Please help confirm/deny my fears - Orchid Board

rtsingleton · #1 10-21-2008, 09:35 PM

I'm pretty sure that I have a virus in the greenhouse, maybe more than one. Please look at the pics and let me know what you think. And if there is anything to do to stop it from killing the plants. I already use physan 20 during watering and for preventative misting. Thanks for your help.

orchidingram · #2 10-21-2008, 10:40 PM

It may be a virus but could be from water either cold at application or water sitting on leaves and getting cold. Try suing hydrogen peroxide it sometimes does a better job than Physan. It is worth a try.
Chuck

smartie2000 · #3 10-21-2008, 11:01 PM

They might not necessarily be virused. i think the best way to tell is to get a test kit

unhappykat · #4 10-22-2008, 10:56 AM

Those don't look virused, they look fungal. That happens when the leaves stay too moist for long periods of time, usually with not enough air movement, try reducing the humidity a bit and using a systemic fungicide, orthonex is a good one, on all your plants to prevent it from spreading. What plants is it affecting, the ones in the picture look like oncidiums and the secon picture looks like a catt.

SeanJS · #5 10-22-2008, 02:02 PM

If its a virus youd want to burn them. Id personally do that if testing was out of the question, or at the very least move them to the opposite end of the hemisphere.

If it was a fungus, I would isolate the plants and remove infected tissue, soak in RD-20 solution for 10 minutes then seal the wounds with cinnamon. I dont really have any history with fungicides beyond RD-20 and cinnamon, thats just what works for me.

The first image might suggest sucking insect damage.

Is that a King Canopy GH?

camille1585 · #6 10-22-2008, 02:15 PM

I don't think it is viral at all. Looks like fungus to me as well. What kind of orchids are they?

Ross · #7 10-22-2008, 03:24 PM

I've personally had the same small sunken brown spots as the third picture. I stopped them from advancing or spreading by using Thiomyl.

susiep · #8 10-22-2008, 03:43 PM

Well, seems to me what is happening to the leaves in the first 2 pics is different than what is on the leaf in the third pic. The first situation... I have no idea, very ugly, remove that for sure. The second situation is familiar to me. I grow outside in south Florida and I get that on leaves sometimes. However I have never treated it and it doesn't progress to something worse. It is just ugly. I would like to know what that is and how to prevent it, too. Almost positive it is not a virus.

Des · #9 10-22-2008, 04:18 PM

Yes I agree looks fungal to me especially the second plant
Treat with a systemic fungicide then adopt a regular spray program . Spray all your plants with a contact fungicide spray such as Captab or Dithane at two week intervals I alternate with these. And be sure to use a wetting agent with the spray as this gives longer protection.
It stops the fungicide from washing off. Also don't only spray the plants but also your growing area you need to reduce the pathogen count in your growing area to give your plants a chance. At times the pathogen count in the growing environment can build up to very high levels Especially during cold spells.
The first plant with the heavy pitting in the leaves this could also be due to the mix being 'off' or too acid so repot that plant into fresh media and also cut back on the amount of fertilizer you give the plant and flush your plants regularly with fresh water Some plants are more salt sensitive than others
If you are using tank water be sure to sterilize the water, I use Hydrogen Peroxide Many fungi are water borne. Hope this helps . Good luck Sorry if this all sounds a little disjointed ,but is way past my bed time

Ross · #10 10-22-2008, 04:26 PM

I really think what is happening ( at least in my case, which has identical damage to the third picture) is that rot has started by way of a break in the leaf - maybe sun, maybe something else. Then it prgresses. I use Thiomyl (which is a systemic for rot) and it stops the growth and spread but (of course) won't get rid of the leaf damage. Hope this helps.