March 14, 2013

Attack on the Aphids

There were so many aphids in the greenhouse it was almost embarrassing.  Remember the pictures of leaves covered in aphids?  It was about time I did something to stop them. 

Goodbye greens!  This cart full of plants contained the very worst of the aphids.  So they got thrown out in the blue dumpster.  (Usually I compost everything, but the road to the compost pile is too mushy to drive on right now.)

Luckily the aphid infestation is in the non-organic certified greenhouse.  So, we sprayed two types of pesticide (by 'we' I mean the farm manager did the spraying).  The cocktail contained one part Botanigaurd and one part Azatin.  

BotaniGaurd is a mycoinsecticide, meaning spores adhere to the host and produce enzymes that dissolve the hosts cuticle.  

Azatin is an insect growth regulator.  When an aphid (and many other insects, fish and aquatic invertibrates) comes in contact with the pesticide it interferes with with the organisms ability to molt, thus killing it.  This is a pretty typical kind of pesticide.

Next week I'll release two beneficial insects: ladybugs and parasitic wasps.  They will control the aphids on a long term basis.  (The picture above is neither of these.  It's just an ordinary wasp on goldenrod.  I don't take many insect pictures.)  I'll write about them in detail next week when they get released.


  1. If the ladybugs or wasps eat contaminated aphids, will they become poisoned as well? Or do you have a waiting period between spraying and added predator insects?

    1. The short answer: probably not.

      The detailed answer: BotaniGaurd works on soft bodied insects (like aphids and thrips) and is safe to use with many beneficials like ladybugs. Azatin kills some beetles, but only when they are juveniles and are molting. We are waiting a week between spraying and releasing beneficials. By then the pesticides will have done there work. Furthermore, parasitic wasps don't actually eat aphids - they lay their eggs in the aphids. I'm going to write about this next week because it's so cool. Truthfully, we should have had an IPM program in place ahead of time, making pesticides making pesticide application a last resort. A last thought - the two pesticides were sprayed at very low levels, and the greens could still be consumed after they were sprayed. I hope that answers your questions!