Sanitation When Transitioning High Tunnels

Sanitation practices limit resources pests need to survive, kill existing pests, and also minimize pests from spreading.
Sanitation When Transitioning High Tunnels - Articles

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High tunnel tomatoes. Photo: Elsa Sanchez

Integrated Pest Management or IPM is a strategy for pest management that uses a combination of practices to minimize risks to people and the environment while reducing pest problems.

Figure 1 below, Overview of the IPM Strategy, depicts the IPM process using a pyramid. The IPM process starts at the bottom of the pyramid with sanitation and cultural methods as the first step. The last step, pesticide application, is used only when other practices are ineffective at keeping pests below acceptable levels. Today Scott DiLoreto, manager of the College of Agricultural Sciences 50,000 ft2 greenhouse facility, talked with students in our Hydroponics and Aquaponics course and reminded us about the importance of sanitation.


Figure 1. Overview of the IPM Strategy. Provided by Scott DiLoreto

Sanitation practices limit resources pests need to survive, kill existing pests, and also minimize pests from spreading. Practices include cleaning equipment, removing infested plants and plant parts, removing crop residues, weeding, avoiding the re-use of potting mix, and disinfecting pruning, cutting tools, pots, and flats. When transitioning high tunnels from spring/summer to fall/winter crops or vice versa, sanitizing tunnels before planting next season's new seed or planting stock is a great strategy to avoid the spread and build-up of certain pests.

It can be difficult to find the time to clear and clean out a tunnel entirely before planting the next crop and having a combination of spring/summer crops with fall/winter crops during the transition is common. However, this sanitation step can really help with pest management later in the growing season as is shown in Figure 2. Crop Production Timeline.


Figure 2: Crop Production Timeline, provided by Scott DiLoreto

Two situations are presented in the figure. The top arrow, labeled "dirty start", illustrates what can happen when a crop is started without adequate sanitation practices. The bottom arrow, labeled "clean start", illustrates what can happen when a crop is started after sanitation practices have been used. In both situations crop seeding is done at the same time. For the dirty start, pests are discovered and exceed thresholds much sooner than for the clean start, requiring four pesticide applications before harvest. In this example, when plants are started in a clean, sanitized growing space only two pesticide applications are required to secure the crop. Good sanitation practices provide growers with a longer pest free window, reducing the need for pesticide and reducing labor and expenses associated with pesticide application.

How does this apply to transitioning high tunnels? For example, if summer crops are not removed and tunnels are not cleaned out before switching out crops, pests can use summer crops as hosts and then easily move to newly planted crops. We are seeing this happen in a high tunnel experiment where we are studying aphid management. Aphids will move from tomato plants to the next crop of lettuce or other leafy greens. When this happens, aphid outbreaks in lettuce and leafy greens usually occur very early in the crop production timeline. Good sanitation when transitioning high tunnels can go a long way to avoid this problem.

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