NDSU Crop and Pest Report
Plant Pathology


ISSUE 3  May 15, 2003

 

INTERCEPT WG FOR SCLEROTINIA MANAGEMENT

Intercept WG (Encore Technologies) is a biological control product for specific control of diseases caused by Sclerotinia (white mold, stem rot, stalk rot, head rot, and wilt). The active ingredient in Intercept is actually a fungus known as Coniothyrium minitans, which has the ability to parasitize and kill sclerotia (Sclerotinia survival structures) in the soil.

For Intercept to be effective, it must be applied and incorporated (2 to 3 inches) into the soil approximately 2 to 3 months prior to a Sclerotinia disease outbreak. Spring application may be suitable for canola, because Sclerotinia strictly causes a stem rot that occurs just after flowering. However, in sunflower, Sclerotinia has the ability to infect the roots anytime they come in contact with sclerotia including spring and early summer, which can cause wilt. Because of the potential for root infection of sunflower, it is advised that Intercept be applied post_harvest in the fall on ground that will be cropped to sunflower the following year. This would give the appropriate time period for the Intercept to kill sclerotia in the soil that could potentially infect sunflower roots.

Intercept was tested on sunflower and dry bean in NDSU trials in 2002. However, Sclerotinia disease pressure was not at an adequate level to show any significant results. More field trials testing Intercept are being planned for 2003.

Other factors to consider when applying Intercept:

 

ERROR IN 2003 ND FIELD CROP FUNGICIDE GUIDE

Headline fungicide (pyraclostrobin) was mistakenly listed as being registered for use on field pea (pg 46 of 2003 Fungicide Guide). Headline is NOT currently registered for use on field pea. BASF is currently seeking approval for a field pea label, but if granted, it would not be available for the 2003 season.

Carl Bradley
Extension Plant Pathologist  
cbradley@ndsuext.nodak.edu

 

CEREAL RUST UPDATE

The USDA Cereal Disease Lab in St. Paul indicated that rainfall and warmer temperatures in southern plains states should favor an increase in wheat leaf rust in those states. As of May 7, (Cereal Rust Bulletin # 4) trace levels of leaf rust were seen in southern Kansas winter wheat fields, while up to 10% severities were observed in fields in Oklahoma. The wheat pathologist (Bob Hunger) at Oklahoma State indicated that a common winter wheat variety, Jagger, is showing some high leaf rust severities on lower leaves in parts of north central Oklahoma. Further development and movement of leaf rust will be dependent on environmental conditions. As of May 9, much of the wheat in Oklahoma was under moisture stress.

The Cereal Rust Bulletin # 4 also indicates that some severe oat stem rust was observed in plots in south and central Texas, and trace amounts of oat crown rust were observed in north central Texas. Moderate to heavy infections of the overwintering stage of oat crown rust were observed on emerging buckthorn leaves in St. Paul, Mn. Buckthorn serves as the alternate host for oat crown rust. The symptoms on buckthorn are pale orange eruptions or cups on the underside of the leaf. The buckthorn shrubs in Fargo were not showing these symptoms as of May 13. The Cereal Rust Bulletin # 4 indicated that no barley leaf rust or barley stem rust has been observed in southern plains states, as of May 7.

 

SECTION 18 GRANTED FOR FOLICUR FOR WHEAT AND BARLEY

The ND Dept. of Agriculture announced this week that the EPA granted a Section 18 Specific Exemption for the use of Folicur (tebuconazole) fungicide for the control of Fusarium head blight (scab) in wheat and barley. The Sec. 18 allows use on up to 2 million acres of wheat (all wheats) and 250,000 acres of barley in ND.

The maximum use rate of Folicur is 4 fl oz/acre. For optimum disease control, the lowest rate of a spray surfactant should be tank-mixed with Folicur. Folicur may be applied up to the 50% heading stage; application may not be made within 30 days of harvest. Straw cut after harvest may be fed or used for bedding. Fields treated with Folicur should not be entered for 12 hours after application.

The specific exemption label states that Folicur may be applied in a minimum of 10 gallons of spray solution per acre (gpa) by ground sprayer or in a minimum of 3 gallons of spray solution per acre (gpa) by aircraft spray equipment. NDSU research indicates that higher water volumes than this (15 gpa by ground, 5 gpa by air) are more optimal for good control.

Marcia McMullen
Extension Plant Pathologist
mmcmulle@ndsuext.nodak.edu


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