Category Archives: Fungicides

Downy mildew of brassica vegetables

Downy mildew of brassicas (Hyaloperonospora parasitica syn. Peronospora parasitica) is a fungal-like oomycete that can be devastating in cooler, wet weather. While the ideal temperature for downy mildew development is 8-16˚C it can infect in temperatures outside that range. Prolonged leaf wetness due to fog, dew, or evening irrigation can create ideal conditions for the pathogen to develop.

Downy mildew is most devastating on Continue reading Downy mildew of brassica vegetables

Switch® Fungicide label expanded for Celery Leaf Curl

J. Chaput, OMAFRA, Minor Use Coordinator

The Pest Management Regulatory Agency (PMRA) recently announced the approval of an URMULE registration for Switch® Fungicide for control of anthracnose (leaf curl) on celery in Canada. Switch® Fungicide was already labeled for use on a number of crops in Canada for control of several diseases.

This minor use project was submitted as a result of minor use priorities established by growers and extension personnel.

The following is provided as an abbreviated, general outline only. Users should be making pest management decisions within a robust integrated disease management program and should consult the complete label before using switch fungicide.


Switch® Fungicide is TOXIC to aquatic organisms. Fludioxonil is persistent and may carryover. It is recommended that any products containing fludioxonil not be used in areas treated with this product during the previous season. Do not permit Switch Fungicide to contaminate off-target areas or aquatic habitats when spraying or when cleaning and rinsing spray equipment or containers. 

Follow all precautions and detailed directions for use on the Switch® Fungicide label carefully. 

For a copy of the new minor use label contact your local crop specialist, regional supply outlet or visit the PMRA label site.

This article is not intended to be an endorsement or recommendation for this particular product, but rather a notice of registration activity.

 

 

Late blight alert – July 27th, 2017

This information is updated from an earlier article by Janice LeBoeuf.

We have had multiple reports of late blight in conventionally managed tomato fields this week.  Typically, this disease is well managed in tomatoes with a broadspectrum fungicide program including chlorothalonil.  However, high disease pressure due to environmental conditions, combined with a dense leaf canopy and rapid growth may have resulted in poor spray coverage and reduced efficacy.

Commercial growers should scout often and ensure they are using fungicides with good late blight activity in their fungicide program.  When late blight is in the area, spray intervals should be shortened.

Under continued high disease pressure, growers should consider adding a targeted late blight fungicide to the spray program.  If late blight has been identified in a field, use a fungicide with curative and antisporulent activity, see the table below for late blight fungicides and their properties. Continue reading Late blight alert – July 27th, 2017

Time to Start Scouting for Powdery Mildew

This is a re-post from 2016 – Late-July to early-August is the key time for powdery mildew management!  With any disease, preventative management provides the best control.

Powdery mildew typically arrives in Southern Ontario in mid-to-late July. Plants are most susceptible to infection during the fruit sizing and development. Poor control results in decreased yield and poor fruit quality at harvest. The threshold for treatment is 1 lesions/50 plants. Optimum powdery mildew control is a combination of variety selection, fungicide timing and fungicide selection.

Powdery Mildew Lesion on the Lower Leaf Surface
Powdery Mildew Lesion on the Lower Leaf Surface

Cheryl Trueman, a vegetable pest management researcher at the University of Guelph’s Ridgetown Campus, has been conducting powdery mildew efficacy trials since 2009. In these trials, several products consistently provided good control of powdery mildew. These products are powdery mildew targeted, and have a single site mode of action. To prevent the development of resistance, it is essential to always rotate between different fungicide groups and/or tank mix with a broad spectrum fungicide.

Powdery Mildew Targeted Fungicides Showing Consistent Control in the Ridgetown Field Trials:

Group 13: Quintec (quinoxyfen)
Quintec was the most consistent powdery mildew product tested in Ridgetown. It provided excellent control in 4/5 years and good control in 1/5 years tested.

Group U8: Vivando (metrafenone)
Vivando provided excellent control in 1/3 years and good control in 2/3 years and tested.

Group 7: Fontelis (penthiopyrad), Aprovia (benzovindiflupyr), Sercadis (fluapyroxad) and Pristine (boscalid/pyraclostrobin).
Fontellis was somewhat less consistent. Control with this produce ranged from excellent to poor, depending on the year. It provided excellent control in 1/5 years, good control in 2/5 years and poor control in 2/5 years. Note: Aprovia, Sercadis and Pristine were not tested in the Ridgetown Campus trials.

Group 3: Inspire (difenoconazole), Proline (prothioconazole) and Quadris Top (azoxystrobin/difenoconazole)
Inspire provided a level of control similar to Fontelis; good control in 3/5 years, and poor control in 2/5 years. Proline and Quadris Top were only tested for one year in the Ridgetown trials, in which they both provided good control.

Fungicides containing chlorothalonil (Bravo ZN and Echo) provided a lower level of powdery mildew control, but are still better than the untreated checks. They also control a broad range of other foliar diseases including scab and alternaria.

Research in Ontario and other jurisdictions indicates that the group 11 (QoI) fungicides, Cabrio (pyraclostrobin) and azoxystrobin (a component of Quadris Top) no longer control powdery mildew. However, they may provide control of other cucurbit diseases such as anthracnose and alternaria.

Additional reading: http://www.omafra.gov.on.ca/IPM/english/cucurbits/diseases-and-disorders/powdery-mildew.html#advanced

Confine Extra fungicide label expanded via minor use program for suppression of bacterial spot of leaf lettuce

The Pest Management Regulatory Agency (PMRA) recently announced the approval of URMULE registrations for Confine Extra fungicide (mono and di-potassium salts of phosphorus acid 53%) for the suppression of bacterial leaf spot (Xanthomonas campestris p.v. vitians) on leaf lettuce in Canada.  Continue reading Confine Extra fungicide label expanded via minor use program for suppression of bacterial spot of leaf lettuce

Late blight alert – June 28

Late blight foliar lesionLate blight has been confirmed on tomatoes in Chatham-Kent.

Recent weather has been conducive to the development and spread of late blight.  Commercial growers should scout often and ensure they are using fungicides with good late blight activity in their fungicide program.  When late blight is in the area, spray intervals should be shortened. Continue reading Late blight alert – June 28