JoAnne Skelly: Tomato questions

Time to haul the tomato crop in.

Time to haul the tomato crop in.

All of your hard work has paid off. You now have ripe tomatoes, and you are thrilled. While some tomatoes are perfect, there are others with cracks, brown bottoms, and tough skin. Why?
Cracks or splits in tomatoes are fairly common. They are a physiological disorder, not a disease that has to do with the elasticity of the “skin” of the tomato. Cracking often results from the fruit taking up too much water too quickly after a heavy irrigation or rain (not too likely here).
This may cause the fruit to grow too quickly. If the plant has too much nitrogen or too little potassium, cracks are more common. Fruits in too much sun are more prone to cracking. And some cultivars or varieties are more prone to cracking.
A remedy is to keep the soil evenly moist. Mulch and timely watering will help reduce soil moisture fluctuations. As for sun exposure, keep the plants healthy so there are enough leaves to shade the fruit. Of course, timely fertilization with the appropriate fertilizer analysis is important, so plants don’t have too much nitrogen or too little potassium. (Texas A&M -
Brown bottoms on tomatoes are blossom end rot (BER), another physiological rather than pathological problem. The bottom of the fruit looks water-soaked and then turns brown, sunken and leathery.
BER is a result of a calcium deficiency in the fruit caused by rapid growth during the early part of the season. Follow this with hot dry weather and conditions are perfect for BER. Fruits are most susceptible when 1/3 to 1/2 grown. Too much nitrogen or too much soil moisture fluctuation increase the likelihood of BER.
Unfortunately, once the bottom starts discoloring, it’s too late. Just as is with cracking, there has to be balance of nitrogen and potassium as well as even moisture. Not too much or too little nutrients or water. Deep irrigation is best
Why do some tomatoes have tough skins? Mostly it’s the variety. When you select varieties that resist cracking or blossom end rot, you may find they have thicker skins. Underwatering can cause tough skins. The tomato is trying to survive, and thicker, tougher skins help the plant and fruits to conserve water.
Once again, the solution is to maintain even moisture from time of planting to harvest. However, high temperatures can also encourage a thick skin necessary to prevent sunscald. Give your tomato plants some shade during the hottest part of the day
JoAnne Skelly is Associate Professor & Extension Educator Emerita at University of Nevada Cooperative Extension. Email 


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