Morning Ag Clips logo
  • Subscribe ❯
  • PORTAL ❯
  • LOGIN ❯
  • By Keyword
  • By topic
  • By state
  • Home
  • Events
  • Jobs
  • Store
  • Advertise
  • Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar
  • Skip to footer
  • Subscribe to our
    daily email
    ❯
  • Portal Registration❯
  • Login❯
  • policy
  • tractors & machinery
  • education
  • conservation
  • webinars
  • business
  • dairy
  • cattle
  • poultry
  • swine
  • corn
  • soybeans
  • organic
  • specialty crops
  • Alabama
  • Alaska
  • Arizona
  • Arkansas
  • California
  • Colorado
  • Connecticut
  • Delaware
  • Florida
  • Georgia
  • Hawaii
  • Idaho
  • Illinois
  • Indiana
  • Iowa
  • Kansas
  • Kentucky
  • Louisiana
  • Maine
  • Maryland
  • Massachusetts
  • Michigan
  • Minnesota
  • Mississippi
  • Missouri
  • Montana
  • Nebraska
  • Nevada
  • New Hampshire
  • New Jersey
  • New Mexico
  • New York
  • North Carolina
  • North Dakota
  • Ohio
  • Oklahoma
  • Oregon
  • Pennsylvania
  • Rhode Island
  • South Carolina
  • South Dakota
  • Tennessee
  • Texas
  • Utah
  • Vermont
  • Virginia
  • Washington
  • West Virginia
  • Wisconsin
  • Wyoming

Morning Ag Clips

  • By Keyword
  • By topic
  • By state
  • policy
  • tractors & machinery
  • education
  • conservation
  • webinars
  • business
  • dairy
  • cattle
  • poultry
  • swine
  • corn
  • soybeans
  • organic
  • specialty crops
  • Home
  • Events
  • Jobs
  • Store
  • Advertise
Home » Downy mildew detected on South Carolina cucurbits
Downy mildew ... Comments

Downy mildew detected on South Carolina cucurbits

Downy mildew is caused by the oomycete Pseudoperonospora cubensis mold

PUBLISHED ON May 31, 2022

Downy mildew is a water mold that destroys plant foliage and is common on cucurbits, a family of plants that includes cucumbers, various melons, squashes and gourds. It makes annual unwelcome visits to South Carolina in late May or early June. The first sighting for 2022 was in Bamberg County on May 25. (photo by Clemson University)

CLEMSON, S.C. — Now is the time for growers to come to the aid of their cucurbits and rise against downy mildew.

Downy mildew is a water mold that destroys plant foliage and is common on cucurbits, a family of plants that includes cucumbers, various melons, squashes and gourds. It makes annual unwelcome visits to South Carolina in late May or early June. The first sighting for 2022 was in Bamberg County on May 25.

Rob Last, Clemson Cooperative Extension Service horticultural agent, said cucumbers and cantaloupes are currently most at risk to downy mildew. However, all cucurbits are susceptible. The strain affecting squash and watermelons had not moved out of Florida as of May 26.

“Cucumber is the first cucurbit crop to display downy mildew symptoms,” Last said.

Downy mildew is caused by the oomycete Pseudoperonospora cubensis mold. It does not overwinter in South Carolina but spreads from more southern states via wind-blown spores and can travel up to 1,000 miles in two days.

Cucurbit downy mildew also can be spread through infected transplants. The disease begins as dark, irregular spots that spread quickly on plants’ leaves, causing them to curl and ultimately leading to a reduction in photosynthesis that can interfere with the development of fruit.

Cucurbit growers can fight downy mildew using an arsenal of fungicides. One fungicide proven effective against downy mildew is Orondis. Growers using Orondis in their spray programs are asked to limit the number of Orondis applications to 1/3 of the spray program. Growers making 1 to 5 applications, can use Orondis for one application. Growers making 6 to 8 applications, may use Orondis for two of the applications.

For cucumbers, Clemson Extension horticulturists suggest one application of Orondis per crop. If other fungicides are used, Last advises growers to make applications seven days apart.

“A stretch longer than seven days is likely to increase the potential for disease spread,” he said.

