Photo Courtesy of Timothy Coolong, University of Kentucky
Gray Wall/Blotchy Ripening of Tomato
Life Cycle: Gray Wall or Blotchy Ripening is a physiological disorder that can be caused by several environmental factors. Extreme high heat, high humidity, temperature fluctuations, low light levels during high temperatures (potentially from dense vine coverage, or from fog or clouds during hot weather), high nitrogen, low potassium, low boron, bacterial/fungal infections, TMV (Tobacco Mosaic Virus), or excessive soil compaction can all potentially contribute to gray wall/blotchy ripening. Some of these causes seem contradictory, but the disorder is believed to be caused by many different factors contributing to the symptoms listed below.
Plants affected: Tomatoes
Symptoms: Tomato fruits look as though they have uneven ripening. When still green, areas of gray wall/blotchy ripening may appear gray or brown from the outside. As fruit ripens, it will have blotchy green or yellow areas. Yellow shoulders are another symptom that can be observed with or without other symptoms listed here. Upon cutting the fruit open, there may be areas of yellow, brown, or white tissue in the fruit wall, denoting uneven ripening. There are varying degrees of symptoms involved with this disorder.
Control: Keep plants healthy by providing a well-rounded nutrient and irrigation program. A soil test on a yearly basis where tomatoes are/will be grown is recommended to assess what soil nutrient requirements will be. Keeping tabs on the weather is important. If hot cloudy or hot foggy weather is predicted, then removal of the leaf blade above ripening fruit will allow more light to penetrate the canopy. Be aware that too much canopy removal and high light levels can cause sunscald. It is important that the plant has adequate potassium levels in the soil. Grow varieties that are resistant to TMV.