Barnacle looking things on plant stems?

Richmond, CA

Hello, does anyone have experience with this? These brown bumps are on this plant and also all over my fava bean stems. What is it and what can I treat or prevent it with? ( I prefer not to use pesticides or chemicals).


Thumbnail by Tatyana929
Ayrshire Scotland, United Kingdom

Never seen this before and can only assume it's Animal as in, something maybe laid eggs along the stems. OR disease carried by animal or wind.
Before you do anything, why don't you wear gloves, remove one of the bumps, place on paper and squash it, this will tell you if it's an insect inside or a GALL from some form of plant disease.

There certainly appear to be a lot of it whatever it is and I would also suggest IF it's some disease after you inspect it, then I would prune the stems right back to below the lowest black / brown Gall, burn the stems to prevent these spores / galls from spreading.

Maybe I'm way off track here BUT I give the treatment I would be doing, others may come in here with personal experience of this and give better advice.
Best OF Luck.

Calgary, AB(Zone 3b)

Looks like a scale insect.

Contra Costa County, CA(Zone 9b)

Black scale.

Most scale have a life cycle like this:

The adults mate.
The female keeps the eggs under her shell.
Eggs hatch, babies called CRAWLERS emerge from under the mother's shell.
Crawlers may do any of several things, but the end result is they are away from the parents.
Crawlers eat, grow, then develop a shell.

The shell is hard and waxy, most pesticides cannot get past it.

You need to spray the plants when the crawlers are migrating to control this.
When they are not protected by the shell most scale can be killed by even the less toxic things, but you might want to do some research to be sure. (The link is to the UC Davis IPM information) If they live long enough to make a shell you have to use stronger poison from inside the plant.

Ayrshire Scotland, United Kingdom

Never had a sighting of these here, and so glad you gave the help you did Diana, it's just always great when you get new info, especially when you've been gardening for years, just show you Diana, there no such thing as a know all LOL.
Best Regards.

Contra Costa County, CA(Zone 9b)

I try not to be a 'know it all', but there are some things I do know, and the scales native to (or have invaded) this part of CA are pretty easy to ID. I can usually get pretty close, then a quick google to be sure.

UC Davis has the best Integrated Pest Management database and information site that I know of for plants, both agricultural and ornamental. I link it a lot.

Ayrshire Scotland, United Kingdom

Thanks again, always very informative for sure.
Best Regards.

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