Features

• The Botryosphaeria ribis fungus causes stem end blight, or water stage nut drop, in pecan trees. According to Texas A&M University, the disease is "associated with insect feeding." It damages nuts late in the summer.
  
  

Effects

• The stem end blight fungus causes the shuck, which houses the pecan, to turn black and drop from the tree. The liquid inside the kernel turns brown and the nut develops shiny black lesions, according to Texas A&M.
  
  Clemson University Extension notes that the Success cultivar is particularly susceptible to stem end blight.
  
  

Prevention/Solution

• As a preventative measure, Texas A&M recommends spraying pecan trees with a fungicide when the pecans enter water stage and again 10 days later. The Clemson Cooperative Extension website, however, indicates that chemical control is usually impractical on large trees because adequate tree coverage is not possible. It suggests providing sufficient irrigation and thinning out crowded trees to reduce outbreaks.