# Need help! Crust on leaves



## dodidoki (Apr 3, 2016)

I don't know the reason, I noticed it on the center, appears just afret watering, dry and doesn't spread. Maybe something wrong in water? But what? I use RO system and 80-100 ppm urea based fertilizer.
Many thanks: Istvan


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## Justin (Apr 3, 2016)

Looks like spider mite damage


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## dodidoki (Apr 3, 2016)

I can't see mites on leaves even with magnifier.


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## troy (Apr 3, 2016)

Spider mite death!!! with Something obtainable from a hardware store, would be????


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## dodidoki (Apr 3, 2016)

troy said:


> Spider mite death!!! with Something obtainable from a hardware store, would be????



Yes, I found them....what can I do?


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## gonewild (Apr 3, 2016)

dodidoki said:


> Yes, I found them....what can I do?



Spray with a miticide, be sure to follow the directions and complete the program of repeated sprays.


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## Wendy (Apr 3, 2016)

5-10ml of horticultural oil in 1 litre of water.....shake well and apply. Simple, non toxic and works perfectly.


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## dodidoki (Apr 3, 2016)

Wendy said:


> 5-10ml of horticultural oil in 1 litre of water.....shake well and apply. Simple, non toxic and works perfectly.



Many thanks for advices, I have systemic pesticide at home so I srayed them. I will go to my local agricultural shop tomorrow for further advices. Interesting, I didn't see them on leaves but I found them at the base of plants with magnifier. I had this problem for I while, I saw this one of my malipoense when I bought it but I thought that it could be something cultural problem. I think I brought disease with this malipo, because after this many of plants became "crusted".


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## eggshells (Apr 3, 2016)

Textbook spider mite damage. Horticultural oil should work. Spray every 5-6 days for 6-8 weeks. Spray everything though.


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## Leo Schordje (Apr 5, 2016)

read label of your systemic pesticide. If it does not list mites, don't use it for mites. Mites are in the spider family and some insecticides will not kill them. One common systemic insecticide, imidacloprid, one brand is Merit, Bayer Tree & Shrub, it is a neonicotinoid and will not kill mites, and in some instances will cause mite populations to increase (documented in trees, not orchids). So please read your label before applying the systemic and make sure mites are listed. 

Most garden centers will have something that lists mites as target species. The Hort oils will work, repeat according to directions on label. Nothing will work completely with just one application. If there are not interval directions, once a week for 3 weeks should do it.


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## Hien (Apr 5, 2016)

This is my observation:
the damages or patterns on the leaves are mirror images , that means whatever happened to cause the pattern started when the leaves were still in the young stage (both sides of the leaf still facing each other, not fully open )


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## Ozpaph (Apr 6, 2016)

Hien said:


> This is my observation:
> the damages or patterns on the leaves are mirror images , that means whatever happened to cause the pattern started when the leaves were still in the young stage (both sides of the leaf still facing each other, not fully open )



I agree.


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## orcoholic (Apr 6, 2016)

Hien said:


> This is my observation:
> the damages or patterns on the leaves are mirror images , that means whatever happened to cause the pattern started when the leaves were still in the young stage (both sides of the leaf still facing each other, not fully open )



Me too.


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## dodidoki (Apr 6, 2016)

Hien said:


> This is my observation:
> the damages or patterns on the leaves are mirror images , that means whatever happened to cause the pattern started when the leaves were still in the young stage (both sides of the leaf still facing each other, not fully open )



Yes.it is is true, but what is the agent? Chemical burn, toxic symptom or mites? I don't know. I thougt it is chemical burn, but I use weak fertilizer cc, 60-80 ppm.I bought special miticide and sunflower oil based spay, too and combined two. Now I wait. I tr They are very small, I tried with systemic fungicide, ineffective so I think it is not fungus. Otherwise however I couldn't see mites on the leaves but I found them at the base of plants.They are very-very small, I could see them only with strong reading glass combined with mignifier.


