Crop Protection – Keeping Pests off the Plot
Getting the seeds to germinate and the plants hardened off outside is just the start of getting a good crop from your plot. The juicy young tender plants are a magnet for all manner of beasts on the ground and flying pests in the air.
Some form of protection is vital to keep the plants growing strongly because it stops birds and insects damaging or removing leaves while you are away from the plot. Plants need all the leaves they can get to ensure photosynthesis keeps plant growth at the root and leaf level going strongly. With no leaves the plant dies.
Choosing Crop Protection
Depending on the size of pest and the crop, you have several choices of material and many ways to deploy it.
Typically a large mesh size, the mesh size is the size of the hole in the netting measured either as the diameter of a circular hole or the sides of a square hole. It is designed to keep birds away from crops and can be draped over the plants, although it is usually fixed to cloche / tunnel hoops or a framework.
Bird netting can be of a ‘knitted’ type where strands of material are knitted together to form a soft flexible mesh. A large mesh size is around 20mm x 20mm and is ideal for use on a framework.
If your bird pests are small finches then consider using a smaller mesh size. If you drape your netting over the crops smaller birds are capable of sitting on the netting and pecking at the plants through the net. A way of stopping this is by using cloche / tunnel hoops or a frame as these keep a gap between the crop and the netting.
For larger areas fruit cage netting is recommended. It has a typical mesh size of 10mm x 10mm and is semi-rigid and can be fitted to the framework of a fruit cage. A typical fruit cage will be person height so you can walk around in it. This netting can be used on plot crops over hoops or in a low cage type structure.
Anti-Bird / Insect
A smaller mesh size is required to keep insects away from your crops, 2mm x 2mm is suitable for all birds and larger insects such as butterflies. It is made by weaving strands of polypropylene to form a mesh that is very flexible and can be used on all types of structures, tunnels and cloches.
Important things to know about netting:
As the mesh size on netting decreases the thickness of the materials used to make the net become more important.
With small holes and thick strands used to make the net three important plant growth factors can change.
Light getting to the crops is reduced – the smaller the mesh size the lower the light levels
Water getting to the crops is reduced – the small holes do not let as much water through.
Air circulation is reduced.
Insect netting has a typical mesh size of 1mm x 1mm which will keep out most insects with bodies bigger than this. It is suitable for most of the common allotment insect pests such as cabbage root fly, carrot root fly, turnip root fly. It is lightweight and can be draped over the crops directly or fitted to cloche hoops or tunnels. The holes are small enough to stop birds landing on the net and pecking the crops.
Very Small Insects
An Ultra-Fine netting or an almost sold barrier is required to keep these pests away.
Ultra-fine netting has a mesh size 0.2mm x 0.8mm and is suitable for the very smallest of flies and thrips. It can keep the pests out but will reduce light, air and water as mentioned before.
Alternative crop protection for small insects is horticultural Fleece. It is a woven product that is blanket like and the holes in it are microscopic. It will let sufficient light, air and water through to the crops and it doubles as a sun screen on very hot days and insulation if temperatures drop.
All of these neeting types acn be found in our Bird & Insect Netting Section