Seasonal, Landscape, and Attractant Effects on Lesser Grain Borer, Rhyzopertha dominica (F.), Captures in Northeast Kansas

The lesser grain borer, Rhyzopertha dominica (F.), is a highly diverse feeder and widely distributed throughout the United States in agricultural and non-agricultural landscapes. Six four-funnel Lindgren traps were deployed in feed mill, grain elevator, and native prairie landscapes, to determine the most attractive food and pheromone combination (attractant) and patterns in seasonal captures. Traps were baited with combinations of wheat (crimped, high moisture, pre-fed) with or without an R. dominica specific aggregation pheromone in 2017 and 2018. Traps were deployed for 48 h, collected, and the number of R. dominica counted. Rhyzopertha dominica was captured among all landscapes with all attractants. There was a significant correlation between temperature and R. dominica captures, with peak captures occurring during the warmest months. Significantly more R. dominica adults were captured in traps containing the pheromone. In 2017, pheromone traps captured 818% more R. dominica and 543% more than in 2018. The pheromone component in the trap was more attractive than any natural stored wheat condition and should be included in future studies. Understanding the seasonal patterns and changes in capture rates in agricultural and non-agricultural landscapes may be useful in determining times of increased immigration pressure into the newly harvested grain.

Diversity Is Not Everything

Since the passage of legislation in 1977, Appalachian mineland reclamation is typically completed using non-native C3 grasses and forbs. Alternatively, reclamation with native prairie (C4) grasses and forbs offers a more ecologically friendly alternative that can contribute to native plant conservation and potentially improve soil properties more quickly than shallower rooted C3 cool-season grasses. We assessed the establishment of native prairie after reclamation, evaluating three treatments for six years after planting—traditional cool season planting, native prairie planted at light density, and native prairie planted at heavy density. All treatments reached the objectives of reclamation—percentage of ground covered by vegetation—within 2 years after planting. All treatments at all sites, except for one site by treatment combination near a forest, showed an increase in plant species richness and Shannon–Wiener diversity in the first four years of reclamation, a peak around 5 years, and subsequent decrease. Little difference in plant richness and Shannon–Wiener diversity among treatments was observed. However, the two native seed mixes quickly diverged from the traditional mix in terms of community structure and diverged further over time, with both native treatments heading towards a more desirable native prairie grassland state, while the traditional mix remained dominated by non-native cool season grasses. The native treatments also exhibited greater increase in microbial biomass and fungi:bacteria ratio over time compared to the traditional mix. Soil organic carbon increased over time regardless of seed mix treatment. Exchangeable base cations and phosphorus generally decreased over time, as expected, regardless of seed mix treatment, likely due to uptake from established plants. Native grassland species were able to establish despite inclusion of some traditional species in the native mix. Native plant establishment likely resulted in benefits including pollinator resources, bird and wildlife habitat, and increased soil health, and we recommend that native prairie mixes be used directly in reclamation moving forward, as they are able to meet reclamation goals while establishing a successful native prairie plant community.

Moisture modulates soil reservoirs of active DNA and RNA viruses

Soil is known to harbor viruses, but the majority are uncharacterized and their responses to environmental changes are unknown. Here, we used a multi-omics approach (metagenomics, metatranscriptomics and metaproteomics) to detect active DNA viruses and RNA viruses in a native prairie soil and to determine their responses to extremes in soil moisture. The majority of transcribed DNA viruses were bacteriophage, but some were assigned to eukaryotic hosts, mainly insects. We also demonstrated that higher soil moisture increased transcription of a subset of DNA viruses. Metaproteome data validated that the specific viral transcripts were translated into proteins, including chaperonins known to be essential for virion replication and assembly. The soil viral chaperonins were phylogenetically distinct from previously described marine viral chaperonins. The soil also had a high abundance of RNA viruses, with highest representation of Reoviridae. Leviviridae were the most diverse RNA viruses in the samples, with higher amounts in wet soil. This study demonstrates that extreme shifts in soil moisture have dramatic impacts on the composition, activity and potential functions of both DNA and RNA soil viruses.

Origin of agricultural plant pathogens: Diversity and pathogenicity of Rhizoctonia fungi associated with native prairie grasses in the Sandhills of Nebraska

The Sandhills of Nebraska is a complex ecosystem, covering 50,000 km2 in central and western Nebraska and predominantly of virgin grassland. Grasslands are the most widespread vegetation in the U.S. and once dominated regions are currently cultivated croplands, so it stands to reason that some of the current plant pathogens of cultivated crops originated from grasslands, particularly soilborne plant pathogens. The anamorphic genus Rhizoctonia includes genetically diverse organisms that are known to be necrotrophic fungal pathogens, saprophytes, mycorrhiza of orchids, and biocontrol agents. This study aimed to evaluate the diversity of Rhizoctonia spp. on four native grasses in the Sandhills of Nebraska and determine pathogenicity to native grasses and soybean. In 2016 and 2017, a total of 84 samples were collected from 11 sites in the Sandhills, located in eight counties of Nebraska. The samples included soil and symptomatic roots from the four dominant native grasses: sand bluestem, little bluestem, prairie sandreed, and needle-and-thread. Obtained were 17 Rhizoctonia-like isolates identified, including five isolates of binucleate Rhizoctonia AG-F; two isolates each from binucleate Rhizoctonia AG-B, AG-C, and AG-K, Rhizoctonia solani AGs: AG-3, and AG-4; one isolate of binucleate Rhizoctonia AG-L, and one isolate of R. zeae. Disease severity was assessed for representative isolates of each AG in a greenhouse assay using sand bluestem, needle-and-thread, and soybean; prairie sandreed and little bluestem were unable to germinate under artificial conditions. On native grasses, all but two isolates were either mildly aggressive (causing 5–21% disease severity) or aggressive (21–35% disease severity). Among those, three isolates were cross-pathogenic on soybean, with R. solani AG-4 shown to be highly aggressive (86% disease severity). Thus, it is presumed that Rhizoctonia spp. are native to the sandhills grasslands and an emerging pathogen of crops cultivated may have survived in the soil and originate from grasslands.

