Palouse Region Of Eastern Washington Research Articles

Evaluating buffer methods for determining lime requirement on acidified agricultural soils of the Palouse

AbstractAcidification of agricultural soils under intense management in the Palouse region of eastern Washington and northern Idaho is of increasing concern. Buffer methods can provide lime requirement estimates (LREs); however, locally calibrated methods are lacking. Our objective was to evaluate buffer methods and to determine which can produce optimal LREs for Palouse agricultural soils. Samples from 10 regionally dominant agricultural soils (initial pH ≤5.3) were assessed for pH changes after incubation with nine levels of calcium carbonate (CaCO3) for 90 d under laboratory conditions. Achieving a target pH of 6 in the top 15 cm of the soil profile required 3.36–8.36 Mg ha−1 of CaCO3. Laboratory incubation results were compared with LREs calculated from 10 established calibrations using data from seven buffer methods: Shoemaker–McLean–Pratt (SMP), Adams and Evans (AE), Woodruff 6, Woodruff 7, Western Region Woodruff 7, Sikora, and Modified Mehlich (MM). The SMP (R2 = .47) and AE (R2 = .56) calibrations demonstrated the lowest correlation with observed incubation lime requirement (LR) and are not recommended for use on Palouse soils. The MM (R2 = .90), Woodruff 6 (R2 = .78), and Woodruff 7 (R2 = .75) buffer calibrations produced the strongest correlation between LREs and the LRs determined by laboratory incubation. Combining organic matter (OM) with KCl‐extractable aluminum (KCl‐Al) or soil pH was also predictive of LR (R2 = .72) in a stepwise multivariate analysis. The recommendation from this study is to assess LR on Palouse soils using the MM buffer or to use soil analytical results and compute LR from OM and KCl‐Al or pH.

Genotype × environment interaction and stability of β‐glucan content in barley in the Palouse region of eastern Washington

AbstractGenotype by environment (G × E) interactions for the dietary fiber β‐glucan, one of the deciding factors for the end use of barley (Hordeum vulgare L.) grain, are not well understood. The objectives of this study were (a) to investigate G × E interactions for β‐glucan content of diverse barley genotypes across dryland grain‐producing environments in eastern Washington, and (b) to determine the range and stability of β‐glucan content exhibited across precipitation zones. We examined 17 two‐row, spring barley varieties and breeding lines across eight locations for β‐glucan, protein, and yield in 2017 and 2018. β‐glucan ranged from 1.81 to 7.18 (%, w/w), with a mean of 4.01 (%, w/w). Genotype × year (Y), G × location (L), L × Y, and G × E (G × L × Y) interactions were found for β‐glucan. Univariate models including the regression model with slope (bi) and deviation from regression (), Wricke's ecovalence stability index (), and Shukla's stability variance () agreed that there was moderate rank stability amongst genotypes. Data generated through this research will provide a better understanding of which cultivars that farmers can grow in their area will meet industry targets and standards for both food and malt barley.

Windrow Burning Eliminates Italian Ryegrass (Lolium perenne ssp. multiflorum) Seed Viability

Windrow burning is one of several harvest weed seed control strategies that have been developed and evaluated in Australia to address the widespread evolution of multiple herbicide resistance in annual weeds. Herbicide-resistant Italian ryegrass populations are common in the Palouse region of eastern Washington and northern Idaho. Field and greenhouse studies were conducted to evaluate the effects of burning standing stubble and narrow windrows on the survival of Italian ryegrass seed on the soil surface and to determine the amount of crop residue remaining after both practices. Italian ryegrass emergence was 63, 48, and 1% for the nonburned check, burned standing stubble, and burned windrow treatments, respectively. Crop-residue dry weights were 9.94, 5.69, and 5.79 Mg ha−1 for these same treatments. Windrow burning can be an effective tactic in an integrated weed management strategy for Italian ryegrass control in the Palouse region of eastern Washington and northern Idaho.

