Question on Potentially Contaminated Water Supply and Solutions

[nhbeek]

First picture looks like virus, the next is fungal. The other two are fine. The cattleya looks like purple sun spotting

[Roberta]

Virus identification by appearance is extremely inaccurate. The only way that one can diagnose it is by testing - plants that look fine can be virused, and some that look awful aren't. One of the members of one of my orchid clubs (who is a scientist working on immunoassays, has done considerable work on orchid viruses) did a little test with a group of very knowledgeable people (AOS judges and such) , showed them photos and had them diagnose virus. The results... slightly worse than chance for both positives and negatives. They would have done better flipping a coin.