Our speaker at the July Meeting was Mike Abel who gave us a very informative and useful talk on how to control the pests who eat our plants and ruin the appearance of our gardens without using chemicals.
Mike’s recent career has been in selling bumble bees to commercial growers to pollinate plants in greenhouses. He explained he is not an organic gardener but doesn’t use chemical controls. There are limited chemicals that are now available to amateur gardeners. He told us about some various methods available:
Predator and Parasite – A predator will eat the pest from the outside while a parasite will eat the pest from the inside. E.g. there is a nematode that will eat slugs from inside. (One called Nemaslug is available on-line). It is less effective on snails as snails live above soil while slugs live in the soil. You just water it on. There is also a mite that will kill fuchsia gall mite. This is a recent pest that infects our fushcia’s and deforms the buds. If it takes hold you have to destroy the plant. Ladybirds are a good predator. It is their larvae that eat the aphids (green and blackfly). The problem is that if you kill the aphids with chemical sprays the ladybird larvae have nothing to eat and will not survive. Mike commentated that he seems to have a lot of ladybirds this year.
You will never eradicate the pest but you can get it under control. With biological controls you cannot overdose so it is less important to keep to the stated dosage although you may just be wasting your money if you use too much. There is no biological control for lily beetle but you can treat the soil with a nematode to kill the larvae. The adults chew the leaves and petals, but it is actually the larvae that do the real damage as they eat the roots.
If you do use chemicals then pests can build up resistance. You should use brands that have different chemicals in them to try and prevent this from happening.
Disadvantages of Biological Control:
· Likely to be slower acting
· Not effective when there are high numbers of pests (Prevent better than cure)
· More expensive
· You have to have faith that they are working (e.g. when you don’t see lily beetle is that because the neamotode killed the larvea or just because there aren’t many beetles.
· They need the right conditions to be effective.
· More effective in greenhouses and limited use outside.
Cultural Controls:
· Avoid Stress on the plant
· Regular and well balanced feed and watering
· No extreme temperatures
· Partner with complimentary plants (Companion planting)
· Plant Mesh – Buy the right grade mesh for the bug you are trying to prevent and not to harm other wildlife.
· Various substances you can spray – Washing up liquid (leaves a sticky substance on leaves, potato starch (but this will also kill bees)
· Stimulants (To promote stronger healthy plants – seaweed, mycorrhizal, fungal controls, bacterial and Garlic spray.
