By Robin Siktberg
While cranberries are ubiquitous in our diets, they are unique agriculturally. Cranberries are a small-scale fruit with an uncommon cropping system and a limited geographic range. They are grown in acidic, sandy soil, often near a waterway to allow flooding of the fields at harvest. Because of the crop’s particular needs—and the shift of pest pressures due to climate change—cranberries face complex pest challenges without straightforward solutions. IR-4 is working proactively with cranberry growers and researchers, as well as product manufacturers and regulatory agencies, to secure more options for safe and effective pest management in cranberries.
Manufacturers of herbicides, insecticides, and fungicides are not inclined to focus registration efforts on a crop that occupies limited acreage, needs to be grown in a specialized way, and must be near a waterway. However, cranberry growers are dependent on these products because there are few non-chemical ways for them to manage pests. Cultivation is not possible because cranberries are perennials that form a thick, continuous mat across the field, and tractor (or foot) traffic will damage the plants. There are no rows to allow equipment to pass. Crop rotation and cover crops do not work in cranberry fields either.
IR-4 fills an important niche by helping crops like cranberry, knowing that specialty crops often have specialized needs. By funding field trials and facilitating the collection and submission of data needed by the U.S. Environmental Protection Agency to register crop protection tools, IR-4 delivers solutions that would otherwise be inaccessible to specialty crop producers.
“Without IR-4, we wouldn’t have the tools that we have,” says Cesar Rodriguez-Saona, extension specialist in entomology at Rutgers University. “They work with researchers and the industry to provide solutions for specialty crops that otherwise we would not have.”
“We joke that cranberries are the most special of the specialty crops because we have this unique growing system,” says Katie Ghantous, extension educator at the University of Massachusetts Cranberry Station, and advisor with the Cranberry Institute. “Cranberries are grown near water, and I think manufacturers see risk there that they don’t want to take on by themselves. I would say the vast majority of our tools come to us through IR-4. It’s very, very rare for a company to register a product for cranberries on their own.”
A long history with a bright future
Cranberries (Vaccinium macrocarpon) were used by Native American populations for food, medicine, and dying clothes long before Europeans arrived in North America. Larger-scale cultivation began after the American Revolution. Salty-soil pine barrens in New Jersey and Massachusetts were rich in iron, which was used to produce cannonballs. Once the soil was dug out, swampy depressions were left, and cranberries preferred these areas.
Wisconsin leads U.S. cranberry production with 20,300 harvested acres in 2022 (the latest year for which statistics are available), followed by Massachusetts (11,600 acres), New Jersey (2,800 acres), and Oregon (2,400 acres)2. Total U.S. harvested cranberry acreage totaled 37,100 acres in 20222. Canada has a growing industry as well, harvesting 19,645 acres of cranberries in 20211. In the U.S., cranberries are a $305 million industry2 with cranberries used in juice, sauce, and health products, along with being sold dried and frozen.
This history has caused a few issues with modern cranberry production, according to Thierry Besançon, associate extension specialist in weed science at Rutgers University. The best way to apply herbicides and other pest-control products is with a large boom driven on the dam surrounding the bed. For this to be effective, the bed needs to be rectangular.
“But many older cranberry beds are irregularly shaped–nobody was thinking about using booms in the early 1800s,” Besançon says. “We have more and more growers in New Jersey who are trying to shape their beds so they can use a boom to spray. Application is so much more precise with this system. The other alternative is using chemigation, but that’s not as accurate because there is a higher concentration of product closer to the sprinkler and a lower rate farther away.”
Besançon says that using drones for pesticide application is a new technology that holds excellent promise for use in cranberries, not only because the shape of the bed doesn’t matter, but because it will allow growers to target only the areas that need it—something that hasn’t previously been possible. However, as a weed specialist, he says the regulations haven’t caught up with the technology; many of the herbicides used in cranberries are not labeled for aerial application.
Constant change means constant updates
Changes in pesticide use and products are also having an impact on the cranberry industry. Across all crops, from corn to cotton to cranberries, tightened regulations on broad-spectrum products and emphasis on human and pollinator safety concerns means many older products are being phased out. Pest and weed resistance to many chemistries is also a factor in the loss of crop protection tools.
“When you lose a broad-spectrum product, you can’t just replace it with one product,” says Ghantous. “You’re going to need five or six modes of action that we can mix together or rotate. “For example, one of the major problems in cranberries from a pathology standpoint is fruit rot. That’s a disease complex that’s made up of at least 12 different pathogens. A broad-spectrum fungicide could do a reasonable job on most of those, but a more targeted product won’t. So we need more than one tool to replace these older ones.”
Because of this, fungicides have been a priority for IR-4 cranberry projects. Several are in process currently and are close to application and approval. One current project is on Switch®, a Syngenta chemistry that combines the active ingredients cyprodinil and fludioxonil and is effective on fruit rot.
“That would be really exciting for us since those are in FRAC Group 9 and Group 12, and we don’t have any of those registered for cranberries yet,” Ghantous says.
An additional product in the pipeline for registration approval is Aprovia® (active ingredient benzovindiflupyr), another broad-spectrum fungicide for fruit rot, also from Syngenta and in FRAC Group 7.
Rodriguez-Saona says the same issues impact insecticides, and IR-4 has been instrumental in obtaining registration for cranberries of some previously unavailable classes of insecticides. Two groups he mentions in particular are diamides and spinosyns. Both are very effective against lepidopteran pests. Another particular problem in cranberry culture is blunt-nosed leafhopper (Limotettix vaccinii) because it is a vector for false blossom disease.
“IR-4 helped us to get cranberries on the label for [several] products which have provided a good solution, “ Rodriguez-Saona says. “We are now working with growers to educate them on how to use these products to avoid water contamination and harm to non-target insects.”
Besançon says one of the most recent herbicides for which IR-4 has obtained labeling for cranberries is Zeus® XC, which has the active ingredient sulfentrazone. It controls mosses, sedges, and other early-emergent weeds, which are major problems in cranberries. It was one of his first research projects with IR-4, and it involved three years of data collection, communication, and coordination with FMC (the manufacturer) to obtain the cranberry registration.
Additional active ingredients registered for use on cranberries through IR-4’s efforts include rimsulfuron, quinclorac and cyantraniliprole*.
IR-4 helps make cranberry industry’s needs visible
All three researchers agreed on the critical importance of IR-4 to the cranberry industry, and all three emphasize the need for continuous awareness of weed, insect, and disease pressure as the climate changes.
“If you look at old pest management guides from the 1940s, you’ll see some of the same species listed there, but they were minor problems and not really even managed,” Ghantous says. “Now we see them at the top of growers’ lists of things they are struggling to control.” She cites mosses as one example of a formerly minor problem that’s now a big one, and it has increased its range as well.
“Mosses were a problem mainly in the Northeast, but now they’re having problems with it in Wisconsin as well,” she says. “It’s really hard to determine if it is from the changing climate or if it’s from changes in management strategies. An insect example of changing pest pressure is the armored scale, or vaccinium scale (Diaspidiotus sp.). There were some reports of it from the 1940s or 1950s, and it’s not necessarily a completely new problem, but nobody talked about it or saw it for decades, and then it exploded back in Massachusetts about 10 years ago out of the blue.”
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