Drought that has stunted development of Indiana’s corn and soybean crops doesn’t necessarily spell disaster for specialty and produce crops, some of which have survived the long, hot, dry spell with less damage.
But as the season wears on, Purdue University horticulture specialists say the weather is becoming a greater concern - even for drought-tolerant crops and growers with irrigation systems.
“Indiana irrigation systems have not been designed for the extreme conditions of this summer, and it has been difficult to get enough water on all the crops when they need it,” said Liz Maynard, Purdue Extension horticulture specialist. Here is a summary of how specialty and produce crops are faring:
Tree fruits, such as peaches and apples, have been some of the least affected by the heat and drought. Purdue horticulture professor Peter Hirst explained that water is important in the first month of plant development because the fruit is the primary recipient of water. The drought currently is affecting shoot growth much more than fruit growth. Shoots are not growing at their normal rate, which can be beneficial for trees because less pruning is needed and the fruit has more opportunity to receive sunlight.
Irrigation is typical for berry crops, including strawberries, blueberries and raspberries. But the extreme conditions might have made it difficult for irrigation systems to keep up with the crops, said Bruce Bordelon, Purdue Extension horticulture specialist. The hot temperatures cause berries to ripen quickly and may result in soft, less flavorful fruit. Reduced soil moisture also can reduce berry size.
The weather is now beginning to pose a serious problem for the grape crops. Well-established vineyards have deep, extensive root systems and, until recently, vines were showing only slight drought stress. Bordelon said dry weather usually increases fruit quality because there is less fruit rot, and sugar concentration within the fruit is increased. But with the extended drought and heat, vineyards are beginning to show signs of stress. Young vines are dropping leaves, while older vines are showing stress on hot, sunny days. Rain is needed soon or the crop might not ripen.
Watermelon has suffered because of reduced fruit set and yield. Purdue Extension specialist Dan Egel estimates that about half of watermelon fields are not irrigated. Recent rainfall aided some watermelon fields but came too late for others. Cantaloupes have not been as seriously affected by the drought because most fields are irrigated. Some cantaloupes, however, have suffered from the extreme heat.
Despite proper irrigation, tomatoes have been affected by the weather. Like berries, the heat has made it difficult to keep tomato crops well watered, Maynard said. When there are lapses in irrigation, the tomato may develop blossom-end rot, a disease that occurs when the fruit receives insufficient calcium and shows as a dark lesion on the bottom of the fruit. During seasons of drought, there may be sufficient calcium in the soil, but the lack of water prevents the calcium from reaching the fruit.
Although trees have deeper moisture-reaching roots than agricultural crops, they are not immune to this summer’s persistent drought.
Trees across Indiana and the Midwest are struggling, said Lindsey Purcell said.
“Drought can have a major impact on tree health and survival by effectively slowing and reducing growth,” he said. “If drought is severe enough or lasts for a prolonged period of time - such as what we’re experiencing now - it also can cause death to all or portions of a tree.”
More common, however, is the effect drought has on a tree’s ability to withstand insects and diseases. All 92 Indiana counties are experiencing some level of drought,.
“Drought not only influences the number of leaves but also the size, as well as twig extension the following year when those buds expand,” Purcell said.
“The result of prolonged dry conditions may not inhibit the first growth but may decrease the number of stem units formed in the new bud that will expand during the second or third, or more, flushes of growth. If drought continues, all growth flushes will be affected..”
While not something most homeowners think about doing, watering trees of any size and age can go a long way. When watering younger and newly established trees, homeowners should follow the “5 plus 5” rule each week: give the tree 5 gallons of water plus 5 gallons for every diameter inch of tree trunk. For example, if a tree has a trunk diameter of 4 inches, provide 20 gallons of water slowly over the root zone.
For older, well-established trees Purcell recommends providing an additional inch of water every week or so to keep leaves turgid. To measure an inch of water, place an empty tuna or cat food can under a tree’s canopy and turn on a sprinkler system. Turn off the sprinkler when the water is 1 inch deep in the can.
“For those trees with mulch beds, you should consider adding a half gallon of water per square foot of mulch area,” Purcell said.
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