Not all fungi are good. Pathogenic fungi are behind many cherry diseases, including brown rot, black knot, and cherry leaf spot. This is where the concept of competitive colonization comes into play. Benign bacteria and fungi that live on the aboveground surfaces of the tree are integral to crowding out disease organisms. A holistic orchardist supports these microscopic partners with a spray that combines foliar nutrition with biological reinforcements, affording trees a far better ability to stand up to pathogens. Here the holistic approach totally breaks from strategies that involve fungicides, and frankly is more fun.
The holistic spray recipe consists of unpasteurized liquid fish, pure neem oil, seaweed extract, and a probiotic microbe formulation, all mixed together in a backpack sprayer. Raw milk can be added to the mix for brown rot as cherries ripen. Rates, nuance, and sources for the spray ingredients can be found on the community orcharding website, Grow Organic Apples.
This mixture is sprayed onto leaves and fruits alike at regular intervals to help prevent disease. Time applications to straddle the disease-infection window by spraying at bud swell, just before flowers open, petal fall, and a week after petal fall. The earliest sprays target buds, bark crevices, and fallen leaves on the ground—precisely where many pathogens lie in waiting—with fatty acids from the fish and neem oils. Growers in more humid locations should carry this effort further into the season to prevent brown rot from moving onto fruit as it ripens. Remove all visible black knot lesions to limit further spread of that particular affliction.
Bacterial canker can kill limbs prematurely. The solution here is to not prune during the dormant season in regions where winter tends to be rainy, but rather after the harvest in late summer. Copper applications in earliest spring are organically acceptable for canker, but keep in mind that copper residues reduce fruit set on treated trees.
The holistic approach applies to pests, as well. Cherry fruit flies will get caught up on yellow sticky cards. The latest scourge, spotted wing drosophila, can be checked with an organic formulation of spinosad. All species of moths drawn to cherry trees will be impacted by the neem in holistic sprays. Birds are often the most impactful pest, calling for a serious netting effort to protect the harvest.
What really counts on the pest front, however, is outrageous biodiversity. The more flowering plants a garden includes, the more nectaries there will be to support all sorts of beneficial insects, which in turn seek out pest larvae. A mulberry tree down the block may even keep the birds happy. Put that lawn mower away and let nature grow.
Pest and disease problems are frustrating when you’ve worked so hard to plant, water, and cultivate, only to see moths gain the upper hand or rot ruin nearly every cherry in a particularly wet summer. In a sense, pests and diseases in the orchard should be thought of as symptoms resulting when growing conditions are less than optimal. Natural defense mechanisms abound in a holistic orchard. Our foremost job as growers, starting the very day we plant those precious saplings, is to support the home team.
Photography by William Reavell; Matthew Benson.
Originally published in Organic Gardening magazine, June/July 2014