Clean nursery, healthy plants

As a nursery owner, you probably have implemented some sort of disease-control program to keep fungal, bacterial and viral pathogens at bay. You devote a lot of time, money and resources to keeping your plants disease free. But you may not realize that one simple misstep could undo all that work.

Your crew’s hand tools are a potential vector for these pathogens. Proper sanitation of these tools can minimize the risk of spreading plant diseases.

Chris Uhland, owner of Harmony Hill Nursery in Downington, Pa., says sanitation should be part of any nursery's routine maintenance procedure. Harmony Hill grows shade, ornamental and specimen trees, shrubs and perennials. His crews often clean mud and burlap off their spades and shovels, spraying them down to prevent any rot from penetrating the metal.

“The mud sitting on the metal of a shovel or spade will rot it, then you'll lose lifespan on the tool,” he says.

Aside from decreasing the life of the tool, an improperly maintained blade can reduce transplant success.

“If your spade isn't sharp, and it doesn't have a quick, clean cut, then when you're transplanting the tree, the root will have damage where it was cut,”

Uhland says. “It will have cracks, which will then cause disease and decay, and it won't take properly.”

Which tools?

Many tools used in day-to-day nursery operations need to be sanitized, including hand pruners, shears or saws that are used to make pruning cuts on ornamentals.

Thomas A. Dudek, senior extension horticulture educator, Michigan State University Extension, says it is best to have two sets of tools on hand while pruning. That way, one set can be in the disinfectant while the other is in use.

Equipment and tools can be sanitized with a number of different common disinfectants. A 10% sodium hypochlorite (household bleach) solution, 70% alcohol, hydrogen dioxide and quaternary ammonium compounds are all common disinfectants that can be used in a nursery environment for tool and equipment sanitation.

Dudek says there is some evidence that Lysol (either un-diluted or a 10% solution) and Listerine at full strength can be effective, although neither product is labeled as a disinfectant for pruning tools.

However, he says, do not use Pine Sol as it has been shown to cause plant injury.

Application tips

Some growers use a spray bottle to apply disinfectant. They thoroughly wet the surface and allow the tool to drain and dry before making any cuts to prevent plant injury from one of the products. Others dip the tools in the disinfectant.

Dudek says if there is a build-up of plant sap or resins on the tools, they should be removed prior to treatment with disinfectants so the disinfectant will work. This task can be done with a rag or scrub brush.

Tool sanitizing should be done when moving from one cultivar/group of plants to another, or at the beginning of each work day. But any time a plant is pruned with a tool that hasn’t been sanitized, there is the danger of pathogens being spread.

“I suggest that a sanitized tool be used for every pruning cut made so the risk of plant disease spread is minimized,” Dudek says.

Disease management in nurseries is critical because of the limited air circulation encouraged by tight spacing and constant irrigation. The ensuring high humidity provides optimal conditions for the reproduction of many fungal and bacterial pathogens.