A Nine-Step IPM Program

As with most everything, having a plan in place is critical and having a sustainable pest management plan in your greenhouse is no exception. According to Dr. Roger T. Huber, professor emeritus in the Department of Entomology at the University of Arizona, there are nine steps growers need to follow to keep their greenhouse vegetables healthy and pest-free.

#1 Documentation
Over time, growers can use information regarding what occurred a year or two ago, or what Huber refers to as building up of the experiential base. By knowing what has been a problem from year to year, growers will know what to look for in the future. “Without record keeping, you are starting from scratch every time,” he adds.

#2 Monitor Plants
If there is a fundamental of fundamentals, it would be having a good sampling or monitoring program, says Huber. The only way growers can know what is going on in their crops is by frequent plant monitoring. This is particularly important in order to keep pest problems localized, he says. They need to diagnose the problem early
before it has a chance to spread.

#3 Identify Pests And Damage Symptoms
“The more you know about your enemies in the greenhouse, the better you are going to be able to manage them,” explains Huber. In addition to knowing when insects show up, growers also need to know how long it takes for the pest to complete a generation, and what type of environment it flourishes in, etc. For example, he says spider mites like a warm and dry environnment so growers need to pay particular attention to plants when these conditions exist. “Knowing which biologicals to use and knowing how the insects interact gives growers some wiggle room to know when certain pests will show up,” he adds.

#4 The Biology Of Beneficials
When releasing predators and parasites into the greenhouse, they are pest specific. If you are going to use a biocontrol program in your greenhouse, Huber suggests making sure you identify your target pest and understand its life cycle.

#5 Exclusion
Most pests come in from the outside unless they are brought in on the plants. Going back to the first step, growers who keep good records will know when to be on the lookout for specific insects. In general, however, take every precaution to make sure the proper screening is present and that only clean plants from a reliable nursery are brought into the greenhouse.
Exclusion, Huber adds, is about
nine-tenths of the battle. Growers avoid problems by preventing pests from entering the greenhouse in the first place.

#6 Sanitation
Huber says keeping both the inside and the outside of the greenhouse clean and weed-free is critical to keeping pests at bay. “Make sure you don’t have areas that act as nurseries for pests as a lot of the virus vectors come from surrounding crops.” He points out that alfalfa harbors viruses yet shows no symptoms. For greenhouse tomato producers, be sure to remove tomato leaves that have fallen as they may be harboring pathogens.

#7 Healthy Plants
It may be very obvious that healthy plants are the end goal, but to get to that point growers must employ good cultural controls, use the right amount of fertilizer, make sure light and moisture are optimum for the plant, etc.

#8 Resistance Management
The potential for resistance in the greenhouse is big, says Huber, and greenhouse growers do not have many products from which to choose. “We need to extend the life of these products,” he says. “All products have a number assigned to them so if a grower is going to use a material that is a number 1, for example, and he has to come back and spot treat later in the season, then he is going to want to use a number 3, so a different mode of action is used.” He also points out the benefits of insect growth regulators and materials that suffocate pests where resistance isn’t an issue.

#9 Know Your Options
The bottom line is growers need to determine how they are going to handle pest problems before the season starts. “Are you going to use biocontrols or are you going to use oils?” Huber asks. “That has to be determined when you are marketing your crop as you will have to figure out who your pest control suppliers are going to be.”
Bringing things full circle, Huber concludes that it all goes back to good record keeping and knowing what has been a problem in the past and which controls worked — and which ones didn’t.