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## Hien (Apr 7, 2016)

dodidoki said:


> Yes.it is is true, but what is the agent? Chemical burn, toxic symptom or mites? I don't know. I thougt it is chemical burn, but I use weak fertilizer cc, 60-80 ppm.I bought special miticide and sunflower oil based spay, too and combined two. Now I wait. I tr They are very small, I tried with systemic fungicide, ineffective so I think it is not fungus. Otherwise however I couldn't see mites on the leaves but I found them at the base of plants.They are very-very small, I could see them only with strong reading glass combined with mignifier.



I hope other members with more experience can tell you what the damages came from.
But from my limited knowledge , my cymbidiums, oncidiums, dendrobiums which have this kind of mirrored burn/spotted patterns all have mites (when I sandwiched the leaf between a folded piece of tissue paper and run from bottom to top of the leaf with pressure , I found dead mites collected on the tissues )


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## Wendy (Apr 7, 2016)

Wipe the leaves with a soft white tissue. If there are mites you will have a red/reddish stain on the tissue.


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## SlipperFan (Apr 7, 2016)

Wendy said:


> Wipe the leaves with a soft white tissue. If there are mites you will have a red/reddish stain on the tissue.



True if they are the red mites. But not if they are the two-spotted type. Strong magnifying glass will show either.


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## Wendy (Apr 7, 2016)

I did not know that about two spotted mites. Thank you Dot.  (maybe if you wipe them there will be spots on the tissue....:rollhappy: )


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## Cheyenne (Apr 8, 2016)

I will post more later I am at work now. I can tell you that for sure it is more damage. I have been dealing with the same destruction for the last few months. Actually I think they were there for a lot longer. I am very familiar with spider mites from working at Longwood gardens. These mites are different. No webs, and so freaking small it's ridiculous. I spray folic and humid acid which is brown in color. I started to see brown residue on the leaf junctions so I thought it was dried humid acid. Until I bought a plant in ebay and noticed the same brown residue, had never bought from them before. Compared new plant with mine and realized they both were mites. Researching I think they could be russet mites. Not positive. Brown residue was there for months. I new some plants were not doing well but all of a sudden one week about 50 plants died. Next week about 100. Out of 500 or so plants I think I lost 150-200. Looking back I saw the damage in your picks a long time ago, though it was something else. Genocide happened very suddenly.


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## NYEric (Apr 8, 2016)

Use a formula/solution with alcohol in it. Most mites don't like humidity also.


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## Happypaphy7 (Apr 8, 2016)

SlipperFan said:


> True if they are the red mites. But not if they are the two-spotted type. Strong magnifying glass will show either.



True. It only applies if it's red spider mites, which I actually don't need to do this because they are about the biggest pest mites I can see with naked eyes.

It's those super duper little guys that are almost invisible that pose real problem.


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## Happypaphy7 (Apr 8, 2016)

NYEric said:


> Use a formula/solution with alcohol in it. Most mites don't like humidity also.



Some do, some don't.

Red spider mites are typical ones that thrive under hot and dry conditions.


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## Happypaphy7 (Apr 8, 2016)

Hien said:


> This is my observation:
> the damages or patterns on the leaves are mirror images , that means whatever happened to cause the pattern started when the leaves were still in the young stage (both sides of the leaf still facing each other, not fully open )



My initial thoughts also.
I didn't think it looked like typical mites damage.


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## Kawarthapine (Apr 8, 2016)

Wendy.

Is there a particular brand of horticultural oil you prefer?

Can you spray the hort oil onto buds without damaging them?

Thanks,


Duncan


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## Wendy (Apr 9, 2016)

It's Green Earth Horticultural Oil concentrate. You can get it at most plant places....I got mine in the plant section at Canadian Tire. I don't recall ever spraying flowers or buds. I do give the entire plant a coat, both top and bottom of leaves. I try to do it at least once a month....growing indoors is dry and mites love dry.


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