulatory concerns, and, in the long run, it can be a whole lot easier and less expensive.

Effective resistance management involves judicious selection and accurate application of pesticides, and integration with other sound pest management strategies.

To minimize the prospect of arthropod pest populations developing resistance, follow these guidelines:

• Scout crops regularly and time pesticide applications to target larvae and adults.
• Implement sound cultural practices and good sanitation with prompt weed removal.
• If feasible, screen greenhouse openings to prevent insect pests from migrating into greenhouses.
• Use biological control agents or natural enemies.
• Use synergists when applying pesticides to inhibit detoxification enzymes.

Read the label to determine whether a synergist has already been incorporated into the formulation. Certain demethylation inhibitor fungicides and plant growth regulators may act as synergists by blocking the same enzymes as the conventionally used synergist, piperonyl butoxide. Certain insecticides also may be used as synergists when mixed together.

• Rotate pesticides with different modes of action.
• Use pesticides with broad modes of activity, such as insect growth regulators, insecticidal soap, horticultural oils, selective feeding blockers, beneficial bacteria and fungi and microorganisms.

Rotation

In developing a resistance management program, it is important to rotate common names (active ingredients), not trade or brand names. It is important to rotate pesticides with different modes of activity from the Insecticide Resistance Action Committee (IRAC) groups, not just active ingredients or chemical classes. This is because some chemical classes have similar modes of activity. “Mode of action” or “mode of activity” refers to the specific target affected in an arthropod pest. The classification of an insecticide or miticide is listed by its IRAC label designation. For example, organophosphates and carbamates, despite being different chemical classes, have identical modes of activity. These chemical classes block the action of acetylcholinesterase, an enzyme that deactivates the neurotransmitter acetylcholine and results in total loss of nerve function. Using acephate for two consecutive spray applications during a generation and switching to methiocarb would not constitute proper rotation.

Although acequinocyl, pyridaben and fenpyroximate are in different chemical classes – napththoquinone, pyridazinone, and phenoxypyrazole, respectively, all three are active on the energy production system and should not be used in succession. The neonicotinoid chemical class contains a number of insecticides including imidacloprid, thiamethoxam, acetamiprid and dinotefuran. Neonicotinoid-based insecticides have similar modes of action, so it is essential to avoid using them in succession. It is recommended that an insecticide with a different mode of activity be used before using a neonicotinoid-based insecticide. Rotation schemes based on IRAC groupings are not fail-safe for avoiding resistance. They only take mode of action into account, not mode of detoxification.

Another essential strategy is to rotate pesticides with specific modes of activity with those having non-specific or multiple modes of activity, such as insect growth regulators, insecticidal soaps, horticultural oils, selective feeding blockers, beneficial bacteria and fungi, and microorganisms. It is also important to rotate insect growth regulators with different modes of action because certain insect pests have demonstrated resistance to a number of insect growth regulators. In general, modes of activity should be rotated every two to three weeks, or within one to two arthropod pest population generations. Timing will depend on the time of year because temperature influences life cycle duration from egg to adult. Combining or tank-mixing pesticides with different modes of action may delay resistance. Arthropod pests in the population resistant to one or more pesticides would likely succumb to the other pesticide in the mixture. This approach, however, risks selecting for detoxification mechanisms that may permit survival to both pesticides.

The author is a professor and extension specialist in horticultural entomology/plant protection in the Department of Entomology at Kansas State University. rcloyd@ksu.edu or 785-532-4750 

Photo courtesy of Bayer

It is an honor to partner with Greenhouse Management and Nursery Management in supporting this “State of the Market” special report, as it is an important time for production ornamentals.

At Bayer, I help lead development of new solutions across the North American Environmental Science Division. In this role, I am fortunate to manage a team of dedicated and highly skilled scientists who conduct the extensive work necessary to ensure optimal performance for each innovation we introduce to greenhouse and nursery growers, as well as our many customers across Environmental Science.

We do this with one guiding principle: innovation without customer insight is not innovation. The Bayer team spends significant time working with customers, understanding key challenges and identifying what solutions in our pipeline are best positioned to drive value. We see three predominant themes in production ornamentals that are driving innovation: labor, stewardship and emerging pests.

LABOR

Qualified labor is a fundamental challenge for the growth of the industry, making efficiency and profitability a critical focus. Bayer understands this challenge and supports growers by giving them back precious time in their days – our contribution to a better life for them. For years, growers have trusted Marengo^® as the longest-lasting preemergence weed control on the market. With a residual of up to eight months, Marengo is a key tool for nursery growers, helping to eliminate repeat applications, postemergence applications, hand-weeding and other peripheral costs that hurt profitability.

STEWARDSHIP

Growers have always been dedicated environmental stewards, so themes like pollinator safety, compatibility with beneficials and Integrated Pest Management have become increasingly more prevalent. Meanwhile, big-box retailers and others have demanded neonicotinoid alternatives in the care and production of ornamental plants. Bayer introduced Altus® to the ornamentals market in 2017, and since then, greenhouse growers have noted its efficacy on piercing-sucking pests and its compatibility with honey bees, bumble bees and many beneficial insects. Developments like Altus as well as new biological solutions will continue to be a key focus for future innovation.

EMERGING PESTS

Insects, weeds and diseases continue to evolve – whether that means feeding on new plants, entering a new region or developing resistant populations. And growers will constantly need new solutions to manage these new challenges. Botrytis, for example, is widely considered to be the costliest disease in greenhouse management due to fungicide resistance. Last year, Bayer introduced Broadform® – an excellent rotational tool for control of Botrytis, leaf spot and other key foliar diseases. By working closely with customers, university researchers and our internal cohort of developmental scientists, we can continue to identify these needs and deliver new solutions for emerging pests.

Thank you, Greenhouse Management and Nursery Management, for sharing this important report with the countless growers who have spent their careers strengthening the industry and growing beautiful, healthy plants. Here’s to another incredible year!

Sincerely,

Richard Rees
Head of Environmental Science Field Solutions, North America, Bayer

ALWAYS READ AND FOLLOW LABEL INSTRUCTIONS
Bayer Environmental Science, a Division of Bayer CropScience LP, 5000 CentreGreen Way, Suite 400, Cary, NC 27513. For additional product information, call toll-free 1-800-331-2867. environmentalscience.bayer.us. Not all products are registered in all states. Bayer, the Bayer Cross, Altus, Marengo and Broadform are registered trademarks of Bayer. © 2019 Bayer CropScience LP. ES-319-ALT-21-A-R1