Balancing the need for seed against invasive species risks in prairie habitat restorations

Adequate diversity and abundance of native seed for large-scale grassland restorations often require commercially produced seed from distant sources. However, as sourcing distance increases, the likelihood of inadvertent introduction of multiple novel, non-native weed species as seed contaminants also increases. We created a model to determine an “optimal maximum distance” that would maximize availability of native prairie seed from commercial sources while minimizing the risk of novel invasive weeds via contamination. The model focused on the central portion of the Level II temperate prairie ecoregion in the Midwest US. The median optimal maximum distance from which to source seed was 272 km (169 miles). In addition, we weighted the model to address potential concerns from restoration practitioners: 1. sourcing seed via a facilitated migration strategy (i.e., direct movement of species from areas south of a given restoration site to assist species’ range expansion) to account for warming due to climate change; and 2. emphasizing non-native, exotic species with a federal mandate to control. Weighting the model for climate change increased the median optimal maximum distance to 398 km (247 miles), but this was not statistically different from the distance calculated without taking sourcing for climate adaptation into account. Weighting the model for federally mandated exotic species increased the median optimal maximum distance only slightly to 293 km (182 miles), so practitioners may not need to adjust their sourcing strategy, compared to the original model. This decision framework highlights some potential inadvertent consequences from species translocations and provides insight on how to balance needs for prairie seed against those risks.

Comparing Evapotranspiration Products of Different Temporal and Spatial Scales in Native and Managed Prairie Pastures

Grasslands in the Southern Great Plains of the United States have major ecological and economic importance, with strong climate and water cycle connections. The historic native prairie grassland has been managed differently for enhancing productivity, while consequently altering water vapor fluxes. However, little is known about the impacts of different management activities on evapotranspiration (ET) at different spatio-temporal scales. In this study, we quantified and compared ET between co-located introduced managed pasture (MP) and native prairie (NP) pasture. Additionally, we compared the Moderate Resolution Imaging Spectroradiometer (MODIS)-derived ET at four different spatial scales: 30 m (ETMOD30), 200 m (ETMOD200), 500 m (ETMOD500), and 1000 m (ETMOD1000) with eddy covariance-measured ET (ETEC). Large differences in ETEC were observed between two pastures from half-hourly to seasonal scales, with variations mainly controlled by the amount of rainfall and management activities. The results demonstrated differential responses of MP and NP in a pluvial year. The ETMOD30 showed a better agreement with ETEC than did the ETMOD200, ETMOD500, and ETMOD1000. The ETMOD200, ETMOD500, and ETMOD1000 largely underestimated ETEC, most likely due to their inability to capture the spatial heterogeneity of vegetation growth impacted by various management activities. Our results facilitate understanding of the difference in ET of MP and NP due to differences in vegetation resulting from different management activities and their differential responses to precipitation.

PSI-8 Evaluation of two burning dates and addition of spices on stocker cattle gains on tallgrass native range

Burning pastures in April has historically been a method to increase stocker gains for summer grazing in Kansas, yet is becoming an issue from smoke management. Finding alternative burning windows along with feed options that maintain a similar gain to April burns is important from producer’s perspective. Therefore, the purpose of this study is to evaluate spices/essential oils and timing of pasture burning on growing steer gains. 281 steers (292 ± 28 kg) were randomly assigned to one of 8 pasture of tallgrass native prairie in a completely randomized design model. The treatment structure was a 2 x 2 factorial where the first factor was pasture burning date at two levels (March and April) and the second factor was free-choice mineral type (control (CON) or spices (SPICE)). Spices include garlic oil and a 4-spice blend (Solus, Wildcat Feeds LLC, Topeka). Steers were weighed at the start and end of 90 d grazing period. Total gain, average daily gain, and final body weight were evaluated. There was no interaction between burning time and mineral type (P > 0.10) for average daily gain, total gain, nor final body weight. Steers on pastures burned in April had a 0.16 kg/d ADG advantage over burning in March which resulted in 14.3 kg more gain over 90 d (P < 0.0001). Steers on SPICE averaged 0.06 kg/d and gained 5 kg more (P = 0.02) than steers on CON mineral. Burning in April results in greater steer gains than March burning and feeding a mineral with spices increase gains, yet these two are not additive. Addition of SPICE mineral may be one method to allow producers to extend burning window and maintain cattle production.