What are mechanical pest controls?
Another element of IPM, mechanical pest control includes any physical or hands-on control methods. Mechanical control is most valuable when you have acute pest problems- when pests are abundant enough that you can quickly remove or kill a large number.
If you are also employing a biological control, it will probably be most efficient to use a mechanical method to remove the worst of the pest population, then release biocontrol agents. As usual, you should consider how mechanical controls will work with your other IPM strategies.
Three goals of mechanical pest controls
Goal 1: Exclusion
The idea is pretty straight-forward: keep pests away! Exclusion can be achieved by several means, one of which is row covers. Row covers are not only useful for frost protection and weed control, but can provide a barrier from insect pests.
Another exclusion method is use of a mesh screen around plants or garden beds. If you grow in a greenhouse, you already have an exclusion method in place: your greenhouse walls. However: don’t sink into a false sense of security- insect pests are sneaky! Your greenhouse will keep many insects out, but a few will find their way in, and as per the cruel humor of nature, the two insects that find their way in will be a fertile male and female with ambitions of setting a Guinness world record for most eggs laid. The bottom line is: don’t rely on your greenhouse walls to keep out pests altogether.
Goal 2: Destruction
While working in a greenhouse a few years back, I was instructed in a particularly... gooey destruction method against slugs involving scissors and many a disgusted grimace. The "cut them in half" method was unpleasant but certainly effective, and a perfect example of destruction. Another common destruction method is the use of diatomaceous earth to kill insect pests. Destruction methods are unique to the pest and the situation (and whether you mind getting slug guts on your hands). Use your imagination! And if you can’t figure anything out, recruit some young boys to kill some insects for you.
Goal 3: Removal
Removal methods include handpicking (which is usually followed by destruction), use of traps, water pressure sprays, and insect vacuums. Light traps, color traps, and sticky traps are all useful not only for collecting the offensive insects, but to monitoring pest population and the species that are present. Sticky traps are cheap and easy to use.
Don't forget to diversify!
Mechanical pest controls should only take up a fraction of your control effort.