watering - Orchid Board

missy--mouse · #1 05-13-2008, 12:19 PM

ok, i need advice again, you sure helped me with the fungus gnats, i put 1/4tsp physan 20 in a quart of water, put it in a spray bottle and sprayed them away, no more gnats, this is what i need help with now, i have cattleyas, phalaenopsis and dendrobium, how dry do you let them get before you water them?, i have been letting them get quite dry but not dry all the way to the bottom of the pot, do they need to dry out completely so you cannot feel wet at the near bottom of the substrate or have i been doing it right, i am going to water in a few days so any suggestions would be appreciated, is anyone familiar with phyton 27. how often can you use it, i have been advised from an orchid grower to use it every 3 months, but i want to make sure the fungus gnat larvae is gone, so can i use it now?, it has been six weeks since i used it or should i use physan 20 and will this kill not only the larvae but take care of any other pest that might be present, i am concerned about fungus growing in my substrated, it is new, just repotted all of them but i am still concerned, also if need to repot now, what kind of material would you suggest, i got a ready made one from the green house, i used miracle grow, what can you tell me about this?, thank you, donna

Ross · #2 05-13-2008, 07:12 PM

I'm not sure I understand this post. Physan 20 and Phyton 27 are fungicides. So you would be treating the fungus the gnats want to feed on. Yes this would work, but so would repotting along with a drench of neem oil on the roots. If you are looking for a drench of the pots for the fungus gnat larvae, you need an insecticide. The frequency of watering is only sort-of related to the reappearance of fungus gnats. Even with daily watering of bark-based mixes - given proper repotting, there should be minimal fungus build-up that would attract the gnats. I fertilizer with every watering. Some plants get daily, some every-other-day, and some every 4-5 days depending on kind. I regularly watch the mix and repot or remount when the bark starts breaking down.

missy--mouse · #3 05-14-2008, 01:46 AM

i just repotted them so i know they do not need repotting but i am going to do it anyway, putting them in a different medium than bark, i read on the net somewhere that if you are having trouble with fungus gnats, you can put 1/4 tsp of physan 20 in a quart of water and spray them, that the adult would die and they sure did, no more gnats, if anymore hatch i will have to do this again, but it took care of the problem no matter how crazy it sounds, i have also read the dendrobium and cattleyas need to dry out pretty good before you water them again but with phalaenopsis, you should not let them dry out as much, so i am trying to figure out just what i need to water, how much i need to water, and when i need to water, i have only been at this for a few months and so far it has been a learning experience, i know other people know much more than i do, but i am trying to learn and so i appreciate any help or input that i get, because there is so much to know, i appreciate your help, donna

Dorothy · #4 05-14-2008, 11:55 AM

It makes sense that in using Physan 20 that you are eliminating the fungus .. and in doing so are taking their 'food' away and the pests will have nothing to feed off of. Therefore you are altering their environment where they can not survive ... I don't believe that it is killing the bugs so much as you are starving them .. but if it works ..

missy--mouse · #5 05-14-2008, 01:16 PM

well, you may be right, but when the spray hit the flying or crawling ones directly, they died immediately, so i really do think that it works as an insecticide for the gnats, it kills the fungus if any present but it also kills what feeds on the fungus like th nymphs, anyway, i am glad it worked and it doesnt really matter how, i am just glad to be rid of them, they were getting to be a problem as others things i used did not work, really appreciate your input, thank you, donna

Ray · #6 05-14-2008, 02:26 PM

Be very careful of that. Fungus gnat larvae are known to eat roots if the fungus supply runs out.

Ross · #7 05-14-2008, 02:37 PM

Quote:

Originally Posted by Ray

Be very careful of that. Fungus gnat larvae are known to eat roots if the fungus supply runs out.

I second that, and I really doubt the larvae are dead. Those are really tiny white worms. I just think you drowned the adults. The adults are super easy to kill (via the sticky traps). If you've repotted, then you possibly got rid of the larvae. I am very sure the Physan 20 did not kill the larvae, even if circumstance says otherwise. Once again, those with flying, fruit-fly things around orchids most probably have at least one plant in real need of repotting.