QUIZ: Leaf Ailments - 8 photos

[beccahoo]

Thank you to everyone in advance who participate in this quiz to help us newbies learn how to identify ailments on our leaves!!

[Tindomul]

I want to learn too, so I am subscribing.

[beccahoo]

Yes hopefully we can get more people to help!!

[Selmo]

Being that these photo are of leaves only, there are usually only a few choices, leaf spots or viruses. But, here goes (these are just my guesses, fore I'm not an expert and would need more information to make better guesses)
A. One of the leaf spots, guignardia
B. Cymbidium virus
C. One of the leaf spots, phyllosticta
D. Sun burn and erwinia maybe
E and F. Looks like one of the leaf spots
G. Erwinia or pseudomonas
H. Anthracnose
Once agian, these are only guesses. These pathogens can look different on different types of orchids. The link at the top of the page is a good place to start. And will give you better information on how to treat these pathogens. Hope this is a start and others can chime in that are more knowledgable than I. Would like to know if I passed the quiz.

[Tindomul]

H looks like something I see a lot in my collections.

[beccahoo]

Selmo thank you for you reply!! I did some homework for you. Perhaps it can help ?

photo uploading

[Ray]

This is a nice idea, but diseases are awfully difficult to diagnose by visual inspection alone, as many look quite similar. Not to mention that what looks like a disease might be a response to some cultural issue.

One misdiagnosis, for example, is attributing dead, black tips on new growths to a fungal infection, when in fact it is due to a deficiency in calcium. Sure, fungi can grow on necrotic tissue, but a fungicide won't fix it.

[charlesf6]

okay where's the answers?

[Gage]

D. There are 2 issues here. One is most certainly sunburn, indicated by the gray haze on both leaves and the large black area on the lower leaf. The second is the tiny black speckles that appear to have been present prior to the sunburn, which could be from any number of things including insect damage or fungus.
F. This looks like mite damage. If the mites are still present, you can wipe a white cloth or paper towel underneath the leaf and see them on the cloth as a orange or brown smear.

[beccahoo]

I only sterelize my tools with flame over my cutters on both sides for 10seconds each to ensure the virus is denatured. I've also had the grand privilege of meeting an orchid judge Dr. Julian Coker who taught me many things. His CD on pests and diseases was a real eye opener and that made me pull the plug on the Cymb Katmantoo. The rosette flowering was not an indication of virus but was fasciation. Nonetheless, the new growth had signs of mosaic virus and so it went straight to the bin. As for the other leaf ailments, here is my conclusion based on Dr. Coker's DVD and everyone else's comments. This is of course only my opinion following my research and cannot be taken as gospel

A- ticking in zygopetalum (from lack of watering)
B- slugs, scale, likely to be burns from white oil on leaves exposed to heat, less likely to be cymb. mosaic virus as the pattern is circular and irregular compared to the mosaic virus photo in above comment
C- two spotted mite, sunburn, hail damage (small white spots) followed by bacterial ticking (black spots surrounding)
D- sunburn
E - insufficient watering, too much fertilizer, excessive deadroots
F- orchid fleck virus, fascination on flower, cymbidium orchid virus will attach photo of F following this post (I have binned this orchid)

If anyone is interested like me in orchid pests and diseases, I highly reccomend Dr. Julian Coker's DVD which can be purchased through him by googling Atlantis orchids. He has been in the industry for many years and I could not be more grateful for his advice and privileged to visit his orchid nursery.

I hope this post is helpful. Good luck everyone