UACES Facebook Aphids

Aphids

December 2014

QuestionCan you please tell me what cause the white oak trees to be scaly looking and their leafs sickly looking?  Also, we have 5 white oaks on our property that were invaded by something... we thought aphids; which caused snow-like particles and also sticky residue to cover everything near the trees.  The trees look sickly. They have dropped their leaves and billions of acorns. What gives?

 

AnswerMy guess would be aphids—but maybe some spider mites too. The sticky residue you mention is honeydew droppings from the aphids.  White wooly aphids can also look almost like snow falling.  The sticky substance can cover car windshields, patio furniture and even plants beneath the tree.  If left for long, a black sooty mold forms on the honeydew.  Aphids suck sap out of the leaves and spider mites also withdraw fluids and leave a chlorotic looking leaf.  I would not be concerned with either problem as long as it happens late in the season.  If you had damage very early, this could impact the overall health of the tree if it happened year after year. Late in the season, the leaves have pretty much completed their job and the trees health will not be impacted.  Since they have good acorn production, it sounds like they are healthy.  Dry weather late in the season tends to incur larger populations as rain can often clear the insects off the leaves. 


 

June 2012

Question I need some info concerning a crepe myrtle plant. It came with the house 8 years ago and was then a well established plant that has bloomed beautiful every summer. A couple of days ago I noticed that the blossoms were not as dark pink as in previous years and upon further inspection I noticed that the leaves of the whole plant were sticky. I had never seen this on this plant in previous years and am now worried about what to use to treat it with. I did spray the whole plant with Sevin bug spray but don't know how to proceed.

Answer It looks to me like you have a heavy infestation of aphids. As these sucking insects feed, they give off a very sticky substance called honeydew—that is what is causing the sticky, shiny substance on the leaves. Left long enough, the sticky honeydew will turn black as black sooty mold begins to form. Sevin is not a good insecticide for sucking insects. You can use a contact insecticide such as insecticidal soap or Malathion or Orthene which is a systemic. Even a strong spray of water can dislodge them. Aphids multiply rapidly in ideal conditions and can quickly explode in populations


 October 2011

Question   I just got a new car and I park under a neighbors oak tree. The tree seems to rain a fine mist of sap during the day, seems more so when it is sunny. Is this possible, and if so, how long does this happen? I guess I have never noticed on other cars I have owned. When I have searched online I see info about honeydew aphid infestation? If so how is this treated?

Answer It is honeydew from aphids. They build up quickly, especially when it is dry. It doesn’t really hurt the tree, but it can be a nuisance on car windshields and patio furniture. The honeydew is the droppings form the aphids as they feed. It is extremely sticky, and if allowed to stay on the surface of leaves, cars, etc. it can eventually form a black sooty mold. Try spraying the lower limbs of the tree with a strong spray of water periodically. Aphids are poor swimmers and you can control the insects at the base of the tree. Unfortunately, they multiply prolifically, so it must be repeated. There are insecticides as well, but for a large tree, they too would need to be repeated, so the water works almost as well.


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