Additional origins of Ownbey's Tragopogon mirus

The allotetraploids (2n = 24) Tragopogon mirus and T. miscellus have become textbook examples of recently and recurrently formed allopolyploids. Both species formed following the introduction of three diploids, T. dubius, T. porrifolius and T. pratensis (each with 2n = 12), from Europe into the Palouse region of eastern Washington and adjacent Idaho, USA, in the early 1900s. The parentage of both allotetraploids is well documented (T. mirus = T. dubius × T. porrifolius; T. miscellus = T. dubius × T. pratensis), and both allotetraploids have formed repeatedly in the past approximately 80 years in the Palouse. On a larger geographical scale, T. mirus has also been reported from Flagstaff, Arizona (AZ), and more recently from Oregon (OR). However, the populations from OR and AZ have not been previously analysed with molecular markers to test the hypothesis of separate origin (vs. long-distance dispersal). Here, we show that both the AZ and OR collections of T. mirus combine distinctive parental genotypes and are genetically differentiated from the T. mirus genotypes found in the Palouse. The OR sample of T. mirus has a genetically distinct T. dubius contribution that forms a clade in our analyses with a sample of what has been referred to as T. major (now considered a subspecies of T. dubius). Consistent with other naturally occurring T. mirus populations, plastid sequences indicate that T. porrifolius was the maternal parent for both the AZ and OR collections. Microsatellite data are also consistent with local formation of T. mirus from co-occurring populations of T. dubius and T. porrifolius in OR and AZ. As with sequence data, T. dubius from OR is distinct from other samples of T. dubius at microsatellite loci, contributing a unique signature to T. mirus from this location. It will be useful to include these additional geographical origins of T. mirus, particularly the more genetically distant sample from OR, in ongoing investigations of the genetic and genomic consequences of recent allopolyploidy. © 2012 The Linnean Society of London, Botanical Journal of the Linnean Society, 2012, 169, 297–311.

Alternative hosts and plant tissues for the survival, sporulation and spread of the Ascochyta blight pathogen of chickpea

Various crop and weed species were infected naturally by Didymella rabiei (anamorph: Ascochyta rabiei) in blight-affected chickpea fields in the Palouse region of eastern Washington and northern Idaho, USA. The fungus was isolated from asymptomatic plants of 16 species commonly found in commercial crops in this region. Isolates of the pathogen from crop and weed species were pathogenic to chickpea and indistinguishable in cultural and morphological characteristics from isolates of D. rabiei from chickpea. Both mating types of D. rabiei were isolated from eight naturally infected plant species. Chickpeas were infected by D. rabiei when plants emerged through infested debris of seven crop and weed species. The teleomorph developed on overwintered tissues of seven plant species infected naturally by D. rabiei in a blight screening nursery and on debris of wheat, white sweet clover and pea inoculated with ascospores of D. rabiei or conidia of two compatible isolates of the pathogen. Didymella rabiei naturally infected 31 accessions of 12 Cicer spp. and the teleomorph developed on the overwintered debris of all accessions, including those of three highly resistant perennial species. The fungus developed on the stem and leaf pieces of ten plant species common to southern Spain inoculated with conidia of two compatible isolates of D. rabiei, and formed pseudothecia with asci and viable ascospores on six of ten species and pycnidia with conidia on all plant species.

Mineralogy of loess and volcanic ash eolian mantles in Pacific Northwest (USA) landscapes

Eolian mantles consisting of Quaternary loess, Holocene volcanic ash, and mixtures of the two are prominent features of most landscapes in the inland Pacific Northwest region of the USA. Soils of the loess-mantled Palouse region of eastern Washington and northern Idaho exhibit regional mineralogical trends related to mean annual precipitation and age. Clay content increases and CaCO 3 decreases from areas of lower to higher precipitation. Clay mica is the dominant clay mineral in soils formed in the youngest loess (ca. < 15 ka). In the next older loess paleosol (ca. 40 ka), vermiculite is dominant, indicating a time-dependent mica-to-vermiculite weathering sequence. Smectite and kaolin also occur to a lesser extent in soils of the region. This mineralogical signature provides a useful tool in identifying paleosols and interpreting the complex pedogenesis occurring in local Palouse landscapes. More recently, Holocene volcanic ash has influenced many mid- and high-elevation forested soils. Relatively thick mantles of volcanic ash from the cataclysmic eruption of Mount Mazama 7600 years ago have undergone slight-to-moderate weathering, giving rise to Andisols (Andosols). Environmental conditions generally promote development of allophanic properties across the region, with allophane and ferrihydrite being dominant mineral components. Non-allophanic mineralogy is much less extensive in ash mantles of the region, but is favored in two pedogenic environments — E horizons of podzolized soils and horizons supporting vigorous growth of bracken fern.

Soil Quality and Water Intake in Traditional‐Till vs. No‐Till Paired Farms in Washington's Palouse Region

Many farmers in the steeply sloped Palouse region of eastern Washington and northern Idaho practice no‐till (NT) farming. Soil quality and water intake parameters were assessed in standing wheat (Triticum aestivum L.) stubble along summit, side, and toe‐slope positions in a 2‐yr study at three paired‐farm sites using traditional tillage (TT) vs. NT management. Paired sites had similar south‐facing aspect, slopes ranged from 29 to 45%, and NT fields had not been tilled from 2 to 20 yr. Soil aggregates &gt;1000 μm were 5.4 to 9.8% higher in NT compared with TT. Soil organic carbon (SOC) in NT was 30% greater than in TT at the toe‐slope position. Dehydrogenase enzyme activity (DEA) was higher in TT, mainly due to the exposed CaCO3 layer at the side‐slope position and higher pH of TT. Phospholipid fatty acid methyl ester (PLFA) analysis showed that fungal biomarkers were higher and Gram positive and Gram negative biomarkers were lower in NT compared with TT. There were no differences in over‐winter soil water storage or ponded water infiltration rate in undisturbed standing wheat stubble between TT and NT, indicating soils that produce high wheat grain yield of 6 Mg ha−1 or more have similar water intake regardless of tillage history as long as the stubble is left standing over winter. Results show long‐term cumulative benefits of NT vs. TT on soil quality, but no differences in soil water intake when stubble is left standing over winter, possibly due to the high quantity of wheat root channels produced in both systems.

