IMPACT OF SUGARCANE DISEASES ON CANE AND JUICE QUALITY

Authors: Grisham, Michael; Legendre, Benjamin

Submitted to: Inter-American Sugar Cane Seminars Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 9/6/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: Sugarcane pathogens cause yield loss in the field, but may also cause changes in cane and juice quality that adversely affect mill efficiency. The effect of four pathogens on cane and juice quality was determined in a series of experiments. The most common effect on cane quality of the virus that causes sugarcane mosaic was an increase in fiber content. Increased fiber content adversely affects the extraction of sucrose from the cane. Other quality components including juice Brix, sucrose, and purity did not differ between diseased and healthy plants. In contrast, plants infected the bacterium that causes ratoon stunting disease had increased sucrose content, while fiber content did not differ between diseased and healthy plants. Leaf scald, caused by a bacterium, reduced the concentration of sucrose and purity in extracted juice of symptomatic stalks when compared to asymptomatic stalks. Again, mill efficiency may be adversely affected. Juice from the tops of sugarcane plants infected with the luteovirus associated with yellow leaf syndrome had a significantly higher concentration of Brix, sucrose, and purity as well as a higher estimated yield of theoretical recoverable sugar per ton of cane when compared to healthy plants. It may be assumed that the concentration of starch was also increased and can lead to severe problems at the refinery. An understanding of the effects of diseases on cane and juice quality in addition to cane yield adds an emphasis on the need to control these diseases and may help explain reduced efficiency in sucrose extraction.

Technical Abstract: Sugarcane pathogens cause yield loss; but how different pathogens affect the sugarcane plant varies. Understanding the way different pathogens affect the sugarcane plant can influence the methods used to determine cane and juice quality and may show that the impact of the disease extends beyond losses that occur in the field. The effect on sugarcane plants by sorghum mosaic virus (SrMV), the causal agent of sugarcane mosaic; Clavibacter xyli subsp.xyli, the causal agent of ratoon stunting disease (RSD); Xanthomonas albilineans, the causal agent of leaf scald; and a luteovirus associated with sugarcane yellow leaf syndrome (YLS), was determined in a series of experiments. The most common effect of SrMV on cane quality was an increase in fiber content. Other quality components including juice Brix, sucrose, and purity did not differ between diseased and healthy plants. In contrast, plants affected by RSD had increased sucrose content, while fiber content did not differ between diseased and healthy plants. In cooperative studies with J. W. Hoy, Louisiana State University, leaf scald reduced the concentration of sucrose and purity in extracted juice of symptomatic stalks when compared to asymptomatic stalks. Preliminary studies conducted in 1997 in Louisiana found that juice from the tops of sugarcane plants infected with the luteovirus associated with YLS had a significantly higher concentration of Brix, sucrose, and purity as well as a higher estimated yield of theoretical recoverable sugar per ton of cane when compared to healthy plants.