Can you tell us where you are located so we have some idea of what your winter weather will be like? Photos of these pests would also be useful. Personally I would not pull a plant just because it had whitefly or aphids. They can be dislodged by a strong jet of water.

Many of the species of aphids common on cold-weather brassicas (cabbage and turnip aphids, for example) are much more cold-tolerant than their predators. Some can be active through much of the winter, depending on how harsh winters get where you are. So their predators are often already in an overwintering cycle or well on their way to that, leaving the aphids to multiply without much challenge. Also, many aphid predators rely on nectar or pollen to sustain their adult phase, and if you don't have lots of late-blooming flowers of a suitable shape and size for them, they won't stay in your garden for fall.

I agree, you can probably take care of the infestation without pulling a plant. I frequently check all my plants for signs of bugs, the sooner they are noticed the better. Removal of a plant doesn't guarantee pests won't be back, they most likely will. A stream of water from the hose, will dislodge them, also I tend to gently squeeze the clusters of the aphids with my fingers and rub them till they bust, its a lil gross.

"I would love any suggestions and encouragement that winter vegetable growing can work!"

Oh it can definitely work but as others have mentioned, your location makes a big difference in the problems that may arise. Gorbelly did a great job of explaining why some pests are more common in the fall/winter in all climates but especially in the warmer climates. But most of them are easy to control or eliminate without resorting to pulling plants or even bringing out the big gun pesticides. And the results from your efforts are well worth it with fresh veggis to harvest even in the coldest weather.

In my climate for example I often find that a plant covered in whiteflies on one day has few the following day simply because of the previous night's temps. Those few that remain I spritz with water or water with a bit of dish soap. If i get a couple of nights in a row of warmer temps the flies may reappear and then disappear a day or so later. Meanwhile the plants do just fine. So try to avoid panic or over-reacting and 9 times out of 10 the issue resolves itself.

Dave

Thanks for all the information! I live in San Jose, California. USDA Zone 9B, Sunset Zone 15. I'm short on time at the moment, but will read all your great information again and keep working on this. By the way - I took out the one plant because it was all of 4 inches tall and I had others to plant in it's place. If sending a photo is easy I'll do that later as well.

Many thanks again!

Correction about which new whitefly in Oregon is a serious pest of kale.

We do have several recent invasive which arrived during the past few years. Yes, the ash whitefly is a newcomer but it peicializes on ash and severl other deciduous trees.

But another recent arrival is the cabbage whitefly. It's more cold tolerant than other whiteflies and specializes on cole crops, especially kale.

In fact, some local extension agents have suggested that gardeners not try to overwinter kale,etc., if they're having serious problems with the whiteflies.

See http://oregonstate.edu/dept/nurspest/cabbage_whitefly.html

Cabbage Whitefly is very common here and doesn't stop us overwintering Brassicas. They rise in clouds when I harvest winter leaves and the remainder I just wash off. They make little difference to the crop. The RHS states 'infestations can usually be tolerated. .... Complete eradication is neither feasible nor necessary as it is only heavy infestations that are likely to cause problems with sooty mould.'Cabbage Whitefly

Sounds pretty discouraging. Thank you all for your information.

ginjj - you have come away with completely the opposite message than I intended. Read the bit above in italics again. Brassica white fly is really no big deal.

I read that article again but not sure how to approach this in my garden. The idea of eating them doesn't sound good. They are now on the leaves of my kohlrabi and I don't eat those leaves so no problem here, but with the kale and other leafy vegetables I do eat what's the best approach to be able to enjoy that vegetable?

Why is the idea of eating them not good? The whiteflies won't harm you, and you wash them off and then eat the vegetables. Is there something I'm not understanding?

Thanks, Jean. I guess I got my Whiteflies mixed up. They didn't stop me from eating Collards all winter last year. I should not overwinter by Brassicas? That would be half the reason I have a vegetable garden. If the SVB ever comes here I'll give it up entirely.

ginjj - Brassica white fly will not hurt you in any way at all. If you rinse the leaves thoroughly, which you'd do anyway, the white fly will rinse off. They do no harm to the plants either - just a bit of superficial sap sucking.

Many things called "a serious pest of [x]" in various agricultural publications are less of an issue for home gardeners. This is because we don't have to produce veggies with perfect eye appeal. We accept that stuff that comes from our gardens has the marks of nature on it. For market gardeners and farmers, even minor visible pest damage can be a big deal because customers, distributors, markets etc. won't buy that stuff, but it's not for people growing their own veggies in their back yards for their own uses. So as long as the pest doesn't render veggies inedible/untasty and doesn't stunt production too much or kill the plant, it can be entirely tolerable.

Thank you for the encouragement and information.