It's easy to forget that orchards are living and breathing ecosystems. These days, a modern orchard looks more like an agriculture factory, but between the trellis posts and high-efficiency irrigation systems, biotic and abiotic factors coexist. Insects, cover crops, and even the soil itself all live together within the orchard, and each plays a critical role in the overall health of the orchard.
Some of the insect species that call the orchards home are harmful to the long-term health of the trees that produce our fruit. Aphids, specifically, can be quite the pest. These little buggers are tiny insects that suck the life out of trees and can cause permanent damage to the orchard. They attack new growth on trees and leave behind a sticky substance called honeydew, which can cause mold to grow on the tree. Luckily, there are several tools available to growers to address them.
Typical damage seen in an orchard that is dealing with a heavy aphid population. Note the curling leaves.
Insecticides are not always the best solution. Aphids usually feed on the underside of leaves, making it difficult for sprays to target them. Leaves on trees that have had aphid damage for an extended period of time will actually begin to curl, making it virtually impossible for chemical applications to make contact with the aphids thriving inside the curled leaves. Sprays are expensive! The last thing we want to do is waste time and resources on a treatment that may not be the right tool for the job.
As sustainable stewards, we aim to promote balance within the orchard at all times. When things are perfectly balanced (#growergoals) there are insects living within the orchard that are beneficial to the health of the trees because they'll eat the bugs that are causing damage. These carnivore insects are constantly hunting for other bugs to snack on, and they could care less about the trees themselves. Mites, lacewings, spiders, and ladybugs are some of the most common "beneficials" that you'll find in an apple or pear orchard.
A farmworker gently places ladybugs on trees that are showing signs of aphid damage.
Freshly released ladybugs in a block of Organic Gala apples.
When aphids and other pests flourish and start to damage trees, we often decide to add beneficial insects to the orchards to tip the scale and bring balance back to the ecosystem. This practice is called Integrated Pest Management, or IPM for short, and is widely used in tree fruit and other agriculture systems. IPM can be very effective in the right situation.
Sprays may not be able to penetrate a curled leaf, but a hungry ladybug definitely will. A single ladybug can eat over 50 aphids per day, and one sack of ladybugs from our supplier typically contains about 77,000 ladybugs. Aphids can detect when ladybugs are near, so they'll often stop reproducing and feeding even if they're able to avoid being eaten. Just the smell of ladybugs is enough to scare off even the thickest of aphid populations.
One sack contains around 77,000 ladybugs. We source our beneficial IPM bugs from sustainable insectaries.
Lacewings are another predator bug that we'll deploy as part of our IPM practices. The larva of these flying insects can be dropped by a drone and are attracted to the odors emanating from trees with aphid "hot spots." Once the beneficial bugs have eaten all of the aphids in the orchard, they'll move on to other farms in the area or nearby trees and forage, always on the hunt for tasty pests.
Lacewing larva being dropped via drone.
IPM in action: a young lacewing larva gorging on tasty aphids.
IPM is often a more effective solution to control aphids than a traditional insecticide application, especially in Organic orchards. Although most of the beneficial predators will move on to other sites as the aphid issue is resolved, some will remain and become permanent residents of the ecosystem and reproduce so that their offspring can continue to protect the orchard.
Next time you drive by an orchard, take a second to think about all of the species that are coexisting inside of their own little universe, it is truly fascinating.
