Help with Phalaenopsis - Orchid Board

GloriaGatti · #1 11-26-2008, 10:39 PM

Hello,

I'm new to this forum and hope one of you can help me. I live in north central Texas grow predominantly phalaenopsis orchids. I house them in my weaving studio during the winter and summer and put them outside in spring and fall when temperature permits.

I've had consistent trouble with scale. Right now I seem to have it under control by spraying every other week with Neem oil and Safers insecticidal soap alternating with Physan 20.

However - I also have a splotchy discoloration that developed on some of the phals leaves. The discolored areas are slightly darkened, and of no specific shape, they are on both leaf surfaces, although not through-and-through. The spots are not as dark as "black" but have a light - almost translucent black/brown or Grey tint (as opposed to white or yellow). There is no depression or shriveling on the leaves and the plants appear otherwise quite healthy without any crown or root damage.

The discoloration began on a few plants before I started spraying for Scale. Now a few more plants have it.

Can anyone give me a clue?

Thanks, Gloria

BikerDoc5968 · #2 11-27-2008, 12:47 PM

Gloria, let me be the first to welcome you aboard. Thanks for joining our family. You'll find that posting pictures regarding "help" questions as well as just wanting to "show off" are extremely helpful at arriving at a reasonably correct answer to your query.... so how about some pics? BTW, Physan won't do much for insect problems. I will help with secondary infections from biting insects and fungal problems.

priz_m · #3 11-27-2008, 01:39 PM

Hi Gloria welcome to the OB!

I agree with Doc, I am afraid a

will make all the difference in assisting you define the problem, all we know so far is that its contagious.

Sorry

mehitabel · #4 11-27-2008, 08:39 PM

For scale problems that persist, you need a systemic insecticide. This is one that is absorbed by the plant, which then becomes poisonous to the insects. Use a systemic developed for roses-- these are safe for orchids.

You will probably need at least three sprayings a week to ten days apart to get all the little buggers.

After you spray, wait a day or so,then wash the now-dead scale off the plant with a soft cloth moistened with soapy water. Use a soft baby toothbrush to reach into the cracks like stem-leaf junctures.

Repeat at least three times.

The best preventive for pests and problems of all types is to "pick up" each plant at least once a month. Pick it up in your hand and bring it up to reading distance, and look it over, ALL over, under the leaves, in the cracks, etc. That way you have a good chance of finding scale when there are still only one or two, before they become a big infestation.

The spots on the leaves. Sounds to me like a fungus problem. I say this because bacterial rots "move" fast--bacterial will spread over the whole leaf in a couple of days. Fungus problems move slower.

Spray with a *systemic* fungicide-- again use one for roses. Draw a circle around the spots with an indelible pen, and if the spot spreads you will have to cut it out with something like an exacto knife or razor blade. USE A NEW BLADE.

Cut out the spot, cutting into clean tissue, then spray the edge with Physan or dust with cinnamon to seal the edge.

Pictures do make a difference but a scale is a scale is a scale. You don't need a picture to recommend a product for it. IMO

GloriaGatti · #5 11-27-2008, 09:05 PM

Thank you for your kind welcome and quick responses.

I think I have successfully uploaded 4 photos. One of my studio space where the orchids live plus three of the plants in question. The studio windows face E/NE and are protected by "sheer" curtains. I have two mist fountains to maintain adequate humidity.

I'm not sure how to direct you to my photo gallery - but I named it Plant Problems. Let me know if you have trouble finding it and I'll try some other way.

Is there a specific rose fungicide and insecticide I should look for or will any be OK as long as it says for use on Roses?

Thanks again for all your help.

mehitabel · #6 11-28-2008, 01:38 PM

It's okay if it says for use on roses. This is per information in one or more of phal culture books and websites. Sorry no time today to look up reference.

Be sure you get a *systemic*

unhappykat · #7 11-28-2008, 02:23 PM

I have noticed similar patches of translucent gray and even black spots on phalaenopsis as well as vandas and some oncidiums when spraying with soaps and fungicides. I am not sure what it is, I am guessing something in the surfactants that causes the cuticle of the leaves to become thinned or even lost allowing for dehydration and death in certain sections, you mentioned neem oil which i have found to cause spotting on almost all phals when used at all. you may just be spraying your plants too often without having any effect on the problem when using soaps and oils. I would recommend something like bayer 3 in 1 rose care or shrub care used at ten day intervals for at least two, three is better, applications to remove your problem and allow your plants to recover a little from all the spraying and rinsing.

dorothy m taitt · #8 12-10-2008, 12:12 AM

still havent heard anything about taking care of phal. wedding promenade orchid pink

BikerDoc5968 · #9 12-10-2008, 08:38 AM

Dorothy M, not sure why your post ended up in this thread dealing with scale insects on phals but to quickly address your query: Phal Wedding Promenade isn't any different than other phals. Good light but not direct sun, water but not soaking all the time, feed weakly weekly with the food of your choice, good air cirulation and temps no lower than about 58 ~ 60F... and repot when the medium looks nasty or about every 2 years...If you just got the plant, you may want to remove it from its home and do an inspection of the roots to be sure you don't have rot and if so, remove nasty roots and repot in bark mix or sphag whichever you like.