Karen Cambre, Sharpe, Kenneth W.
News article for May 14, 2018
Vegetable gardens have been slower than normal. We have had some really cool nights this spring which slowed growth. Seems that the cool is over and growth has picked up.
I have received a number of reports of blossom-end rot in tomatoes. This is a condition where the bottom end of the tomato, also called the blossom end, rots and turns black. The rot is hard and leathery and causes a flat black spot that connects to the bottom of the tomato. The first indicator is small tomatoes turning red prematurely, but when you go to pick them you see the bottom rot.
There are several factors that can cause blossom-end rot, but they all are the result of poor absorption of calcium. It could be that you have low levels of calcium in the soil and the plant cannot meet its calcium needs.
Another possibility is that you have a low soil pH and calcium is tied up and not available for the plant.
The third possibility is either too much water or not enough water and a constant drying out and wetting of the soil. Tomatoes need a consistent supply of water so they can uptake nutrients correctly.
It is important to figure out what is causing the problem so you can correct it. Take a soil sample and that will tell you the soil pH and more importantly how much lime is needed to correct any pH deficiency. A soil sample will also give you your soil calcium levels and how to bring them up if they are low. If the soil test results tell you that your pH and calcium levels are adequate, then we know that blossom-end rot is caused by water surplus or deficiency. We can then develop a plan to provide consistent soil moisture.
While we can usually get a soil sample back pretty soon, I would try some short term relief solutions so you might get some good tomatoes this year. Spray your tomato plants with a calcium chloride product designed to be used as a foliar spray that say “blossom set” or “stop rot”. Make a weekly spray according to directions until you are ready to end harvesting. Late afternoon sprays will give you the best absorption. Spraying will not reverse any damage already done, but hopefully you will stop the rot from occurring on the new fruit that is set.
Another problem I am seeing is tomato plants that look healthy and then for no apparent reason just wilt. One day the plant looks fine and the next day it looks like you poured hot water over it and it has lost all rigidity. This is bacterial wilt and there is no cure.
The bacteria live in the soil and will enter tomatoes through small abrasions in the root system. The bacteria will eventually clog up the plants vascular system until it can no longer take up water and will collapse.
Bacteria wilt is a problem in tomatoes, peppers and eggplant and they are susceptible in that order. No other vegetable are affected and bacteria is not harmful to you.
The solution is to pull up wilted plants and throw them in the garbage can. Rotate your tomatoes to the opposite side of the garden next year if possible. Many people will lose all their tomato plants after a few years. They eventually develop a new garden site for tomatoes, such as a raised bed, but you must be careful not to move infected soil into the new garden.
There are no fungicide controls, but the variety Florida 7514 has some resistance.