The Sugarcane Disease Detection Lab is now accepting samples for ratoon stunting disease (RSD) testing. The lodging caused by Katrina is going to make sampling more difficult, but samples can still be collected from the downwind ends of fields. Disease testing may not be in the forefront of many people’s minds, but there is still a need. Monitoring is an important component of a successful healthy seedcane program. It is good to perform a quality control assessment to make sure that a program is working as intended or determine if a problem is developing on farms that try to save some money by not buying as much healthy seed.
Sampling old stubble fields of cane intended for the mill is the best means of determining whether a healthy seedcane program is working as intended. This means sampling needs to be conducted soon. We still recommend collecting 20 stalks scattered across the end of a field. Each sample should consist of a complete joint, two nodes with an intact internode, collected from the lowest portion of the stalk. Place the stalks in a sealable plastic bag, keep them out of direct sun and deliver them to the lab for testing. Please fill out a form (see attachment) to provide information about the farm, field and seedcane history. RSD testing has provided a valuable survey of how we are doing in the effort to reduce the impact of this long-term industry foe.
There is always some discussion about how to describe the healthy seedcane source or history of a field of cane. When does cane derived from healthy seedcane become “field-run” cane? The current form defines this as “any cane that has been increased more than three times.” Some confusion enters in the use of the term “increase.” This implies cutting and planting. Essentially, any harvest of the cane represents a possible RSD spread event.
We have shown in experiments that RSD spread into planted cane is greater than occurs in the ratoon regrowth, so stubble of healthy seedcane can provide a good seed source. Any combination of plantings and regrowth involving more than three harvests should be considered field-run cane. As examples, this would mean that fourth stubble of cane off-the-truck and first stubble of cane that had been increased twice before establishing a field intended for the mill would both be considered field-run. We do not recommend increasing seedcane more than three times.
As in past seasons, there will be no charge for the testing. Please let Lori or Jane know when you plan to bring in some samples. We will leave a box out on the Life Sciences Annex dock to receive the sample bags. With the increased traffic in Baton Rouge, you may not want to venture into campus (I would not if I did not have to). Therefore, if you let us know the samples are coming, you can drop them off at the St. Gabriel Research Station or the West Baton Rouge AgCenter office.
The lab also offers testing for our most recent disease, yellow leaf. To test for this disease, collect one of the young leaves close to the whorl. Trim the leaves (one per stalk) to fit in a 1-gallon zippered bag (keeping the base of each leaf). Leaves are easier to collect, so larger sample sizes (more plants) per field are encouraged, because they will give a better estimate of infection. You can stockpile stalk samples for a week, but the leaf samples will need to be refrigerated if they are to be held for more than a couple of days before delivery.
We look forward to working with you. If you have any questions or comments, please let me know. The lab is staffed by lgrelen@agcenter.lsu.edu, Lori Grelen and jpaccamonti@agcenter.lsu.edu Jane Paccamonti, and the number is 225-578-0760.