- Author: Steven A. Tjosvold
The previous post described the importance of inspecting incoming plants and keeping a clean nursery to avoid pest introductions. Many important root pathogens and other pathogens, weeds, and insects can be introduced in contaminated soil and growing media, and so the focus of this post will be on ways to prevent introductions from these potential sources.
Soil- inhabiting plant pathogens can be found in growing media and associated root and crop debris. Anything that has contacted the ground, such as equipment, tools, irrigation hoses, and workers' hands and shoes could be contaminated. Pots should not sit directly on the ground. Phytophthora infecting the roots of just one potted plant can produce thousands of propagules that can move in water draining from the pot and infect roots of nearby plants.
Likewise, during a vigorous rain storm, these propagules can be splashed from the contaminated pot or ground onto nearby plants. Benches or similar structures that support plants above the ground can eliminate or minimize this. In greenhouse structures, concrete floors or other impervious surfaces are ideal for walkways between benches. Floor surfaces should be kept clean of plant debris, soil, or growing media. After a crop cycle, benches should be cleaned of plant debris, washed and dried. Drying can kill sensitive plant pathogens.
Benches can be sprayed with diluted chlorine bleach (0.5 % sodium hypochlorite solution) or other suitable disinfectant. Potting media and plant debris will inhibit the activity of most disinfectants.
There are many clever ways to raise pots and containers off the ground.
The bottom of clean shoes can be sanitized with disinfectants such as quaternary ammonium compounds .
Store and handle growing media so it does not come in contact with the ground or water runoff. Cover the media when not in use.