Check for spider mites now!

A little more detail about specific pests and some information about diseases will be provided in following posts.  This post will serve as an introduction…….

What is different about tunnels?

They are normally warmer and drier than outdoors – That’s why we build them! Unless they aren’t vented properly and get too hot, tunnels provide a more comfortable environment for plants but the same conditions also favour insects and mites, so there are some important rules that are worth remembering.

Rule 1

Under tunnels it is warmer so both plants and insects grower more rapidly. Life-cycles are completed in a shorter time. Routine pest control operations timed for outdoor crops won’t be right for tunnels. You can often predict this using simple heat unit models but this should not be a substitute for diligent crop-walking or scouting. This is especially important when using modern plant protection products that are not persistent and may only act against a specific life stage.

Rule 2

Get the venting and watering right. A good stand of foliage provides a more stable micro-climate for beneficial organisms. Stressed plants are more prone to certain pests. Spider mites are a good example. Predatory mites such as Phytoseiulus enjoy the relatively high and stable humidity that is characteristic of the air close to the leaf surface. If soil dries out, transpiration slows down causing the humidity to drop and the temperature to rise around the leaves. This harms Phytoseiulus and, worse than that, tends to encourage spider mites.

Rule 3

Get your bios in early! Taking mite control as an example: In England Phytoseilus isn’t normally introduced to open field crops until May, when the risk of frosts and cold winds has declined. Under tunnels we often introduce them in March and certainly before the end of April. This is because WE CAN (the environment is relatively stable and bio friendly) and WE SHOULD because pest mites will come out of diapause and start to multiply earlier than they will outside.

More on all this later.

Here are two useful links. Please remember to check the side effects of any plant protection products you intend to use before introducing bios.

http://www.koppert.com/pests/mites/spider-mite/detail/spider-mites/

http://www.ipm.ucdavis.edu/