Page 27 - Simply Vegetables Autumn 2024

Pheromone trap
Carrot fly defence
Protecting Brassicas
like fine mesh, fleece, or cabbage root fly collars.
Pest monitoring is something we should do more as many gardeners rarely look carefully at their plants so don’t realise, they have a pest problem until too late and there is an epidemic. Whenever you go out into the garden or to the allotment have a walk around and check your plants (called crop walks in commercial horticulture). When watering or doing other plant maintenance look at your plants and check their health.
If problems are spotted early, they are
the crop yield and in the case of pests like slugs kill the crop. If the pest population is very low and not increasing possibly owing to natural controls, then no action may
be taken if they increase then something needs to be done before economic damage and crop yields are reduced.
The preferred use of biological, physical, or non-chemical control methods (cultural methods) are using methods of control not involving chemicals which is what most magazines and books written in the last five or so years mention. These could
a broad-spectrum insecticide that kills many insects including predators and harmless species that do not attack
plants. In the good old days, (only joking) we had chemicals like organo-chlorine (DDT, Aldrin) and organo-phosphorous (malathion, parathion they work well but were lethal!) products that killed everything which is not our aim these days. If you decide to use a chemical only use types that kill specific insects or limited range of insects and use carefully.
Keeping the use of interventions to levels that are necessary is to only take action if really required, if only a few pests and the population does not build up it may not be necessary to use chemicals or even take much action but keep an eye on things.
Following anti-resistance strategies is
to avoid using the same chemicals every time as pests can then quickly build up resistance to the chemical and it is no longer effective. So, try to swop to different chemical ingredients with each treatment to reduce the likelihood of pest resistance building up. Usually, two chemicals with different modes of action is enough three is better. The mode of action is how it works or put another way how it kills the pest.
Evaluate the success of strategies just means at the end of the crop or season have a look back at what worked well and anything the did not work or became a problem and plan some different actions for the next crop / year.
The various photographs show different methods of physical and cultural control mainly different forms of barriers to prevent pest access to the crop.
I hope the above gives you some idea of IPM and its use and hopefully you can keep on top of any pest and diseases.
easy to control and little if any damage is done. Five aphids are easy to squash, fifty-five are becoming
a problem, five hundred and fifty is a problem and damage is being caused; taking prompt action avoids this.
If problems are spotted early, they are easy to control and little if any damage is done
be barriers like mesh to prevent pest access which can work well for many flying pests. Or it could
be the use of biological controls the range of which has increased in recent years and more will come onto the market in future years. These can work well but not always and do not give often 100% control as
As I am sure members
have noticed the gardening
magazines and TV
programmes mention the reduced use of chemicals and greater use of other pest prevention and control methods. Many of the recommendations are preventatives rather than controls which is a good thing as prevention is better than cure! But do they all work, if it was so easy we would not have as many pest problems, having said that they are worth using to reduce pest attacks. So what are thresholds or normally written economic threshold levels, this is basically the level at which a pest or disease starts to cause economic damage to the crop, so as mentioned above five aphid would cause little damage, but as they breed and the population increases they will cause enough damage to reduce
if all the pests were killed there would be no food for the predator, and it would die out. They work better in greenhouses and polytunnels which are enclosed rather than outdoors where the flying insects can fly away! If the biocontrol is watered onto the soil it will stay in the area it is applied to so is fine outdoors. There is a lot of research into various bio-controls using bacteria, fungi and viruses to control both pests
and diseases and these will come onto the market in future years; I am aware of at least three or four which should be out in the next couple of years.
The selection of target specific pesticides is to select chemicals that only control
a limited range of insects rather than
Simply Vegetables 27