the cucumbers on our Devon farm have been under attack from the cotton aphid. We are usually prepared for it in late June but this year high numbers of them came early. The aphid isn’t interested in the cucumbers but feeds on the leaf to take in sugars. Anything they can’t use is secreted onto the leaf as honeydes and invaded by sotty mould. The leaves then can’t photosynthesise so the plant struggles to grow.
sooty mould on the leaves
To keep aphids down we send in a parasitic wasp, aphidious colemani, that stings up to 300 aphids in two days, injecting an egg. This parasitises the aphid so the egg can use the aphid’s body to feed on. We’ve got them under control now but it’s too late for some of the plants and we’ll get around 50% of expected yield of cucumbers this year. Next year we’ll anticipate an early attack!
Hoverfly lay eggs on leaves and the larvae is another natural predator of aphids:
hoverfly
2 responses so far ↓
clarke // November 8, 2009 at 6:55 pm |
I was surprised to learn that the hoverfly was so beneficial to plants and so antagonistic to aphids. Any tips on how one can encourage them to hover in one’s garden?
riverford // November 9, 2009 at 9:35 am |
there are a few plants that attract them that you might like to try: cosmos, sunflowers, lupins and foxgloves.