Tracks of yellow on Phal leaves

[bethmarie]

None of the pictures I've seen of fungus/bacteria/pest infected leaves match the track pattern of yellow on this plant. A couple of the Phals I ordered this summer arrived with mesophyll cell collapse. The one pictured below also shipped during high heat, but does not have sunken areas of collapsed cells, just this yellow tracking on all four leaves, some worse than others.

I haven't seen this before, and wonder if someone here might have.

Thanks

[Ray]

I'm sorry to say that it looks vaguely reminiscent of the so-called "microfungus". From the St. Augustine OS website:


Microfungus or Virus or Mites? We've heard this malady described as all three.

Symptoms: In the order of appearance, the leaves display yellow chlorotic spots, then more defined yellow spotting that can grow into elongated yellow streaking, then pitting, and finally large areas of grayish tissue collapse. It can be confused with mesophyllic cell collapse caused by watering with cold water, although cold damage weathers to dark rather than light sunken spots in phals. Paph infections weather to darkish sunken spots. Cattleya may have small black spots on the leaves.

From Bob Gordon Culture of the Phalaenopsis Orchid: "sometimes a condition prevails that is caused by a systemic infection of microfungi. As there are literally hundreds of these, the symptoms vary from plant to plant. Some of the more common are a spotty, ill-defined chlorosis; a streaky chlorosis beginning at the edge of the leaf where it looks as if the leaf edge had been burned with a match or candle; a red-brown coloration appearing at the apical third or half of the lower leaves followed by a dehydrated and senescent (old) appearance and also mesophyll tissue collapse where deep pitting becomes apparent on the surface of the leaves. This latter condition can also be caused by cold water and by virus infections. However, in the latter instance, the pitting is usually dark-brown to black in appearance rather than the white to light fawn caused by fungi."

Treatment: If you believe it is broad mites, spray with a miticide (labeled for Tarsonemidae family mites) at the first sign of chlorotic spotting. If you believe it is a microfungus, follow the recommendations from Alan Koch of Gold Country Orchids: spray first with Banrot plus Aliette, then Cleary's plus Subdue, then Banrot plus Subdue. These sprays / drenches should be 7 days apart in summer and 10 to 14 days apart in winter, all at label strength. The combination of fungicides results in a synergistic effect. Follow all label instructions and wear protective equipment.

[bethmarie]

Thank you for posting that, Ray.

The plant has lost one leaf, which eventually went completely yellow, but didn't show grayish areas or tissue collapse. I've been treating with Sucrashield while searching for a better idea of what I may be dealing with (which you provided)

Is Sucrashield effective on Tarsonemidae family mites?

[NYCorchidman]

Given that it is running along the vein, I would suspect virus.
Test your plant for virus.