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2017 IPM Survey Results – Small Grain Summary (09/14/17)

The purpose of the IPM (Integrated Pest Management) Survey is to detect the presence and population levels of diseases and insect pests in various crops, including those that are common in wheat and barley grown in North Dakota.

2017 IPM Survey Results – Small Grain Summary

The purpose of the IPM (Integrated Pest Management) Survey is to detect the presence and population levels of diseases and insect pests in various crops, including those that are common in wheat and barley grown in North Dakota. Six individuals were hired as full-time survey scouts and they operated out of the Dickinson Research Extension Center, the North Central Research Extension Center (Minot), the Carrington Research Extension Center, the Langdon Research Extension Center, the Williston Research Extension Center and the Fargo Agricultural Experiment Station.

NDSU IPM field scouts surveyed a total of 882 wheat fields (winter wheat, hard red spring wheat, durum wheat) and 113 barley fields for 18 diseases and 6 insect pests of North Dakota in 2017.  The survey was initiated on May 25 and continued through August 9, 2017. Crops were surveyed from the 2-leaf stage (seedling) through ripening stages. IPM survey data/maps provide near real-time pest information to North Dakota producers and others in agriculture to assist with scouting and pest management decision making. Pest maps from the 2017 IPM Survey in North Dakota were uploaded weekly onto the NDSU IPM website. Some of the IPM highlights for wheat and barley are reported below.

Insect Pests:

Grasshoppers - A total of 2,204 fields was surveyed in North Dakota. Grasshoppers were found in 36% of fields surveyed from early June through the end of the survey (mid-August). The number of grasshoppers per 4 sweeps (1 yd2) ranged from 1 to 60 per 4 sweeps. Although hot and dry weather conditions are favorable for grasshopper infestation, most fields primarily had feeding damage on field edges during the period of IPM scouting.

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Grain aphids were found in about 17% of the wheat fields and 18% of the barley fields surveyed in North Dakota. Grain aphids were first detected early (May 26); however, populations did not develop into economic levels (85% of stems infested with one or more aphids) until mid-July. By then, most of the wheat fields were advanced beyond the susceptible crop stages for damage from aphid feeding. It is estimated that 5-10% of the cereal fields required insecticide control in central, southeast and east central regions.

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Wheat stem maggot was observed in 20% of wheat fields surveyed in North Dakota and damage ranged from two to 54% of plants with damaged heads (white heads). Wheat fields with >25% damaged heads were observed in McKenzie and Williams Counties in the northwest, Benson County in the north central region, and Cass County in the east central region.

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Wheat stem sawfly populations increased in wheat fields in 2017. Wheat stem sawflies were observed in only 1.3% of the fields surveyed, but were found in 7 counties total, in Burke, Divide and Mountrail Counties in the northwest, Bottineau County in the north central region, McLean and Sheridan County in west central counties, and Golden Valley County in the southwest. The highest numbers of sawflies observed were in Divide and Mountrail Counties. 

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Cereal leaf beetle is no longer a pest of export concern for shipments of hay from North Dakota to California or Canada; however, we monitor cereal leaf beetle as an economic insect pest of wheat and barley. No cereal leaf beetle was observed in wheat and barley fields surveyed in 2017. North Dakota counties that previously have been positive for cereal leaf beetle include:  Burke, Divide, McKenzie, Mountrail and Williams counties in the northwest; Renville and Ward counties in the north central district; and Cavalier county in the northeast.

Barley thrips were observed in 25% of the barley fields surveyed from June through July. Barley thrips prefer dry, hot weather conditions, which some areas of North Dakota experienced. Economic populations of barley thrips (>13 thrips per stem for malting barley) occurred in Ransom County in the southeast, Stutsman County in the central areas, Williams County in the northwest and Hettinger County in the southwest.

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Diseases:  

Wheat disease incidence and severity were low for much of the state. This can be attributed to the dry weather conditions and the lack of morning dews in heavy wheat acreage counties. As a result, reports of dry weather diseases (root roots and virus) was higher when compared to previous years.

The most common disease detected by IPM scouts was tan spot. This disease was detected in approximately 24% of the surveyed fields (Figure 1) with an average severity of 5.5% (about 2-3 small lesions on a leaf). Higher severity levels of tan spot were noticed late in the growing season (dough development) and likely had little effect on yield and test weight

Wheat streak mosaic virus (WSMV) was recorded in approximately 5% of the wheat fields (Figure 2) with most reports from central and northwest ND. Given the higher incidence levels in these regions, growers should make sure to follow appropriate management strategies to reduce WSMV risk in next year’s winter wheat and spring wheat.

Fusarium head blight (scab) risk was low across much of the state. The area at greatest risk was northeast North Dakota. However, several growers in this area used less susceptible varieties and timely triazole fungicide applications to reduce both scab and vomitoxin (deoxynivalenol) risk.

Similar to wheat, barley disease incidence and severity were low this year. The most common diseases detected by scouts were the residue-borne fungal leaf spots spot blotch and net blotch. Spot blotch and net blotch were recorded in 8% and 11% of the fields, respectively.

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Acknowledgments:  Many thanks to the hard-working field scouts of 2017:  Marc Michaelson, Brittany Aasand, Grace Dragseth, Hannah Kempler, Jaime Lundquist, Scott Knoke and Isabelle Wieseler. We appreciate the help of Darla Bakko, NDSU Dept. of Plant Pathology, for data compilation and Honggang Bu, NDSU Dept. of Soil Science, for ArcMap programming. This survey was partially supported by the National Institute of Food and Agriculture, U.S. Department of Agriculture, Crop Protection and Pest Management, Extension Implementation Program (Project No. 2014-70006-22562), and the North Dakota Department of Agriculture.

 

Janet J. Knodel  

Extension Entomologist

 

Andrew Friskop

Extension Plant Pathology, Cereal Crops

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