The Fruit Doctor

For the most part we see tunnels as helping to reduce pest and disease pressure but (!) there are some problems that can sneak up on the unsuspecting grower. In England we have a phrase: “Forewarned is for forearmed” that is very appropriate for the management of tunnel pests or diseases.

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/

Where dogs fly!

Chile Tunnels

Haygrove ventured close to the Antarctic to help with a project growing Ribes in the far south of Chilean Patagonia. A wonderful bunch of INIA scientists, advisers and growers are trying to beat huge winds to produce fresh currants well outside the normal shipping season. On the flight down from Santiago Punta Arenas John Berry was told that Punta Arenas was the only place ‘were dogs fly’ and that it was necessary to have ropes along the street to assist the elderly…In the Summer! Correctly specified and with appropriate windbreaks it should be possible to build Haygrove tunnels to cope with growing conditions close to Cape Horn just as they do in the South Africa Cape region but it’s a challenge.

Wind protection required both for the tunnels and the crops

From these chilly tunnels we visited cherry and raspberry growers in the Central Plain before looking at an exceptional blueberry project north of Santiago. A very high standard of technical management at the farm has resulted in very early blueberry production on the foothills of the Andes with Haygrove tunnels providing additional earliness together with protection from both frost and wind.

Early blueberries, north of Santiago

A big thank you to our hosts and everyone who helped us! You are setting very high standards of hospitality and horticulture – even for bees which is a subject to be discussed later…..

Catering for honeybees

Wet Midlands

Back home in England the West Midlands hasn’t been dry for weeks. Famously Cumbria, 200 miles north of here, recorded 372mm in 24 hours. Ledbury hasn’t been that wet but many growers have been pleased that modern tunnel designs have allowed them to keep covers on over peat and coir grown crops during this difficult time. Telescopic and Solo tunnels have been OK during a series of November storms. Raspberries were still picking in un-heated glass last week but most growers are now concentrating on preparations for 2010.

Waiting for Summer to return