Cherry Powdery Mildew Treatment Tips

Everyone associated with the Washington cherry industry is painfully aware that 2009 has been the most severe powdery mildew year in recent memory. Although the damage done to fruit cannot be undone there are steps to be taken to help lower disease pressure in 2010. The fungus that causes powdery mildew produces cleistothecia on infected foliage and fruit. Cleistothecia are tiny spherical structures that contain ascospores. They are blown or washed into bark fissures where they (most importantly) provide the means for the fungus to survive the winter and cause potential problems in 2010. Previous research at WSU has shown that a large portion (but not all) of these survival propagules can be eliminated using liquid lime sulfur. Reducing the amount of overwintering inoculum should delay the onset of disease next spring. Given the large amount of “survival” inoculum that we currently have in some of our orchards it is advisable to apply the compound this fall.

The decision to apply lime sulfur should be made only after careful consideration of several other factors. First, the application of this compound would not preclude the application of fungicides during the 2010 growing reason. Second, the practice will not eliminate all carryover inoculum, which indicates that the need for a fungicide program is virtually guaranteed next year. Third, lime sulfur should be applied only where powdery mildew was a severe problem in 2009. There is little reason for application if mildew was kept at acceptable levels. Fourth, growers should carefully weigh the economics of lime sulfur and all other fungicide applications before making the decision to treat.

Usage directions:


1) apply just prior to leaf fall and again next spring (several weeks prior to bud break)

2) allow for thorough wetting of foliage, tree trunks, and scaffold limbs

3) apply 10-20 gallons per acre just prior to leaf fall. If applying in spring, use 7.5 gallons per acre in the delayed dormant period

4) always read the pesticide label

Information courtesy of Mike Bush, Gary Grove, Gwen Hoheisel, and Karen Lewis of Washington State University Extension.

Leave a Reply

Featured Stories

All Vegetables Stories >All Fruits Stories >All Nuts Stories >All Citrus Stories >

The Latest

IrrigationFlorida Growers Seize Control Of Water Challenges
September 22, 2014
New irrigation projects and fertilizer practices have tremendous potential for protecting resources, while enhancing productivity. Read More
CitrusNew Superhero Aims To Save Florida Citrus
September 22, 2014
Unique marketing partnership comes to life through comics. Read More
Apples & PearsKasumin Now Registered For Fire Blight Control
September 22, 2014
EPA approves use of bactericide on pome fruit as disease management tool. Read More
Food SafetyUSDA Issues Updates To Food Safety Modernization Act
September 19, 2014
Water testing, definition of applicable farms based on produce sales among clarifications to proposed rules. Read More
GrapesThird Straight Record Crop For Washington Grapes
September 19, 2014
Numbers expected to climb as more vines planted in the state. Read More
GrapesFrench Winegrowers Face Higher Labor Costs
September 19, 2014
French wineries may come under added financial pressure as the government considers imposing social charges on wages paid to harvest workers with short-term contracts. Read More
IrrigationCalifornia Boosts Local Water Control
September 19, 2014
Governor Jerry Brown signs historic legislation to strengthen local management and monitoring of critical groundwater basins. Read More
VegetablesSakata Seed America Shows Heart Through Charitable Prog…
September 19, 2014
Company’s corporate giving mission bears fruit for the American Heart Association. Read More
Insect & Disease UpdateAdditional Aid Coming For Florida Citrus Growers Gouged…
September 17, 2014
Through USDA’s Tree Assistance Program, eligible growers can cash in on cost share for diseased tree removal and replanting. Read More
FruitsFlorida Fruit & Vegetable Association Seeks Fresh A…
September 17, 2014
New partnership bolsters Fresh From Florida program. Read More
CitrusFDA Announces Cooperative Agreement To Implement Nation…
September 17, 2014
Agreement will provide information to help plan and carry out the produce safety rule in partnership with state regulatory agencies. Read More
NutsAchieving A Super-Premium Walnut Crop
September 17, 2014
What are the best ways to get high quality walnuts that are light in color and fully developed? Read these 8 harvest best practices to find out. Read More
NutsAlmond Growers Highly Dependent On Groundwater
September 17, 2014
Fully 87% of large growers use groundwater to irrigate their trees. Read More
NutsWarm Winter And Drought Casting Doubt On Pistachio Harv…
September 17, 2014
Though Rabobank report says that one billion pounds still attainable by 2019. Read More
Crop ProtectionBagrada Bug On The Move In California
September 16, 2014
Find out more on management tactics and what counties are impacted by this invasive pest. Read More
Cucurbits14 Stand-Out Melon Varieties [Slideshow]
September 15, 2014
Browse the slideshow below for information on these exceptional melon varieties from the nation’s leading seed breeders and distributors. Read More
Grower Achievement AwardView Highlights From The 2014 United Fresh Washington P…
September 15, 2014
Browse this slideshow to view photos from the 2014 United Fresh Washington Public Policy Conference, including pictures of this year’s Grower Read More
Apples & PearsCanneries Hope To Encourage Growers To Grow Pears For P…
September 15, 2014
Higher wholesale prices offered as means to boost canning pear acres. Read More