Aphids in a red oak

July 31, 2011 11:50 AM

Aphids infesting a red oak! Help me understand our risk.

Professional arborist inspected our trees and reported "leaf piercing (aphids) insect infestation" in a 35' red oak. Said not urgent but we should address in next few years. Arborist is a consultant only, not invested in outcome.

What could the aphids do in the meantime? How soon? What will it cost to dispatch them to aphid heaven?

posted by LonnieK to Home & Garden (7 answers total)

I've never seen it used on a tree, but in my garden I've had very good luck with applying agricultural cornmeal to the ground and if that doesn't work to my satisfaction within a couple of days, about 4oz/gal of garlic/pepper tea sprayed.

I'd think a ~$25, 40lb sack of agricultural(!) cornmeal would be plenty. I dunno how people spray trees, though, but the garlic pepper tea is basically free once it's diluted out.
posted by cmoj at 12:22 PM on July 31, 2011

Ladybugs eat aphids. Go buy some ladybugs.

Slightly dish-soapy water controls aphids. So does slightly vegetable-oily water. Hosing down the infected parts with a high pressure garden hose also works.

Dig up/poison any nearby anthills - they sometimes farm aphids and if they are they will repeatedly reinfect the tree..
posted by srboisvert at 12:53 PM on July 31, 2011

Ladybugs usually run about a penny apiece and can be bought by the thousand, online or at a garden-supply store.

If you do this, read up on tricks to make them stay in your yard. I forget the fine points, but it has to do with time of day you set them free, various enticements (sugar water?), etc. to make your yard seem like a great place to live. With luck some of them will stay and multiply. Most will fly of, but will probably have a hearty aphidy meal before they leave.

And it looks cool as hell.
posted by jessicapierce at 1:14 PM on July 31, 2011

Physical removal, via a hose sprayer, is the least invasive option. You might also want to apply compost around the base/drip line of the tree. Aphids don't attack plants that aren't already in trouble, so you need to perk up your tree or you'll just end up having to do this again before too long.
posted by Gilbert at 5:01 PM on July 31, 2011

Thx all. What will happen if we delay?
It's an oak tree, fer Pete's sake. Can the little aphids bring it down?
posted by SallyHitMeOntheHead at 5:45 PM on July 31, 2011

No idea if aphids can bring down an established oak tree (though I'd bet they can, if left totally unchecked) but at the very least, if you don't remove or deter them, that oak tree is giving them a huge breeding ground from which they could move on to all your other plants as well.
posted by jessicapierce at 7:29 PM on July 31, 2011

Aphid pee will stick to everything under the tree, black and sticky and gross. I bought a granule pesticide at Lowes that you just scatter under the tree, wait a few weeks, and they're gone. Worked great, no more aphid pee. I'm not home right now so I can't give you the specifics, but it said aphids on the label.
posted by raisingsand at 8:17 AM on August 1, 2011