Question
QUESTION: Hi, Dr. Vann,

I live in Hawaii and grow 2 bunches of green onions in a container.  My family
and I cut whatever we need from time to time but I've noticed for the first time
there are a number of very small, dark orange bumps that have formed on the
green onions.  It's been raining quite a lot recently but what do you think they
are?  It could be diseased so should I destroy the green onions?

ANSWER: Hi Sean:

Can you send along a photo of these bumps?  Do the plants seem to show any decline or are the bumps merely present and not doing anything? Do the bumps look dusty or shiny?    
If you can attach a photo, take it as close as you can get to the plant and be sure to review it on your computer to be sure it is in focus before you send.  An out of focus photo is of no value.

Thanks

Steve

---------- FOLLOW-UP ----------

QUESTION: I'm so sorry but I don't own a camera.  However, I've found a photo online that looks very similar to what's on the green onions (though the infestation is far from this):
http://upload.wikimedia.org/wikipedia/commons/4/49/Rust_on_garlic_plants2.jpg

In fact, it could very well be rust because of the rains.  The plants appear to be normal and the bumps look dusty.  When I took a rock and rubbed the bumps, the bumps remained but dusty particles came off.

Answer
Sean:
Rust is usually easily ID'd.  There are several fungal organisms that produce rust on various plants and many look similar to each other.  The individual "pimples" are about the diameter of a pin head and are raised off the leaf and appear powdery after the "pimple" ruptures.  These pimples are called pustules.  Pustules can be produced on either side of the leaf.

An easy way to have a very good idea of whether you have rust or not is to wipe a few individual "rusted" leaves with a piece of white bathroom tissue or Kleenex.  Examine the paper and look for an orange or yellow smudge that shows up on the paper after wiping a leaf. The smudge is actually "microscopic seeds" called spores.  These spores can travel long distances on wind currents and splashing water. You can even accidentally buy "infected" plants and not realize it.  Starting from bulbs should be OK--rather than transplants with leaves on them.

Vegetables can be sprayed with a fungicide.  These chemicals work best if they are applied as soon as the pustules become visible, not afterwards.  Curing diseased plants is much much harder than good prevention. If you decide to start some new plants, be sure to remove and destroy the entire old plants (roots and even any dead leaves on the soil surface).

Regards

Steve