Question
QUESTION: Hello,

I am pretty new to the orchid world.  All of my experience thus far has been with my mother's phals.  Last week, she sent me 2 bare rooted dens, a thongchai gold and a pattaya red as a present.  Unfortunately though, the plants were mailed to me - she got them on ebay - and some of the leaves had turned yellow and gotten slightly shrivelly.  One or two of the leaves showed some damage - bits eaten or broken off - and the immediate damaged areas are drying.  I've noticed that the pattaya has a couple tiny black spots on 2 leaves that don't rub off. Is this some sort of bug or disease?  Also, I've *just* noticed a weird spot on one of the thongchai gold leaves.  It's a small brown, raised spot that looks almost like hardened sap?

I've repotted them both with standard orchid mix in 5.5" clay planters that have drainage holes at the bottom.  I water once a week with a weak solution of orchid food, making sure the water drains out and that they're not sitting in water etc.  I live in an apt. in Southern Ontario and they are about one or two feet away from my north facing window.  The leaves are darkening up slowly and the shrivelling is going away. Is there anything else I should do to make sure they're happy?  Should I spray them with some sort of pesticide just in case the grower wasn't quite uhm...reputable?  I'm quite wary about pesticides, but my mom gave these to me in an effort to share her interests - though she only keeps phals - and I'd like to keep them alive.  Not only that, I've seen pictures of the blooms these plants are capable of, and they look gorgeous!

Thank you ahead of time for your help! :)

ANSWER: Samanths, it is likely that the black spots are sunburn.  The alternative explanation is a leaf fungus.  For now, ignore it.  If it appears to be spreading then you may want to spray the plant with a fungicide.  I recommend a copper salt fungicide.  The fungicide will not "cure" the spotting, but may prevent further spreading.

See if you can remove the small brown raised spot on the Thongchai Gold leaves.  If so, it is most likely brown scale.  This is the adult stage of this sucking insect and, where there is an adult, there are likely to be eggs or immature insects.  Remove the adults with a paper towel soaked in alcohol.  The immature Crawler stage is more difficlut to spot as they blend in with the plant tissue but is the way the scale moves about the plant and, if left unchecked, could destroy the plant in a few months.  Thus, you will want to find a suitable insecticide that is effective against scale and spray it as recommended on the label.  Do this outside on a day when the sir is calm.

Dendrobiums like to be tightly potted. so be sure you have potted them into a pot in which they just fit-- real snug.  Withhold your feeding until you see new growth.  Until the plant is in active growth, it cannot use plant food.  Dendrobiums are a fairly high light plants-- much more so than phalaenopsis.  In the house they will prefer a south or west window sill. For now, it won't matter much, but when they are in active growth try to raise the light level.  Fell free to ask followup questions if my response is unclear or raises other questions.

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QUESTION: I just thought of an additional question - do you know of/recommend any "natural" or "homemade" solutions for the fungus or the scales?  I'd be interested in pursuing those first in lieu of a harsh chemical if its a viable option.

Answer
Good question Samantha.  Listerine has antifungal properties.  It can be used full strength. To prevent fungal infection of an open wound, powdered sulphur is a product I have used with good success. For black spot fungus, a solution of Copper sulphate in a product called Kocide has been very useful in protecting new growth from becoming infected (this is just prepared as a water solution and sprayed on the new growth.)  Neem oil, the sap from the Indian Neem tree has been used with fair success on scale and other insects and is available in most garden centers. My current favorite for insects is a new commercial product called Bayer Advanced.  It is a systemic insecticide that gets absorbed into the plant tissues and is effective for up to 6 weeks.  It a new, safer product than most other commercial insecticides.  Some have used rubbing alcohol with a little dish soap to be sprayed on the plant.