Disease threat looms over sugar crop

A difficult-to-detect cane disease is likely widespread in Barbados and threatens next year’s sugar crop, a leading researcher has warned. Andrew Stoute, research director at the West Indies Central Sugarcane Breeding Station in Groves, St George, cautioned on Wednesday that affected fields would now have to be replanted with hot water-treated material. Stoute told Barbados TODAY that while no scientific survey had been conducted since the 2000s to determine the current impact of ratoon stunting disease (RSD), it was likely widespread. He said: “It is transmitted by harvesters as they cut the cane. I am not aware that any sanitising takes place. So, it is likely widespread. But if there was recent hot water treatment of planting materials, the ratoons would be disease free.” The quality of the canes in the field was “very” variable at present, Stoute said. “It looks to me like we are still having some fields that still have RSD and would need to be replanted with hot water-treated material in order to show maximum yields.” But the researcher pointed out that he knew of several plantations and farming operations using hot water-treated material. You Might Be Interested In “When you see those fields, it is obvious they are receiving the proper management. Ratoon stunting is a particularly difficult disease to handle because the symptoms are not visible until you get a drought or until you get a dry spell. And increasingly, in our environment, we are getting more droughts and more dry spells. There are no visible symptoms other than the plants stop growing. You never know exactly why…is it a fault in the nutrition, is it just for rainfall?” He explained that research showed that RSD greatly inhibited a sugar cane plant’s ability to respond positively or maintain its growth in dry conditions. “And I think that’s severely impacting a lot of our yields currently,” he stressed. Stoute suggested the likely impact of the disease on the sugar harvest was “permanent”: “The disease builds up every year in a plant. So, the later he ratoon, the harsher the conditions, the more impacted every subsequent crop will be. “A plant needs to be vigorous in order for the ratoon to be well established. If the plant isn’t vigorous you don’t get the same regrowth in subsequent years.” Stoute argued that even though some farmers might be correct in forecasting higher output for next year based on expanded planting, that had to be placed in context. “If they are planting hot water-treated material that would hold. You should get more yields particularly if they are planting hot water-treated material or material from a hot water-treated nursery. “The ideal way that this should be done… you should take the material and plant a nursery with it; and that nursery can give clean material for two to three years, and give you good planting material.” He continued: “So, yes, planting more material will give you higher yields, but you might be looking at the difference between a 25-tonne per acre crop, versus a 40 tonne per acre crop, depending on management. “Planting more acreage will give you more yields, but planting disease-free material will maximise the yield that you get.” Highlighting the importance of the work being done at the research station, he insisted that it was critical to keeping the sugar cane industry alive and active. Stoute noted that the environment was constantly changing and that new diseases and pests were always arriving or posing potential threats. He recalled that a few years ago, a pasture mealy bug had been imported into Barbados and was now causing problems in many other places. “Fortunately, it hasn’t been here [since then]; but the point is that we always have new threats and changes in the environment. “If you stay with the same varieties that you have grown in the past, they are not going to be adapting to the new environment. What we do here, is we regenerate that new… the base for that new variety programme to generate those new varieties that would not only continue performance, but improve in performance and adaptation to the environment in the coming decades.” (EJ)