I am in the process of converting my garden from an annual crop base to a perennial one (haven't been able to swing my better half yet on converting it all to a full blown food forest). Last year I swapped out my regular kale for sea kale. It came in quite nicely, but unfortunately succumbed to an aphid infestation. I started looking through studies on natural forms of aphid control and came across this one which shows companion plants that can help. The table in the study lists the specific plants and the mechanism they use. I think I will be trying some of these this year. Has anyone tried this before, or had success with other methods of perennial pest/disease control (or just aphids in general)?
I've found in my own garden the best form of pest control is to make sure plants are growing under the best conditions. I've noticed my plants only tend to get problematic levels of insects if the plants are stressed. Typically in my garden this means getting too hot and/or too dry. If the plants are happy the insect "pests" stay at a level where their predators keep them under control.
I agree with Tyler above. My greenhouse often gets aphids in the winter when it's all under a greenhouse. It seems to be correlated with the plants having too much nutrition in the soil, and definitely when it gets very hot in the greenhouse and if there isn't enough ventilation. I squish the aphids by hand where are just a few, and that helps to keep them under control. Also watering more frequently to both reduce wilting and maybe reduce the intense nutrition in the soil. When the greenhouse comes off in early summer the aphids invariably reduce back to very few or none really visible.
Works at a residential alternative high school in the Himalayas SECMOL.org . "Back home" is Cape Cod, E Coast USA.
Ive been fortunate to not have bug issues on my perrenials which is currently blackberry, asparagus and wolfberry (goji). The balance is natural natives (mustang grape, argarita, wild blackberry(dewberry?) My trees are not mature enough yet.
I watched an episode of The Permaculture Orchard about aphids. It was interesting. His theory was too much nitrogen attracted aphids. He told a story of a lady that was confused because one tree had aphids the rest didnt. She was explaining how this tree was treated the same as the others. During the conversation, the husband fessed up and said every morning he goes to that one tree and urinates. 300+ days a year.