Featured Research

from universities, journals, and other organizations

Citrus greening affects roots before leaves

Date:
May 9, 2014
Source:
University of Florida Institute of Food and Agricultural Sciences
Summary:
Although citrus greening enters trees through their leaves, researchers have discovered that the deadly disease attacks roots long before the leaves show signs of damage -- a finding that may help growers better care for trees while scientists work to find a cure.

Orange blossoms at the UF Research and Education Center in Lake Alfred.
Credit: Image courtesy of University of Florida Institute of Food and Agricultural Sciences

Although citrus greening enters trees through their leaves, University of Florida researchers have discovered that the deadly disease attacks roots long before the leaves show signs of damage -- a finding that may help growers better care for trees while scientists work to find a cure.

"The role of root infection by insect-carried bacterial pathogens has been greatly underestimated," said Evan Johnson, a research assistant scientist with UF's Institute of Food and Agricultural Sciences.

Hundreds of researchers throughout the world are rushing to find a viable treatment for citrus greening, which is devastating Florida's $9 billion citrus industry and has affected citrus production throughout North America.

Johnson was the lead author of a scientific paper outlining the research published in the April issue of the journal Plant Pathology. He and his fellow team members -- Jian Wu, a graduate student in soil and water science, researcher Diane Bright and Jim Graham, a professor of soil microbiology -- are based at the UF/IFAS Citrus Research and Education Center in Lake Alfred.

Citrus greening first enters the tree via a tiny insect, the Asian citrus psyllid, which sucks on leaf sap and leaves behind bacteria that spread through the tree. Johnson said the bacteria travel quickly to the roots, where they replicate, damage the root system and spread to the rest of the host tree's canopy. The disease starves the tree of nutrients, leaving fruits that are green and misshapen, unsuitable for sale as fresh fruit or juice. Most infected trees die within a few years.

It was originally thought that the leaves and fruit were affected first, but the team's research found that greening causes a loss of 30 to 50 percent of trees' fibrous roots before symptoms are visible above ground.

"This early root loss means that the health of a citrus tree is severely compromised before the grower even knows it is infected," Johnson said.

Experts say this research is significant in the fight against greening.

"Based on the work of Dr. Johnson and his colleagues, we now know how important roots are in the development of greening disease," said Jackie Burns, director of the CREC. "We hope further investigations on the role of roots in this disease will lead to future management solutions that help growers remain productive until a permanent solution can be found."

To battle greening, UF/IFAS researchers have attempted everything from trying to eradicate the psyllid to breeding trees that show better greening resistance. While Johnson's research is not a cure, it may help more trees survive as scientists continue their search.

"We are still trying to determine how the bacteria are killing the roots," Johnson said. "This finding suggests that growers should focus more effort on maintaining the health of the root system in relation to other soilborne pests and overall soil quality to maintain as much of the root system as possible."

Johnson suggested that growers increase the acidity levels of irrigation water and soil to match the optimum pH for the rootstock (preliminary results show that this improves root density compared to untreated groves) and water more frequently for shorter periods. Those treatments are being studied by UF researchers in Lake Alfred and at the Southwest Florida Research and Education Center in Immokalee.

He added that while psyllid control is essential, growers should make careful decisions on how many resources to devote to any management strategy for greening-infected trees, based on their economic means, until field trials have been completed.


Story Source:

The above story is based on materials provided by University of Florida Institute of Food and Agricultural Sciences. The original article was written by Kimberly Moore Wilmoth. Note: Materials may be edited for content and length.


Journal Reference:

  1. E. G. Johnson, J. Wu, D. B. Bright, J. H. Graham. Association of ‘CandidatusLiberibacter asiaticus’ root infection, but not phloem plugging with root loss on huanglongbing-affected trees prior to appearance of foliar symptoms. Plant Pathology, 2014; 63 (2): 290 DOI: 10.1111/ppa.12109

Cite This Page:

University of Florida Institute of Food and Agricultural Sciences. "Citrus greening affects roots before leaves." ScienceDaily. ScienceDaily, 9 May 2014. <www.sciencedaily.com/releases/2014/05/140509172547.htm>.
University of Florida Institute of Food and Agricultural Sciences. (2014, May 9). Citrus greening affects roots before leaves. ScienceDaily. Retrieved September 16, 2014 from www.sciencedaily.com/releases/2014/05/140509172547.htm
University of Florida Institute of Food and Agricultural Sciences. "Citrus greening affects roots before leaves." ScienceDaily. www.sciencedaily.com/releases/2014/05/140509172547.htm (accessed September 16, 2014).

Share This



More Plants & Animals News

Tuesday, September 16, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Conservationists Face Uphill PR Battle With New Shark Rules

Conservationists Face Uphill PR Battle With New Shark Rules

Newsy (Sep. 14, 2014) New conservation measures for shark fishing face an uphill PR battle in the fight to slow shark extinction. Video provided by Newsy
Powered by NewsLook.com
Shocker: Journalists Are Utterly Addicted To Coffee

Shocker: Journalists Are Utterly Addicted To Coffee

Newsy (Sep. 13, 2014) A U.K. survey found that journalists consumed the most amount of coffee, but that's only the tip of the coffee-related statistics iceberg. Video provided by Newsy
Powered by NewsLook.com
Lion Cubs the Pride of San Diego Zoo

Lion Cubs the Pride of San Diego Zoo

Reuters - US Online Video (Sep. 13, 2014) Roars of excitement as a proud lioness shows off her four cubs at the San Diego Zoo Safari Park. Jillian Kitchener reports. Video provided by Reuters
Powered by NewsLook.com
'Magic Mushrooms' Could Help Smokers Quit

'Magic Mushrooms' Could Help Smokers Quit

Newsy (Sep. 11, 2014) In a small study, researchers found that the majority of long-time smokers quit after taking psilocybin pills and undergoing therapy sessions. 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