Question
QUESTION: Ive had sap on my car all summer from a 35 yr. Locust tree.  Is this normal or is it Diseased or maybe aphids? Will this sap do damage to my vehicle if not washed constantly?
Thanks

ANSWER: Sounds like the tree is infested with aphids or scale insets. These insect suck the plant juices from the tree and secrete a substance called honeydew which is high in sugar content and sticky.

To control the sticky honeydew you will need to control the aphids--on large trees is would be next to impossible to get a good spray coverage of all the foliage to kill the insects. there is a soil applied insecticide called Bayer Advanced Tree and Shrub Insect Control that can be used. It is applied around the tree and the roots will carry the insecticide to the leaves and twigs and when the insects suck the plant juices they are killed, This treatment will last the whole season. It will take a week or so for the insecticide to reach the top of large trees especially if the weather is dry. Here is a web link to this product--check with your local garden type store for it.

http://www.bayeradvanced.com/tree-shrub-care/products/12-month-tree-shrub-insect

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QUESTION: Thank you for the info.  Will this do damage to my car paint if not washed constantly?

Answer
I would wash the car weekly and try to find a parking place as far from the tree as possible. At least until the trees are treated or drop their foliage. Here are a couple of web link on how to remove the sap from cars.

http://howto.yellow.co.nz/automotive-and-marine/vehicle-maintenance-and-repairs/

http://www.usautoparts.net/bmw/repairs/detailing/tree_sap.htm