[New Jersey Agricultural Experiment Station]
Jersey Fresh Information Exchange
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Tomato Help!

Tomatoes may be one of the most common plants in the home vegetable garden, but they still pose many challenges to home gardeners. Read below for some answers from our agricultural agents to common questions. To get help for your tomato and other gardening challenges, contact the Master Gardener hotline at your county Rutgers NJAES Cooperative Extension office. Find New Jersey county offices here. For other states, find your local cooperative extension here. Find factsheets for growing tomatoes and common problems here.

Seedlings overwatered
Q - I started tomato seeds and the seedlings emerged, but someone else kept over-watering them and now they seem very yellow and dwarfed. Is there anything I can do to save them?
A - I am sure by now you have stopped watering the plants to relieve the problem. Next inspect the roots. Are they dark, slimy, not white and healthy? If so, there may be some disease organisms that flourish when soils are overwatered. If roots look healthy then I would recommend a dilute dose of liquid fertilizer to help the plants grow and green up. If using a liquid or granular fertilizer, first use ½ of a dose if roots are healthy and do another ½ dose in 4-5 days. If the plants are responding well and recovering by growing and turning green, then just follow your standard watering and fertilization regiment. If you are unsure about root health, you can mail (overnight would be suggested) samples to our Rutgers Plant Diagnostic Lab.

Seedlings died
Q - I am not an experienced tomato grower but I did read everything on the topic. I consulted with my local nursery, purchased small growing boxes, enriched soil and plant lights. I planted seeds and got about 40 plant sprouts. The plants were indoors but after a couple of weeks they all died at about the same time. None of the tomato plants ever made it to the garden so this year's blight could not be the culprit.

A - It is hard to postmortem diagnose seedling problems long after the fact, but it does sound exactly like seedling damping-off due to Pythium spp. or Rhizoctonia fungus. Especially since you mention using enriched soil under plant lights.
Damping-off tomato seedling diseases from Pythium and Rhizoctonia can be devastating. Seedlings fail to emerge in the greenhouse or plant bed, or small seedlings wilt and die soon after emergence or transplanting. Surviving plants have watersoaked areas on the stem close to the soil line.
Common Prevention & Treatment:
Damping-off is often a problem in plants that are planted too early in the spring.
T he fungi are more active in cool, wet, rich soils. To prevent damping-off, take these precautions:
Plant a bit later under better temperature and lighting.
Consider getting a heat mat to warm soil and get seedlings going.
If you reuse containers wash them out well and maybe even wash them in 10% bleach to make sure there are no damping off fungus spores to infect plants next year.
Start seeds indoors in sterilized potting mix.
Do not start seeds in soil that has a high nitrogen level. Add Nitrogen fertilizer after the seedlings have produced their first true leaves.
Allow the surface of the soil to dry between waterings.

Upside down hanging pots
Q -
Would you recommend the upside down hanging pots for growing tomatoes?

A - While these pots are promoted as a space saving system, our Rutgers NJAES agricultural agents don't necessarily recommend them. They do, however, offer a few suggestions below:

We have no formal research data on this system but it should work as long as the plant is kept watered and fertilized like in any other container.  Gardeners should be aware that a mature tomato plant with fruit plus wet potting soil will get very heavy and consider that when hanging it. They normally require more management than most people are willing to provide. In full sun, these relatively small containers for hanging can dry out rapidly and expose roots to high temperatures. Your best bet is to provide adequately sized light-colored pots that won't get too warm during hot days. In the early season, warmth helps roots to establish, but in late season, temperatures can climb too high and damage roots of vegetables.

A drawback of this system is that the plant will try to right itself (towards light, away from gravity), but as it grows, the weight of the plant will keep it growing downward. The roots will continue to grow downward from the rootball until they hit the bottom of the pot and then grow in circles to fill the pot. Plant the rootball as 'deep' as possible, i.e. as close to the top of the container so the roots have more room to fill the pot before hitting the bottom. To do that, it would help to grow a tall, leggy seedling so there's a longer stem allowing the top of the plant to reach out of the bottom of the container. Make sure the container has adequate drainage besides just the hole where the plant is coming out.

Also - try web reviews/garden blogs for people's experiences with them.

Plants drooping
Q - I had soil of my vegetable garden tested by Rutgers. Results came back slightly acidic, but lime was not recommended at this time. I have a problem with all my tomato plants. Plants are about 2 ft in height and dark green in color. With all the current rain, my plants are “drooping” as if not enough water.  I had same problem last year and rotated this year with same result.

A - Drooping plants means water is not getting from roots to the top of plant.  This means the roots are dying or dead or something is clogging the vascular tissue (plumbing) of the plant.  Some possible causes.

  • Walnut wilt - Is there a black walnut tree near the garden?  The roots of black walnut give off a substance that causes tomatoes and other plants to wilt and die. 
  • Too much water.  Roots need oxygen as well as water.  If roots sit in water for ~24 they will die and plant will wilt.  Dig up one plant.  Roots should be light tan or white not brown = dead.
  • Wilt diseases.  Verticillium and Fusarium wilt are fungus diseases that clog vascular tissue and cause wilting.  Some hybrids are resistant to these diseases heirlooms are typically not.  Do you know variety names?

    These are most likely causes there may be others but you should try to rule these out first.

Update: This gardener got back to us reporting that there is a black walnut tree in his neighbor's yard.

Misshapen fruit
Q - I am attaching a picture of our first red tomato and wanted to know if you have ever seen a tomato grow like this before.

A - The picture you sent are typical of catfacing and zippering of tomatoes. This is a physiological disorder caused by cool temperatures. It also can be variety related. I do not know the variety you planted, but if it is an heirloom it could be partially the variety.