North Dakota (ND) is the largest producer of durum wheat, hard red spring wheat, and barley in the United States. To a lesser extent, winter wheat is grown in ND, with acres fluctuating between 200,000 and 600,000 in the past six years. Wheat streak mosaic virus (WSVM), a virus vectored by the wheat curl mite (Aceria tosichella), has historically impacted yield in ND, and depending on the year, the effect can be severe. For example, wheat streak caused an estimated $40-million loss in 1988 (5), and yield losses of up to 100% have been observed in severely infected fields (3). Yellow dwarf viruses such as Barley yellow dwarf virus strain PAV (BYDV-PAV) and Cereal yellow dwarf virus strain RPV (CYDV-RPV) (formerly classified as a strain of Barley yellow dwarf virus) are also important viruses in ND that can impact both yield and grain quality (2). Two relatively newly described viruses, Wheat mosaic virus (WMoV), formerly known as High plains virus (HPV), and Triticum mosaic virus (TriMV) have recently been detected in the region (6, 7). TriMV has not been confirmed in ND despite efforts to detect it as part of a wheat virus survey sponsored by the Great Plains Diagnostic Network (GPDN) in 2008 (1) and subsequent years. WMoV has been detected in ND every year since 2007. Yield losses due to virus infection have been estimated between 5 and 10% in the nine-state region of the GPDN, and as a result, viruses of small grains continue to be identified as important pathogens (1).

The purpose of this survey was to identify the prevalence and distribution of four small grain viruses in ND: WSMV, WMoV, BYDV-PAV, and CYDV-RPV. With the seeming increase in prevalence of virus symptoms in ND in recent years, a second objective was to use the survey information as a platform to communicate management strategies to growers.

Between 2008 and 2011, 321 small grain samples were submitted to the NDSU Plant Diagnostic Lab for virus screening. Samples were received from nearly all counties (48 of 53 counties) and were routinely screened for WSMV, BYDV-PAV, WMoV, and CYDV-RPV using standard double-antibody sandwich enzyme-linked immunosorbent assay kits (Agida Diagnostics, Elkhart IN) and processed per the manufacturer’s instructions. Samples included those collected during field surveys conducted by NDSU crop scouts, those solicited by extension area specialists and extension agents, and those submitted by growers and crop advisors for routine diagnosis. Once received, samples were refrigerated until processed, usually within 1-5 days. Small grain samples included hard red spring wheat, winter wheat, durum wheat, and barley. Samples generally exhibited chlorotic streaking, stunting, or general chlorosis, but asymptomatic samples were occasionally screened.

WSMV was the most common virus, detected in 53.3% of all samples. Winter wheat had the highest infection by WSMV, with 58.5% of the submitted samples infected, followed by spring wheat (50.9%), durum wheat (43.8%), and barley (9.1%).

WMoV and BYDV-PAV were detected in 12.1% and 10.9% of the samples, respectively, between 2008 and 2011. Although CYDV-RPV was detected in 3 of 13 samples in preliminary virus screening in 2007 (Table 1), it was not detected in the 2008-2011 survey. No viruses were detected in 37.4% of samples among years.

Co-infection with two viruses occurred in 11.8% of samples among years. Co-infection with WSMV and WMoV was most common followed by WSMV and BYDV-PAV, with 10.9% and 1.9% of samples infected, respectively. Infection by all three viruses detected in the survey was rare (0.94%). WMoV usually occurred in conjunction with WSMV; it occurred alone in only 1.2% of samples among years (two samples in 2009 and two samples in 2011).

WSMV was detected in 40 counties, WMoV in 21 counties, and BYDV in 14 counties (Figure 1). In general, virus incidence was distributed throughout the state, a pattern that corresponds to production locations of barley and spring, winter, and durum wheats (NASS, USDA).

When years were examined individually, detection of WSMV in submitted samples was highest in 2010, with 61.7% of samples testing positive (Table 1). In this same year, according to NDSU’s Integrated Pest Management survey of wheat diseases, the number of WSMV-positive fields based on symptoms was also highest at 13% (4). Yield losses due to WSMV infection were reportedly extensive in 2010 in parts of the state, and the higher infection rates were attributed to several factors, including wet fall conditions in 2009 followed by high snowfall that protected infected volunteers and the vector.

BYDV was detected most frequently in 2011. Early arrival of viruliferous aphids and late planting in 2011 compared to previous years of the survey led to predictions that incidence of BYDV would be higher, and survey results supported this prediction.

Differences in yield response to virus infection among older cultivars of hard red spring wheat, durum wheat, and barley have been documented in ND (2, 3, 8), but yield response of newer varieties is not known. Thus, for the mite-vectored viruses WSMV and WMoV, current management recommendations in the state emphasize breaking the ‘green bridge’ and implementing proper planting date. Management recommendations for the aphid-vectored yellow dwarf viruses include proper planting time and aphid control. Efforts by extension specialists and extension agents to educate growers on these management strategies have increased over the past six years, and such efforts are critical to help mitigate yield losses due to virus infection in ND.

1. Burrows, M., et al. 2009. Occurrence of viruses in wheat in the Great Plains region, 2008. Plant Health Progress doi:10.1094/PHP-2009-0706-01-RS.

2. Edwards, M.C., et al. 2001. Effect of Barley yellow dwarf virus infection on yield and malting quality of barley. Plant Disease 85:202-207.

3. Jons, V.L., et al. 1981. Effect of wheat streak mosaic virus on twelve hard red spring wheat cultivars. ND Farm Research. ND Ag Exp Station, Fargo

ND. 39(2):17-18.