Pea Aphid Outbreaks and Virus Epidemics on Peas in the US Pacific Northwest: Histories, Mysteries, and Challenges

This review documents the history of pea aphid outbreaks and epidemics of pea aphid-transmitted viruses on peas in the Pacific Northwest, with emphasis on outbreaks and epidemics in the Palouse region of eastern Washington over 23 years. This article will enable researchers and industry leaders to target resources to areas requiring more research for better understanding of pea aphid-host plant-virus relationships in the Pacific Northwest. Accepted for publication 3 August 2006. Published 18 October 2006.

Subsoil ridge tillage and lime effects on soil microbial activity, soil pH, erosion, and wheat and pea yield in the Pacific Northwest, USA

Soil erosion and the gradual acidification of soils are two major obstacles limiting crop productivity in the Palouse region of eastern Washington and northern Idaho. New tillage practices that replace the traditional moldboard plow are needed to maintain more surface cover to reduce erosion. Two tillage systems and lime were compared at two locations on silt loam soils. Treatment combinations were two levels of tillage (subsoil ridge till (SSRT) and plowing) and two levels of lime (0 and 2.68 Mg ha −1). Crop rotations were barley ( Hordeum vulgare L.)–pea ( Pisum sativum L.)–wheat ( Triticum aestivum L.) at both sites in the US that receive 500–560 mm precipitation annually. Tillage and lime options were implemented after barley stubble and studied for 2 years. Microbial biomass, respiration, and dehydrogenase enzyme activity were enhanced at the Washington site under SSRT because of the initially higher residue levels and because residues were maintained at or near the soil surface compared to plowing. Liming increased soil pH and respiration and maintained microbial biomass at about 100 ug C g −1 higher than for the unlimed plots at the end of 2 years. Soil moisture increased under SSRT at some profile depths. Pea seed yield at the Washington site and wheat yield at the Idaho site were significantly higher for SSRT compared to plowing. Lime significantly increased wheat yield only at the Washington site. Significantly higher surface residue was maintained during the study period from SSRT compared to plowing which contributed to lower rates of soil erosion in winter wheat 30 months after plot establishment. At the Washington site, surface residue levels were 20% in spring of 1992 for SSRT compared to less than 1% for plowing. One year later, soil erosion under winter wheat in spring of 1993 was 1.3 Mg ha −1 for SSRT compared to 8.4 Mg ha −1 for plowing. In general, the higher surface residue maintained under SSRT increased microbial activity, maintained higher surface residue, and reduced erosion in winter wheat, the vulnerable phase in the crop rotation for erosion.

Socioeconomic Growth, Culture Scale, and Household Well‐Being

Socioeconomic growth is an elite‐directed process that concentrates social power in direct proportion to increases in culture scale. Power elites have controlled social power to their own advantage in at least three different ways: domestically, by means of kinship, politically, by means of rulers, and commercially, by means of the market. Each method produces its own growth trajectory and scale of culture and a distinctive distribution of elite power and household living standards. Ethnographic data on urban property ownership in 27 municipalities in the Palouse region of eastern Washington suggest that when power is commercially organized and villages become towns and cities, there is a dramatic increase not only in the number of prosperous households but even more in the number of poor and maintenance‐level households. Elite property owners, who most benefit from growth, assume a larger role in municipal government, where they can encourage further growth through municipal annexations and zoning changes. Thus, as elite power becomes increasingly concentrated, the growth process itself tends to become self‐perpetuating. In the Palouse example, small, no‐growth municipalities appear to be politically more democratic than larger‐scale, growing municipalities and household well‐being in them more equitably distributed.

