Submitted to: American Society of Sugar Cane Technologists
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/4/2009
Publication Date: 10/18/2009
Citation: Grisham, M.P., Johnson, R.M., Viator, R.P. 2009. Effect of ratoon stunting disease on yield of recently released sugarcane cultivars in Louisiana. Journal of the American Society of Sugar Cane Technologists. 29:119-127.
Interpretive Summary: The popularity of the sugarcane variety LCP 85-384 increased rapidly following its release in 1993 until it occupied 91% of the Louisiana sugarcane production area in 2004; however, because of concerns over declining yield of the variety, growers are replacing it with newer varieties. A series of four field experiments were conducted between 2000 and 2007 to determine the susceptibility of the seven varieties released since 1999 to ratoon stunting disease (RSD) caused by a bacterium that lives in the water vessels of the sugarcane stalk. In two of the newer varieties, L 99-226 and L 99-233, a high percentage (>50%) of the water vessels were infected with the RSD bacterium and yield loss was detected in infected plants of both varieties. In two other varieties, HoCP 91-555 and HoCP 00-950, a moderate number of water vessels (25-50%) were infected, but yield loss was only observed in one, HoCP 91-555. In the other three varieties, Ho 95-988, HoCP 96-540, and L 97-128, a low percentage of water vessel were infected and no yield loss was detected. Although yield loss was not observed in plants with low levels of bacterial infection, growers should continue plant stalks of cane that are free of the bacterium to prevent spread to more susceptible varieties and to prevent the compounding of effects that may occur if the infected crop is exposed to additional biological or environmental stresses.
Technical Abstract: A series of four field experiments were conducted between 2000 and 2007 to determine the susceptibility of seven commercial sugarcane cultivars (HoCP 91-555, Ho 95-988, HoCP 96-540, L 97-128, L 99-226, L 99-233, and HoCP 00-950) released in Louisiana since 1999 to ratoon stunting disease caused by Leifsonia xyli subsp. Xyli. Susceptibility was based on the percent of stalk vascular bundles colonized (CVB) by the bacterium and yield loss observed in infected plants compared to uninfected plants. Cane and sucrose yields were determined in the plant-cane, first-ratoon, and second-ratoon crops of each experiment and the percent CVB was determined for randomly collected stalks from each plot of the experiments. The percentage of CVB was high(>50%) in stalks of L 99-226 and L 99-233, and cane and sugar yield was reduced (24%) in the second-ratoon crop of L 99-226 (24 and in all crops of L 99-233 (an average 0f 32% across the crop cycle). A moderately high percentage of CVB (15-50%) was observed in HoCP 91-555 and HoCP 00-950, but cane and sucrose yield was reduced only in the first-ratoon crop of HoCP 91-555. The percentage of CVB in stalks of the remaining three cultivars, Ho 95-988, HoCP 96-540, and L 97-128, was low (<15%) and no cane or sucrose loss was detected. Although no cane or sucrose yield loss was detected in cultivars with low percentages of CVB, and in only one of the two cultivars with moderate percentages of CVB, seed cane free of the L. xyli subsp. xyli infection should be planted to avoid spread of the pathogen to more susceptible cultivars and to prevent the compounding of effects that may occur if the infected crop is exposed to additional biological or environmental stresses.