4. McMullen, M., et al. 2011. Fluctuations in wheat diseases in North Dakota, 2004–2010. Phytopathology 101:S2.6

5. McMullen, M.P. and Nelson, D.R. 1989. Wheat streak mosaic severe in 1988. ND Farm Research. ND Ag Exp. Station, Fargo, ND. p. 14-16.

6. Seifers, D.L., et al. 2008. Triticum mosaic virus: A new virus isolated from wheat in Kansas. Plant Dis. 92:808-817.

7. Skare, J.M. et al. 2006. A new eriophyid mite-borne membrane-enveloped virus-like complex isolated from plants. Virology 347:343-353.

8. Timian, R.G., and Lamey, H.A. 1985. An update on wheat streak mosaic virus in North Dakota. ND Farm Research. ND Ag Exp. Station, Fargo, ND.

42(5):20,27,31.

We thank Montgomary Botschner and Aimee Thapa for technical support for the years extending this survey, and thanks to the growers and other agricultural professionals who helped provide samples. Partial funding for this survey was provided by the Great Plains Diagnostic Network.

Table 1. Viruses detected in small grain samples, 2007 through 2011.

Year*

Number of samples % WSMV % WMoV % BYDV-PAV % CYDV-RPV

2007 13 53.8 30.8 30.8 23.1

2008 33 36.4 6.1 3.0 0.0

2009 78 51.3 12.8 7.7 0.0

2010 120 61.7 14.2 9.2 0.0

2011 90 50.0 11.1 18.9 0.0

*Samples submitted in 2007 were routine diagnosis samples only and not solicited as part of a survey. They are included here only as a reference point. For years 2008 through 2011, samples included both those submitted for routine diagnosis and those submitted as part of the virus survey.

Figure 1. North Dakota counties where

viruses were confirmed, 2008-2011.

Top, WSMV; Middle, WMoV; Bottom, BYDV-

PAV. CYDV-RPV was not detected during

this period. No samples were received from

counties in grey. Number of positives/total

number of samples received for virus

screening is shown for each county.

Sargent 0/2

Ransom 10/12

Grand Forks 1/4

Cass 2/20

Traill 0/2

Richland 0/4

Walsh 1/1

Benson 7/7

Cavalier 4/12

Stutsman 0/3

Dickey 1/4

LaMoure 0/1

Logan 9/10

Barnes 1/3

Pembina 1/3

Foster 2/2

Kidder 0/3

Nelson 4/6

Wells 5/7

Rolette 1/2

Ramsey 2/4

Eddy 1/1

Bottineau 4/13

Grant

Stark 13/29

Morton 3/7

Sioux 1/1

Mercer

McKenzie 2/2

Billings 1/1

Mountraill 2/7

Dunn 4/5

Williams 1/1

Burke Divide

McHenry 2/2

Ward 36/43

McIntosh 4/6

Emmons 6/10

McLean 2/6

Burleigh 4/9

Oliver 2/2

Hettinger 6/9

Bowman 5/12

Adams 4/7

Slope 0/1

Renville 9/10

Towner

Golden Valley

2/8

Griggs 4/8

Steele 1/1

Sheridan 1/4

Pierce

0/3

Sargent 0/2

Ransom 1/12

Grand Forks 0/4

Cass 0/20

Traill 0/2

Richland 0/4

Walsh 0/1

Benson 1/7

Cavalier 0/12

Stutsman 0/3

Dickey 1/4

LaMoure 1/1

Logan 0/10

Barnes 0/3

Pembina 1/3

Foster 0/2

Kidder 0/3

Nelson 2/6

Wells 0/7

Rolette 0/2

Ramsey 0/4

Eddy 1/1

Bottineau 0/13

Grant

Stark 5/29

Morton 1/7

Sioux 0/1

Mercer

McKenzie 2/2

Billings 0/1

Mountraill 0/7

Dunn 1/5

Williams 0/1

Burke Divide

McHenry 0/2

Ward 11/43

McIntosh 1/6

Emmons 1/10

McLean 0/6

Burleigh 1/9

Oliver 1/2

Hettinger 1/9

Bowman 1/12

Adams 1/7

Slope 0/1

Renville 2/10

Towner

Golden Valley

0/8

Griggs 1/8

Steele 0/1

Sheridan 0/4

Pierce

0/3

Sargent 2/2

Ransom 10/12

Grand Forks 0/4

Cass 4/20

Traill 0/2

Richland 0/4

Walsh 0/1

Benson 1/7

Cavalier 4/12

Stutsman 0/3

Dickey 1/4

LaMoure 0/1

Logan 3/10

Barnes 0/3

Pembina 0/3

Foster 0/2

Kidder 0/3

Nelson 1/6

Wells 0/7

Rolette 0/2

Ramsey 0/4

Eddy 0/1

Bottineau 0/13

Grant

Stark 6/29

Morton 0/7

Sioux 0/1

Mercer

McKenzie 0/2

Billings 0/1

Mountraill 0/7

Dunn 0/5

Williams 0/1

Burke Divide

McHenry 0/2

Ward 2/43

McIntosh 0/6

Emmons 0/10

McLean 2/6

Burleigh 0/9

Oliver 0/2

Hettinger 3/9

Bowman 2/12

Adams 3/7

Slope 1/1

Renville 0/10

Towner

Golden Valley

0/8

Griggs 0/8

Steele 0/1

Sheridan 0/4

Pierce

0/3

Introduction Results

Methods

References

Acknowledgements