Prevention Measures For Impatiens Downy Mildew Start At Plug Production, Chase Says

Impatiens downy mildew leaf yellowing and downward curling
Impatiens downy mildew leaf yellowing and downward curling

Impatiens downy mildew is a fast-moving disease that can go from bad to worse in as little as one month if conditions are right, says Agricultural Consulting’s Ann Chase, who covered the latest impatiens downy mildew developments during her Cultivate’14 presentation. The rapid spread is one of the challenges with controlling downy mildew, one minute it doesn’t look like it is going to be a big problem, then all of a sudden it explodes by the end of the season.

During her presentation, Chase said growers should start treating for prevention of impatiens downy mildew at the beginning of plug production for the best chances of effective control throughout the season.

Downy mildew symptoms include curling leaves, yellowing or speckled leaves and leaves that have white undersides. Curling leaves can make it difficult to get spray coverage on the undersides of the leaf surfaces, which is where systemic products come into play.

Although researchers don’t believe there is any evidence that impatiens downy mildew is in the seed, field trials have shown that it can linger in the soil for up to 10 years, which complicates the problem, Chase said.

She cited Dr. Aaron Palmateer’s (University of Florida) research, which evaluated the effectiveness of fungicide rotations for downy mildew control in the landscape. The research showed that phosphonates are a good long-term treatment for the landscape, but growers should keep in mind that impatiens downy mildew cannot be eradicated with fungicides.

Fungicide resistance does occur, often due to using a product repeatedly without rotation or tank-mixing and using products at lower than labeled rates. Recently, mefenoxam resistance has been reported in Florida. Chase said even if growers use half the rates of two chemicals to cut costs, they would still get resistance. It is more effective to use the products at full rates in rotation, rather than tank-mixing, unless the label says to tank mix.

Chase also talked about the use of drenches versus sprays for effective control of downy mildew. She referred to trials on the longevity of drench published by Dr. Colleen Warfield of Ball Horticultural Co., which have shown that drenches last better than sprays on impatiens. Warfield found that drenches of Adorn and/or Subdue MAXX exhibited the longest residual efficacy (21 to 28 days) of all the fungicides tested in a limited number.

Leave a Reply

More From Crop Inputs...
tomato spotted wilt virus angular-necrosis-of-leaves-and-plant-stunting

September 28, 2016

Tips For Managing Tomato Spotted Wilt Virus In Mums

According to a report from Michigan State University, symptoms of tomato spotted wilt virus on chrysanthemum include yellow blotching and rings, necrotic lesions, and stem collapse.

Read More
cannabis-crop-protection

September 27, 2016

Washington State Outlines Pesticide Criteria For Cannabis Production

The state has also compiled a searchable list of pesticides that fit the criteria for use on marijuana.

Read More
Orius_June 2015

September 25, 2016

Peace Tree Farm Hosting Biocontrols Event In October

“Advanced Greenhouse Biocontrols for Ornamental and Vegetable Producers” will feature advice from biocontrol authorities Lloyd Traven and Suzanne Wainwright-Evans.

Read More
Latest Stories
tomato spotted wilt virus angular-necrosis-of-leaves-and-plant-stunting

September 28, 2016

Tips For Managing Tomato Spotted Wilt Virus In Mums

According to a report from Michigan State University, symptoms of tomato spotted wilt virus on chrysanthemum include yellow blotching and rings, necrotic lesions, and stem collapse.

Read More
cannabis-crop-protection

September 27, 2016

Washington State Outlines Pesticide Criteria For Cannab…

The state has also compiled a searchable list of pesticides that fit the criteria for use on marijuana.

Read More
Orius_June 2015

September 25, 2016

Peace Tree Farm Hosting Biocontrols Event In October

“Advanced Greenhouse Biocontrols for Ornamental and Vegetable Producers” will feature advice from biocontrol authorities Lloyd Traven and Suzanne Wainwright-Evans.

