Fungicide Efficacy for Control of Corn Diseases in Ontario (Corn Disease Working Group)

The hot, dry weather conditions to date have not been very conducive to foliar leaf diseases across most of the province.  In most cases, besides high relative humidity, prolonged wet conditions on the leaves are necessary for infection but only under favourable temperatures (16-30oC).  What has started to show recently in the southwest are the first common rust pustules but at very low levels.  Common rust in corn does not overwinter in the province and spores are carried into the area on storm fronts or wind currents from the U.S.

The Corn Disease Working Group (CDWG) has developed the following information on fungicide efficacy for control of major corn diseases in the United States and Ontario.  Efficacy ratings for each fungicide listed in the table were determined by field testing the materials over multiple years and locations by the members of the committee. Efficacy ratings are based upon level of disease control achieved by product, and are not necessarily reflective of yield increases obtained from product application. Efficacy depends upon proper application timing, rate, and application method to achieve optimum effectiveness of the fungicide as determined by labeled instructions and overall level of disease in the field at the time of application. Differences in efficacy among fungicide products were determined by direct comparisons among products in field tests and are based on a single application of the labeled rate as listed in the table.  Table includes the most widely marketed products available, but is not intended to be a list of all labeled products.

 

Fungicide(s)

 

 

 

 

 

 

 

 

 

Class

Active ingredient (%)

Product/

Trade name

Anthracnose leaf blight

Common rust

Eyespot

Gray leaf spot

Northern leaf blight

Southern rust

Diplodia ear rot

Fusarium

ear rot

Gibberella

ear rot

Strobilurin

Group 11

Azoxystrobin

Quadris

VG

E

VG-E

E1

G

G

NL

NL

NL

Pyraclostrobin

Headline EC

2

E

E

E

VG

E

NL

NL

NL

Triazole

Group 3

Propiconazole

Tilt 250 E

 Bumper 418 EC

2

VG

E

G

G

G

NL

NL

NL

Prothioconazole

Proline 480 SC

2

VG

E

VG

VG

2

NL

SUP

SUP

Mixed mode of action

Azoxystrobin

Propiconazole

Quilt

G

VG-E

E

E

VG

VG

NL

NL

NL

1Efficacy categories: NR=Not Recommended; P=Poor; F=Fair; G=Good; VG=Very Good; E=Excellent; SUP=Suppression Only; NL = Not Labeled for use against this disease

2Insufficient data to make statement about efficacy of this product

3Multiple generic products containing tebuconazole may also be labeled.

Many products have specific use restrictions about the amount of active ingredient that can be applied within a period of time or the amount of sequential applications that can occur.  Please read and follow all specific use restrictions prior to fungicide use.

This information is provided only as a guide.  It is the responsibility of the pesticide applicator by law to read and follow all current label directions.  Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Persons using such products assume responsibility for their use in accordance with current directions of the manufacturer. Members or participants in the CDWG assume no liability resulting from the use of these products.