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Kelley Conversations: Montana State University Diagnostic Lab helps identify plant concerns

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Posted at 3:04 PM, May 22, 2023
and last updated 2023-05-22 17:04:09-04

I’ve got some tomatoes that are looking a little sad, but at Montana State University, the diagnostic lab can help us figure out what to do. MTN’s Donna Kelley spoke with Dr. Eva Grimme, associate specialist and plant disease diagnostician at MSU Extension.

Donna: Thank you for visiting with us. I don’t know what this is on some of my tomatoes. It showed up with some little white spots and the leaves are starting to yellow. Can I save them? Do you know what this is?

Dr. Eva Grimme: I like to look at the complete picture. So that’s perfect that you bring the whole plant. Just looking at it, you can see the new growth. It’s nice and green, so the plant should grow nicely in the future. What you can do is you can look at the roots and the roots are nice and white like this. So, I don’t think it's an issue at all. It’s just a good sign.

Looking at the yellow leaves that are older leaves, it more looks like a nutrient deficiency. Tomatoes in general need a lot of nutrients to grow. They’re really vigorous growers. I would recommend that you put them in a larger cup, and get some extra fertilizer and they should do fine.

Donna: These white spots aren’t anything to be concerned about. That’s not like a fungus?

Dr. Eva Grimme: It’s like a physiological response. It’s if there’s too much moisture and plants cannot evaporate. They should outgrow it.

Donna: Great! You have saved two tomato plants.

Dr. Eva Grimme: Thank you! Good luck.

If you have plants or a crop that needs an expert eye, the place to start is your local extension agent. The agent can help submit samples to specialists at the Schutter Diagnostic Lab on the MSU campus.

You can learn more from MSU Extension with publications and resources online at