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Name: Jay
Status: student
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We have a oak tree which seems to be discharging sap from it. It appears to be coming down on occasions like fine rain. Is this normal, and could you explain what is going on?


When you describe your situation like observing a "fine rain", it sounds to me as if there may be an aphid infestation. Simply put, aphids feed by sucking sap from various tree species; in turn, when they release thier waste, called honeydew, it often ends up coating things like car windows, etc. situated beneath the affected trees.

On occasion, trees will emit sap after injuries, e.g. getting hit by a lawn mower, but your "fine rain" description sounds more like the aphid problem I described.

You can call your county extension agent, located in the city which is the county seat for your county. If you describe your situation to them in detail, they may have pamphlets with recommendations which can be mailed to you. Alternatively, you can google "aphid" to see if their honeydew is what you are seeing, or you can visit a local college or public library which likely contains either botanical texts or those dealing with care of trees, identifying insect and disease pests.

Thanks for using NEWTON!

Ric Rupnik

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