scholarly journals Phenology and Dispersal of the Wheat Stem Sawfly (Hymenoptera: Cephidae) Into Winter Wheat Fields in Nebraska

2020 ◽  
Vol 113 (4) ◽  
pp. 1831-1838
Author(s):  
Chris T McCullough ◽  
Gary L Hein ◽  
Jeffrey D Bradshaw

Abstract Historically, the wheat stem sawfly, Cephus cinctus Norton was a pest in spring wheat-growing regions of the northern Great Plains. However, in the 1980s, it was found infesting winter wheat fields in Montana. Infestations were first detected in western Nebraska in the 1990s, and have since spread throughout the Nebraska Panhandle. Larval damage occurs from stem-mining, but stem girdling that results in lodged stems that are not harvested results in the greatest yield losses. The biology and phenology of the wheat stem sawfly are well described in the northern portion of its range, but they are lacking in Colorado, southeast Wyoming, and Nebraska. In this study, the phenology and dispersal of the wheat stem sawfly in Nebraska winter wheat fields is described using sweep net and larval sampling. During this 2-yr study, adult activity began on May 23 and ended on June 21. Adult sex ratios were 2.32 males per female in 2014 and 0.46 males per female in 2015. Both sexes demonstrated an edge effect within the wheat fields, with greater densities near the field edge. The edge effect was stronger for male wheat stem sawfly than females. Wheat stem sawfly larval density also had an edge effect, regardless of the density of female wheat stem sawfly present. This information will be useful for developing management plans for the wheat stem sawfly in Nebraska and neighboring regions.

2005 ◽  
Vol 137 (4) ◽  
pp. 497-500 ◽  
Author(s):  
Tuilo B. Macedo ◽  
Paula A. Macedo ◽  
Robert K.D. Peterson ◽  
David K. Weaver ◽  
Wendell L. Morrill

The wheat stem sawfly, Cephus cinctus Norton (Hymenoptera: Cephidae), is an insect pest in dryland wheat cropping systems in the southern Canadian Prairies and the northern Great Plains of the United States (Morrill 1997). Yield losses caused by C. cinctus are due to reduced head weight (Holmes 1977; Morrill et al. 1992) and lodging, which decreases harvest efficiency. Estimates of yield losses in Montana alone are about US$25 million per year.


Plant Disease ◽  
2015 ◽  
Vol 99 (9) ◽  
pp. 1261-1267 ◽  
Author(s):  
J. A. Kolmer ◽  
M. E. Hughes

Collections of Puccinia triticina were obtained from rust-infected leaves provided by cooperators throughout the United States and from wheat fields and breeding plots by USDA-ARS personnel and cooperators in the Great Plains, Ohio River Valley, and southeastern states in order to determine the virulence of the wheat leaf rust population in 2013. Single uredinial isolates (490 total) were derived from the collections and tested for virulence phenotype on 20 lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes. In 2013, 79 virulence phenotypes were described in the United States. Virulence phenotypes MBTNB, TNBGJ, and MCTNB were the three most common phenotypes. Phenotypes MBTNB and MCTNB are both virulent to Lr11, and MCTNB is virulent to Lr26. MBTNB and MCTNB were most common in the soft red winter wheat region of the southeastern states and Ohio Valley. Phenotype TNBGJ is virulent to Lr39/41 and was widely distributed throughout the hard red winter wheat region of the Great Plains. Isolates with virulence to Lr11, Lr18, and Lr26 were common in the southeastern states and Ohio Valley region. Isolates with virulence to Lr21, Lr24, and Lr39/41 were frequent in the hard red wheat region of the southern and northern Great Plains.


Plant Disease ◽  
2009 ◽  
Vol 93 (5) ◽  
pp. 538-544 ◽  
Author(s):  
J. A. Kolmer ◽  
D. L. Long ◽  
M. E. Hughes

