Drought stress starting to set in on specialty and produce crops

July 24, 2012  

WEST LAFAYETTE, Ind. – 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. "The high temperatures also add additional stress that can reduce yield or quality even for crops that are irrigated."

Here is a summary of how specialty and produce crops are faring:

* Tree fruits: 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.

* Berries: 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.

* Grapes: 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.

* Cantaloupe and watermelon: 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.

* Tomatoes: 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.

A compilation of drought information and resources is available at http://www.purdue.edu/drought

Writer: Abigail Maurer, 765-496-2384, maurer@purdue.edu

Sources: Peter Hirst (tree fruits), 765-494-1323, hirst@purdue.edu

               Liz Maynard (vegetables), 219-531-4200, emaynard@purdue.edu

               Bruce Bordelon (berries and grapes), 765-494-8212, bordelon@purdue.edu

               Dan Egel (melons), 812-886-0198, egel@purdue.edu

Ag Communications: (765) 494-2722;
Keith Robinson, robins89@purdue.edu
Agriculture News Page

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