Avoid Blueberry Rust

Avoid Blueberry Rust

Whether in Michigan, California, Hawaii, or elsewhere, blueberry growers must stay vigilant to thedanger of blueberry leaf rust. With epidemics of it occurring sporadically in past years, both in the eastern U.S. and on California’s Central Coast, highbush blueberry crops are at risk unless growers learn to recognize the symptoms and solutions.

Eyes Wide Open

According to Scot Nelson of the University of Hawaii at Manoa’s Department of Plant and Environmental Protection Sciences, leaf rust is caused by Naohidemyces vaccini, formerly named Pucciniastrum vaccinii, and is heteroecious, meaning it has two hosts. It also occurs on many hosts and has two forms in North America — an eastern form and a western form. Hosts of the pathogen include Vaccinium spp. (blueberry, cranberry, huckleberry), Tsuga (hemlock, hemlock spruce), Rhododendron (including azalea), Lyonia, Menziesia (mock azalea), Pernettya, Hugeria, Pieris, Leucothoe, and Oxycoccus.

“Blueberry leaf rust first appears as tiny yellow spots on the upper surface of young blueberry leaves about 10 days after inoculation,” writes Nelson in a 2008 plant disease report. “Spots later turn reddish brown and may be surrounded by a slight yellow halo. The lower leaf surface gathers a yellowish-orange dust, which is associated with the leaf spots. This dust is the spores of rust, and produced in the uredinia, which is at the center of each spot. Yellowish-orange rust pustules soon become visible, scattered over the surfaces of lower leaves. Affected leaves may redden and on heavily diseased plants, leaves often turn brown, curl up, and drop. This defoliation is the principal direct cause of harm to the plant, The indirect effect of leaf loss is reduced plant vigor and poor fruit production.”

In many climates, like California’s Central Coast, leaf rust is active the first four months of the year during fruit production, and young fruit are very susceptible to infection, according to a 2006 “Blueberry Leaf Rust” report by Franklin Laemmlen and Mark Gaskell at the University of California. This combination of fruit production and rust spore activity causes leaf rust to be dangerous economically because infected fruit is unmarketable. While a few leaf spots are not a problem, when fruit infection occurs, berries are a total loss.

In the northern U.S., the fungus overwinters in infected leaves and reinfects hemlock needles in early spring; however, it needs both species — blueberry and hemlock — to complete its life cycle in cold climates. In the southeastern U.S., where hemlocks do not grow, the fungus overwinters in uredia on evergreen blueberry leaves.

Solutions For Rust

In a Michigan State University Blueberry Fact Sheet released in 2009, experts recommended implementing a preventive control program to control rust, including removing hemlock trees within a third of a mile in northern climates, avoiding susceptible cultivars, limiting overhead irrigation, and applying effective fungicides. Even with frequent fungicide sprays, however, this disease may prove too difficult to manage. Fungicide sprays may also cause phytotoxicity to blueberry leaves, so they must first be tested and tankmixes of incompatible products must be avoided.

Nelson says one of the best ways to control blueberry leaf rust is to plant a resistant variety. A Cornell University online report lists Northern highbush varieties resistant to blueberry rust to include: Bluecrop, Burlington, Collins, Dixie, Earliblue, Gem, Ivanhoe, Olympia, Stanley, and Weymouth. Moderately susceptible varieties are: Jersey, Herbert, Berkeley, Blueray, and Pacific. Susceptible varieties to blueberry rust include: Coville, Pemberton, Washington, and Atlantic.

Topics:

