Hobby Farms Editors
August 19, 2011
Green tomato
Photo by Stephanie Staton
Extreme heat in the South has impeded tomato ripening or has prevented them from setting fruit at all.

A summer of hot, dry weather has disappointed home vegetable and fruit growers in the South, who despite lavishing care on their plants, aren’t seeing the fruits of their labor.

“I am getting tons of calls,” says Jerri Lephiew, Ouachita County extension agent for the University of Arkansas Division of Agriculture. “Everyone’s garden is crashing. People aren’t seeing fruit setting on their plants.”

Home gardeners are lamenting the lack of tomatoes, beans, squash and okra. Lack of fruit set can have many causes. High nighttime temperatures are a major problem. Several cities in Arkansas saw record highs this month, with some cities hitting 107 degrees F and not dipping below the mid 80s.

The heat causes the plant’s flowers to drop. No flowers means no fruit.

“If nighttime temperatures don’t fall below 75 degrees F during flowering to early fruit development, tomatoes just won’t set fruit,” says Sherri Sanders, White County extension agent for the University of Arkansas Division of Agriculture.

“As it cools and we have three or four nice evenings, we should be seeing tomatoes set some fruit,” says Craig Andersen, extension vegetable specialist for the University of Arkansas Division of Agriculture.

The high temperatures can also affect ripening.

“Temperatures in excess of 110 degrees F inhibit the ripening chemistry of the tomato in a similar manner to which cold temperatures damage fruit ripening,” Andersen says. “However, there is always the alternative and that’s fried green tomatoes.”

The same goes for green beans and squash.

“Beans won’t set pods when there are high temperatures, especially high nighttime temperatures,” he says. “Squash is probably being affected by water and heat stress. When it cools down a little bit, the fruit will come back.”

Andersen says the situation with the okra is more perplexing, though, because okra usually withstands heat well. He credits the problem in the southern part of Arkansas to fire ants, which have been eating the okra flowers.

“There have been other problems recently, like blister beetles coming out of alfalfa and soybeans and going into the garden and eating the flowers and young leaves,” he says. “This has not been a great season for gardening.”

Where blossoms have stayed aboard, pollination problems can also contribute to a lack of fruit. According to Jon Zawislak, extension apiculturist for the University of Arkansas Division of Agriculture, there may not be any pollinators in some areas.

“Tomatoes require big bees,” Zawislak says. “Because of the way tomato pollen sticks, the plant requires buzz pollination, which calls for bumblebees. Honey bees are too small to pollinate tomatoes effectively.”

In buzz pollination, the bee vibrates the pollen loose.

Dan Chapman, director of the University of Arkansas’ Fruit Research Station in Clarksville, Ark., says the heat has also affected blackberries and peaches.

“In blackberries, it’s not the female flower, but the male flower that can’t take the heat, and you have to have both to get fruit,” he says. “Our peach crop is down, the fruit size is down and all the growers have had problems with size and quantity, too. It’s just a pitiful year.”

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