Question
QUESTION: When the largest bulb on my Oncidium neared the end of its flowering it sent out a leafy shoot on the same side as the spike, but from the base of the bulb. This shoot is a lighter green, very slightly sticky, and the leaves were tightly wrapped, almost braided together. The shoot has now reached about 4 inches (10 cm) and the leaves at the tip are starting to lengthen and loosen up. Can you tell me what's happening?

ANSWER: Chris, members of the oncidium group do tend to leak sticky sap as they grow.  Because they are thin leaved, and because they leak plant sap, they tend to attract mites and other sucking insects that feed on the sap.  Leakage of plant sap in these thin leaved varieties is normal but you should guard against the pests that feed on this plant sap. The two main culprits are mites and mealy bugs.  Mealy bugs tend to develop inside of leaf sheaths and other places where they remain hidden doing their damage. Carefully check inside the rolled up leaves and leaf shesths to look for the white fuzzy mealy bugs and, at first sign, spray with an appropriate fungicide-- preferably a systemic type.  Both mites and mealys multiply rapidly, so, if you notice any damage other than the sap leakage, you should immediately begin treatment. Mites are very tiny and do their damage in largely invisisble numbers. When in sufficient numbers, they can be identified by the web-like structure they build and by a lighter colored pattern of leaf damage.  If you have mites, you will need a different insecticide than for the mealy bugs-- one specifically for spider mites.  Spider mites thrive under dry conditions so, as a preventative you might try misting the plant lightly in the morning to deter them.

Oncidiums do prefer a lot of light and plant food so try to make that available as new tissue develops.

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Onc_Shoot   QUESTION: Thanks for the answer Wayne - lots of good stuff I had no idea about! But the main point was what exactly is this new shoot? (Image attached). Is it a new pseudo-bulb in development or a new growth on the existing bulb?

Answer
Thanks for the attached image Chris.  It is a new growth which, when it gets large enough, will develop a pseudobulb at its base.  New growth only develop pseudobulbs as the last stage in their growth. Your new growth probably has 4-8 weeks of growth ahaead before you will notice the development of a pseudobulb at its base. Then it will take a comparable period for that pseudobulb to mature and "harden off".