Leave a Reply

2 comments on “Avoid Blueberry Rust

Crop Protection Stories
Choosing the right fungicide can be critical as shown here by the stark contrast between a fungicide-treated garlic leaf (right) and an untreated leaf covered with a pathogenic rust fungus.
Photo credit: S. T. Koike
Crop Protection
April 30, 2016
How To Elect The Right Fungicide For The Job
Fungicide application is one tool of a successful IPM program for crop diseases. Used judiciously and appropriately, these chemicals are powerful allies in the fight against the fungi and bacteria that attack crops. Read More
Brandt logo
Citrus
April 28, 2016
Brandt Acquires Majority Interest In Utah-Based Baicor
Baicor will operate as a subsidiary in Brandt’s specialty formulations division. Read More
red blotch featured image
Crop Protection
April 27, 2016
Vector Transmitting Red Blotch Virus Found
Researchers at the University of California, Davis (UC-Davis) have found the vector that seems to be spreading grapevine red blotch, a Read More
tomatoes and strawberries
Berries
April 27, 2016
New Herbicide For Tomatoes, Strawberries
The product from Helm Agro US is registered to control more than 100 broadleaf, grass, and sedge species. Read More
Torrey Farms onion crop
Crop Protection
April 25, 2016
Ranman Fungicide Registered For Downy Mildew Control In Bulb Vegetables
Product features a zero-day pre-harvest interval, allowing application up to the day of harvest. Read More
A tattered and wrinkled thank you note
Citrus
April 22, 2016
Happy Trails To A Great Researcher, Better Friend [Opinion]
Dr. Brian Boman worked with growers to examine their nutrient and water use and how practices could be modified to not only lessen environmental impacts, but also increase growers’ profitability. Read More
Brown Marmorated Stink Bug
Citrus
April 20, 2016
USDA Offers $4 Million For Pest Management
Funding to be used to increase crop protection practices, tackle high-priority pests. Read More
The Latest
Crop Protection
May 5, 2016
Michigan Researcher Leads $2.3-Million G…
Michigan State’s Mary Hausbeck along with a multistate research team will work to enhance and refine early detection methods, allowing growers to identify the pathogen’s presence in the air -- before it infects fields. Read More
Crop Protection
May 3, 2016
Almond Board To Hold Three Weed Manageme…
The second in a series of free educational workshops aimed at the state’s almond growers will cover weed identification and Read More
Crop Protection
April 30, 2016
How To Elect The Right Fungicide For The…
Fungicide application is one tool of a successful IPM program for crop diseases. Used judiciously and appropriately, these chemicals are powerful allies in the fight against the fungi and bacteria that attack crops. Read More
Citrus
April 28, 2016
Brandt Acquires Majority Interest In Uta…
Baicor will operate as a subsidiary in Brandt’s specialty formulations division. Read More
Crop Protection
April 27, 2016
Vector Transmitting Red Blotch Virus Fou…
Researchers at the University of California, Davis (UC-Davis) have found the vector that seems to be spreading grapevine red blotch, a Read More
Berries
April 27, 2016
New Herbicide For Tomatoes, Strawberries
The product from Helm Agro US is registered to control more than 100 broadleaf, grass, and sedge species. Read More
Crop Protection
April 25, 2016
Ranman Fungicide Registered For Downy Mi…
Product features a zero-day pre-harvest interval, allowing application up to the day of harvest. Read More
Citrus
April 20, 2016
USDA Offers $4 Million For Pest Manageme…
Funding to be used to increase crop protection practices, tackle high-priority pests. Read More
Crop Protection
April 20, 2016
A Cool, Wet Spring Means Increased Pest …
Growers in the East seeing increasing pressure from green fruitworm and rosy apple aphid, need to start scouting for black stem borer. Read More
Crop Protection
April 18, 2016
Researchers From Clemson University Offe…
A new online spray guide is designed to help growers deal with three major diseases that affect watermelon leaves in the Southeastern U.S. Read More
Crop Protection
April 18, 2016
Valent BioSciences Announces Biorational…
Valent BioSciences Corporation has announced plans to construct a new state of the art Biorational Research Center as an expansion Read More
Berries
April 16, 2016
California Strawberry Field Day On Tap I…
The annual Santa Maria Strawberry Field Day will cover pest management and shelf life studies. Read More
Crop Protection
April 7, 2016
6 Steps To Increase Efficiencies On The …
Embracing industry changes, New York’s Turek Farms looks to find better ways to get the job done. Read More
Crop Protection
April 6, 2016
Fungicide Receives Registration For Down…
With a zero-day pre-harvest interval, Ranman can be applied up to the day of harvest. Read More
Crop Protection
April 5, 2016
Vegetable Growers: Don’t Take Lygu…
California’s Central Coast has perfect conditions for lygus bug, a pest of strawberry, celery, lettuce, Brussels sprouts, to be successful. Read More
Crop Protection
April 1, 2016
Take Control Of Bacterial Spot And Spo…
Preventive measures needed to keep these two diseases in check. Read More
Crop Protection
April 1, 2016
The Problem With Powdery Mildew In Pumpk…
Do your best to reduce the chances of getting the disease in pumpkins, but be prepared with the proper plan of action if it shows up. Read More
Crop Protection
March 30, 2016
Bayer Nematicide Gets The Nod For Use On…
Velum Prime is a non-fumigant nematicide offering disease control benefits. Read More
[gravityform id="62" title="false" description="false"]