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

Crop ProtectionNimitz Nematicide Receives EPA Approval
September 12, 2014
New product from Adama has a unique mode of action and is approved for use on a variety of vegetables. Read More
FruitsUSDA Needs Your Help In Tracking Brown Marmorated Stink Bug
September 11, 2014
Researchers seeking voluntary information to track how pest overwinters. Read More
Disease ControlNew Findings On Beetle Flight May Help Control Deadly Walnut Tree Disease
September 10, 2014
Pheromone disruption may be the answer in minimizing thousand cankers disease. Read More
Crop ProtectionGiant Snail Threat Spreading In South Florida
September 10, 2014
Dangerous invasive pests found well outside Miami-area hot zone. Read More
Crop ProtectionStockton’s Timorex Gold Biofungicide Receives EPA Registration
September 9, 2014
This broad spectrum fungicide can be used in rotation or in a tank mix. Read More
FruitsStrategies To Prevent Secondary Pests Following Sprays For Brown Marmorated Stink Bug
September 9, 2014
Penn State University researcher offers guidelines and control strategies for minimizing the impacts on mites for the next season. Read More
CitrusFMC Acquires Cheminova
September 9, 2014
Transaction expected to close in early 2015. Read More

The Latest

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
Crop ProtectionNimitz Nematicide Receives EPA Approval
September 12, 2014
New product from Adama has a unique mode of action and is approved for use on a variety of vegetables. Read More
Crop ProtectionGiant Snail Threat Spreading In South Florida
September 10, 2014
Dangerous invasive pests found well outside Miami-area hot zone. Read More
Crop ProtectionStockton’s Timorex Gold Biofungicide Receives EPA Reg…
September 9, 2014
This broad spectrum fungicide can be used in rotation or in a tank mix. Read More
CitrusFMC Acquires Cheminova
September 9, 2014
Transaction expected to close in early 2015. Read More
Crop ProtectionBayer Opens Worldwide Biologics R&D Center In Calif…
September 5, 2014
$80 million facility will also be used to develop vegetable seed. Read More
Crop ProtectionHow To Control Corn Earworm, European Corn Borer In Swe…
September 5, 2014
Monitor traps, plant varieties with good husk cover, and rotate modes of action to avoid resistance. Read More
Crop ProtectionMost Fresh California Produce Has Little/No Detectable …
September 4, 2014
State Department of Pesticide Regulation finds that 95% of produce was in compliance. Read More
Crop ProtectionGetting To The Root Of Good Soil Health Requires Some D…
August 21, 2014
Dave Gilliam of Horticultural Alliance says more citrus growers are paying attention to what's happening below the ground in their groves. Read More
Crop ProtectionBioConsortia Inc. Bolsters Executive Team
August 18, 2014
Industry veterans Christina Huben and Dr. Susan Turner bring experience to plant biotechnology firm. Read More
Crop ProtectionCover Crop Solutions Offers New Three-Way Cover Crop Mi…
August 13, 2014
A fast-growing cover crop mix needs 45 to 60 days of growth in warm conditions. Read More
Crop ProtectionBiopesticides Vs. Traditional Agrochemicals
August 4, 2014
To effectively control pests, understand how the products work and know the biology of insect pests. Read More
Crop ProtectionFrench Crop Protection Firm Acquires Fine Holdings Ltd.
August 4, 2014
De Sangosse group seeks to bolster its business with purchase of plant growth regulator specialist. Read More
CEU SeriesCEU Series: Gain A Deeper Understanding Of Fertilizers
August 1, 2014
It's never too late to grow your knowledge of plant nutrients. Read More
BerriesNew Study Finds Simple Solution To Monitoring Spotted W…
July 31, 2014
UF/IFAS researchers are using a mixture of yeast, sugar, and water to lure, trap major berry pest. Read More
Crop ProtectionNew York Combats Giant Weed
July 30, 2014
The state continues efforts to control this species that is harmful to humans. Read More
CitrusThe Exponential Rise Of Biopesticides
July 28, 2014
The first sustainable commercial success stories in the biopesticide market were seen in the 1980s and 1990s. Since then, the market has grown exponentially, and is projected to exceed $3 billion by 2016. Read More
Citrus9 Resources For All Of Your Biopesticide Questions
July 25, 2014
As the use of biopesticides continues to increase at a staggering rate, more and more resources are being made available to the public to help increase awareness of the sector. Read More