READING, United Kingdom – Perennial flower strips, or bands of land intentionally planted with a mix of flowering plants, could be a cost-effective way to control rosy apple aphid (RAA), research from the University of Reading finds.

“Our research was inspired by earlier studies showing that flower strips help pollinators thrive,” Charlotte Howard, postdoctoral research associate at the University of Reading, said via email. “That got us thinking, could they also support other beneficial insects, like natural pest predators?”

At the same time, Howard said apple growers were facing major challenges with RAA, a pest that can cause significant damage to orchards, such as leaf curling and small, deformed fruits. Although the pest can be well controlled under conventional management programs, infestations can vary with environmental factors. For example, cool, wet springs can help RAA populations increase rapidly because conditions are unfavorable for natural predators.

Even at low population levels, RAA can cause significant damage to orchards. Economic losses are estimated to be 30-80 percent if RAA is left untreated. Typical treatment includes spraying with insecticide and maintaining properly trimmed trees to make conditions less favorable for the pest.

Still, broad-spectrum insecticides can contribute to the problem by killing off natural predators of RAA, such as ladybugs and lacewings. Howard and her team were interested in investigating practical, sustainable control options for apple growers.

Previous research by Howard and her colleagues has shown that flower strips can reduce damage by RAA by up to 32 percent in bad pest years by attracting natural predators. The team also found that in years with high pest pressure, orchards with flower strips could see profits increase by around $4,000 per hectare, through reducing the damage done by pests. Importantly, this is one of the first studies to put real numbers to the financial benefits of flower strips, Howard added.

“That matters because farmers need to know if these practices are worth the investment, and our findings suggest they are,” she said. “Even in quieter pest years, flower strips (especially those planted around the edges on non-crop land) were a good investment and paid for themselves.”

Wildflower plots reduced the spread of RAA on infested trees, up to 50 meters away from the flower plot, and reduced the number of trees with RAA-damaged apples from 80 percent to 50 percent, reads a pamphlet Howard created for farmers. The wildflower plots were from two to six years old, sown with four low-growing fine grasses and 15 perennial wildflowers, 18 meters wide along the length of the orchard edge, and cut short once annually. Not only do these plots reduce RAA, but they also improve the diversity of beneficial predators and parasites in the orchards and do not spread weed species into the orchard.

“Our flower strips were sown with native perennial wildflowers like clover, birdsfoot trefoil, oxeye daisy, black knapweed, and dandelion, along with grasses that provide shelter in the winter,” Howard said. “The mix was carefully chosen to provide something in bloom all season long, offering consistent nectar for beneficial insects year after year.”

Flower strips aren’t just beneficial for controlling RAA and other pests. Howard said that flower strips offer many other additional benefits, including contributing to carbon capture and supporting broader biodiversity and wildlife. The research is still ongoing, with the group working to understand how the benefits play out over time and under changing conditions. Additionally, Mike Garratt, a research professor at the University of Reading, and his group are investigating how flower strips support beneficial insects, such as natural enemies and pollinators, in tropical crops like mango and moringa.

“There’s strong evidence that flower strips lead to benefits in many kinds of crops, not just apples. A recent large-scale study found that flower margins boost both the abundance and diversity of helpful insects in and around all sorts of fields,” Howard said. “There’s still a lot to learn about how flower strips can best serve both farmers and ecosystems.”

For farmers interested in more information about flower strips and wildflower plots, there are resources available at https://northsearegion.eu/beespoke/guides-evalution-tools-other-publications/establishing-perennial-wildflower-areas/. It’s important to note that native wildflowers and plants will vary from region to region.