Jerry Brust, IPM Vegetable Specialist, University of Maryland; jbrust@umd.edu
This is just a reminder, with the peculiar weather we have had lately — stretches of very high temperatures then cooler days along with the very heavy down pours we have had over the last few weeks — blossom end rot can become a real problem in tomatoes. The sunny days with low humidity will suck water through a plant quickly and the downpours will disrupt calcium movement through the plant. The key is to try to maintain consistent soil moisture while the fruit is developing. Easier said than done, I know, but soil moisture levels need to be monitored as best as they can. When you see something like Figure 1, with all the tomatoes on a cluster with blossom end rot, you know the soil moisture fluctuated greatly over a period of time. Applying some foliar calcium sprays will help, but the applications can’t overcome poor soil moisture management.
Figure 1. All the tomatoes on this one cluster have blossom end rot—indicating poor soil moisture management.