Read More
steve-larson-bayer

September 23, 2016

Bayer Continues Its Shift Into The Ornamentals Market

The company has announced its 12 distributor partners, and also recently named Steve Larson — formerly with Color Spot Nurseries — as its ornamental specialist.

Read More
Biocontrols and beneficials absolutely can be used in outdoor production, with the use of banker plant systems

September 19, 2016

Learn About Biological Controls In The Greenhouse In A …

Michigan State University Extension (MSU) and Kansas State University Research and Extension are collaborating on a pre-recorded online course on “Biological Control for Greenhouse Growers.”

Read More
Bees And Pesticides

August 23, 2016

Studies Offer Conflicting Views On Neonic Effect On Bee…

How much exposure to neonicotinoids do bees need before their health becomes affected? That’s the question two research teams look to answer.

Read More
Chrysanthemum Aphid

August 22, 2016

How To ID And Manage Black Aphids In Chrysanthemums

Growers in Michigan have recently been reporting a higher presence of this pest. Here are some tips on how to control it.

Read More
Cannabis Crop Protection

August 22, 2016

Cannabis Group Stays Focused On Consistent Standards Fo…

The Foundation of Cannabis Unified Standards (FOCUS), is an independent, third-party, not-for-profit organization, is in the process of developing cannabis-specific standards for everything from cultivation and extraction to packaging and retail.

Read More
Leaf Septoria In Cannabis

August 21, 2016

Three Diseases To Watch For In Cannabis Production

The development of root rot, powdery mildew, and leaf septoria can damage cannabis to the point of complete crop loss.

Read More
Greenhouse Whitefly

August 18, 2016

Vestaron Planning For More Research And Development Of …

On the heels of launching Spear-T, its first bioinsecticide, Vestaron has received additional financing that will be used to develop new products with new modes of action.

Read More
BioWorks Mycotrol

August 17, 2016

New Organic Mycoinsecticide From BioWorks Now Registere…

BioWorks’ Mycotrol can be used to manage whitefly, thrips, aphids, and other insects in greenhouses and nurseries.

Read More
Downy mildew lesions on light coleus cultivars feature

August 12, 2016

How You Can Control Downy Mildew In Coleus, Roses, And …

Downy mildew diseases are potentially devastating to ornamental crops and at the very least can cause unsightly damage. Check out the latest research and recommendations for preventing it.

Read More
Jen Browning BASF

August 4, 2016

Horticulturist And Entomologist Jen Browning To Speak A…

Browning will discuss the use of nematodes in managing pests in greenhouses and nurseries.

Read More
Poinsettia, Heavy Whitefly Infestation -Lower Leaves, Insect - Feature

August 3, 2016

Tips For Successful Late-Season Whitefly Control

Managing late-season whiteflies successfully on poinsettia requires preventative measures put in to action early in the production cycle.

Read More
Cannabis Crop Protection

July 28, 2016

Solving The Cannabis Crop Protection Problem

A largely unregulated sector of the industry, state departments of agriculture, biocontrols companies, and other industry pros are dedicated to helping growers make the right pesticide decisions for their operations.

Read More
Aphids On Older Leaves

July 25, 2016

How You Can Stop Aphids By Understanding Their Interact…

Knowing which aphids target which crops and how aphids colonize and move on plants goes a long way toward setting up an effective management plan.

Read More
BASF Orkestra Intrinsic

June 21, 2016

New Mode Of Action From BASF Offers Deeper Disease Cont…

When it comes to disease control, you need all the help you can get. BASF recently hosted growers, Extension personnel, and trade media to present its newest fungicide with two active ingredients, offering dual modes of action.

Read More
Nematodes-feature

June 4, 2016

New Biocontrols Provide Effective Pest Control In Green…

Biological chemistry manufacturers have introduced several new products recently that offer a range of insect and disease management options. Here’s a look at some of them.

Read More
[gravityform id="35" title="false" description="false"]