Saturday, July 11, 2015 By: Ask A Master Gardener

Tomato Fruit Problems--Blossom End Rot

Root-top growth imbalance in tomatoes can cause rot

Brian Jervis:  Ask a Master Gardener

Saturday, July 11, 2015

Q: Some of my tomatoes are rotting. I keep them off the ground, but they still have rot. What should I do? T. S., Tulsa

A: Tomato fruit splits, rots or develops blemishes for several reasons. Usually the causes are not due to insects but to infections or, more likely, related to growing conditions. Your tomatoes may have a condition called blossom end rot.

Tomato health is dependent on the balance of root function and the plants’ top growth. In some situations, tomato plants will not have enough roots to supply water and nutrients to the rapidly growing top part of the plant. In this situation, water and nutrients, including calcium, are directed to the plants’ leaves rather than the fruits. The energy-producing leaves are more important for survival than fruits.

Even though soils may have ample amounts of calcium (and our soils usually do), the redirection of sap into leaves, rather than fruits, causes a calcium deficiency in the developing fruits. In areas of the fruit that have a lack of calcium, the tissue dies. Because the part of the fruit farthest from the stem develops calcium deficiency first, that is where the fruit is damaged. This is where the blossom once was, so therefore it is called blossom end rot.

This imbalance of roots to plant-top growth is seen more often early in the growing season and also occurs after deep hoeing has damaged roots. Another cause is applying too much fertilizer, especially ammonium fertilizer, which may stimulate top growth of the plant to the extent imbalance develops.

To prevent the problem, tomatoes should be mulched and have consistent watering. Fortunately, this problem is usually self-correcting as the season progresses and root growth catches up with the top growth.

Other fruit problems are splitting, sunscald and fungal infections. Fruit splitting occurs in plants that have gone from too little to too much circulating water. Tomato skin growth cannot contain the surge of water coming into the fruit, and the skin splits.

Sunscald occurs later in the summer. The hot sun may cause sunburn of the tomato skin, and large blisters usually develop in a sun-exposed area. These may become secondarily infected and rot. Sunscald can occur when too many leaves have been removed from the plant. The use of cheesecloth to shade the tomatoes is a workable solution.

Tomato fruit infections often come from fungi and bacteria in the soil. A good layer of mulch along with careful watering will help prevent splashing from soil to tomato fruits.

More detailed information can be had from four Oklahoma State University fact sheets about growing tomatoes and the various problems related to disease, insects and growing conditions. These are available at in the Lawn and Garden section under vegetable information.

Garden tips
When watering your lawn, ornamentals or vegetables, always do so in the morning if possible. If watered in the evening, plants will go into the night still being moist. Most disease-causing organisms need moisture, and because they grow best at night, leaving leaves wet in the evening will promote many plant diseases.

Bulb onions are ready to harvest when the tops fall over. They should be removed and allowed to dry in a well-ventilated, shaded area. After the tops are completely dry, they may be stored in a cool, dry area.

Tall, spindly tomato plants with scarce fruit are usually due to either too much nitrogen fertilizer or too much shade


Healthytips said...
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Healthytips said...

Thanks for sharing such beautiful information with us. I hope you will share some more information about tomato. Please keep sharing.
Health Is A Life

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