by Myrna Stark Leader
Nothing tastes like a dark red, firm, juicy, sweet cherry. After biting into that deliciousness, eating only one is nearly impossible. Over 95% of the cherries produced in Canada are grown in BC’s interior with its longer growing season, warmer winters and hot summers. However, growing perfect clusters of this stone fruit involves complex crop management.
How they grow
While artists often depict stunning cherry blossom time as tall, round-shaped trees covered in blossoms, modern orchards have shorter trees that are planted in rows and trained to branch certain ways. Commercial orchard trees are intentionally pruned to ensure maximum sunlight, essential for great fruit. Pruning also sets the stage for future harvests as cuts from this year produce the branches that will grow cherries two years into the future. Pruning and cherry harvesting are done by hand, protecting the tender fruit from damage like pitting (marks on the surface) that consumers don’t want and which can cause quicker spoiling.
To accommodate and protect workers from climbing ladders more than 10 feet high, most commercial tree varieties are grafted onto dwarfing rootstock. All orchards are irrigated for trees to thrive. Trees in some newer-style orchards are planted closer together to produce more pounds of fruit in a smaller space. They may be supported by poles and wires and look quite different than a traditional backyard-type cherry tree.
Growing consistently great cherries is hard
Canada’s cherries are some of the best worldwide. Harvest begins early in June closer to the US border, moving northward until about the first week in September. Cherry trees, most of which have been bred in BC at the Agriculture and Agrifood Canada research station at Summerland, are challenging to manage.
This is partly because these trees are intentionally bred to tolerate a more northern climate, producing fruit later in the world market growing season to capture international demand for cherries later in our summer. The trees need certain nutrients and also face greater risks from insects and diseases because of their later season. Growing awesome fruit takes ongoing rigour, as farmers combine their experience and knowledge with continuous research, adjusting for whatever weather and outside threats come their way.
“Cherries in the supermarket, conventionally grown or organic, look a lot different than 15 or 20 years ago because of how the agricultural industry works, how the global food system works and how the science that goes into growing food is always improving,” says BC cherry grower Erin Carlson.
She and her family manage 100 acres of cherries in about a dozen orchards in southern BC. They’re significant-sized growers who’ve focused on cherries since the early 90s as Carcajou Fruit Company Ltd and Savanna Ridge Cherries Inc.
Erin says more is known today about the nutrients a tree needs as well as how to protect the plants from disease and insects which, if unchecked, could destroy her orchard and even the industry. It’s why she’s continually monitoring her orchards and protecting her livelihood in all sorts of ways, including application of sprays.
What is sprayed?
Tractors passing between rows are spraying into the trees one of three things – nutrients to promote tree health and better fruit quality, a pesticide to suppress or control a pest or disease, or crop protectant to prevent tree or fruit damage.
“Everybody who grows fruit for supermarket consumers knows about and applies foliar [which means on the leaves] nutrients to grow a better product that will last long enough to make it to the supermarket and then to someone’s house,” Erin explains. “We spray nitrogen, calcium, boron and zinc to grow healthy cherries. Sometimes they are applied alone or, if the label allows, sometimes mixed together in a tank with water. It’s like humans taking vitamins. Applying spray is how cherries get their vitamins and how we can ensure the right dosage,” says Erin.
Whether adding crop enhancements or routinely scouting, each orchard has its own unique microclimate and crop needs that is managed by the orchardist. Sprayers are calibrated to project the right amount of spray. Products have specific, scientifically-calculated application rates. This, combined with the grower’s skills, helps ensure consumer and worker safety, cares for the environment and minimizes the cost of these inputs for the farmer. No one wants to apply more than is needed, or have spray end up where it wasn’t intended.
Additionally, cherry orchards are monitored with specific traps designed to capture and help detect pests like cherry fruit fly and spotted wing drosophila. If they lay their eggs in the fruit, it can lead to worms inside the cherry and substantial crop loss without preventative treatment.
“There are dozens of different insect pests and diseases that damage BC cherry crops and trees that the proper application of treatments can help control. Treatments can be one part of a grower’s Integrated Pest Management Plan, along with things like regular tree care, nutrition, irrigation, equipment practices, and more,” says Susanna Acheampong, an entomologist with BC’s Ministry of Agriculture and Food. “All these help farmers support and maintain their orchard’s overall health and fruit production.”
Since BC’s cherry industry was built by developing relationships with foreign countries, growers who export must also meet safety standards set by each country.
