BASF’s Kathie E. Kalmowitz On Downy Mildew

Kathie E. Kalmowitz Of BASF

As BASF’s Kathie Kalmowitz made her way across Florida in mid-February, she saw firsthand just how poorly impatiens were faring in landscapes. Every bed Kalmowitz saw was stripped of leaves, the result of a downy mildew pathogen gone wild.

Recently, Greenhouse Grower caught up with Kalmowitz, a technical expert who offers guidance to growers in need of getting downy mildew under control on America’s number one bedding plant.

GG: Why do you think the impatiens you saw in Florida earlier this year are struggling so mightily with downy mildew?

KK: I think the disease has simply been carried over in the soil from the previous year. When plants aren’t cleaned out and the residue is left to rot, the [downy mildew] spores are overwintering. So when the crop is replanted, the crop is coming into contact with those spores.

The key is for consumers not to plant impatiens where they had impatiens last year. Downies are very host-specific pathogens, meaning this particular downy goes to the walleriana impatiens. If you had a snapdragon with downy mildew or a rose with downy mildew, those pathogens would not move to impatiens.

GG: How fast is the disease spreading on impatiens in the landscape?

KK: Let’s say a tray has gone through the broker, a garden center and now it’s finally gone into the hands of a landscaper – so it’s probably been a couple weeks since it came out of the greenhouse. At that point, the last fungicide is starting to wear off. As beds are planted, you may all of a sudden see more typical symptoms of downy mildew – a little bit of a bronzing effect, or you turn the leaf over and see the fuzzy sporulation on the back of the leaf.

Still, I doubt if landscapers will be back in beds once they’re finished planting. By four weeks out of the greenhouse, the sporulation is taking hold and you see the plant start to defoliate. If you go back to a bed that was absolutely spectacular in color, all of a sudden you see sticks.

GG: What’s your impression of how growers are handling their own impatiens material in the greenhouse?

KK: I think the greenhouses are pretty clean. Growers are being cautious and putting out flats that are clean when they exit. But when impatiens are in a production greenhouse as plugs or as finished products, they’ve had at least two cover sprays. They’ve had a drench in the plug stage and at least one finished spray. So they’re clean going out, but impatiens probably also need a cover spray in the landscape.

GG: What advice can you offer growers looking for guidance as they try to manage their way through this particular pathogen?

KK: BASF has Stature SC fungicide for growers. This product, applied preventively, can stop sporulation of downy mildew, hence stopping the infection cycle. Stature is an excellent fungicide choice for growers as a last protective spray. We know garden centers are not going to apply fungicides. So it’s up to growers to provide at least the two-week window of greater protection once it gets out of their production greenhouses.

Additionally, there are things landscapers need to do. Landscapers should be responsible for putting a cover spray on, which they probably have not done in the past. They need to explain to their customers why because there’s going to be a cost built in.

If landscapers go back to a job and see that plants are already showing signs of infection (beginning to defoliate), they need to take those plants out immediately. They’re not going to save them. They need to remove them from the landscape and actually keep that residue isolated from any of their other beds.

Downy mildew is wind borne, so if you had an open landscape truck moving down the road, those spores could move off the material. Landscapers need to enclose the residue in a paper or plastic bag so they get the inoculum out of the environment.

GG: What can growers learn from the downy mildew on impatiens scene in Europe, where the issue has become an even bigger problem than here in the United States?

KK: Based on what I read from England, they thought the problem subsided. The truth is it’s an epidemic. I do believe it’s because England went through low years of not paying any attention that they’re struggling again.

For us, I think it’s going to take more than a one-year cycle in the U.S. to clean up our beds. The moral of the story is you have to watch how you plant impatiens. Even with a cover spray in the landscape, you could still get some disease in the newly planted beds. But you certainly can’t put new impatiens behind last year’s impatiens.

GG: How does downy mildew on Impatiens walleriana compare to other disease issues you’ve encountered?

KK: It’s a perfect storm when the inoculum appears in the environment and the present climatic conditions allow the disease to move quickly toward devastating an entire planting.

