Transparent spots on young leaves

[WhiteRabbit]

My first thought too is sucking insects - I get this a lot on outside orchids - the thinner leaved ones - cyms, oncs. Tho what I see on mine is quite tiny, but otherwise similar looking ...

[Bobfharris]

Usually when you see the spots it is after the thrips have done their work. You have to catch them in the act and they are sneaky. But I really don't think it's viral or fungal because of the very regular nature of the spots. I deal with thrips a lot in Hawaii and that's what one kind of them does.

[Eyebabe]

The level of depigmentation of the spots is more than I have seen with any pictorial references to virus.
Not having the experience of actually seeing virus in person with any great frequency makes it difficult to be sure. Virus also will affect the older portions of the plant more so than the younger portions as the viral load in the older plant leaves is higher.
If you have tests or know someone with tests that you can get a single test from, then it's easy enough. But you have to buy $125 worth of test at a shot and if you just have one plant to test can be financially cumbersome.
Fungal infection Phyllosticta causes depigmented leaf spots but they usually are sunken and at some point turn brown.
Sap sucking insects are high on my list of suspicion. Bringing the plant indoors for a few months and establishing if the new growth gets "spotted" may be part of the detective work necessary...unless thrips can get in ur house too
Also, if you are spraying chemical near the plant you can see depigmentation as well. X-clude 1600 insecticide will do this to my plants with thinner leaves if the can sputters and I get spits of chemical interrupting the usual fine mist.
Hope this helps

[goofy]

Thank you all for your respond. A viral test would be somewhat expensive for me as I have only a few cymbidiums. I can take it inside and see if the new leaves will have spots too, but my inside space is too small and does not have enough sunlight for cymbidium. I will try to look more often and catch the thrips on the act if there are any.

Thuy

[Bobfharris]

I'm pretty sure this is not virus. Virus actually shows more on the NEW leaves (yes in Cymbs this is true as I have a commercial nursery and can attest to it). It will show normally for ORSV at irregular chlorotic lines in more or less a chevron or as reddish lines streaking. Ken Jacobsen I believe had an article about Virus in Cyms in a back issue of CSA Journal (a good reason to join CSA!!) with pictures. For now I would treat for thrips. Either use pesticides or horticultural oil depending on your preferences.

[D_novice]

I have something quite similar to this, and it appears to be spreading to all of my cymbidium plants, and not to adjacent Zygos, D. kingianums, and L anceps. Looking closely the marks appear brown at the center; seem to be more apparent on young growth; and some are more white than translucent.

I know this isn't scale as I've had that and treated it, though I've seen bad cases of scale leave marks like this, after the scale was killed and cleaned off.

It doesn't look like the photos of thrip damage that come up on the web - though I did have thrip damage to a Catt flower that was in close proximity to these, outside.

[Cym Ladye]

I totally agree with B Harris that this is thrips! It is a persistent problem in one area of my collection under a bay tree if I do not keep a close eye on it. I keep mine at bay with a spray of Bayer 3 and 1 Mite and Insect spray twice at 7 days apart.

Since you are in Marin you should be able to obtain this spray at Home Depot or Summerwind or through Amazon.

[D_novice]

Thanks. I avoid toxic pesticides for a multitude of reasons.

Will stick with Cinnamon, soap + oil, and am giving Captain Jack's Dead Bug Spray a try. Will report back if I remember on whether this is as successful as the "big guns".

Thanks for the input, probably will be dealing with Thrips for a while.

[D_novice]

Thrips Management Guidelines--UC IPM

Chemical Control
Although thrips damage is unsightly, it does not usually warrant the use of insecticides in gardens and landscapes. Feeding injury typically does not become apparent until after tissue grows and expands. Thus, by the time damage is noticed on ripening fruit or distorted terminals, the thrips that caused the damage are often gone. No pesticide application will restore the appearance of injured tissue; plants will remain damaged until leaves drop, injury is pruned off, or new unblemished fruit is produced. Where plant viruses are a problem, insecticides typically do not kill thrips fast enough to prevent the transfer of virus from thrips to plants. Using row covers or other methods to prevent thrips infestation is the most effective way to prevent infection by thrips-vectored viruses.

Thrips can be difficult to control effectively with insecticides, partly because of their mobility, feeding behavior, and protected egg and pupal stages. Improper timing of application, failure to treat the proper plant parts, and inadequate spray coverage when using contact materials are common mistakes that can prevent potentially effective insecticides from actually providing control. Before using a pesticide, learn more about the biology of your pest species and the characteristics of available products by reading the label and consulting the Active Ingredients Database in the online version of this Pest Note at Home Page - UC Statewide IPM Program. Often you will learn chemical control cannot be effective until the next season, when new plant growth develops. Certain products are available only by hiring a professional applicator. If insecticides are used, combining their use with appropriate cultural practices and other methods usually improves the pest control.

Insecticides Most Compatible with IPM
Contact insecticides that do not leave persistent residues can be effective for greenhouse thrips and other species that feed openly on plants. These products have low toxicity to people, pets, and pollinators and relatively little adverse impact on biological pest control; because they do not leave toxic residues that would kill natural enemies migrating in after their application. Contact insecticides include azadirachtin (AzaMax, Safer Brand BioNeem), insecticidal soaps (Safer), narrow-range oil (Bonide Horticultural Oil, Monterey Horticultural Oil), neem oil (Green Light Neem, Schultz Garden Safe Brand Neem Oil), and pyrethrins, which many products combine with piperonyl butoxide (Ace Flower & Vegetable Insect Spray, Garden Tech Worry Free Brand Concentrate). To be effective, contact sprays must be applied to thoroughly cover buds, shoot tips, and other susceptible plant parts where thrips are present. On plants with a history of unacceptable damage, begin treatment early when thrips or their damage is first observed. Unless directed otherwise by the product label, periodically repeat the application as long as pest thrips and susceptible plant parts are both present.

Spinosad (Captain Jack’s Deadbug Brew, Green Light Lawn & Garden Spray with Spinosad 2, Monterey Garden Insect Spray) is generally more effective against thrips than the products above. Spinosad lasts 1 week or more and moves short distances into sprayed tissue (has translaminar activity) to reach thrips feeding in protected plant parts. Adding horticultural oil to the spray mix can increase its persistence within plant tissue. This insecticide is a fermentation product of a naturally occurring bacterium, and certain formulations are organically acceptable.

[Cym Ladye]

To each his/her own when it comes to toxic or "green" solutions to this problem. But when the infestation is not controlled by the "green" products and becomes heavy enough to affect the buds, you may want to try another answer. Little transparent holes in Cym flowers, which ultimately necrose, are not a pretty sight.