Greenhouse Pest Control
Spring isn’t only a good time for plant growth. It’s also a great time for pests, especially in the greenhouse. An occasional greenfly in the greenhouse can quickly become a full-blown attack on every plant benefiting from the warmer glasshouse conditions. When you’ve filled every available space in the greenhouse with pots of developing seedlings, grow bags of burgeoning plants and much more, don’t sit back and let all your hard work become pest fodder.
It’s galling enough to discover an epidemic of something munching on your plants, but knowing that you could have prevented it is even worse.
As the weather warms pests start to emerge from their winter shelters and begin to procreate. In the greenhouse it happens even faster as we actually provide the ideal conditions and a perfect food source for many pests.
The secret of control is to act as soon as you see the pest. Certain problems can linger undetected until they are a major problem e.g. whitefly.
Early detection
Whatever your type of control preference you can use yellow sticky traps. Far from being simply a mechanism for trapping flying insects, these sticky cards are the look out scouts. Hang these at the growing point of your plants, spaced out around the greenhouse, and they’ll capture flying pests to give you an indication of problems that might be present. Examine them regularly to determine exactly what is moving into your glasshouse and take action. Likely culprits will be aphids and whitefly. Early detection is essential. BUT Remove the sticky traps if you are introducing biological control as they may become caught on the sticky trap
Once you’ve identified the problem you need to think and act fast. Think because now is the time to decide what method of control you intend to use. Chemical, or organic. If you use the former then you can’t resort to biological control later in the season, it won’t work, because you have already used persistent chemicals that will affect the beneficial insects (biological controls) that you now want to use.
Pesticide residues designed to kill the pests will also kill your new friendly bugs, and they can persist in the greenhouse for up to ten weeks depending on the active ingredient. So, it is essential if you are considering using green options to make the commitment, either way. You can’t swap between the two. Often biological control is attempted as a last resort, but it will not work if you have already sprayed your plants with chemicals because the pests you are trying to obliterate are of the same make up as the predators and parasites you are trying to introduce.
The green approach
Using a greener method of pest control with an integrated approach is much more likely to achieve your pest free ideal and it is healthier for you and your greenhouse. You are simply utilising the power of nature to take the hard work out of pest control. What’s more, once introduced it keeps on working even while you are away on holiday and more importantly pesticide resistance is no longer a problem.
It’s nothing new, after all nature has been doing it for aeons. Ladybirds eat aphids, beetles eat slug eggs etc etc. Biological control is a system that uses other naturally occurring organisms to eat or parasitise your greenhouse pests. It’s a bug eat bug system that leaves your greenhouse (or conservatory) free from pests, chemical residues and means that your crops of tomatoes and other edibles remain pesticide free. If your greenhouse is a summerhouse too or even a conservatory you may dine in comfort.
Biological controls need to be used with respect. These are microscopic living organisms and have strict requirements when it comes to conditions. The temperature needs to be right and of course they need a food source – your pests! The only other drawback is that is can be a bit costly, however when you consider the cost of chemical sprays, not to mention the cost to the environment and the money you’ll save in healthy plants and plentiful, edible crops, it’s a small price to pay.
If a pest is out of hand you need to try and get it under control first using a product that has a mechanical action, this means that it blocks the breathing holes of the pest or strips its coating and doesn’t linger in the greenhouse. Soft soap products and oil seed rape products which blocks pores and are available at the garden centre. You can introduce biological control as soon as the soft soap is dry. Other organic pest controls can affect these beneficial insects so check with the experts for advice on the best control for your problem. When the temperature is an average of 50F you can start to use biological controls. Be patient you are working with living organisms and must allow them time to settle and establish before they start to make a marked effect on your pest problems.
Remember that healthy well-fed and watered plants are less susceptible to pest and disease problems. Keep them free from stress and away from extremes of temperature to keep them healthy.
Greenhouse hygiene is another weapon in the battle against pests. By using fresh, clean compost each season and cleaning out pots and trays and even capillary matting with a dedicated greenhouse cleaner you reduce the chance of overwintering pests and diseases re-infecting your plants.
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