Urban (Garden) Blight

July 11, 2007 9:43 AM

One of my container garden tomato plants is sick. What's wrong with it?

In the last week, one of my tomato plants suddenly had yellow leaves appear on the bottom-most layer of leaves. I cut off the stalks hoping it'd help. Now I noticed this morning that there are little white spots on the main stalk right above the soil.

Is this early blight? Or Southern blight? Or something else? And is there some way I can knock this back? It's set seven tomatoes that are a couple weeks from being ripe, which seems really good for Seattle.

posted by dw to home & garden (7 comments total)

I say early blight--we had it, too. We applied an organic fungicide, and it stopped the progress. The plants have been stressed by the blight, but they're recovering well--I had a tomato for breakfast!
posted by MrMoonPie at 9:53 AM on July 11, 2007

Should have included this--we used Serenade.
posted by MrMoonPie at 9:56 AM on July 11, 2007

Yeah, I was suspicious of it being Southern blight, being that Seattle isn't exactly Southern.

And being Seattle, I'm willing to guess Serenade is everywhere. Thanks!
posted by dw at 10:14 AM on July 11, 2007

I don't think it's early blight unless you are seeing dark spots on the leaves as well. What do the white spots on the stem look like?

Yellowing of the bottom set of leaves is a common response to a multitude of different stresses - lack of nitrogen, water stress, etc. - so you're not necessarily in serious trouble.

You'll want to make sure that it's not fusarium or verticillium wilt, either of which would necessitate destroying the affected plants.

See if you recognize anything on this page (or google tomato disorders for other pages).
posted by aquafiend at 1:09 PM on July 11, 2007

I don't think it's early blight unless you are seeing dark spots on the leaves as well. What do the white spots on the stem look like?

Like little knobs. Kind of like a mold. Or little white raised spots. Mostly in the first inch above the soil.

Yellowing of the bottom set of leaves is a common response to a multitude of different stresses - lack of nitrogen, water stress, etc. - so you're not necessarily in serious trouble.

Problem is, what exactly is it? I have three other tomato plants, all in basically the same supply of potting soil from the same company, and none of them are showing these signs. Only one other Early Girl, but it looks OK.

You'll want to make sure that it's not fusarium or verticillium wilt, either of which would necessitate destroying the affected plants.

It really doesn't look like either of these.

See if you recognize anything on this page (or google tomato disorders for other pages).

The only thing that jumps out at me is this:

Early blight, caused by the fungus Alternaria solani, appears first on the lower leaves, usually after a heavy fruit set.

The one affected plant is the only one setting a lot of fruit -- at this point, seven, maybe eight, and this has been in the past week. The others have, at most, two.
posted by dw at 3:12 PM on July 11, 2007

OK, now that I am home and had a second look:

1. I think the yellow leaves are being caused by a combination of fruit-setting stress and aphids. I found a number of aphids on the stems. The leaves that are yellow have no spots whatsoever. They just turned yellow.

2. The white spots are more like little lumps, like oblong warts, on the lower stem. And they're not white, more light green.

So, on the aphids, one source says to hose them down with insecticidal soap, another says leave them be unless you really have an infestation.

On the lumps, I don't know. I guess they're related to the aphids? Maybe?
posted by dw at 5:28 PM on July 11, 2007

the lumps are probably the start of adventitious roots - totally normal. if the stem touches the ground there, those bumps will turn into real roots.

link
posted by aquafiend at 7:12 PM on July 11, 2007