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All my brassicas were infected by cabbage aphids. Is there any way I can avoid these next year? Do they overwinter?

The best way to deal with most pests is to be sure you have a very diverse garden that is attractive to beneficial insects that prey on your pests, like these aphids. That will never reduce your pests to zero, but it should keep them in check, so they are not so destructive. Natural enemies of the cabbage aphids include ladybugs, syrphid fly larvae, and some tiny stingless parasitic wasps.

Plants to attract ladybugs to your garden include all the Umbelliferae such as fennel, dill, cilantro, caraway, angelica, tansy, wild carrot & yarrow. Other plants that also attract ladybugs include cosmos (especially the white ones), coreopsis, scented geraniums, dandelions, calendula, marigolds, feverfew, sweet alyssum. Most of those are also attractive to the syrphid flies (hover flies) along with buckwheat, lavender, mints, bee balm, thyme , zinnia.

Grow a good selection of these mixed in with and around your garden and you will have lots of help managing your aphids and other pests! Aphids are soft bodied and are susceptible to soapy water spray. But the leaves are sensitive. It has to be soap (like dr Brunner's pure soap) not detergent (dish "soap" is usually detergent). The trouble with the aphids is they get down inside the head, so you need to pull the wrapper leaves back. Best is to treat frequently when the plant is younger, before it heads up. After the soap spray, be sure to rinse, and don't do this in direct sun.

I had an abundance of those things on my kale even though my garden rarely has an aphid problem. The kale was a weak plant, so I pulled it. I planted another in a better place. It was healthier and did not have the same problem. Insecticidal soap or horticultural oil will work, but you must also control the ants by putting out ant bait. Rainbow's suggestions for the homemade soaps also work.

"The kale was a weak plant"

Yes, this is key. The healthier and more vigorous your plants, the better able they are to fight off/ withstand various kinds of attacks (disease, pests, etc). This also implies not over fertilizing, especially with high Nitrogen ferts. Lots of N stimulates lots of tender, weaker, new growth. You want plants that are smaller and sturdier.

I sympathize!

Aphids in cabbage can be so bad the plants begin to decay. Once the bugs are between the leaves, it is impossible to hit them with a spray. I bet this is a crop industrial ag uses a systemic insecticide on, early in the season ...

You can take that idea for what it's worth - and, I don't think it's worth much. The scheduling might help, tho'. The contact organic sprays mentioned can be used early in the season before the plants begin to head.

Also, I have had much less aphid problems in cabbage by growing celosia, strawflowers and other dry flowers, nearby. I don't spray those plants with anything! The ladybugs and yellow jackets seem to love them.

I mean, when I'm out cutting an armful for drying and arrangements for the fall and winter, I've gotta move like a sleepwalker! Tolerate those predatory wasps. They carry off lots of pests and a "bad" yellow jacket year will mean almost no aphids in my garden.

Steve

True. Yellow jackets do not make friendly neighbors but they do clean up a lot of pests.

Diatomaceous Earth

I had problems for a while with cabbage aphids. What worked for me was not planting any brassicas for a year.

Plant fennel somewhere in the yard, not in the garden. It is an aphid trap and lure aphids to it and away from the other plants. When fennel blooms it will attract beneficial insects and ladybugs will raise their larvae on the fennel and they will happily eat up the aphids. Trap plants work better if they are established well before you start the other things in the garden. Pests will not be zero but they will be more manageable.

imafan26 wrote:Plant fennel somewhere in the yard, not in the garden. It is an aphid trap and lure aphids to it and away from the other plants. When fennel blooms it will attract beneficial insects and ladybugs will raise their larvae on the fennel and they will happily eat up the aphids. Trap plants work better if they are established well before you start the other things in the garden. Pests will not be zero but they will be more manageable.

I've seen aphids on many plants but have never once seen an aphid on my fennel. Not on the ones I've planted intentionally nor on the countless volunteers I have every year. But I absolutely agree that fennel in bloom attracts a ton of beneficials.

-Rodney