How often do I apply copper fungicide to my tomato plants to prevent bottom rot?
You don’t! Bottom rot (blossom end rot) is not a diseases, it’s the result of lack of calcium in the fruit. A very common problem on tomatoes (can also happen on peppers, squash, melons, cucs, eggplant, etc), and can be the result of many factors:
-Water stress (uneven soil moisture available to the plant – when plants take up moisture from the soil, it goes to the foliage first, then to the fruits – lack of even moisture affects the fruit first.) This also results in less calcium being carried to the fruit. -Lack of calcium in the soil available for the plant to take up. -Plants trying to get rooted in / established, producing new growth and fruit all the same time. Root damages can cause this as well. -High feedings of Nitrogen – High salt levels in the soil -Too low or too high pH. -Cold air and soil temperatures – Soils high in salts -Again, this problem usually occurs early in the season (especially if wet spring, then dry ad fruit begins to set), and seems to taper off as the season progresses (plants become better rooted, etc.). It is a physical problem, not a disease, so the ripened fruits can still be eaten (slice off the black spot) if desired. So, how do you control it? -Add calcium to the soil, using lime or gypsum, before planting the plants in the ground or containers (add to soil and till in). These can also be added (top dress and light raking) once Blossom End Rot shows up on the fruit, to help correct future fruit from being affected. -Regulate your watering, so the plant is receiving even soil moisture at all times. Increased timely watering, as well as mulching tomatoes to retain soil moisture will help. Proper watering and adding calcium are the two most important steps in controlling Blossom End Rot. -Do not over feed the plants, especially with a high nitrogen fertilizer. Excessive growth, stimulated by the high Nitrogen, increases foliage production, which increases the need for water and calcium to the leaves, and results in the lack of moisture and calcium to the fruits. Use an all-purpose garden food, which is lower in N and higher in Potassium and phosphorus, as well as other needed nutrients, including Calcium. –Check pH levels.
-Cold temperatures (soil and air) will also affect the flow of calcium / water to the plant and fruit. Another good reason to not plant tomatoes too early in the season! Plant when the temperatures get warmer. –Keep records as soon selections are more susceptible than others. NOTE: Blossom End Rot may be more of a problem in containers – potting mixes do not contain calcium / harder to keep evenly moist. Add calcium to the mix / use Soil Moist to help keep even moisture levels / water as needed. The larger the pot, the less watering needed. There are Blossom End Rot sprays, but are slow to be absorbed, it’s temporary, and you’re better of correcting the overall situation causing the problem. Remember: This very common tomato problem typically becomes less of a problem as the season progresses. Do what we’ve recommended, be patient, and the Blossom End Rot should go away on your future fruits. Then your tomatoes will be just right for the squirrels to take a bite out of them!