Featured Research

from universities, journals, and other organizations

Crab Apple Trees: Long-term Apple Scab Resistance Remains Elusive, Expert Says

Date:
September 8, 2009
Source:
Purdue University
Summary:
There are hundreds of choices when picking a crabapple tree from the nursery, but an expert says only a handful are resistant to a widespread fungus or other serious diseases.

Janna Beckerman examines a Ralph Shay crabapple tree that is infected with apple scab. The fungus shows up as brown lesions on the leaves and fruit of crabapple trees, causing early defoliation.
Credit: Purdue Agricultural Communication photo/Tom Campbell

There are hundreds of choices when picking a crabapple tree from the nursery, but a Purdue University expert says only a handful are resistant to a widespread fungus or other serious diseases.

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 a serious disease of crabapple trees. 

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."

The Venturia inaequalis fungus produces black scab-like lesions on the fruit and leaves. Crabapple trees with scab tend to defoliate, or lose all their leaves, in early summer, a condition that can weaken and eventually kill the trees.

"When a tree loses all of its leaves, it will try to produce more leaves, using the energy reserves it needs to get through the winter," Beckerman said. "Over time, this repeated defoliation weakens the tree. A tree that is defoliated is under stress and can be susceptible to opportunistic insects and other diseases. The apple scab won't kill the tree, but the chronic weakening will."

The data, collected from observations at the Secrest Arboretum in Wooster, Ohio, showed that only 29 varieties of crabapple trees had resistance to scabbing for at least 10 years. Only 15 varieties lasted the entire 33 years, but 10 of those had problems with fire blight and other diseases.

The five that showed resistance to scabbing and other serious diseases were: Beverly, Sargentii, Jackii, White Angel and Silver Moon. A promising new variety, Adirondack, showed resistance for 12 years, but it was not considered enough time to count in the study.

Another major finding was that scab has infected the Japanese flowering crabapple, Malus floribunda. This variety was considered scab resistant in the early 1900s and provided the resistance gene bred into other crabapple trees to protect them from scabbing. But a trace of scab was found in Malus floribunda in 1997, and by 2003, the trees were defoliating, Beckerman said.

"You can actually see the pathogen evolving by looking at the data over time," Beckerman said. "Finding scab on this crabapple suggests that all commercial apple varieties with this resistant gene are at risk of scab."

Beckerman said even susceptible crabapples can be protected with about three well-timed fungicide treatments per year. Certified arborists have access to proper chemicals that the average homeowner wouldn't be able to obtain.

Beckerman said using information on scab resistance could minimize the need for those fungicides, though.

"What tree owners are doing is putting in an investment that could live in their yards for 100 years," Beckerman said. "A few minutes of research and choosing the right tree can pay out dividends over the course of decades."


Story Source:

The above story is based on materials provided by Purdue University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Janna Beckerman, James Chatfield, Erik Draper. A 33-year Evaluation of Resistance and Pathogenicity in the Apple Scab-Crabapples Pathosystem. HortScience, June, 2009

Cite This Page:

Purdue University. "Crab Apple Trees: Long-term Apple Scab Resistance Remains Elusive, Expert Says." ScienceDaily. ScienceDaily, 8 September 2009. <www.sciencedaily.com/releases/2009/06/090625152931.htm>.
Purdue University. (2009, September 8). Crab Apple Trees: Long-term Apple Scab Resistance Remains Elusive, Expert Says. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2009/06/090625152931.htm
Purdue University. "Crab Apple Trees: Long-term Apple Scab Resistance Remains Elusive, Expert Says." ScienceDaily. www.sciencedaily.com/releases/2009/06/090625152931.htm (accessed September 2, 2014).

Share This




More Plants & Animals News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

U.N. Says Ebola Travel Restrictions Will Cause Food Shortage

Newsy (Sep. 2, 2014) — The U.N. says the problem is two-fold — quarantine zones and travel restrictions are limiting the movement of both people and food. Video provided by Newsy
Powered by NewsLook.com
Sharks Off the Menu and on the Tourist Trail in Palau

Sharks Off the Menu and on the Tourist Trail in Palau

AFP (Sep. 2, 2014) — Tourists in Palau clamour to dive with sharks thanks to a pioneering conservation initiative -- as the island nation plans to completely ban commercial fishing in its vast ocean territory. 01:15 Video provided by AFP
Powered by NewsLook.com
We've Got Mites Living In Our Faces And So Do You

We've Got Mites Living In Our Faces And So Do You

Newsy (Aug. 30, 2014) — A new study suggests 100 percent of adult humans (those over 18 years of age) have Demodex mites living in their faces. Video provided by Newsy
Powered by NewsLook.com
Coffee Then Napping: The (New) Key To Alertness

Coffee Then Napping: The (New) Key To Alertness

Newsy (Aug. 30, 2014) — Researchers say having a cup of coffee then taking a nap is more effective than a nap or coffee alone. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins