The issue of pest control in organic gardening becomes even more important when considering aquaponics. Will the pest control used harm the fish? Will it make them inedible? What pests might harm both plants and fish?
Apparently snails and birds must both be kept away from the fish, as they may carry parasites which can also attack fish. Does that include slugs I wonder? What if you feed a slug off your lettuce to the fish?
I found a DIY aquaponics unit on Youtube where the legs of the grow-bed stand were stood in containers of water to avoid slugs climbing up. It seems to me that it would be wise to prevent access to the unit for slugs and snails, and under cover, birds should not be a problem.
There seem to be a number of pesticides which can be made from plant extracts, and the most widely spoken of is garlic, which is suggested by Murray Hallam in his DVD. Another is rhubarb leaf, and I am still trying to establish if this is harmful to fish. My new best email friend Charlie, at Aquaponics UK, also mentions elder, and chilli. I quote here his responses to my email query about the use of rhubarb.
I also notice frequent mention of soap spray – with the warning that it should be ‘soft soap’, e.g. washing-up liquid, not detergent. This seems to make life difficult for aphids, as well as enabling any pesticide to stay on the leaves.
Of course we should never forget that all this produce is to be eaten by US!
I’m afraid I’m not sure (even though 6 years of my PhD research was focusing on aquatic ecotoxicology or replacements to organophosphate pesticides), i don’t have a scoody doo, I’m afraid.
i have made formulations with rhubarb and elder which both worked great, but i have only used them in soil... but I’d be very interested to hear how you get on, please keep my updated...
Garlic, and soap sprays are well proven options... and ones we use with good effect, but you make reference to a Keder house, so I’d suggest making sure they don't get in and if they do, then establish a healthy population of beneficials... “
“Yes, we've used garlic, chilli, and soap sprays and they have been fine, ultimately it’s a foliar treatment and providing the surface area of your growbeds, if media, is not wet, which it shouldn't be, then any active ingredient should volatilise before it’s an issue.. if indeed it would be in the first place, similarly with rafts.
I would think it would be fine, and next time I get a pest issue, I’ll definitely try it... and keep you posted too