Question

orchid   QUESTION: Hi Sir,
 
 I encountered some problems with my Antelope Dendrobium, of which I've grown for about 3 years. Few of bulbs are quite soft and almost all the leaves are yellowing/brittle. I checked the orchid but did not notice any visible signs of pest infestations. I've been using the same orchid hormone fertilizer for few months on this orchid and other orchids(which are fine). Will attach more pictures for your reference.

ANSWER: The most common problem with dendrobium culture is rot.  This is evidenced by canes that turned soft. Rot most commonly occurs when the potting mix is kept too wet-- especially during the resting period wwhen they should be kept dry.  To prevent the spread of the rot, you will need to cut off the cane as far down as possible and seal the wound with sulphur or a copper based fungiicide.

---------- FOLLOW-UP ----------

QUESTION: Hi Sir,

 Thanks for great advice! May I know when's the resting period? This is first time I encounter such problem in the 3 years of growing of orchid. How far should I cut the cane? Or do I need to uproot the entire plant?

Answer
The normal growth/resting cycle for a dendrobium starts with the rest period when watering is suspended. The plant will announce the end of its rest period with the start of new growth.  At that time watering and feeding may be started and light levels increased.  Usually mature growth is announced with the start of flowering when watering can be greatly reduced anticipating the start of the next rest period.  Rest periods can last for several months.

Usually rot begins at the base of a cane and moves upward.  Therefore, you will need to remove the entire cane. Occasionally, rot may start higher up on the cane. If this is the case, make succession of cuts below the soft area until the last cut is healthy green tissue.

Uprooting the plant is not necessary but may be done during the rest period without damage.