In 2007, leaf rust of wheat was severe throughout the Great Plains region of North America. Yield losses in wheat due to leaf rust were estimated to be 14% in Kansas. Collections of Puccinia triticina were obtained from rust-infected leaves provided by cooperators throughout the United States and from surveys of wheat fields and nurseries in the Great Plains, Ohio River Valley, southeast, California, and Washington State in order to determine the virulence of the wheat leaf rust population in 2007. Single uredinial isolates (868 in total) were derived from the collections and tested for virulence phenotype on lines of Thatcher wheat that are near-isogenic for leaf rust resistance genes Lr1, Lr2a, Lr2c, Lr3a, Lr9, Lr16, Lr24, Lr26, Lr3ka, Lr11, Lr17a, Lr30, LrB, Lr10, Lr14a, Lr18, Lr21, and Lr28, and on winter wheat lines with genes Lr41 and Lr42. Fifty-two virulence phenotypes were found. Virulence phenotypes TDBJG, MFPSC, and TDBJH were among the four most common phenotypes and were all virulent to resistance gene Lr24. These phenotypes were found throughout the Great Plains region. Phenotype MLDSD, with virulence to Lr9, Lr17, and Lr41, was also widely distributed in the Great Plains. In the soft red winter wheat region of the southeastern states, phenotypes TCRKG, with virulence to genes Lr11, Lr26, and Lr18, and MFGJH, with virulence to Lr24, Lr26, and Lr11, were among the common phenotypes. Virulence phenotypes with virulence to Lr16 were most frequent in the spring wheat region of the northern Great Plains. Virulence phenotypes with virulence to Lr11, Lr18, and Lr26 were most common in the soft red winter areas of the southeastern states and Ohio Valley. Virulence to Lr21 was not found in any of the tested isolates.


2006 ◽  
Vol 41 (1) ◽  
pp. 40-48 ◽  
Author(s):  
Thomas G. Shanower ◽  
Debra K. Waters

The wheat stem sawfly, Cephas cinctus Norton, the wheat stem maggot, Meromyza americana Fitch, the Hessian fly, Mayetiola destructor (Say), the wheat jointworm, Tetramesa tritici (Fitch), and the wheat strawworm, Tetramesa grandis (Riley), have long been considered wheat pests in the northern Great Plains. This paper reports results of surveys for these pests conducted over 3 yrs in parts of Montana (10 counties), North Dakota (14 counties), South Dakota (1 county), Nebraska (4 counties) and Wyoming (1 county). Fields were randomly selected and a mean of 191 stems were sampled from each field. The percentage of stems infested with each pest was recorded. The percentage of parasitized wheat stem sawfly larvae also was noted. The wheat stem sawfly, wheat stem maggot, and Hessian fly were the most commonly encountered pests, recorded in nearly every county. Wheat stem sawfly density was twice that of wheat stem maggot (7% vs 3.2%) in infested fields. Wheat stem sawfly densities exceeded 10% in 4 counties: Daniels and Wibaux in MT, Golden Valley, ND and Goshen, WY. Wheat stem sawfly parasitism was low and positively correlated with sawfly infestation. Wheat stem maggot infestations were low (<11% for all fields), averaging 3.2% among infested fields. Hessian fly densities were much lower (2.2% among infested fields) than reported elsewhere in the U.S. The wheat jointworm and strawworm were absent from most fields and only occasionally found at low levels (<1% and <3.5% respectively, among infested fields). This information will help to prioritize wheat insect pest management research and extension programs in this region.


Plant Disease ◽  
2014 ◽  
Vol 98 (8) ◽  
pp. 1060-1065 ◽  
Author(s):  
Z. Miller ◽  
F. Menalled ◽  
D. Ito ◽  
M. Moffet ◽  
M. Burrows

Plant genotype, age, size, and environmental factors can modify susceptibility and tolerance to disease. Understanding the individual and combined impacts of these factors is needed to define improved disease management strategies. In the case of Wheat streak mosaic virus (WSMV) in winter wheat, yield losses and plant susceptibility have been found to be greatest when the crop is exposed to the virus in the fall in the central and southern Great Plains. However, the seasonal dynamics of disease risk may be different in the northern Great Plains, a region characterized by a relatively cooler fall conditions, because temperature is known to modify plant–virus interactions. In a 2-year field study conducted in south-central Montana, we compared the impact of fall and spring WSMV inoculations on the susceptibility, tolerance, yield, and grain quality of 10 winter wheat varieties. Contrary to previous studies, resistance and yields were lower in the spring than in the fall inoculation. In all, 5 to 7% of fall-inoculated wheat plants were infected with WSMV and yields were often similar to uninoculated controls. Spring inoculation resulted in 45 to 57% infection and yields that were 15 to 32% lower than controls. Although all varieties were similarly susceptible to WSMV, variations in tolerance (i.e., yield losses following exposure to the virus) were observed. These results support observations that disease risk and impacts differ across the Great Plains. Possible mechanisms include variation in climate and in the genetic composition of winter wheat and WSMV across the region.


2005 ◽  
Vol 137 (2) ◽  
pp. 202-214 ◽  
Author(s):  
Christian Nansen ◽  
David K. Weaver ◽  
Sharlene E. Sing ◽  
Justin B. Runyon ◽  
Wendell L. Morrill ◽  
...  

