Reduced hazard pest and disease control

[DavidCampen]

Originally Posted by harleymc

I've had some really nasty reactions from Dendrobium new growth to pyrethroids on two occasions (different formulations). Never again.

It is unfortunate that pyrethrin seems to have significant phytoxicity.

I applied pyrethrin again but this time without any PBO and at the reduced level of 0.025% pyrethrin in the tank mix. I think at this level it may not be too phytotoxic, my plumeria which also had a bad reaction to the higher concentration seemed to do OK. I will have to get another Dendrobium speciosum for testing since it seems to be a canary of the orchids.

The next time I use pyrethrin I think I will probably reduce the level yet again to 0.0125% in the tank mix but also use PBO at 0.0625%. For now though I am moving on to other agents as pyrethrin does not appear to be very toxic to insects relative to its phytotoxicity.

Given that pyrethroids are contact insecticides (do not have residual effect) I can't understand the idea of spraying an entire collection unless every plant has a current infestation of a nasty that is causing a lot of damage.

I was trying to do preventative control and on the theory that for every pest insect I see there are others and their eggs hidden away on other plants.

Also going back to the original post - if you are concerned about toxicities of chemicals in the conservatory then it is probably a much safer practice to move your plants outside to spray, then bring them back in afterwards.

I live in the city, in a multi-story condominium, my glass and polycarbonate enclosed conservatory room is the closest that I have to an outside.

The other day I noticed a whitefly in the conservatory so yesterday I sprayed with Enstar II (65.1 % Kinoprene) Insect Growth Regulator at a tank mix concentration of 1.5 ml Enstar II per 4 liter (0.024% Kinoprene tank mix concentration). I applied 4 liter in my 200 sq. ft. conservatory.