Featured Research

from universities, journals, and other organizations

Thermotherapy rids azaleas of deadly fungal disease

Date:
December 13, 2011
Source:
American Society for Horticultural Science
Summary:
Cuttings of 12 azalea cultivars were submerged in 50 C water before propagation, then submerged in a subsequent experiment for 20, 40, 60, and 80 minutes. A third experiment evaluated leaf damage caused by hot water submersion or by leaf removal for the effect on root development and leaf count on rooted cuttings of two cultivars. All cultivars were tolerant of submersion long enough to eliminate binucleate Rhizoctonia species from stem and leaf tissue.

These are rooted cuttings of azalea "Wakaebisu" with lower leaf drop due to Rhizoctonia web blight.
Credit: Photo by Warren Copes

Azalea web blight, caused by a species of the plant pathogen Rhizoctonia, occurs each year on some containerized azalea cultivars during nursery production, particularly in the southern and eastern United States. Azalea shoots can harbor the pathogen, spreading the devastating, costly disease through propagation.

Research has indicated that simply submerging terminal leafy cuttings of 'Gumpo White' azalea in 50C water for 21 minutes eliminates binucleate Rhizoctonia species from plant tissues. Before recommending commercial use of the practice -- known as "hot water treatment" or "thermotherapy" -- industry professionals needed to learn more about potential damage to evergreen azaleas resulting from the treatments. Warren E. Copes of the USDA-Agricultural Research Service (Thad Cochran Southern Horticultural Laboratory) and Eugene K. Blythe of the Coastal Research and Extension Center at Mississippi State University designed experiments to test 12 azalea cultivars for rooting response and sensitivity to a variety of hot water treatments.

Copes and Blythe used terminal cuttings of the azalea cultivars Conleb (Autumn Embers), Fashion, Formosa, Gumpo White, Hardy Gardenia, Hershey Red, Macrantha Pink, Midnight Flare, Red Ruffles, Renee Michelle, Roblel (Autumn Debutante), and Watchet. The cuttings from all 12 cultivars were collected and submerged or not submerged in 50C water for 20 minutes before propagation in one experiment; all cultivars tolerated the submersion test. Cuttings collected from the 12 cultivars were submerged in 50C water for 20, 40, 60, and 80 minutes in a second experiment. "The cultivars varied in sensitivity when exposed to 50C water for 60 to 80 minutes, resulting in differing responses in root development and final leaf count," Copes said.

In a third experiment degrees of leaf damage caused by hot water submersion or by leaf removal were evaluated for the effect on root development and subsequent leaf count on rooted cuttings of 'Gumpo White' and 'Roblel'. According to the results, incremental increases in leaf damage from hot water resulted in incremental reductions in the final leaf count and extent of root development for the two cultivars, while increasing leaf removal caused no reduction until 75% or greater leaf area was removed. "Despite the risks imposed by submersing azalea cuttings, we found all 12 cultivars to be tolerant of submersion durations long enough to eliminate binucleate Rhizoctonia species from stem and leaf tissue with only a low likelihood of sustaining detrimental damage," the scientists wrote in the report published in HortScience.

Copes and Blythe concluded that hot water treatment provides an alternative and effective disease control method for eliminating Rhizoctonia from azalea cuttings. "Thermotherapy provides an example of how simple techniques may provide effective disease control when appropriately applied."


Story Source:

The above story is based on materials provided by American Society for Horticultural Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Warren E. Copes and Eugene K. Blythe. Rooting Response of Azalea Cultivars to Hot Water Treatment Used for Pathogen Control. HortScience, 46: 52%u201356

Cite This Page:

American Society for Horticultural Science. "Thermotherapy rids azaleas of deadly fungal disease." ScienceDaily. ScienceDaily, 13 December 2011. <www.sciencedaily.com/releases/2011/12/111213114719.htm>.
American Society for Horticultural Science. (2011, December 13). Thermotherapy rids azaleas of deadly fungal disease. ScienceDaily. Retrieved July 23, 2014 from www.sciencedaily.com/releases/2011/12/111213114719.htm
American Society for Horticultural Science. "Thermotherapy rids azaleas of deadly fungal disease." ScienceDaily. www.sciencedaily.com/releases/2011/12/111213114719.htm (accessed July 23, 2014).

Share This




More Plants & Animals News

Wednesday, July 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
San Diego Zoo Welcomes New, Rare Rhino Calf

San Diego Zoo Welcomes New, Rare Rhino Calf

Reuters - US Online Video (July 21, 2014) An endangered black rhino baby is the newest resident at the San Diego Zoo. Sasha Salama reports. Video provided by Reuters
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. 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