Dragon Fruit Stem & Fruit Rot
Bipolaris cactivora; Enterobacter cloacae
A soft, wet rot of dragon fruit stems and fruit caused mainly by the fungus Bipolaris cactivora, and sometimes by soft-rot bacteria. Unlike the firm, dry scars of stem canker, this disease collapses tissue into a mushy rot and is a frequent cause of post-harvest fruit loss.
🔎 How to spot it
Look for depressed, water-soaked lesions with olive to black, powdery spore growth that spread and merge until the tissue collapses into a soft rot. It often begins at the tips of branches or on blossoms and developing fruit, and the bacterial form turns stem tips into a slimy, foul-smelling mush. Fruit may rot in storage or transit after looking sound at harvest.
🥀 Damage it causes
Infected stem tips and fruit break down and are lost. Because the rot often shows up after harvest, fruit packed sound can arrive rotten, making it a serious problem for shipping and storage as well as in the field.
🔬 What causes it
The fungus Bipolaris cactivora is the main cause, with bacterial soft rot (Enterobacter cloacae and others) involved in the slimy stem-tip form. Warm, wet, humid weather and wounds from handling, sunburn, or insects let the pathogens in, and spores spread in splashing water.
🛡️ Prevent it
Avoid wounding stems and fruit, water at the base rather than overhead, and keep plantings open and airy so surfaces dry quickly. Harvest in dry conditions, handle fruit gently, and cool it promptly. Remove and destroy rotted stems and fallen fruit to cut the source of spores.
🧯 If it is already here
Cut out and destroy rotted tissue well past the soft margin and improve airflow and drainage. Protectant fungicides can help in wet spells, but there is no rescue for tissue that has gone soft, so careful sanitation and gentle, dry, well-cooled handling at harvest do the most to prevent post-harvest losses.
💡 Good to know
The quick tell from stem canker is texture: canker lesions stay firm, sunken, and dry, while this disease leaves tissue soft, wet, and collapsing. Both are worse in wet, crowded plantings.
🌱 Plants it affects
5 plants in the library can be affected by this problem
For educational and informational purposes only. Disease management advice is general guidance drawn from university cooperative extension sources; always identify a problem positively and read and follow the label on any product before use, especially around food crops, children, and pets.