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Plant Pathology Infobytes

June 24, 1998

Leaf Roll On Tomatoes

What's happening to the leaves on the bottom of my tomato plants? They're rolled up and look terrible -- will my plants still bear fruit?

This has been a common question received by County Extension Offices in recent weeks, and here's what the plant pathologists at Mississippi State University tell us about this problem.

Leaf roll isn't a disease that will spread from plant-to-plant, but it is what is referred to as a physiological disease. The condition has been common statewide and is more likely to happen in either very wet seasons or during periods of extended dryness.

Since the latter weather conditions have predominated in most areas of the state in recent weeks, leaf roll is probably tied in with dry soils. And as a result, tomato plants are showing an upward rolling of the leaflets of the older leaves.

At first, this rolling gives the leaflet a cupped appearance and it continues until the margins of the leaflets touch or even overlap each other. The rolled leaves are firm and leathery to the touch. One half to three-fourths of the foliage may be affected.

The growth of the leaf roll tomato plants is not noticeably checked and a normal crop if fruit is generally produced. In most cases, leaf roll occurs in combination with dry soils and when tomato plants are pruned severely. Also, leaf roll may occur following deep, close cultivation.

Some varieties are more sensitive to leaf roll than others, but none are completely resistant to this problem. The symptoms on tomatoes are very similar to those of a virus disease of potatoes that is known as leaf roll, but the leaf roll of tomatoes is not caused by virus infection.

Suggested control measures which may help avoid leaf roll in a fall crop include:

  • Plant tomatoes in a well-drained soil.
  • Fertilize according to soil test recommendations and do not over fertilize, particularly with nitrogen containing fertilizers.
  • Avoid deep and close cultivation especially in dry weather.
  • Maintain uniform soil moisture through irrigation, supplying an inch of water per week.
  • Mulch tomatoes with plastic or organic material.

Infobytes newsletter was written by the late Dr. Frank Killebrew, Extension Specialist.