Still, I feel this kind of falls into the more normal range of how a host-specific pathogen can spread so quickly in a species. The reason why there’s such heightened awareness is because it’s such a huge crop. It’s loved from the North to the South. It is a staple of landscape color; it’s always been a prolific flowering plant. It holds up really well and has great form. It has all these attributes, so people have a high regard for it.

GG: How does the new boxwood blight issue compare to downy mildew on impatiens?

KK: Boxwoods are a beloved woody ornamental, just like impatiens are a beloved bedding plant. So there is a heightened awareness of this disease. People are really nervous because they don’t want the disease to spread. If we can keep it to the areas where it was already found, it would be better. I don’t think we know enough about boxwood blight [as of late February]. We don’t know how it becomes established in a boxwood planting. Does it infect a mature boxwood as much as one in a production stage?

I know it does move across all boxwoods. Unlike impatiens and the walleriana species, this disease moves from Japanese to American to English [boxwoods]. And that means if you get boxwood blight in your nursery or in your landscape, then you have to switch out of all boxwoods.

Leave a Reply

More From Disease Control...
Botrytis-Symptoms-feature

May 12, 2018

Fungicide Resistance in Botrytis is an International Challenge

Clemson University’s research team is exploring Botrytis in cut roses to find out how to help you maintain postharvest crop quality by avoiding fungicide resistance.

Read More
Xanthomonas-Lesions-in-Begonia

May 5, 2018

Michigan State Experts Offer Tips on Managing Xanthomonas in Begonias

After receiving numerous samples from across the state of begonias testing positive for Xanthomonas, experts at the university have developed a series of articles aimed at helping growers identify and control this disease.

Read More
Troy Bettner

May 2, 2018

OHP Fills Big Shoes With Latest Hire

OHP Inc., provider of pest control products and services for the greenhouse and nursery production industry, has found a replacement for longtime company leader Terry Higgins, who retired March 31. Troy Bettner has officially joined OHP as head of sales and marketing. He was most recently working for Helm Agro, another agricultural-based provider of pest control chemistries. In addition to his time as marketing business development leader at Helm, Bettner has logged many years in the horticulture industry. “We’re thrilled to bring Troy on board to lead our sales and marketing efforts,” stated Dan Stahl, OHP VP and GM. “With his industry experience, Troy has all the qualities to help lead OHP into the future.” Bettner holds a Bachelor of Science in Business from Cal Poly San Luis Obispo as well as a Master of Business Administration (MBA) from Purdue University. He, his wife, and three children live in Carmel, […]

Read More
Latest Stories
Botrytis-Symptoms-feature

May 12, 2018

Fungicide Resistance in Botrytis is an International Ch…

Clemson University’s research team is exploring Botrytis in cut roses to find out how to help you maintain postharvest crop quality by avoiding fungicide resistance.

Read More
Xanthomonas-Lesions-in-Begonia

May 5, 2018

Michigan State Experts Offer Tips on Managing Xanthomon…

After receiving numerous samples from across the state of begonias testing positive for Xanthomonas, experts at the university have developed a series of articles aimed at helping growers identify and control this disease.

Read More
Troy Bettner

May 2, 2018

OHP Fills Big Shoes With Latest Hire

OHP Inc., provider of pest control products and services for the greenhouse and nursery production industry, has found a replacement for longtime company leader Terry Higgins, who retired March 31. Troy Bettner has officially joined OHP as head of sales and marketing. He was most recently working for Helm Agro, another agricultural-based provider of pest control chemistries. In addition to his time as marketing business development leader at Helm, Bettner has logged many years in the horticulture industry. “We’re thrilled to bring Troy on board to lead our sales and marketing efforts,” stated Dan Stahl, OHP VP and GM. “With his industry experience, Troy has all the qualities to help lead OHP into the future.” Bettner holds a Bachelor of Science in Business from Cal Poly San Luis Obispo as well as a Master of Business Administration (MBA) from Purdue University. He, his wife, and three children live in Carmel, […]

Read More

March 13, 2018

Greenhouse Biocontrol Goes Mainstream

Biological control has moved into the mainstream for greenhouse growers. And the timing couldn’t be better, as consumer demands for more sustainable production methods for the plants they buy are moving back upstream.

