Mottled leaves on phal
 

A few of my phals have leaves that are mottled,not sure why..could it be a virus?

There are several possibilities, including insufficient nitrogen and/or magnesium.

Tell us more about your water supply and feeding regimen.

Mottled leaves
 

I water once a week using weak dilution of orchid specific fertilizer of 20-10-20..I had to go out of town for a few weeks recently which,now that I think about it,had disrupted my routine..would it be beneficial to increase the fertilization concentrate for awhile or ?

First what do you mean by weak dilution?

Next does the fertilizer contain any magnesium?

Next are you using tap water or purified water? If tap water can you look at your water company's online water quality report to see whether it has contains any magnesium?

By weak, I use 1/4 tsp per gallon with every watering..looking at my fertilizer ingredients I do not find magnesium listed but manganese is. I do use tap water so I’ll get the analysis on that..

Magnesium and manganese are two different elements. Plants need both but they are not interchangeable. Magnesium can react with other fertilizer components and precipitate out of solution, so many fertilizers lack magnesium. You need to provide it since your fertilizer lacks it.

Plants put one atom of magnesium into each chlorophyll molecule. Without magnesium plants can't make chlorophyll, and they become pale. I think this is your problem.

Epsom salts available at the drug store contain magnesium. On a separate day from using your fertilizer, you could water your plants with a solution of 1 teaspoon of epsom salts per gallon of water. That will provide magnesium. It can take a very long time, even some months, to replenish plants deficient in magnesium, so keep at it.

Some people have enough magnesium in their tap water for plants, but others don't.

Thank you so much for your expertise! I will start the Epsom salts immediately. Would it behoove me to treat all my orchids as well even if their coloring isn’t affected? Is there a reason you have to fertilize separately from Epsom salts? Would you adopt me?

1/4 tsp/gal of that fertilizer is 75-80 ppm N

How often is “every watering”?

I water once every 7-8 days,they have gone 2 weeks on rare occasions.

Yes, all plants need magnesium.

Magnesium and calcium mixed with other fertilizer may lead to formation of insoluble precipitates. This might make the magnesium or calcium unavailable. Calcium and magnesium are often applied by gardeners separately from other nutrients. If your water has enough of them you probably don't need to supplement them, which is why I asked about your water quality report.

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