Question

Orchid1  

Orchid2   Hello,

I've got a double orchid and one of the spikes has started turning white. It first developed white spots in the centre stalk where both spikes join and has started to spread up one spike. The flowers and stems on this spike now all appear limp. The other spike and flowers appear to be in good order.

Your help will be much appreciated.

Thanks.

Answer
Thanks for the pictures Ryan.  There appears to be two explanations. The first is flower senescence. When a flower reaches the end of its flowering cycle, existing flowers will turn white, thin, and fold.  These will eventually fall off.  

The second condition is that at the base of a flower spike I see what looks like mealy bug.  Mealies can be detected by rubbing isopropyl (ie rubbing) alcohol on a q-tip or cotton ball over the base of the flower spike. If mealies are present, they will come off on the cotton as brown flecks. Mealy infestations are common on orchids and are difficult to eliminate or  control because they migrate to locations where they can feed on the plant sap (such as dead or dying flowers).  They also can lay eggs in the potting mix and in plant sheaths.   They are sucking insects that multiply rapidly and can destroy a plant if not controlled at an early stage.