ND SMALL GRAIN PEST SURVEY

  ND SMALL GRAIN PEST SURVEY, 2000 (Summary)

Marcia McMullen, Extension Plant Pathologist/IPM Coordinator

            Wheat and barley fields were surveyed for leaf and head diseases and insects throughout the growing season in all crop reporting districts and in all counties.  Over 1000 wheat fields were surveyed, while a smaller number (137) of barley fields were surveyed.  Six field scouts were employed through the NDSU Extension Service to conduct the survey.  Laura Neal, Allison Marsland, and Holly Semler covered the NW and NC districts and operated under the direction of Jan Knodel, North Central REC Pest Management Specialist; Amy Dukart scouted the SW and WC crop reporting districts, under the direction of Roger Ashley, Dickinson REC Area Agronomist;  Jerry Schneider scouted the SC and C districts, under the direction of Greg Endres, Carrington REC Area Agronomist; and  Matthew Gregoire scouted the SE, EC and NE districts, under the direction of Marcia McMullen, NDSU Extension Plant Pathologist and Phil Glogoza, NDSU Extension Entomologist.

            Fields were surveyed from the one leaf stage through dough stage of kernel development.   Leaf spot and leaf rust were observed as early as the one leaf stage in some fields, and continued to be detected through kernel stages.  Head scab (Fusarium head blight) was detected after flowering.

            Among fungal leaf diseases, wheat leaf rust was observed in 35.1% of all wheat fields surveyed, with the average severity on the flag leaf varying among districts, from 2.0% in the WC district to 8.1% in the C district (Table 1).  Tan spot of wheat was found in 68.2% of all fields surveyed, with average severity on the flag leaf ranging from 2.9% in the C district to 8% in the SC district (Table 1).  Septoria leaf blotch was observed primarily from flag leaf stage and beyond and was observed in 27.5% of all fields surveyed, but in 49.3% of fields surveyed at flag leaf stage or later.  Septoria levels of infection on the flag leaf were more severe than those of tan spot or leaf rust, averaging from 2.8% in the SW to 24.5% in the SE (Table 1).

Table 1.   Fungal leaf diseases -2000 Wheat Survey

* # of Wheat fields with Septoria at flag leaf stage or beyond;

** Septoria not delineated from tan spot in NE

ND Small Grain Pest Survey cont.

            Head scab (Fusarium head blight =FHB) was found in wheat in all districts but the Southwest in 2000.  Of the 284 wheat fields surveyed past flowering, 73.6% had some level of scab (Table 2).  The average field severity of scab ranged from 0% in counties in the Southwest district, to 6.4% in the Northwest district and 11.4% in the West Central district, two districts in which durum acreage was hit hard with this disease.  The statewide average field severity of scab in wheat was 5.8%.

Table 2.   Head scab (Fusarium head blight =FHB) in wheat, 2000 Wheat Survey.

* Field severity = incidence (% of tillers/field showing symptoms) x average % head severity

** Durum fields surveyed in these districts had high scab severity levels, accounting for high average severities

            The majority of headed barley fields surveyed were in the Northeast.  The average scab field severity in barley ranged from 0.6 % in the East Central district to 1.9% in the Northeast to 6.2% in the Central district.  The statewide average field severity of scab in barley was 1.8% in this survey.

            Barley yellow dwarf virus was observed in 13.7% of the wheat fields statewide.  The South central district had the highest percentage of fields showing some symptoms of this virus disease, at 16.8%.  The percent of wheat tillers with symptoms in fields with the disease averaged 12.6% statewide.   Barley yellow dwarf was only reported observed in 3.6% of the barley fields surveyed.  The cereal grain aphids that carry and transmit the virus were observed in 20.6% of the fields surveyed, statewide.

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