Jeffrey W. Hoy, Carolyn F. Savario and Allen E. Arceneaux
LCP 85-384 is a sugarcane variety that will occupy a special place in the history of sugarcane in Louisiana. It ultimately occupied a record-setting 91 percent of the industry acreage in the state during 2004, and its widespread cultivation caused a major shift in harvesting practices that created many new research questions. The heavy tonnage produced by LCP 85-384 often caused plants to fall down or “lodge” during the growing season, so it was necessary to shift from cutting cane with a whole-stalk harvester to harvesting cane with a chopper harvester capable of lifting lodged cane and cutting it into sections called billets. This harvester change then created intense interest in developing practices that would allow successful planting with billets.
Sugarcane is not planted using true seed. Instead, it is vegetatively propagated – new plants develop from buds on sections of planted stalks. Historically, the crop had been planted as whole stalks in Louisiana because of the possibility of stressful climatic conditions during the planting season and the following winter and because of damage from diseases known as stalk rots that can rot the planted seedcane.
Planting takes place at the end of summer when the “parent” plants have produced stalks of sufficient length to provide adequate planting material called “seedcane.” The stalk buds then germinate following planting and establish a stand of shoots during the fall. These young plants must then survive the winter and begin actively growing again during the next spring. The combination of stressful environmental conditions – such as drought, excess rain and numerous or severe freezes – and stalk rots that are more severe when plants are stressed can result in the death of buds and young plants, creating stand problems.
The failure to establish an adequate stand in the first growing season causes the worst loss a sugarcane farmer can suffer. Because sugarcane must be planted in late summer, fields often remain fallow during the season before planting. This means no sugar is produced in that field for that year. In addition, the seedcane used for planting represents a substantial cost. Together, these two factors make planting expensive, and having to repeat the process if an adequate stand was not established would cause a large economic loss.
Stand establishment and survival over the winter are more difficult to achieve when billets are used as the planting material. However, it would be expensive for farmers to maintain a whole-stalk harvester just for cutting seedcane. Labor availability and crop lodging also are factors creating a need for billet planting. Therefore, research was undertaken to identify practices that would maximize the chances of success with billet planting.
Unfortunately, billet-planting research has been only partially successful. Direct control of stalk rots cannot be achieved with planted billets, so cultural practices have been used to avoid conditions favoring severe disease and to allow stand establishment despite disease damage. Planting more seedcane is necessary to improve the reliability of stand establishment with billets, but this adds to the cost of planting. The last remaining option is to select varieties that tolerate billet planting. This need has resulted in an ongoing research project to evaluate tolerance to billet planting in the variety selection program.
Problems with billet planting are closely linked to stressful environmental conditions. The occurrence of these conditions varies from year to year, and varieties in the later stages of the selection program are constantly changing. This means it is necessary to conduct field experiments comparing the performance of different experimental and commercial varieties planted as billets or whole stalks each year.
Experiments have been conducted at the Sugar Research Station at St. Gabriel, La., for the past three seasons. In these experiments, yields obtained from billet plantings have been lower than the yields obtained from whole stalk plantings. The amount of reduction varied strongly among different sugarcane varieties and depended on the weather conditions following planting. A comparison of cane tonnage yields obtained from billet and whole stalk plantings of seven varieties during 2005, 2006 and 2007 illustrates the variability caused by variety and environmental conditions. The results in the figure show yields produced by billet plantings as percentages of the wholestalk plantings for each variety over the three years.
Stressful environmental conditions resulted in greater reductions in billet- planting yields during 2005 and 2007. The two newest varieties, L 99-233 and L 01-283, exhibited the most tolerance to billet planting – they did not sustain a significant yield reduction even in the years with stress. Averaged across all three years, billet plantings of L 99-233 and L 01-283 produced 93 percent and 98 percent, respectively, of the yields obtained from whole-stalk plantings. In contrast, yield reductions were significant every year in billet plantings of Ho 95-988 and were very high when stress occurred. Other varieties, such as LCP 85-384, HoCP 96-540 and L 99-226, tolerated billet planting in the absence of stress conditions but showed reductions when stress occurred.
Over time, whole-stalk planting will provide higher yields with lower cost. However, the periodic occurrence of badly lodged seedcane and the lack of availability of labor are circumstances under which billet planting will be needed. The LSU AgCenter is conducting research that will enable sugarcane farmers to use the best possible practices for billet planting. Knowledge about the ability of varieties to tolerate billet planting under variable conditions will help farmers make planting decisions to minimize stand-establishment problems. This important information is being determined and provided to farmers on a continuous basis.
Jeffrey W. Hoy, Professor, and Carolyn F. Savario, Research Associate, Department of Plant Pathology and Crop Physiology, LSU AgCenter, Baton Rouge, La.; and Allen E. Arceneaux, Research Associate, School of Plant, Soil & Environmental Sciences, LSU AgCenter, Baton Rouge, La.
(This article was published in the spring 2008 issue of Louisiana Agriculture.)