Re: Aphid Infestation


----- Original Message ----- From: <mtnstar@ocsnet.net>
To: <medit-plants@ucdavis.edu>
Sent: Tuesday, July 18, 2006 7:17 AM
Subject: Re: Aphid Infestation


I tried a strong water spray but it wasn't enough for my wisteria. So I used insecticidal soap two times on my wisteria because the aphids were sucking the energy out of the tips so bad that the new growth wouldn't leaf out - so aphids can cause damage to the plant by reducing the plants energy stores needed to produce growth. Now my wisteria is leafing out on new growth. I also use the tangle foot at the bottom of the tree to keep the ants from "farming" the aphids - they have a symbionic relationship whereby the ants protect the aphids from other predators.

Ladybugs (lady beetles) and lacewings eat aphids - not sure what the other beetle might be that eats aphids. There are good bug insectaries where a person can purchase some beneficial insects to release on their property. I understand Ladybugs need to be kept confined in a screened cage for a day or so otherwise they will fly off to some other location.

I haven't had any aphids in my fruit trees but they were in my native willow trees - which were much too large and dense to spray - now the aphid population seems to have decreased naturally.
I think Linda makes most of the points I had been contemplating. Perhaps it is worth using the water jet first (to reduce the problem and then following it up with the insecticidal soap to mop up the strgglers which will otherwise soon produce a refreshed infestation. Neither of these treatments should have an adverse effect on beneficial insects, (apart from the water rather forcibly shifting them on) and will I guess only bother your cat should he be lying under the trees when you spray and get drenched!

Do I gather this aphid attack is something new and the trees have not been much bothered in previous years? If that is the case it may just be a oncer. I have found that almost every year one sees an unusually high infestation of one specific pest insect or another, but in susbsequent years they become quite insignificant once more.. This seems to be a well known natural phenomenon in many animals, not just insects and related to climate cycles, availability of food and other similar factors. One year's aphid attack at least is unlikely to do the trees any serious harm anyway and certainly does not call for any very drastic measures..

Anna, even if you do nothing a generous supply of aphids should attract many beneficials fo a free feed if, as I think you say the area is under an organic regime anyway.
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