Top Crop Manager

Features Fungicides Seed & Chemical
Broad-spectrum fungicide in the works


November 30, 1999
By John Dietz

Topics

A fungicide that’s likely to be widely used in Western Canada is on the ready-to-launch pad. If it goes as anticipated, the launch of the new product marks a big improvement in the way that new products are introduced.

Health Canada’s Pest Management Regulatory Agency (PMRA) is reviewing DuPont’s Vertisan for registration. Vertisan will provide broad-spectrum disease control in a wide range of crops, including canola, sunflowers, pulse crops and potatoes.

Group 7 product
Vertisan is one of two DuPont products using a new Group 7 active ingredient, penthiopyrad. Group 7 products inhibit respiration for plant disease organisms. DuPont’s other penthiopyrad product under review by the PMRA is Fontelis. Fontelis is intended for fruit and vegetable growers.

DuPont states that Vertisan fungicide “is effective against a broad range of damaging plant diseases, including some which have developed resistance to other fungicide chemistry classes.”

Research on the new fungicide has shown activity:

  • Canola – Sclerotinia stem rot
  • Sunflowers – Sclerotinia head rot, powdery mildew, rust and rhizoctonia
  • Pulse crops – Ascochyta blight, powdery mildew, grey mould and rust
  • Potatoes – Early blight and rhizoctonia

Sunflower hope
Manitoba field crop pathologist, Holly Derksen, has seen field trials with Vertisan. She says it will be good news for many crop producers.

“I think it will be a good product for resistance management and rotation of fungicide groups,” Derksen says. “It shares mode of action with several other fungicides, but because it is looking at broad-spectrum control for a number of diseases, it might fit into a lot of rotations that growers have available.”

The biggest impact in Manitoba, short term, may be on sunflower production. Disease issues have taken a heavy toll on sunflower acres in the past two decades in Manitoba. Production has slipped from around 300,000 acres in the 1980s to just over 20,000 acres in 2011. There are no commercial sunflower hybrids that are resistant to sclerotinia, and no fungicides are labelled in Canada or the United States for control of sclerotinia in sunflowers.

“Sclerotinia affects sunflowers two ways: the stems or the heads,” she says. “With the right timing, a fungicide may be able to play a role in controlling head rot – similar to what you do with canola.”Sclerotinia also is troublesome for canola growers. With the new option, they may be able to stretch fungicide rotations and avoid repeated use of one mode of action.

“As a variation in what they’re using for controlling the disease, it lessens the chance of resistance building up within the pathogen population.”

Next generation
According to DuPont, penthiopyrad is part of a next-generation group of products scheduled for delivery to growers in the next few years.

“We call it next-generation because it has a very high potency on a number of diseases,” says Dave Kloppenburg, launch manager for Vertisan. “Penthiopyrad certainly takes disease control to another level of activity. In the lab, we test how active it is in binding fungal respiration. In some cases, our activity is ten- to one hundredfold better than earlier-generation SDHIs (Group 7 fungicides).”

Penthiopyrad has strong preventive, residual and post-infection activity. The strength of penthiopyrad is coupled with activity that is both translaminar and locally systemic. The product goes through the plant tissue to attack fungal organisms. It penetrates internally from the upper, sprayed leaf surface to the lower, unsprayed surface. It also spreads out horizontally within tissue layers.

“It does move well in treated plants. If you spray one side of a leaf or petal, it will move across to the other side. It also has some residual activity, so it does provide an extended period of control. Another thing is that Vertisan provides post-infection activity. You’re using it for prevention, but in some cases it can stop an existing infection.”

Tested at Morden
Khalid Rashid, research scientist with Agriculture and Agri-Food Canada, Morden, has worked with sclerotinia control efforts since 2003. He has tested experimental fungicides as well as products already labelled for other crops. Some products, he says, provide a significant level of sclerotinia head rot control in sunflowers.

Rashid has tested single and double applications of several fungicides, including Vertisan. If only one application is made, the early application is more effective than the late application. Better results were obtained from a two-application system, one at flowering and one 15 days later.

Two applications gave better results than one application alone in reducing disease severity, reducing dockage and increasing sunflower yields.

In his 2010 sclerotinia fungicide research at Morden, he says, all fungicides, including Vertisan, were effective at some level. The best products reduced head rot by 60 to 90 percent, compared to inoculated control plots. They also reduced the amount of sclerotia in harvested samples.

Proposed timing
DuPont regional representative Frances Boddy recently reviewed the AAFC data. Boddy says, “If you go in with a single application toward the end of the application window, the head rot severity will be decreased and there will be yield and dockage benefits. 

“If a single application is made at the beginning of the window, the severity is reduced a great deal more and the yield and dockage benefits are even better. The early-late repeat application provides the greatest reduction in severity and the greatest yield and dockage benefits.” 

The Vertisan formulation is packaged as an emulsifable concentrate. According to company literature, it has excellent crop safety, outstanding rainfastness, ease of use and tank-mix compatibility. 

Many of the Group 7 fungicides are in a chemical group known as carboxamides. Other fungicides in Western Canada using active ingredients in the carboxamide group include Lance and Headline Duo. A Group 3 fungicide, Proline, also is registered for disease control in oilseed and pulse crops.