“If we want to export, it’s actually required to spray for something like Western Cherry Fruit Fly if we see it in our orchard,” explains Erin. “We have to prove we’ve been controlling for that pest. Cherries with bugs won’t be accepted. Nobody wants bugs in their cherries, but especially not if that will become a problematic (invasive) pest in other parts of the world. So we have pesticides that we are able to use in moderation, in a controlled way, to keep that risk low.”
On the diseases front, rain and irrigation can encourage spores of powdery mildew to grow, which also makes cherries unmarketable inside and outside Canada. A spray application can suppress the spread.
“Cherries are very fragile. There is one crop a year and they are extremely susceptible to pests and disease,” says Danny Turner, a certified organic commercial tree fruit producer with five acres of cherry trees on Just a Mere Farm near Creston, BC. “The nutrient balance has to be exactly right. Otherwise, you don’t get the sugar and the size the consumer demands,” Danny explains. “You also have to produce a clean crop for the consumer, so when we spray, we use products that are approved for organic use that address those things. It’s a challenging crop to grow, but when you get it right, it’s a rewarding crop to grow.” All pesticides applied by Canadian growers – organic or synthetic – are approved by Health Canada’s Pest Management Regulatory Agency (PMRA), under one of the most robust regulatory systems in the world.
Safety checks and balances
Just as there are a range of cherry attackers, producers can choose from a range of treatments. Growers consciously rotate products to avoid insects and pathogens from developing resistance.
“It’s pretty sophisticated for producers these days…the industry is doing a good job being progressive as new technologies become available,” says David Nield, a biologist in the pest management program at the Agriculture and Agri-Food Canada Summerland Research and Development Centre. The Centre works to ensure human, plant and environmental health are top priorities in cherries and other BC fruit crops.
Canada also has a strong, science-based regulatory system that governs pesticide registration and use. All pesticides, including herbicides, fungicides and insecticides, are regulated in Canada by Health Canada’s Pest Management Regulatory Agency. Each active ingredient goes through an extensive risk assessment and must be registered prior to being approved for use in Canada. Health Canada takes a risk-based approach to registration, considering significant amounts of data on the environment and human health, including looking at any potential impacts to the most vulnerable populations like children and people who are health-compromised. Products have to be safe for consumption, safe for orchard workers, safe for the environment and must be labeled with use instructions which growers, by law, are required to follow.
Did you know? Little cherry disease is a serious threat to the cherry industry in the Okanagan-Similkameen and Creston Valleys. It can be spread by the apple mealy bug. Japanese flowering cherries, a common ornamental tree grown in many gardens, can carry this disease without showing any signs. To protect cherry orchards, it is illegal to grow these flowering cherry trees in the Okanagan and Similkameen Valleys to help prevent movement of the disease by insects.
For example, every product used in Erin’s orchard has a re-entry interval, the time required between spray application and when workers can re-enter the orchard. Similarly, products will have a pre-harvest interval, which provides the exact length of time the orchard must sit after application before fruit is harvested. This ensures that residues on the crop degrades to a level appropriate for that product. This applies to any crop that uses these kinds of products, not just cherries.
All pesticides in Canada must go through a thorough re-evaluation process every 15 years, and if products no longer meet Canadian standards for human health and the environment, they are removed from the market. “The public may even see growers spraying more frequently, because more harmful older chemistries have been banned. What we spray isn’t as harmful to the environment, to the pests, or the applicator,” says Erin. “They’re safer, well-studied and controlled differently because science has come so far.”
There are strict penalties if an orchardist does not follow the system when it comes to residue. Maximum Residue Limits (MRL) are the maximum amount of pesticide residue that is allowed to remain on a crop when the product is used according to label directions. MRLs are set by Health Canada and are used to facilitate trade with other countries, using internationally agreed upon science-based standards.
“When you’re doing an audit, you must prove your spray timing, your pick timing and all the things in between that makes sure you are keeping your employees safe but also that you’re keeping your customer and their customers safe,” says Erin. “For our overseas retailers, we have to prove to them every year, sometimes multiple times in the year, that there is compliance with MRLs and that it’s safe for consumption. We do that. It’s expensive, but it’s a piece of safety and security.”
David says in his career and prior, there’s been a steady progression of improvement to make products better.
“Canada has a good system in place to ensure that the products are appropriate for the use. That’s part of my job and why I do these field trials to inform Health Canada of how these products interact on cherries or the crops that I’m looking at,” says David.
The more we know, the more things continue to improve. Precision agriculture may help even more, such as scanning the cherries on the tree to target spray applications more precisely.
