Are your tomato plants in a sorry state? Here are the causes, and the solutions
With warm-season vegetables in peak production this time of year, inquiries about blossom end rot have been abundant.
Prevalent in tomatoes but also found in peppers, squash, cucumber, eggplant and watermelon, this physiological disorder is purely the result of a calcium deficiency within the plant itself. However, the causes of the deficiency can differ, making their treatments vary.
The first, most apparent cause is a simple lack of calcium in the soil. Though this is rare in our area due to abundant limestone, the amendment comes as fertilizer to be applied following label instructions.
However, it should not be assumed that your soil lacks calcium. More likely, the plants themselves are lacking calcium uptake due to a high soil pH. In this instance, nutrients may be abundant in the soil, but they are essentially locked in place and can’t be absorbed because of the soil’s alkalinity. Lowering this pH with a sulfur fertilizer, the nutrients become unlocked. A pH close to 6.5 is recommended for vegetable gardens. A soil test can relay that information, and your local Extension office can tell you the necessary amendments.
A lack of calcium uptake, ultimately leading to blossom end rot, can also be caused by sharp changes in outdoor temperatures, extreme fluctuations in soil moisture, drought, root damage, waterlogged roots, and too much growth from overfertilization with nitrogen. The list is varied and extensive. However, noting your gardening practices and the environmental conditions your garden faces can be helpful as you work backward to address the problem.
A mulched garden bed will assist with soil moisture and temperature issues. The more consistently you can keep these soil factors, the better your plants will be.
Remember, it is also best to somewhat mimic rainfall patterns to wean plants off excessive moisture. If an abundance of rain has fallen, followed by extended drought, this fluctuation will likely cause blossom end rot. This can be mitigated by not withholding water after rainfall but slowly decreasing the amount applied. Essentially, it slows down the drying-out process. Of course, this practice should still be done with water conservation in mind so that soil is not over-saturated.
If fertilizing, opt for a calcium nitrate fertilizer over ones that release nitrogen in the form of ammonium, as excess ammonium ions can result in reduced calcium uptake. Also, do your best to avoid over-fertilization so plants don’t grow too rapidly. This is especially important as fruits are small, and the rapid growth will likely show up as blossom end rot, cracking or facing.
Remember, too, that there is only so much we can do to prevent blossom end rot. If weather conditions are not in our favor, it will likely appear. Remove those fruits and allow your plants to push their nutrients toward trying again.
Anthony Reardon is a horticulture agent with Kansas State University Research and Extension. Need help? Contact the Johnson County Extension gardening hotline at 913-715-7050 or email garden.help@jocogov.org.
