Black rot, pineapple disease

Ceratocystis paradoxa

Asia, Africa, North, South and Central America, Europe, Oceania. Black rot, or pineapple disease, is recorded on sugarcane from Australia, Fiji, and Papua New Guinea.

Sugarcane (black rot or pineapple disease), cocoa (pod rot), coconut (stem bleeding), banana and plantain (black end or fruit rot), maize, mango, pineapple (see Fact Sheet no. 190) (black rot or water blister), potato, sweetpotato (see Fact Sheet no. 232) and taro.

The fungus enters the setts through the cut ends. The internal tissues turn red, and then brownish-black with a characteristic pineapple smell (Photo 1). Cavities develop, and here the fungus produces spores; roots fail to form, buds fail to grow, and those that do, die back or remain stunted.

Spread of the fungus is by spores in the wind, or run-off rainwater (or irrigation water). Insects, especially beetles, are said to spread the spores as they bore into the setts. Survival is in the soil for at least a year, and for several months in infected plant remains. High temperatures (28°C) favour sporulation and growth of the fungus.

A wound fungus, causing a number of diseases on crops of economic importance in the tropics - banana, cocoa, coconuts, pineapple, and sugarcane. On sugarcane, it is a disease of the planting material, the setts, although there are reports of damage to the standing crop

When conditions are unfavourable for growth of sugarcane setts after planting, such as water stagnation, rots occur and result in gaps in the stand, and the need for repeated replanting. Also, the sugar content from infected canes is lower than healthy ones, and it does not crystalize properly.

There are reports that borer injury to the standing crop, or drought, increase black rot infection and damage, with cane turning yellow, drying and dying, but this is unusual. More often, infection of standing cane occurs after attack by red rot, Glomerella tucumanensis (see Fact Sheet no. 221).

Look for setts that have not sprouted in the field and split them to see the internal colour. Note that the pineapple smell is only present in early rots and is not useful for detection.

CULTURAL CONTROL
Cultural control is most important.

Before planting:

• Use healthy planting setts; they should be of the right age, with at least three nodes
• Make sure that the fields have good drainage; places where water remains after rain can increase susceptibility to the disease. Drought, too, can increase sett susceptibility, so aim to plant at the accepted time.
• Select varieties that sprout rapidly after planting.
• Treat setts in hot water at 51°C for 30 minutes, if planting is delayed.

After planting:

• Collect and burn or bury as much of the crop as possible after harvest. 

CHEMICAL CONTROL
It is unlikely that fungicides would be an economic option against this disease; however, if they were needed, use carbendazim.

____________________
When using a pesticide, always wear protective clothing and follow the instructions on the product label, such as dosage, timing of application, and pre-harvest interval. Recommendations will vary with the crop and system of cultivation. Expert advice on the most appropriate pesticide to use should always be sought from local agricultural authorities.