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Float Bed Sanitation

December 11, 2020 |

by John Capetanos

Growers know how important it is to clean their float trays before planting anything new in there. Beyond giving plants a clean home to start their lives, sanitized float trays also prevent the buildup of everything from too much dirt to harmful fungi. While many farmers swear by a standard bleach wash to keep float trays clean, experts believe the technique may be creating more harm than good for new tobacco plants.

Lindsey Thiessen, professor of plant pathology at North Carolina State University (NCSU), researches disease prevention in agriculture and shares a major flaw with the use of household bleach: It can hurt the plant itself. “Because float trays have numerous pores, any liquid treatment will create air pockets that prevent some of the solution from getting where it needs to go,” she explains. Also, “if not completely washed out, the bleach’s residue can get into the plants’ roots.”

As a result, Thiessen advocates for steaming treatments. In the past, growers turned to chemical fumigant treatments, but these are no longer viable alternatives. Methyl bromide is no longer an option due to recent regulations, and TriSan dip solutions were not effective at eliminating fungal growth after use.

With these chemical solutions off the table, Thiessen’s team, in collaboration with Grant Ellington, NCSU Extension associate professor of engineering, studied a tried-and-true method of cleaning: heat and water. The creation of steam allows the heated vapors to reach all of the pores of the float trays. According to Thiessen, nothing else needs to be added to the steam solution. “The steam treatment works so well because heat and water can reach places that liquid treatments cannot.”

For both flue-cured and burley tobacco varieties, the heat and water steam-cleaning method surpasses any previous dip or wash-cleaning methods, believes Thiessen. As always, success depends on following the correct process.

First, stack the trays in an enclosed converted container, for example, a shipping container. Once they are arranged inside the containers, pump the steam in so that it goes up and through the trays. “You want the heated, aerosolized water to come in contact with the trays’ pores and kill off any fungal growth that otherwise would have been missed in the air pockets created by wash solutions like bleach,” advises Thiessen.

Maintain a temperature of 80 degrees Celsius or 176 degrees Fahrenheit for about 30 minutes.

“Any higher than 80 degrees Celsius, and you may experience some shrinkage in the trays,” Thiessen warns. “As with all aspects of growing and maintaining the health of your plants, keeping a watchful eye on the process will help make sure that the trays are not damaged and maintain full usability.”

While the steam-cleaning process is highly affective, it doesn’t prevent black root rot—but neither does any other method, according to Thiessen. “Black root rot only becomes an issue with some older trays that, from use or time, have become unsustainable. In those cases, taking the tray out of circulation may be the only thing to be done.”



Category: Chemicals & Fertilizers, Plants & Seeds, Transplanting

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