Featured Research

from universities, journals, and other organizations

Late Blight -- Irish Potato Famine Fungus -- Attacks U.S. Northeast Gardens And Farms Hard

Date:
July 5, 2009
Source:
Cornell University
Summary:
Home gardeners beware: This year, late blight -- a destructive infectious disease that caused the Irish potato famine in the 1840s -- is killing tomato and potato plants in gardens and on commercial farms in the eastern United States. In addition, basil downy mildew is affecting plants in the Northeast.

Leaf lesions due to late blight.
Credit: Copyright College of Agriculture and Life Sciences, Cornell University

Home gardeners beware: This year, late blight -- a destructive infectious disease that caused the Irish potato famine in the 1840s -- is killing tomato and potato plants in gardens and on commercial farms in the eastern United States. In addition, basil downy mildew is affecting plants in the Northeast.

"Late blight has never occurred this early and this widespread in the U.S," said Meg McGrath, associate professor of plant pathology and plant-microbe biology.

One of the most visible early symptoms of the disease is brown spots (lesions) on stems. They begin small and firm, then quickly enlarge, with white fungal growth developing under moist conditions that leads to a soft rot collapsing the stem.

Classic symptoms are large (at least nickel-sized) olive-green to brown spots on leaves with slightly fuzzy white fungal growth on the underside when conditions have been humid (early morning or after rain). Sometimes the border of the spot is yellow or has a water-soaked appearance. Spots begin tiny, irregularly shaped and brown. Firm, brown spots develop on tomato fruit.

McGrath stresses the need to act quickly to protect garden-grown tomato and potato plants and to make sure that plants don't become a source of spores that could infect commercial farms, as late blight spores are easily dispersed by wind.

She recommends that gardeners:

  • Examine their tomato and potato plants thoroughly at least once a week for signs of late blight;
  • Spray fungicides preventively and regularly, and/or
  • Be prepared to destroy plants when late blight starts to become severe.

"If you want to try to control late blight with fungicides, you need to begin spraying now -- even before you see symptoms -- and you need to continue spraying regularly," said McGrath. "Use a product that contains chlorothalonil. Copper is not very effective on late blight."

Petunias, which are closely related to tomatoes and potatoes, can also be infected by late blight and show similar symptoms.

Late blight is very destructive. Uncontrolled, it will kill plants faster than any other disease. And it affects tomato fruit -- especially green ones. Even with fungicide applied every week, there is no guarantee of success, especially if the rainy weather continues. McGrath recommends that gardeners consider growing more of other vegetables this year.

One source of late blight in New York has been traced to tomato plants imported to garden centers from production facilities in the south. If tomatoes were started from seed by a gardener or a farmer in the Northeast, plants are unlikely to be infected, at least initially, she said. If plants were purchased at a garden center and they show signs of late blight, McGrath recommends contacting a local office of Cornell Cooperative Extension or Cornell's Plant Disease Diagnostic Clinic to get confirmation and tell them where you purchased the plants.


Story Source:

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


Cite This Page:

Cornell University. "Late Blight -- Irish Potato Famine Fungus -- Attacks U.S. Northeast Gardens And Farms Hard." ScienceDaily. ScienceDaily, 5 July 2009. <www.sciencedaily.com/releases/2009/07/090701163647.htm>.
Cornell University. (2009, July 5). Late Blight -- Irish Potato Famine Fungus -- Attacks U.S. Northeast Gardens And Farms Hard. ScienceDaily. Retrieved September 23, 2014 from www.sciencedaily.com/releases/2009/07/090701163647.htm
Cornell University. "Late Blight -- Irish Potato Famine Fungus -- Attacks U.S. Northeast Gardens And Farms Hard." ScienceDaily. www.sciencedaily.com/releases/2009/07/090701163647.htm (accessed September 23, 2014).

Share This



More Plants & Animals News

Tuesday, September 23, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Cat Lovers Flock to Los Angeles

Cat Lovers Flock to Los Angeles

AFP (Sep. 22, 2014) The best funny internet cat videos are honoured at LA's Feline Film Festival. Duration: 00:56 Video provided by AFP
Powered by NewsLook.com
Washed-Up 'Alien Hairballs' Are Actually Algae

Washed-Up 'Alien Hairballs' Are Actually Algae

Newsy (Sep. 22, 2014) Green balls of algae washed up on Sydney, Australia's Dee Why Beach. Video provided by Newsy
Powered by NewsLook.com
Raw: San Diego Zoo Welcomes Cheetah Cubs

Raw: San Diego Zoo Welcomes Cheetah Cubs

AP (Sep. 20, 2014) The San Diego Zoo has welcomed two Cheetah cubs to its Safari Park. The nearly three-week-old female cubs are being hand fed and are receiving around the clock care. (Sept. 20) Video provided by AP
Powered by NewsLook.com
Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
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:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

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