Gardening

Catfacing typically refers to tomato fruit that is misshapen, with scars and irregular bulges at the blossom-end of the fruit that may extend to the stem area. This disorder is caused by an abnormal development of the flower and is aggravated by prolonged cool weather during blossoming.
Photo by William M. Johnson.

COOL SPRING WEATHER CAN AFFECT TOMATOES

By Dr. William M. Johnson, Galveston County Extension Agent - Horticulture

May 24, 2007

Many common tomato problems occur when environmental conditions are less than ideal for plant growth. In most cases, the problems will pass when growing conditions improve. The physiological effects on the tomato fruit, however, are determined by how long the unfavorable environmental factor lasts.

The primary causes of these problems are neither insect nor disease related. They are related to environmental conditions and are usually referred to as tomato disorders (as opposed to insect and disease problems). Temperature, plant nutrition, and soil moisture conditions are the most serious environmental factors that affect tomato fruit. Hence, fungicides and insecticides are of no help. Although it is possible for the gardener to make adjustments and corrections in plant nutrition and to some extent soil moisture, there's little we can do to control unfavorable temperature or weather conditions.

Here are some of the most common physiological problems or disorders that local tomato gardeners may experience over the season and some measures to take to avoid or reduce their occurrence:

BLOSSOM DROP: This can occur nearly any time during the growing season but is more common in the spring. This condition occurs when there are extremes in temperature (too hot or too cold), sudden and drastic temperature changes, too little light, too much or too little water, or over-fertilization. In addition, any unpollinated blossom will fall from the plant.

CATFACE: Catfacing is a generic term used to describe a tomato fruit that has a gross deformity. Catfacing typically refers to tomato fruit that is misshapen, with scars and irregular bulges at the blossom-end of the fruit that may extend to the stem area. This disorder is caused by an abnormal development of the flower pistil and is aggravated by prolonged cool weather during blossoming. Cool or cold temperatures (below 50 degrees Fahrenheit) that occur about 3 weeks before bloom can increase the incidence of catfacing. It is commonly found on first-formed fruits

Catfacing appears more frequently on heirloom varieties. However, due to the unusually cool weather conditions that occurred in April and early May, many home gardeners have been surprised to see this oddity develop on their hybrid varieties. The somewhat good news is that the fruit is still edible but in reality it is typically not acceptable for consumption by the home grower nor by his or her neighbor!

LEAF ROLL: The edges of the leaves will roll or curl upward and inward in this common but temporary disturbance. In severe cases, rolling continues until the margins of opposite leaf sides touch. Growth of the plant is usually not inhibited.

Leaf roll is often a physiological response to an irregular water supply or will occur during bright sunny days following a period of cloudy weather. The leaf-roll syndrome is usually temporary and does not harm the fruit. Some tomato varieties are much more likely to develop leaf roll than others.

BLOSSOM-END ROT: This occurs under conditions of high plant water stress and heavy fruit load. Blossom-end rot begins as a small, bruised-like area around the blossom-end of green or ripening fruit. Lesions darken and enlarge rapidly and become depressed and eventually black in color and leathery-like in texture. Usually, blossom-end rot occurs on the first fruits formed or on clusters of fruit formed during prolonged hot, dry periods.

Blossom-end rot is closely associated with moisture availability in our growing region. This means that gardeners should try to avoid fluctuations in soil moisture during fruit set and fruit development. Mulching can be very helpful in stabilizing soil moisture around the plants. Although some gardening references may indicate that a calcium-deficiency contributes to blossom-end rot, calcium is seldom deficient in our Upper Gulf Coast soils.

SUN SCALD: This occurs when green or ripening fruits are exposed to hot sun for several days. A yellowish-white area of sunken tissue appears on the side of the fruit facing the sun. Sun scald on fruits is much more likely to occur after plants have suffered premature defoliation caused by disease, or during an extended period of cloudy weather followed by bright, hot sun. Avoid severe pruning of plants to provide adequate foliage growth to shade fruit from the hot afternoon sun.

Regardless of these and other problems associated with growing tomatoes, the tasty reward of having fresh, vine-ripened fruit makes all our gardening troubles worthwhile.

Dr. Johnson is a horticulturist with the Galveston County Extension Office of Texas Cooperative Extension, Texas A&M University. Visit his web site at http://aggie-horticulture.tamu.edu/galveston/index.htm

Note: Picture updated.

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