Friday, August 28, 2009

Point Rot

Tomato point rotThis trouble, called also "blossom-end rot," and "black-rot," occurs on the green fruit at various stages of development, as shown above. It begins at the blossom end as a sunken brown spot,which gradually enlarges until the fruit is rendered worthless. The decayed spot is often covered in its later stages by a dense black fungous growth (Alternaria fasciculata (C. & E.) J. & G. syn. Macrosporium tomato Cke.), formerly thought to be the cause of the rot, but now known to be merely a saprophyte. Point-rot sometimes occurs in greenhouses, but is more common in field culture. It is one of the most destructive diseases of the tomato, but its nature is not fully worked out, and a uniformly successful treatment is unknown. It has been thought to be due to bacterial invasion, but complete demonstrations of that fact have not yet been published. The physiological conditions of the plant appear to be important. The disease is worst in dry weather and light soils, where the moisture supply is insufficient, and irrigation is beneficial in such cases. Spraying does not control point-rot so far as present evidence goes.


  1. I grow tomatoes in the Chicago area, too. I grow heirlooms in containers and may have seen a version of this problem in the past. I think I read somewhere that it related to uneven watering, so I was more careful with the watering after that and the problem went away with the next round of fruit. Thanks for all the great information on tomatoes. Happy blogging!

  2. P.S.: Oh, I threw the damaged tomatoes away, but wondered if you could just cut off the brown portion and still eat the rest?