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Troubled Tomatoes?

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Tomatoes were once thought to be poisonous and were avoided at all cost.  Today tomatoes are grown in over 86 percent of home gardens in the United States.  This popular plant has many common diseases and problems that can plague it.  With a little help, you can keep your tomatoes in tip top shape.

Early blight is a common tomato disease.  It is caused by a soil-borne fungus.  Rain water, or overhead irrigation, can cause the soil and fungi to splash onto the lower leaves of the plant.  The infection starts as leaf spots on the lower leaves then causes yellowing then eventually causes the stems to turn brown.  The infection works its way up the plant causing the foliage to die.

There are ways to help prevent the spread of this fungal infection.  Some simple steps that you can take are, to avoid overhead irrigation and to mulch around the plants.  This will keep the soil-borne fungus from splashing onto the leaves.  Caging tomatoes is another good way to increase air flow and get the foliage off of the ground.  Be sure to sanitize your cages after each season, they can also harbor the fungal spores and infect the plants.  Crop rotation and planting resistant varieties will also decrease the fungal infections.  If you do notice some of the lower leaves starting to yellow, pick them off.  This can slow the spread of the fungus.  Severely infected plants can be removed, throw them in the trash not the compost pile to decrease the chance of infecting the pile.  Good fall sanitation practices are the final way to keep the spread of the fungus among us down to a manageable level.  Infections can be reduced or slowed with fungicides labeled for tomatoes.  The fungicide applications can be applied preventatively or they can be applied as soon as the symptoms appear on the lower leaves of the plant to slow the spread.  The applications should be repeated regularly, every 7 to 10 days, or whatever is recommended by the label.

Another issue that plagues tomatoes is blossom end rot.  Blossom end rot causes sunken brown or black lesions on the blossom end of developing tomatoes, cucumbers, squash, eggplant, or peppers.  It is caused by a calcium deficiency in the fruit.  There is plenty of calcium in the soil, the plant grew so fast that it had to take the calcium that it was going to use in the fruit and use it in the foliage.  Over-fertilization and hot, windy weather are also causes of blossom end rot.  Preventing moisture stress is important to control blossom end rot, especially during fruit set and when the fruits are enlarging.  Mulching around tomato plants will help regulate the soil moisture throughout the season.  The foliar sprays of calcium or adding Epsom salts to the soil won’t correct blossom end rot and are not needed.  Remove infected fruits, the rotten part can be cut off and the rest of the fruit can be eaten if you wish.

Another common tomato problem is caused by neither a disease nor insect.  Tomato leaf roll is caused when tomato plants grow vigorously during mild, moist weather.  This causes the top to grow faster than the roots.  When the first hot days of summer arrive, the roots can’t keep up, and the leaves roll upward.  Tomato leaf roll can also occur after a heavy cultivation, a hard rain, or any sudden weather change.  Too much rain or irrigation can saturate the soil and suffocate roots.  Plant roots need oxygen and do not do well in heavily saturated soils.  Some ways to avoid this problem are to avoid deep hoeing too close to plants, mulch around plants to moderate soil moisture extremes, and water enough to keep the soil moist, but not water logged.  The good news is that leaf roll is temporary and the plant will grow out of it.

Tomatoes are the most popular vegetable grown in the home garden by far.  With a little help you can have the best looking tomatoes on the block, and eat them too.

Elizabeth Killinger is the Horticulture Extension Educator with Nebraska Extension in Hall County. For more information contact Elizabeth at elizabeth.killinger@unl.edu, her blog at https://huskerhort.com/, or HuskerHort on Facebook and Twitter.

Troubled Tomatoes? (PDF)

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Blossom end rot on tomato. Maintain consistent moisture, try mulching tomatoes first. Don’t reach for the Epsom salts.

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