QuestionWe apparently have an aphid population on our young aspen trees, evidenced by the back and forth movement of black ants up and down the trunk of the trees. The trees are apparently 'healthy' -some more than others- but I am concerned that damage may be occurring that will not be noticed until it is significant. From some answers, it appears that feeding can strengthen the growth of the tree to enable it to withstand an invasion of this sort. Question one, are aphid infestations permanently damaging or fatal, warranting chemical application? Question two, what sort of feeding is appropriate?
AnswerNormally aphids will not cause serious permanent damage or death to trees. A tree when compared to a bush or flower is a very large organism, and has significant energy reserves. Having said that, anything has limits, and the reserves can be depleted. A common way to impact those reserves is continual defoliation, leaves removed and forced to regrow multiple times, without sufficient time to replenish energy by photosynthesis each time.
How large is the tree? You did say young, but not indicate size. How serious is the infestation and what are visible impacts to the tree. Trees or plants each reacts differently to aphids. Some trees or plants will show no visible response to the aphids, while others may produce twisted or curled leaves.
If there is minimal impact, the honeydew may be the most disturbing issue.
There are many insecticides that can be used both contact and systemic. Contact may work well on a smaller, young tree as you can more easily apply. You may need to try vary pious pesticides though, as aphids can become resistant to them. Depending upon your location, pesticides registered may vary, but possibly would include Orthene, Dursban or Talsar. these need to be sprayed on leaves and branches. Should spraying be difficult, systemic may be the answer. Some of the systemics you may be able to apply yourself, while others may need a professional to assist.
Systemics you can apply would include products like Bayer Advanced Garden Tree and Shrub Insect Control. Easy to use and effective. But not available everywhere.
http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect
http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect
For feeding, you really want a very low salt, slow release fertilizer designed for trees. Check your local stores to see what products they carry as most of the commercial products are sold in very large volumes. Deep root fertilization is typically the most effective, but more difficult to perform yourself. Keep in mind, fertilizer does not feed a tree, it only makes nutrients readily available to the tree, allowing it to more easily produce food. Yes, the tree via photosynthesis makes its own food. Using water, CO2, sun energy and elements from the fertilizer it will produce food. Correct fertilizer assists in this process, but too much fertilizer is not good, nor is the wrong fertilizer. Turf fertilizer is fast release, and often high in salts, which is why you will see fertilizer burn from it, which is really the plant reacting to a lack of water situation.
In most trees, fertilizer is not necessary. Sent picture if you can to allow viewing of tree.
Thanks.
