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QUESTION: Problem with Tomato Seedlings

comments (6) April 12th, 2011

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SpeedyGonzalez SpeedyGonzalez, member
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A blighted tomato plant is a tragedy late in the season, but even worse if it happens at the seedling stage. Help this gardener identify and solve his problem now.Click To Enlarge

A blighted tomato plant is a tragedy late in the season, but even worse if it happens at the seedling stage. Help this gardener identify and solve his problem now.

Photo: Ruth Dobsevage

I started tomato seedlings indoors--too early!  Now the plants are 18 to 24 inches high and seem to have developed a problem, especially one plant in particular.  The lowest branches wither and die, sometimes from the outside in and sometimes from the center of the branch out.  The tops are green and healthy and producing new growth.  They have been transplanted from the starter size containers into 8 inch pots, so they are not rootbound.  I water only from the bottom and only when the soil is dry to the touch.  I sterilized the containers before potting and used commercial seed starting mixtures.

Question:   Any idea what may be causing this dieback?

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Comments (6)

nancynursez637 writes: To reduce teh stress when you have leggy, tall tomato plants for the garden, dig a trench about8" deep, and plant your tomato plant on its side, gently turning up the top third and bury the rest. They will develop a root system along the entire stem and generally produce well.

I have done this for the community garden when people donate tomato plants that have gotten too tall. Seems to work great
Posted: 7:13 pm on June 22nd
SpeedyGonzalez writes: Thanks for your replies. It turned out to be stress. Having just about given up on the plants, I moved them to the garden. Despite the fact that it was 2 to 3 weeks earlier than I would normally put frost-intolerant plants outside, they thrived and are now as green and healthy as ever. One of the varieties is Burpee's new seedless tomato. I'll post the results of that experiment as soon as the first tomatoes come in, circa July 15-20.
Posted: 7:06 pm on June 1st
1946 writes: Two things come to mind, the first being perhaps not enough light, like someone else mentioned. The other is maybe lack of nutrition. Those commercial seed starting mixes are great to start seeds but they have no nutrition in them to support larger plants. Have you been fertilizing the plants? I get this lower leaves yellowing on my tomato plants in the greenhouse when they are getting too big for the containers they are in, and not getting enough fertilizer. An added suggestion, when you plant them in your garden, dig a deep hole and sink the plants down to where the leaves start. You will get a great root system.
Posted: 10:12 am on April 23rd
vg_made_simple writes: I've had this issue before, with heirloom varieties in particular. It could be early blight, and if there is any yellowing of the leaves involved or circular striations, then I would throw out the plant as a precaution (do a quick google image search for "early blight", it will give you an idea of what to look for.)

However, I've had a few heirloom varieties that do this when started indoors, the Cherokee Purple and Costoluto Genovese varieties in particular. Their leaves will curl badly for a few days and then go back to normal. And some of the bottom stems will just completely die and fall off for no apparent reason. However, there is never any yellowing involved. The limbs are green one day and shriveled/dead the next.

I think it is often times just a sign of stress. It usually corrects itself as soon as I get them in the ground and I've never had blight in my garden as a result. Also, it gets worse if I'm not watering regularly. If you are letting them get completely dry, try watering more regularly. They need a consistent moist soil when indoors (not soupy wet, but moderately moist.) It also seems worse in my shorter plants that are not as close to the grow lights, so make sure inadequate lighting is not causing the problem.

Good luck!

Posted: 12:13 pm on April 18th
Johamose writes: Die off of the lower leaves on tomatoes is normal; they'll continue to do it the whole season. Sounds like you're doing everything right. As long as the rest of the plant looks healthy and it's just the lower leaves you're just fine.
Posted: 11:42 am on April 18th
tap69 writes: Sounds like early blight...check internet for solutions.
Posted: 2:20 pm on April 17th
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