A Purdue University expert said only a handful of crabapple trees are resistant to a widespread fungus or other serious diseases, according to a report on Science Daily (http://www.sciencedaily.com/releases/2009/06/090625152931.htm)
After reviewing 33 years of data, Janna Beckerman, a Purdue assistant professor of botany and plant pathology, found that only five of 287 crabapple varieties had durable resistance to apple scab.
Beckerman said data on crabapple trees and apple scab had only been done on a year-by-year basis until now. Looking over a prolonged period gives researchers a better idea of which trees have historically maintained or lost apple scab resistance.
"Whenever new plants are released, they are often touted as disease-resistant, but they have only been tested for a few years," Beckerman said. "That isn't enough time. From this data, you could see that varieties that did well for the first few years after planting often developed scab within 10 years."