Issue link: http://read.dmtmag.com/i/459886
www.goodfruit.com GOOD FRUIT GROWER FEBRUARY 15, 2015 19 Introducing Madex HP for control of codling moth and oriental fruit moth larvae. Now you have a selection of highly eff ective granuloviruses. So potent they can be used at ultra-low rates for cost-eff ective control. Ideal for managing insecticide resistance and residues. Four-hour reentry interval (REI) and zero plant harvest interval (PHI). OMRI ® Listed and NOP Approved. Double Trouble for Codling and Oriental Fruit Moths. CYD-X ® HP and ma - dex ® hp The most potent codling moth and oriental fruit moth viruses...ever. © 2015 Certis USA ] [ © 2015 Certis USA 1-800-250-5024 • www.CertisUSA.com RosBREED project, which under a new grant plans to address disease resistance as a priority, she believes other breeders, especially peach breeders, will find this new discovery of keen interest. "There is a long history of not much happening to help combat this disease," she said. "But it is a problem in peaches as well as cherries, and is a terrible prob- lem on almonds." Peach growers with Armillaria-infested sites may find the rootstock Sharpe provides some level of protection. Serious disease How serious is Armillaria in tart cherries? Jim Nugent, a Traverse City area grower and former coordinator of the Northwest Michigan Horticulture Experiment Station, says it's a major problem. "I know many cherry sites that have been converted to houses because of it," he said. Iezzoni will find no shortage of Michigan sites on which to test her trees, he added. Once found in a stone fruit site, there is no way to eliminate it, he said. Fumigation is not effective. The fungus survives on infected wood and roots in the soil for an unknown amount of years—at least 18, Nugent found from personal experience. It is found on sandy sites mostly, but the disease is widespread in nature, attacking hardwoods, especially oak, giving it the common name of oak root disease. It attacks conifer trees as well. While the disease releases spores by sprouting mushrooms in the fall, the major means of spreading is through rhizomorphs, often called shoestrings because of their appearance. It doesn't move rapidly, but it is relentless and long-lived. In fact, in 1992, an organism discov- ered in Michigan's Upper Peninsula was said to be the largest living "creature" in the world and possibly the oldest. The organism, all genetically identical, covered 37 acres and was estimated to be 1,500 years old. That organism was Armillaria. That record stood only a short time until another was found in southwest Washington State that covered 1,500 acres. But in 1998, a still larger one was found in the Blue Mountains of Oregon that covered 2,400 acres and was estimated to be at least 2,400 years old, and perhaps as much as 8,650 years old. "It's like discovering terminal cancer," Nugent said. "It's a death sentence for a stone fruit site." If P. maackii turns out to be graft-compatible and a suitable rootstock, "that would be tremendously lucky," he added. But if not, the discovery of a Prunus species that is resistant provides a base for breeders—and possibly genetic engineers—to build on. • COURTESY MICHIGAN STATE UNIVERSITY Ray Hammerschmidt discovered that Prunus maackii is resistant to Armillaria due to its ability to produce antifungal compounds that ward off the disease.