Battling the Blight
Understanding and managing Pokkah Boeng disease in sugar cane fields
Pokkah Boeng or twisted top is a devastating fungal disease in susceptible varieties of sugar cane.
Indian Technical and Economic Cooperation (ITECH) expert from India, Dr Geetha, who is working with Sugar Research Institute of Fiji (SRIF) as head of crop protection department, said the disease was prevalent in all sectors in Viti Levu and Vanua Levu.
She said the disease occurs below five per cent in Mana, the popular tolerant variety in Viti Levu during dry seasons.
However, in the varieties Kaba and Naidiri, the disease reaches up to 40 per cent with a higher intensity of 20.6 per cent.
“During rainy season, the resistance of Mana is broken, especially in low-lying areas with incidences reaching 80 per cent in some fields in Drasa and Ba,” Dr Geetha said.
“Loss of one or two canes per clump.”
She also said in Viti Levu, the disease severity is high (30 per cent) in the areas that receive more rainfall or suffer poor drainage and under cooler climate.
“In most varieties, it appears during rainy season and the crop usually recovers post-wet season says,” she said.
“Several kinds of symptoms of the disease appear depending on the crop stage, variety, crop husbandry, and climatic factors.”
What happens to the cane caught with this disease?
1. Initially, profuse tiny red patches or streaks appear on the leaves of young plants.
2. Leaves would either be distorted
or wrinkled.
3. Emerging leaves get tangled.
4. Later, the infected crop shows yellow patches or bleaching at the base of the leaves. Advancing disease results in malformation of the cane top and the emerging leaves are unable to open freely, leading to a knotted appearance in the crown of the plant.
5. The internodes get narrower and the stalk bends.
6. Cane becomes stunted. 7. In severe cases, the cane top rots or then dries and snaps off.
8. Side shoots appear.
Dr Geetha said in resistant varieties, the immediate shoot near the top would develop into a cane, but in susceptible varieties, the cane perishes leading to yield loss and field gaps.
In poorly drained soils, the impact of the disease could be observed in all varieties if the rainy season extends.
Management of Pokkah Boeng
Some of the things that sugarcane farmers can do to save their farms from this disease are as follow: Plant healthy setts /certified seed cane as it will prevent the early occurrence of the disease.
Cultivate resistant varieties. Takes pecial care during rainy season especially when cultivating susceptible varieties in soils with poor drainage or low-lying areas.
Canes showing the advanced stage of symptoms should be removed.
Avoid planting unapproved varieties whose resistance status is unknown.
Wherever possible, practice crop rotation as older ratoons exhibit more disease.
Follow proper field sanitation practices.