Jul 28, 2016

Clemson workshop teaches how to grow healthy fruit

Bill Foster of Westminster was one of about 100 people who learned how to grow healthy fruit crops during a workshop at Clemson’s Musser Fruit Research Center Saturday.

“I grow peaches, pears, apples, plums, blackberries, blueberries and muscadines,” Foster said. “I learn a lot from the research that goes on here. And I learn even more by attending events such as this.”

The event highlighted fruit research conducted by Clemson experts such as Ksenija Gasic, a peach breeder. Gasic talked about Clemson’s effort to develop new peach varieties with superior horticultural quality and disease resistance. She explained how development and application of molecular tools in peach breeding helps growers increase yields.

Gasic’s research focuses on two major peach diseases: bacterial spot and brown rot. Bacterial spot affects both the peach leaf and fruit. There is no optimal chemical protection against bacterial spot and in certain conditions there is nothing that growers can do to prevent its development. The best way is to plant resistant varieties, she said.

Brown rot is another disease discussed during the workshop. Guido Schnabel, a plant pathologist, talked about controlling brown rot.

“This is a major disease of peaches,” Schnabel said. “Brown rot is caused by a fungus and begins when the tree starts blooming. It can infect flower blossoms and shoots.”

Infected flowers wilt and turn brown very quickly, Schnabel said. Shoot infections result in gummy-like cankers. These cankers provide the source of infection for fruit rot, which starts as a small, round brown spot, expands and eventually rots the entire fruit. The fungus can survive the winter on the mummified fruit both on trees and on the ground. The fungus also can survive the winter on twig cankers.

While brown rot can be detrimental to a peach crop, there are things growers can do to minimize damage. Protective measures include removing all infected branches from trees, removing all diseased fruit and fruit mummies from trees and the ground around the trees, removing all dried fruit mummies from the tree and, when pruning trees, removing all cankerous parts of the tree. Spraying peach trees with a fungicide that contains captan, thiophanate methyl or propiconazole that is labeled for use on peaches is another step that can be taken to fight brown rot.

Schnabel also said growers who have “weedy orchards” should pull and remove all weeds from orchards. He also warned growers to be extremely careful not to get any spray drift on the tree leaves.

For more information, go to the Peach Diseases (HGIC 2209) fact sheet from the Clemson Home and Garden Information Center.

Clemson researchers also are “bagging” peaches to protect them from disease. Juan Carlos Melgar, a peach pomologist, talked about a project he and Schnabel are working on that involves tying bags around peaches as they grow on the trees. This method is used in China and could open the door for organic, chemical-free peach production in the southeastern United States. The bags shield the peaches from chemicals sprayed on the trees, as well as from insects and worms that can attack the trees.

“We started this study (in 2015),” Melgar said. “So far, we’ve found the bagged fruit have the same quality, taste and firmness as other peaches but without receiving as much pesticides as conventional peaches.”

The bagged peaches do not get the same amount of sunlight as unbagged peaches, which can cause some peach varieties to not develop the intense blush-red color most consumers prefer, he said. Labor costs involved with the bagging method are also higher.

Clemson scientists also talked about rootstock trials and research into the agricultural use of drones.

Other fruits addressed during the workshop included apples, blackberries and strawberries. In addition, participants also learned about a new smartphone tool series designed to help growers fight diseases in their crops. The series of apps, MyIPM, are available for free in the Apple Store and Google Play Store.

The Musser Fruit Research Center, also known as Musser Farm, is located at Oconee Point in Seneca. The research center is a 240-acre fruit tree research farm with an excellent collection of commercial peach cultivars and related wild Prunus species. Foster said he is especially thankful for the research that takes place at the research center.

Peaches are a major fruit crop in South Carolina. According to an Overview of South Carolina Agriculture by the United States Department of Agriculture National Agriculture Statistics Service, 68,880 tons of peaches were harvested from 14,000 acres in 2015. For more information about peaches in South Carolina, go to the Clemson Extension’s Everything About Peaches website.

— Denise Attaway, Clemson University College of Agriculture, Forestry and Life Sciences

Source: Clemson University