Fungicide arsenal to fight downy mildew

In addition to Orondis, other products suggested for use in cucumbers include: Omega ( Fluazinam 7 day PHI in Cucumbers), Bravo (chlorothalonil), Ranman (Cyazofamid), Presidio (fluopicolide), Orondis Opti (Oxathiapiprolin and clorothalonil never use Orondis Ultra in cucumbers), Elumen (Ethaboxam) and Gavel (Zoxamide and Mancozeb).

Fungicides to use in cantaloupes include: Ranman (Cyazofamid), Presidio (fluopicolide), Orondis Opti (Oxathiapiprolin and clorothalonil. Never use Orondis ultra in cantaloupes), Elumen (Ethaboxam), Gavel (Zoxamide and Mancozeb), and Manzate (Mancozeb).

To wage war against downy mildew in squash and watermelons, growers can use: Ranman (Cyazofamid), Orondis Opti (Oxathiapiprolin and clorothalonil), Orondis Ultra (Oxathiapiprolin and mandipropamid), Gavel (Zoxamide and Mancozeb) and Manzate (Mancozeb).

The Cucurbit Downy Mildew Forecast map can be used to determine where downy mildew has been reported. The site also predicts where spores will spread from known sources and where weather will be favorable for a new outbreak in the next 48-72 hours.

Plant cucumbers early to help avoid downy mildew

Two Clemson researchers believe planting cucumbers early can help growers avoid downy mildew in their cucurbit crops.

The study conducted by Tony Keinath, professor of plant pathology, and Research and Extension vegetable pathologist at Clemson’s Coastal Research and Education Center (REC) in Charleston, and Felipe Silva, assistant professor of agricultural economics in Clemson’s Department of Agricultural Sciences agribusiness program, shows downy mildew issues practically can be avoided by planting cucumbers early so that crops mature before downy mildew can take over. This saves growers money normally spent on fungicides and labor.

During the study, Keinath planted a spring crop of slicing cucumbers in 20 plots of 3 rows each at the Coastal REC in Charleston, South Carolina between March 20 and May 10. Results show it is important growers plant cucumbers nearer the beginning of the planting period before temperatures get warm.

Downy mildew outbreaks most often occur during mild, wet weather, when rainwater washes spores out of the air onto leaves. After infecting a plant, downy mildew will continue to spread, even in dry weather, if temperatures stay above 60°.

Early planting can be beneficial for both conventional growers and organic growers. In addition to helping avoid downy mildew, the researchers found planting early also can result in higher yields.

For questions about cucurbits or other crops, contact the local Clemson Extension office.

–Clemson University

Click Here to find out more about your favorite topics

pest management weed management

Spread the word

Browse More Clips

American Sheep Industry Research Update podcast looks at mastitis

New Beef Co-op aims to expand processing

Primary Sidebar

MORE

SOUTH CAROLINA CLIPS

feral wid hog swine (U.S. Department of Agriculture, Public Domain)
USDA to measure feral swine damage to Southern farmers, ranchers
June 28, 2022
Next Gen Ag & Conservation Professional Mentorship
June 28, 2022
ASA now seeking nominations for annual Soy Recognition Awards
June 28, 2022
Nominations open for 2023 Potatoes USA Board Members
June 28, 2022
Clemson Extension course teaches about plant identification and use Share:
June 27, 2022
  • Trending
  • Latest

YOU MIGHT ALSO LIKE...

pesticide drift
Guide outlines steps to take when pesticides drift
June 29, 2022
NDSU Agronomy Seed Farm annual field tour set
June 28, 2022
Md. agencies to treat Potomac River for black fly control, June 29
June 28, 2022
Bats in the house
June 27, 2022
Western bean cutworm degree-day
June 27, 2022

Footer

MORNING AG CLIPS

  • Sponsors
  • About Us
  • Advertise with Us
  • Privacy Statement
  • Terms of Service
  • Customer & Technical Support

CONNECT WITH US

  • Like Us on Facebook
  • Instagram
  • LinkedIn
  • Twitter
  • YouTube

TRACK YOUR TRADE

  • Markets & Economy
  • Cattle Updates
  • Dairy News
  • Policy & Politics
  • Corn Alerts

QUICK LINKS

  • Account
  • Portal Membership
  • Invite Your Friends
  • Subscribe to RSS
  • WeatherTrends
  • Just Me, Kate

© 2022 Morning Ag Clips, LLC. All Rights Reserved.