Shelter from the pests

A simple netting system will help keep out white butterfly and other bugs.
A simple netting system will help keep out white butterfly and other bugs.

It's not often that I get excited about some gardening aspect these days but this week I am very much so.

It all started off recently when the local community newspaper published an article on insect pests that I had written.

Along with the article they placed a picture of a garden with a raised crop cover spread over the vegetables growing.

I saw the picture and did not take any further notice. Then the phone started ringing with local gardeners asking what was the cover and where could they obtain some.

I had come across various crop covers in the past mainly used by commercial growers in limited situations. It can work out very expensive to cover a hectare of land with a raised cover.

I also have noted that the new dreaded pest called the potato/tomato psyllid has big populations currently causing havoc with late crops of potatoes and ruining tomato plants.

Even down in Southland gardeners are not lifting the good yields of potatoes that they are accustomed to because of the psyllids. (They are luckier down there as the psyllid population take longer to get going so they get some reasonable-sized potatoes, which set earlier and then the smaller ones that were affected because they set later). You can spray Neem Tree Oil regularly and apply Neem Tree Granules to the soil to reduce the damage but with each female laying 500 eggs it's a battle.

Wouldn't it be nice if they developed a force field that you could put around your vegetable garden and it kept out all pests including insects, cats, birds and anything else that might harm our crops.

Well a crop cover might not be as good but it would do the same sort of job.

So I went in search of suitable crop covers and found two that would work well.

The first of these is insect mesh, which is 4 metres wide and whatever length required.

It's clear, 45gsm and gives a 15 per cent shade factor. Rain will pass through but cats, birds and most insects would not. Ideal for larger insect pests such as white butterfly, moths, beetles down to about adult aphids. The gaps of the mesh would unfortunately allow some small insects such as psyllids to get through, though it could act as a deterrent. It is priced at about $5 a cut metre.

The other one is a special quarantine mesh - white, 125gsm 3.3 metres wide, 50 x 25 mesh with a 25 per cent shade factor. This is the type under which imported plants are grown until they have met MAF requirements.

I don't think a very small insect like the psyllid would be able to get through this small gauge net. It is more expensive, at about $17 a cut metre.

I see a great potential for home gardeners to use these mesh products for crop protection. I am going to test the quarantine one by planting a late crop of potatoes in one of my raised gardens. I will plant the seed potatoes deep using Neem Tree Granules and then cover the area completely with the quarantine mesh. It will be raised about a metre above the soil to give ample room for the potatoes to grow.

The mesh is available by mail order (contact me for details). There are various ways you can make supports - for small applications make loops of No 8 wire, or form plastic conduit pipe into larger hoops. For bigger plots, build a structure out of wood or other materials.

Problems? Phone me on 0800 466 464 or email

The Southland Times