Cracks and mold on the top of my tomatos

by Charlie Slavik
(Carmel, IN)

A. I'm writing about the tomatoes we grew in a small garden in the Indianapolis, IN area this season. They were "Better Boy" tomatoes. When they first started to ripen - around the end of August - they seemed to be okay... but, as time wore on, the tops started to split and get black mold in the splits (see attached pictures). It was a very hot and dry summer here, and I watered the plants at their base no more than 3 times a week. We grew them last year in pots and had some splitting, but nothing like this year. My question is: what causes this splitting and how can we avoid it next year? Are Better Boys more susceptible to this kind of problem? We really enjoy homegrown tomatoes, but we're thinking of trying a different variety next year, after 2 seasons of relatively low production, small tomatoes, and horrendous splitting and mold! Any suggestions?

Thanks! And, thanks for your newsletter!

A. Two answers for your cracking and white mold problem.

  • Cracking. The most common culprit of tomato cracking is uneven watering. Your drought contributed to this. Good job with keeping the plants watered regularly. Even with that hard work, fruit can try to absorb the water quickly, expand and contract its skin, and then crack. Try using a drip hose and allow water to penetrate the ground very, very slowly. Read more about avoiding tomato cracking.
  • White mold. Once a tomato cracks, pick it as soon as possible. You'll save the fruit before infection takes hold. As you learned, bacteria or fungi enter the crack and lead to mold and other diseases. Specifically, white mold in cracks is sometimes called sour rot, often traced back to a Geotricum fungus. Naturally, by applying fungicides you can avoid the worst of fungus infections from sour rot and scores of other tomato calamities (early blight and Septoria leaf spot, to name a few.)

You might consider planting crack-resistant tomato varieties that have elastic skin, including Daybreak, Early Girl, Earl of Edgecombe, Heinz 1350, Jet Star, Juliet, Mountain Delight, Mountain Pride, and Valley Girl.

Good luck and happy gardening!
Your friends at Tomato Dirt

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