White spots on pea plant leaves

May 22, 2007 1:29 PM

Pea plant problems: Some of the leaves on my "Super Sugar Snap" pea plants (grown from seed, planted about 5 weeks ago) have developed white spots. (sample 'bad' leaf, sample 'good' leaf) What's the deal?

Plants are in a large container with potting soil. Haven't used any fertilizer yet. Spots are NOT powdery.

posted by gwint to home & garden (12 comments total)

Are the plants showing any problems? In other words, you're sure it's a disease and not a variation?
posted by Toekneesan at 1:39 PM on May 22, 2007

I've never grown peas before so I don't know for sure if it's "normal" or not, but found it odd that the spots only appear on some of the leaves. The plants do appear otherwise healthy.
posted by gwint at 1:44 PM on May 22, 2007

Looks ok to me. I agree with it being a variation. If it was mildew or that crap cuke beetles spread it would be powdery.
posted by Iron Rat at 1:50 PM on May 22, 2007

Quick consult of The Vegetable and Herb Expert, which I happened to have at hand:

Pea Thrips: Silvery patches appear on leaves and pods. The pods are disorted and the yield is reduced. Attacks are worst in hot, dry weather. Minute black or yellow insects are just visible. Treatment: Spray with fenitrothion or permethrin. Prevention: Dig over the soil after removing an infected crop.

I've no idea if this is your problem. The book's illustration shows an infected pod, which makes me thing this is more of a problem when the pods start to show, rather than before.
posted by humblepigeon at 2:04 PM on May 22, 2007

Gardenweb is a good forum for asking these questions too. (In addition to askme, of course.)
posted by footnote at 2:31 PM on May 22, 2007

If it is not powdery I would say you might be dealing with Thrips.

Seen any of these little bastards around your house?
posted by dnthomps at 2:32 PM on May 22, 2007

Can you brush the spots off? In your picture of the 'bad' leaf, there looks to be a powdery substance, but you may just be talking about the grayish spots on the leaves.

White spots that can't be removed with a vigorous rub are just variegation within the leaf. The leaves of bush-type snap peas are variegated much more often than pole-type peas. (I pulled out my very vigorous, very healthy bush peas two days ago, else I'd post a picture.)

If the spots are on the surface of the leaf, if they're something you can rub off, it's likely either powdery or downy mildew. Both can kill the plant, and you'll need to treat it right away. You'll also need to make sure that there's adequate air circulation around the plants.
posted by mudpuppie at 4:26 PM on May 22, 2007

Spots are NOT powdery.

Somehow I missed this.

You're fine -- it's normal.
posted by mudpuppie at 4:28 PM on May 22, 2007

A vine that I'm taking care of does this, too--the best explanation I could come up with was that it would produce white spots when it wasn't getting quite enough water... water a little more frequently and the new leaves are solid green, but the old white spots stay (with no apparent harm). I didn't do too much testing, though, for fear of killing the poor thing.
posted by anaelith at 5:06 PM on May 22, 2007

My cukes do this when I first plant them. I have no idea what it is, but they bounce back fine as the season goes on.
posted by jrossi4r at 6:44 PM on May 22, 2007

No idea, but it looks like what happened to my mint. At first I figured it must've been part of the leaf pattern (as this was what it appeared to be if I didn't know better) and I just never noticed but then I noticed it start on my catnip.

There were no visible bugs, aphids ect and both plants were healthy and growing. The mint had been afflicted for some time at this point and it didn't seem to be phased but I wasn't about to start eating it...

I quarantined them separately (they're potted so this was a simple task), removed the offending catnip leaves and stripped the mint of any foliage bigger than 1-2mm and washed and rinsed them.

Mint came back better than before (as is the way of the mint) no more spots at all!

Catnip, well I pulled more spotty leaves off yesterday but was more ruthless this time and took some neighboring yet apparently unaffected ones. And I didn't wash it anywhere near as thoroughly before so I expect that will do the trick this time.

So you could try that?
posted by mu~ha~ha~ha~har at 7:50 AM on May 23, 2007

Sugar snap peas have a pretty short lifespan in the Grand World of Plants. Either the white spots will turn into something and kill the plant (doubtful) or they'll be benign. Either way, peas aren't the sort of plant that you pull out the horticultural oil or pesticides for. Keep 'em watered and in the sun and you should be fine. You'll get some peas and then they'll die at the end of the season. No matter what your white spots are.

Oh, and for one season's worth of sugar snap peas grown in fresh potting soil, you don't need fertilizer. You're more likely to accidentally let it leach out the bottom of the pot and make its way to the groundwater than actually provide any benefit to your plants.
posted by bisesi at 9:00 PM on May 23, 2007