While there are a few different types of trays on the market for use in tobacco float systems, most trays are made of polystyrene. Standard options for growers include high-density, low-density, shallow-well and glazed trays.
While high-density polystyrene trays are more durable, they are also more expensive, as they tend to be bulkier and heavier to ship. Low-density trays are more common; however, problems with difficult-to-remove roots growing into the fragile walls have been reported.
Shallow-well trays help reduce production costs because they are not as expensive to ship, they require less media to fill the cells and they are easier to store. According to research conducted by NCSU, tests have so far shown that there is no change in the quality of transplants grown in the shallow trays versus those grown in traditional polystyrene trays.
Glazed trays undergo an intense heating process while being manufactured, creating a stronger sidewall within each cell to make them more resistant to root penetration and easier to clean. Also, the cells on the glazed trays are slightly shallower than 288-cell trays and require less media to fill them. Tests have shown that fewer roots penetrate these types of trays.
Regardless of your tray selection, be sure to keep trays clean and sterile by rinsing them immediately after use and disinfecting them thoroughly prior to storage or just before use.
Sam Baker, vice president of Cross Creek Seed in Raeford, N.C., says his company offers a new way to sanitize trays—with steam. With the company’s new service, growers bring float trays in, the trays are loaded onto boxes, and they are steamed in a special trailer for an hour. The steam kills pathogens effectively without the use of any hazardous gases or chemicals.