Read More
Downy mildew sporulation on underside of leaf

March 10, 2018

Segovis Fungicide Now Available to Ornamental Growers i…

Segovis, from Syngenta, features a unique active ingredient that helps control downy mildew and Phytophthora.

Read More
Sample-collecting-for-Virus-Testing-Feature

March 3, 2018

How to Keep Your Greenhouse Crop Free of Disease

All growers deal with the possibility of damaging disease issues in the greenhouse. Here’s how Pleasant View Gardens makes sure its greenhouse crops stay disease-free.

Read More
Greenspire-Procidic

December 25, 2017

New Fungicide Helps Control Mildews and Rot in Ornament…

Greenspire Global, Inc. has developed Procidic, a bactericide and fungicide that provides effective disease control without synthetics.

Read More

December 21, 2017

Dümmen Orange Confirms Presence of Xanthomonas in Begon…

In a December 16 letter to its customers, Dümmen Orange said it had encountered an issue in its El Salvador-based Las Mercedes production facility, where bacterial leaf spot had been confirmed in begonia production.

Read More

December 21, 2017

Plantpeddler Provides Guidelines for Xanthomonas Bacter…

A leading producer of Begonia young plant liners and finished plants, Cresco, IA-based Plantpeddler has issued the following informational guidelines on Bacterial Leaf Spot in Begonias.

Read More
BASF Orkestra Intrinsic

December 18, 2017

California Growers Have a New Disease Control Tool

BASF’s Orkestra Intrinsic fungicide has been approved in California for control of several ornamental plant diseases.

Read More
Powdery mildew on rosemary. Photo credit: SHS Griffin

December 14, 2017

New Biofungicide Approved for Disease Control in Orname…

Certis USA recently introduced Carb-O-Nator, a new broad-spectrum foliar fungicide that works on contact to control powdery mildew, Alternaria, Anthracnose, Botrytis, Septoria leaf spot, and other diseases.

Read More
Researchers Study Rose Varieties

October 17, 2017

Rose Rosette Update: Research into Detection and Manage…

Halfway through a five-year, $4.6 million grant to combat rose rosette disease in the U.S., a national research team is encouraged by the amount of information learned, but admits having a way to go before finding how to overcome the deadly problem.

Read More
Botrytis Symptoms on Leaves

October 17, 2017

How One Grower is Battling Botrytis with a New Biologic…

CropKing in Lodi, OH, recently began using a new beneficial fungus in its fight against Botrytis in its greenhouse tomatoes. So far, the results have been promising.

Read More
BASF Pageant

September 29, 2017

New Fungicide Provides Production and Postharvest Disea…

Pageant TR from BASF controls seven key diseases, and can be used both in the greenhouse and in trucks that are on their way to a retail site.

Read More
Ascochyta in chrysanthemum

September 27, 2017

14 Common Chrysanthemum Diseases to Monitor

Penn State University Extension features a section on its website devoted to diseases commonly found in chrysanthemums.

Read More
Boxwood Blight

September 19, 2017

Concerned About Boxwood Blight? Here Are Some Updated M…

AmericanHort’s Horticultural Research Institute has released an updated version of its boxwood blight Best Management Practices document.

Read More
Powdery mildew on rosemary. Photo credit: SHS Griffin

September 9, 2017

Howler Biological Fungicide from AgBiome Gains EPA Appr…

Howler provides preventive, long-lasting activity on a broad spectrum of soilborne and foliar diseases, with no special handling or storage required.

Read More
Aphids

July 7, 2017

New Tools for Your Crop Protection Arsenal in the Green…

Over the past few months, crop protection companies have developed several new products designed to help you manage a wide range of insect and disease pests. Here’s a look at some of them.

Read More