Won't do much good.

From now on, you should always look for nematode-resistant plants. In a veggie garden, that's not much.

Tomatoes are labeled with one or more letters behind the name -- VFFNT -- the N stands for resists nematodes.

Understand that "resists" doesn't mean "completely" resists. But know that you will have more success with tomatoes having the N than with kinds not so labeled.

Beyond that, follow these guidelines:
1. Every season, heavily amend before you plant by mixing in at least 2 inches of compost.
2. Don't direct seed because seedlings are easily attacked.
3. Instead, always use strong healthy transplants as doing so will delay problems.
4. Never, ever, move plants or soil from the infested bed to elsewhere in your garden.
5. If possible, have a separate set of shovels, etc, for the affected bed. If not, work in that bed last, then clean the tools, and your shoes/boots, thoroughly.
6. Forget the so-called remedy of growing marigolds. Doesn't work.

Jean,
who gardened in So Cal for 30-some years, most of those years trying to outsmart the nematodes

Oh.
Too late about moving soil. I composted in all of the veggie beds all winter and used the compost all over the flower garden.

I see that the nematodes love eggplants, tomatoes, peppers, cucumbers and squash. Mikey built me my beautiful veggie garden specifically to grow these plants.

Jean, will they kill my avocadoes and irises too?

I have cut and pasted your advice into my garden journal. I think I'll cry myself to sleep now.

Renee

Oh, dear, don't do that!
Yes, nematodes are no fun, but as Jean said, we just keep gardening despite the nematodes! You learn which plants can power through them, and which can't. You plant twice as many plants, because you know the ones you have will only give half a crop. At least you get some fruit!
And there are a lot worse problems we could have. Although a native Californian, I lived in Seattle for 6 years, and there I had to deal with Late Blight, and it is much worse to have healthy, thriving tomatoes with fruit just blushing red, and 3 days later they have turned into a black mass of goo from Late Blight.
Nematodes aren't the end of gardening, they're just our regional headache we learn to outsmart.

Carla in Sac

Listen to Carla. Her advice is right on. (I like her phrase "regional headache." Nicely descriptive.)

By the way, I neglected to mention my "Thanks" for your follow-up. If more people did the same, we would all learn lots!

Oops. Missed your question about the avocado & irises.

I can't comment about iris because I never grew them in CA.

As for the avocado -- sorry, here's more bad news, but not necessarily a death sentence -- I think the tree is more likely to croak from avocado root rot, another SoCal regional headache. Avocados need adequate water but absolutely must have excellent drainage.

Thanks Carla, and Jean, for the info and pep talk.
I do have excellent drainage here: about seven feet of valley bottom silt then sand (according to grandpa when he dug the hole for the septic tank waaay back when). So far the avocados and irises do very well, probably because of the drainage.

One of the ag sites I visited last night recommended chicken manure on nematode infested soil. I have plenty of that- so I'll leave the bed fallow and start composting the manure in it.

Renee