Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
There have been some reports from growers and educators of several sets of tomato fruit with catfacing or that are deformed (Fig. 1). Catfacing results in fruit with deep indentations in the blossom end or fruit with significant distortions. It is thought to be caused by a problem during the formation of the flower that results in the fruit not developing normally. However, there is little information as to its exact cause.
Figure 1. Tomato fruit with catfacing
At times the first set of tomatoes in fields looked good, but the second, third and in some cases fourth sets are having problems in some fields. The problem is most probably due to the cool night temperatures we had 20-30 days ago in some areas. Tomato flowers do not develop or pollinate properly if temperatures fall below 52-54°F. This is just the nighttime temperatures; the day time temperatures could be in the 80s, but night temperatures at or below 54°F will cause the fruit to develop abnormally. At several places on the eastern shore, where the damage seems to be worse, low temperatures were at or below 54°F from 1 May through the 25 May. This extended period of cool night temperatures is just the scenario that is needed for catfacing to occur over several tomato fruit sets. These temperatures are from official reporting sites and can be lower or higher depending on your location. Some varieties will be more sensitive to these lower temperatures than others. It seems the ‘rounder and larger’ the fruit the greater the chance of catfacing. So in the same field that has several cultivars of round tomatoes that have catfacing the plum tomatoes would have less and the cherries and grapes much less if any.
There are other causes of catfacing, one of which is exposure to 2,4-D. If 2,4-D exposure caused the catfacing you should see a pattern in the field with one edge of the field with more damage and less damage as you move away from that. Heavy pruning in indeterminate varieties may increase catfacing because of reductions in auxins in the plant. Jointless tomato varieties seem to be more prone to catfacing than jointed varieties.
Zippering fruit have lines along the side of the fruit usually from the stem end to the blossom end (Fig. 2) due to abnormalities in early flower development. At times a “hole” forms on the side of the fruit along the zipper (Fig. 2). Although sometimes attributed to high humidity or an anther that is attached to the newly forming fruit the cause of the zipper scar is still not well understood.
Unfortunately there is little that can be done to control either catfacing or zippering, except selecting varieties that are not prone to the problem. Older cultivars appear to be more susceptible. If possible, removal of the catfaced fruit is beneficial because these fruit are unmarketable, but will continue to drain nutrients from the plant.
Figure 2. Tomato fruit with a hole and zippering