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If you are experiencing the continuation of hot, dry conditions shared in many areas of the country, there may be some effects on your garden you haven't seen before. We would like to tell you a few to watch for.
Tomatoes are the most widely planted garden crop, so many of the calls we receive relate to them. First of all, an abundance of blossoms on tomatoes doesn't always result in a bumper crop. Temperatures above 85 degrees F. can affect pollination and fruit set. Studies have shown that daytime temperatures in excess of 95 degrees and night time temps of over 75 degrees may cause flowers to fall off. Temperatures over 100 degrees can make the plant go into survival mode, causing red pigments in tomatoes to stop forming, while the yellow and orange ones continue. If this is the case, it's best to pick the tomatoes when they begin to turn red and allow them to ripen indoors at cooler temperatures. It takes about 5 weeks for a tomato flower to become a ripe fruit - the first 3 weeks to get to full size and the last 2 weeks to fully ripen. Temperatures above 90 degrees will slow fruit growth and ripening, so if you’ve planted a large-fruited variety, you probably won't harvest the big tomatoes you are expecting. This is not the fault of the variety - it is a result of the heat. Once the excessive heat is over, it will most likely take five more weeks to begin harvesting tomatoes again. Tomatoes that have developed to full size in spite of dry weather may suddenly grow again if watered or rained on, and the result may be split fruit.
Cucumbers are also often affected by multiple days of excessive heat, dropping their blossoms and developing fruit may become misshapen with a bulbous end that's somewhat gourd-like. Developing fruits of eggplant and cucumbers experiencing stresses such as high temperatures, dryness, low fertility or foliage disease may acquire a bitterness to their flavor. For cucumbers, the longer ‘burpless’ types are usually not affected with bitter flavor as severely as pickling types. In most cases, cutting off the stem-end and removing the skin of bitter cucumbers will remove much of the bitterness.
Successive 90+ degree days may cause other crops such as squash, peppers, melons, pumpkins and beans to shed their blossoms and go into a temporary 'shut-down' mode to conserve their resources. Cool-season crops such as broccoli, cabbage, lettuce and spinach will bolt. Blossom end rot is also common during hot weather and most prevalent in tomatoes, peppers, and squash.
Hot, dry weather often results in an invasion of spider mites on plants. These insects will cause the leaves to look like they are stressed. To check for spider mites, hold a sheet of white paper under the leaves and tap the plant. The specks on the paper may start to move. If you run your hand firmly over the white paper, streaks will appear on the paper. Insecticidal soap is one of the best controls for spider mites.
Just so you know that all is not gloom and doom, a positive result of hot, dry conditions is a reduction in fungal diseases such as powdery mildew and blight.
While there isn't much we can do about the hot temperatures, you can still save much of your garden if you can keep it sufficiently watered until saving rains come. Last week our email newsletter was filled with tips for watering during a drought. If you would like to reference this information again, click here.
We hope you haven't experienced any of these hot weather effects, but if you have, this may answer some of your questions. Feel free to call or e-mail us with any more of your garden-related concerns. We're here to help if we can!