AbstractThe wheat stem sawfly, Cephus cinctus Norton, is a major insect pest in dryland wheat (Triticum L. spp.; Poaceae) fields in the northern Great Plains of the United States and in southern regions of the prairie provinces of Canada. Field infestations by this pest commonly show a distinct “edge effect”, with infestation levels highest at the field edge and declining inwards. In this study, we characterized the edge effect of C. cinctus infested wheat fields in Montana at four locations in two separate years. "Infestation level" refers to the average proportion of wheat stems infested with C. cinctus in samples collected in a given wheat field. The gradual decrease in C. cinctus infestation towards the centre of wheat fields is referred to as the “infestation slope”, and it was presented as a proportion of infestation level at field edges. We showed that (i) for most of the fields bordering grassland or fallow wheat, a simple exponential decline curve provided a significant fit to the infestation slope; (ii) the infestation slopes in different fields and in different directions within fields were similar and appeared to be independent of the overall infestation level; and (iii) the relationship between infestation level and the proportion of samples infested followed an asymptotic curve, which indicates a high level of dispersal of ovipositing C. cinctus females. The general perception has been that the edge effect of C. cinctus infestation is a result of ovipositing C. cinctus females being both weak flyers and short-lived, but our results do not fully corroborate this perception. Currently, the only reliable way to detect C. cinctus infestations is to dissect individual stems and look for developing instars. However, this type of sampling is extremely time consuming and labor intensive and therefore impractical for wheat growers. Increasing the understanding of the spatial patterns in C. cinctus infestations is a first step towards development of an optimal sampling plan for this important field pest. Thus, the results presented are relevant for researchers involved in sampling designs and integrated pest management procedures for field pests. We discuss behavioral and evolutionary factors that may contribute to the edge effect of C. cinctus infestations.


Plant Disease ◽  
2015 ◽  
Vol 99 (10) ◽  
pp. 1333-1341 ◽  
Author(s):  
Zhaohui Liu ◽  
Ibrahim El-Basyoni ◽  
Gayan Kariyawasam ◽  
Guorong Zhang ◽  
Allan Fritz ◽  
...  

Tan spot and Stagonospora nodorum blotch (SNB), often occurring together, are two economically significant diseases of wheat in the Northern Great Plains of the United States. They are caused by the fungi Pyrenophora tritici-repentis and Parastagonospora nodorum, respectively, both of which produce multiple necrotrophic effectors (NE) to cause disease. In this work, 120 hard red winter wheat (HRWW) cultivars or elite lines, mostly from the United States, were evaluated in the greenhouse for their reactions to the two diseases as well as NE produced by the two pathogens. One P. nodorum isolate (Sn4) and four Pyrenophora tritici-repentis isolates (Pti2, 331-9, DW5, and AR CrossB10) were used separately in the disease evaluations. NE sensitivity evaluation included ToxA, Ptr ToxB, SnTox1, and SnTox3. The numbers of lines that were rated highly resistant to individual isolates ranged from 11 (9%) to 30 (25%) but only six lines (5%) were highly resistant to all isolates, indicating limited sources of resistance to both diseases in the U.S. adapted HRWW germplasm. Sensitivity to ToxA was identified in 83 (69%) of the lines and significantly correlated with disease caused by Sn4 and Pti2, whereas sensitivity to other NE was present at much lower frequency and had no significant association with disease. As expected, association mapping located ToxA and SnTox3 sensitivity to chromosome arm 5BL and 5BS, respectively. A total of 24 potential quantitative trait loci was identified with −log (P value) > 3.0 on 12 chromosomes, some of which are novel. This work provides valuable information and tools for HRWW production and breeding in the Northern Great Plains.


1998 ◽  
Vol 72 (2) ◽  
pp. 388-397 ◽  
Author(s):  
Mark L. Gabel ◽  
Douglas C. Backlund ◽  
Jacob Haffner

The results of the first comprehensive paleobotanical survey of the northern portion of the late Miocene Ogallala Group are discussed. Several species of fossilized fruiting structures from vascular plants (Berriochloa, Celtis, Cryptantha, Biorbia, Lithospermum, Eleofimbris, Carex, and Cyperocarpus) in the mid- to late-Miocene are reported. Fewer taxa (12 genera) were found in the South Dakota-northern Nebraska area than have been reported previously (20 genera) from southern Nebraska-Kansas strata in the same formations and approximately the same area of exposures. Sites of Barstovian age near the Kilgore Flora site indicate that grasses were commonly found in the region. The results presented here support the hypothesis that grassland savanna vegetation was widely distributed in the northern Great Plains by the Clarendonian age.


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