SCAB FUNGICIDE APPLICATION

 

Many area wheat fields are beginning to head. Growers should consider the use of a fungicide for Fusarium head blight (scab) suppression because of the combination of high grain yield potential, recent (and probably continued) wet weather, and continued presence of leaf spot disease. 

 

The optimum timing of fungicide application for scab suppression is at early flowering for spring wheat and durum, and at early full head emergence for barley. Early flowering in wheat means 10-25% of the main stem heads are flowering. The fungicides and timing of application also will provide good control of leaf spot diseases including tan spot, Septoria leaf blotch, and leaf rust.

 

NDSU Extension Service circular AE-1148 ‘Application of fungicides for suppression of Fusarium head blight (scab)’ should be consulted to aid in effectively applying fungicides. A summary of the recommendations include the following:

* For ground application, angle spray toward grain heads, using forward and backward mounted XR8001 nozzles or nozzles that have a two-directional spray, such as Twinjet nozzles.

*When using XR flat fan tips, use 40 psi with 9-10 gpa, and 90 psi with 18 gpa.

*Increase spray volume for durum and barley to improve head coverage and disease control.

*Use a good adjuvant.

*Use dew as additional water.

*When using aerial application, spray in evening or early morning to capture dew as extra water volume, and use a small droplet size.

*Use NDSU’s general guidelines for determining need for fungicide application based on yield potential, crop price, disease presence, recent weather, and forecast for upcoming weather. NDSU also has a disease forecasting system for scab and leaf disease ().

 

SCLEROTINIA FUNGICIDES FOR CANOLA

 

Area canola fields have started to flower at least two weeks ago. Recent rain and continued forecast for more moisture will increase the likelihood of sclerotinia infection in flowering canola.. General considerations to make a decision on fungicide application for sclerotinia include: canola seed yield potential of at least 2000 lb/acre, wet weather in the past 1-2 weeks and forecast for more in the future, and a history of sclerotinia in or near the current canola field.

Timing of fungicide application is critical for satisfactory results and many area fields may be soon past the stage for acceptable results with fungicide application.

 

The following is general information on the two fungicides:

*Quadris: apply at 10 to 25% bloom (about 3-7 days after flowers are detected). Rate = 9.2 to 15.4 fl oz/acre (9.2 fl oz/acre is suggested at a cost of about $21-22/acre plus application costs).

*Ronilan: apply at 20 to 50% bloom (about 4-8 days after flowering begins). Rate = 10.6 to 16 oz/acre (suggested rate is 12 oz/acre at a cost of about $16/acre plus application costs).

Consult labels for details before use!