For the most part, cherry trees are fairly easy to grow, but they are not without their problems, perhaps the biggest of which is the persistent and sap-hungry aphid.
Cherry aphids are a nuisance for cherry tree growers the world over, so what can you do to keep them off your tree?
With early detection, aphids can be knocked or hosed off the underside of cherry tree leaves. A direct application of insecticidal soap or neem oil can be effective in dealing with large colonies as this has a suffocating, paralyzing effect on their soft body structure.
Prevention is the best cure for aphid numbers on your cherry tree, so maintaining good overall care and checking the leaves regularly will keep you on the right path.
Keep reading for tips on how to identify cherry aphids, what contributes to their arrival, and control methods.
There are many things that can go wrong with your cherry trees, and knowing how to identify and deal with issues when they appear is critical. I explain it all in my detailed guide, Cherry Blossom Tree Diseases and Pests.
Understanding Cherry Aphids
To increase your chances of controlling a cherry aphid invasion, it helps to understand a little more about these pests such as identifying characteristics, the tell-tale signs of cherry aphid damage, and what draws them to cherry trees.
Identifying Aphids on Cherry Tree
Wingless adult aphids are 1-2 millimeters long and have shiny black or very dark brown bodies.
They gather in clusters on the underside of leaves and resemble tiny black eggs as they have rounded, almost cylindrical bodies and their legs and antenna are yellowish-black.
Black Cherry Aphid Life Cycle & Habits
Overwintering black cherry aphid eggs are laid on the underside of cherry tree leaves in fall. They then hatch in spring.
It doesn’t take long for huge aphid colonies to form as warm weather allows newborn nymph aphids to develop into reproducing adults in a matter of days.
According to the Colorado State University Extension, the typical habit for a female aphid is to give birth to a genetically identical daughter aphid via asexual reproduction, and most adults will produce 3-5 young per over their month-long lifespan.
To ensure their survival in winter, some aphids will even lay eggs on alternative plant hosts (in the case of black cherry aphids, they will often overwinter on elm trees and choose wild mustard plants as their summer host).
Damage Caused by Cherry Aphids
You will notice leaves appear crumpled or curled and often discolored due to aphids feeding on the leaves and shoot tips.
Another clear sign of their damage is a thick covering of sticky honeydew-like substance that they excrete in large quantities on the leaves.
This soon develops into a black sooty mold fungus that eventually causes the weakened leaves to yellow before dropping.
Susceptibility of Cherry Trees to Aphid Infestations
Black cherry aphids are usually found wherever cherry trees are growing throughout the US, and infestations are thought to be more serious in young and organic orchards and in nurseries where populations are not properly controlled.
Black cherry aphids also generally prefer commercial cherry tree varieties with a particular fondness for sweet cherry trees such as Napoleon, Windsor, Schmidt, and Black Tartarian, according to Greg Krawczyk, Ph.D., research professor and tree entomologist at Penn State University.
Factors Contributing to Cherry Aphid Infestations
Specific weather conditions and poor tree health tend to lure cherry aphids. Ants also play a major role in aphid numbers due to their mutualistic relationship with one another.
Let’s learn a little more about these contributing factors below.
When spring and summer weather is both warm and moist, this provides ideal conditions for aphid populations to thrive as the increase in temperature helps newborn aphids develop rapidly.
Aphids will also be attracted to less-than-vigorous cherry trees experiencing some form of stress, whether this is due to drought, overheating, waterlogged conditions, or overfertilization.
Ants and aphids have an understanding — the aphid’s sugary honeydew excretions provide a tasty food source for the ants while the ants simultaneously guard the aphids from natural enemies such as ladybugs and lacewings.
To ensure their food source remains, ants can get a little manipulative too.
While some ant species will transport aphid eggs into storage chambers in ant nests to protect them over winter, some have been known to go as far as subduing adult aphids into remaining on the plant by tranquilizing them and even biting their wings off.
It’s pretty clear then — get rid of the ants, get rid of the aphids!
Prevention and Management Strategies
Thankfully, there are numerous ways to deal with a cherry aphid infestation from physical removal on sight to long-term care measures and traps to eliminate their protective ant buddies.
Take note of the following strategies to help win the war against these pests.
Keep a close eye on your tree care practices, particularly your watering and fertilizing habits.
Overfertilizing your cherry tree promotes the growth of tender new shoots that aphids go wild for, so opt for a slow-release organic fertilizer and apply only once during the growing season to balance out the nitrogen.
Secondly, fend off water stress by keeping your tree well-watered during hot, dry spells.
Studies have shown that sugar levels become more concentrated in drought-stricken trees, making the sap appear doubly attractive to aphids.
Physical Control Methods
If you notice aphid numbers on leaves before any real damage and distortion takes place, you can knock them off by hand or hose them off with a well-aimed spray of your garden hose.
Around early spring, it’s also a good idea to deter ant numbers from crawling up into the tree by placing a barrier of sticky material around the trunk – Tanglefoot works great.
A direct spray of neem oil or insecticidal soap on the underside of leaves is an effective way of dealing with aphid colonies in one fell swoop since these natural chemicals suffocate them and fracture the membranes of their soft bodies.
For extra natural assistance in dealing with aphids, it helps to make changes in your landscape.
Planting sacrificial trap crops, for example, is a great way to attract aphids and keep them off your cherry tree. Nasturtiums is a great trap crop for aphids.
Likewise, you can also grow plants in the vicinity of your cherry tree with natural aphid-repelling powers — opt for super aromatic flowers like marigolds, catnip, and peppermint.
The Importance of Monitoring and Early Detection
As aphid populations can grow and multiply quite rapidly, it’s essential to spot infestations for the best chance of knocking them off your tree before chemical control is necessary.
The Pest Management Program at the University of California advises checking for aphids at least twice a week, preferably in early spring as aphids cause the greatest damage during the warmer late-spring weather.
Regular monitoring is also helpful for spotting the presence of natural aphid enemies such as ladybugs and lacewings so that you know when to use chemical control methods and when to hold back and let nature take its course with aphid numbers.
Does Neem Oil Kill Aphids?
Yes, neem oil can kill aphids, but a repeat application of 3-4 days may be necessary to kill populations.
Neem oil causes suffocation when sprayed directly onto aphids, but a general application onto the affected area simply deters them from feeding, so a targeted approach is best.
Can Black Cherry Aphids Kill the Tree?
Black cherry aphids can cause unsightly damage to tree foliage due to feeding on the leaf sap in large numbers, but this does not affect fruit-bearing, so trees will normally survive an aphid infestation.
Black cherry aphids are drawn to leaf sap and will cause unsightly damage to cherry tree foliage if left to fester.
Thankfully though, these pests are relatively easy to manage and deter with insecticidal soap sprays and trap/repellent crops.
Aphid populations will grow thick and fast in warm spring weather, so frequent monitoring is essential for detecting them early.
An all-encompassing approach to your care practices, such as balanced watering and fertilizing, can keep trees in a healthy condition that isn’t as inviting to aphids as a stressed and defenseless tree is.
You now have the knowledge to deal with a black cherry aphid infestation, but what about other common problems? Continue to learn with these helpful articles: