ISSUE 8   July 3, 2008

MOST RECENT NDSU IPM SMALL GRAIN SURVEY RESULTS

The NDSU IPM field scouts surveyed 117 wheat fields and 25 barley fields last week. Field scouts are also looking at row crops for aphids and diseases now. Aphid counts in small grains remain quite low, with a few aphids observed in 6% of scouted fields.

Tan spot continues to be the predominate disease observed in wheat, but 11 fields showed symptoms of leaf rust last week, five were winter wheat fields and six were spring wheat fields. The greatest leaf rust severity (25%) was observed in winter wheat in the south central region. Septoria leaf blotch, bacterial leaf stripe, black chaff, loose smut, and powdery mildew also were observed occasionally in wheat. In barley, fungal leaf spots are the only diseases observed at this point.

 

PREHARVEST INTERVALS FOR SMALL GRAIN FUNGICIDES

A recent temporary embargo of some Kansas wheat occurred because the fields had been treated with Quilt fungicide beyond the appropriate preharvest interval (PHI) for that product (45 days). The following preharvest intervals are indicated on our currently registered small grain fungicides:

Product

PHI

Headline*

Feekes 10.5 (~ 40 days PHI)

Quadris

45 days

Caramba

30 days

Folicur**

30 days

Proline

30 days wheat, 32 days barley

Tilt**

40 days

Quilt

45 days

Stratego

35 days

* Headline is the only product that doesn’t specify number of days in their PHI. Feekes 10.5 is approximately 40 days before harvest in ND, depending on air temperatures. Hot temperatures push the crop to flowering, Feekes 10.51, more quickly.
** Additional tebuconazoles such as Orius, etc., or additional propiconazoles, such as Propimax, etc., have ND state supplemental labels that specify the same PHIs as the original registered products.

Products recommended by NDSU for heading or flowering application for Fusarium head blight suppression all have 30 day PHIs in wheat (32 days for Proline in barley), a duration that should allow ample time in ND for maturity before swathing or harvest. Producers and applicators need to take heed of these PHIs, as what happened in Kansas is a very strong reminder that labels are the law and must be followed.

Marcia McMullen
NDSU Extension Plant Pathologist
marcia.mcmullen@ndsu.edu


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