Socioeconomic Growth, Culture Scale, and Household Well-Being: A Test of the Power-Elite Hypothesis

Socioeconomic growth is an elite-directed process that concentrates social power in direct proportion to increases in culture scale. Power elites have controlled social power to their own advantage in at least three different ways: domestically, by means of kinship, politically, by means of rulers, and commercially, by means of the market. Each method produces its own growth trajectory and scale of culture and a distinctive distribution of elite power and household living standards. Ethnographic data on urban property ownership in 27 municipalities in the Palouse region of eastern Washington suggest that when power is commercially organized and villages become towns and cities, there is a dramatic increase not only in the number of prosperous households but even more in the number of poor and maintenance-level households. Elite property owners, who most benefit from growth, assume a larger role in municipal government, where they can encourage further growth through municipal annexations and zoning changes. Thus, as elite power becomes increasingly concentrated, the growth process itself tends to become self-perpetuating. In the Palouse example, small, no-growth municipalities appear to be politically more democratic than larger-scale, growing municipalities and household well-being in them more equitably distributed.

Multiple independent formations of Tragopogon tetraploids (Asteraceae): evidence from RAPD markers

Polyploidy is widely recognized as a significant force leading to the formation of new plant species. Estimates of the number of angiosperm species with polyploid origins are as high as ≈ 50%; however, in spite of this prevalence, many aspects of polyploid evolution remain poorly understood. Recent studies have suggested that recurrent origins of polyploid species are the rule rather than the exception. The present study is one of only a few designed to quantify the number of independent origins of a polyploid species. The two tetraploid species Tragopogon mirus and T. miscellus (Asteraceae) arose within the past 50 years in the Palouse region of eastern Washington and adjacent northern Idaho. Previous work using morphology, cpDNA and rDNA restriction site analyses, allozymes, cytology, and flavonoid chemistry established that T. mirus had arisen at least five times, and T. miscellus at least twice, on the Palouse. To assess the frequency of multiple origins of these species more rigorously, seven populations of T. mirus and three populations of T. miscellus that were indistinguishable based on previous markers were surveyed using random amplified polymorphic DNA (RAPD) markers; populations of the diploid progenitor species from the same sites were also analysed. Each tetraploid population had a unique RAPD marker profile, suggesting that each population surveyed originated independently of the other populations in the region. Only two of the tetraploid populations combined the RAPD marker profiles of the diploid progenitors occurring at the same site. Both polyploid species, whose ranges and numbers have greatly increased since their formation in the early part of the twentieth century, have formed repeatedly on a local geographical scale and during a short time frame. Furthermore, each tetraploid species is spreading not primarily by dispersal of propagules from a single population of origin, but through repeated, independent polyploidization events that recreate the polyploid taxa.

Seed Yield and Residue Production of Lentil Cultivars Grown at Different Slope Positions

The presence of crop residue on the soil surface is important in controlling soil erosion, but residue amounts from lentil (Lens culinaris Medik.) are often insufficient to control soil erosion during subsequent phases of the cereal-grain legume cropping systems of the U.S. Pacific Northwest. To gain knowledge of residue production by lentil in typical production environments, six lentil cultivars were grown at four slope positions in southeastern Washington over 3 yr. Residue and seed production varied significantly among cultivars and slope positions (P < 0.01). Total residue production ranged from four to 20 times the 290 lb/acre required by conservation standards, however, the amount remaining after sowing of the subsequent winter wheat (Triticum aestivum L.) crop was much less, indicating that large losses occurred during harvesting and tillage operations. On lower slope positions, grain and residue yields were inversely correlated for all cultivars. On upper slope positions, grain yields were nearly constant among cultivars, but ‘Laird’ produced an average of 42% more residue than ‘Brewer’. No single cultivar met yield and residue production criteria across all landscape positions. Growers can improve erosion control by site-specific sowing of high-residue cultivars such as Laird. Breeding programs should consider the differences in the upper and lower slope positions for seed and residue production when selecting for cultivars with improved biomass production. Research Question Surface residue is a very important factor in preventing erosion on the steep slopes in the Palouse region of the Pacific Northwest. Lentils produce relatively small amounts of residue compared with wheat and other small grains and, in order to maintain sustainable farming systems in the region, this study was undertaken to identify lentil cultivars that produce large amounts of residue across a wide range of slope positions. Literature Summary The soils on the rolling hills of the Palouse region of eastern Washington, northern Idaho, and northeastern Oregon are becoming increasingly eroded. Soils on these slopes vary considerably in type and productivity. In general, the upper slope positions are less productive than the lower slope positions due to poorer soil types caused by erosion, leaching of nutrients, and reduced moisture content. Ironically it is the upper slope positions that are in greatest need of residue, however they are the positions that have the lowest potentia1 for residue production. In order to meet regulations regarding minimum surface residue levels set up by the Natural Resource Conservation Service, many fmers have incorporated tillage practices that leave a rough soil surface over the winter while others are eliminating lentil from their rotations altogether. Eliminating lentil from the current rotations could be quite detrimental to the small grain crops, since lentil crops return N to the soil and break up disease cycles. In order to make it more equitable for the farmer, lentil cultivars that produce high levels of residue in the poorer, upper slope positions must be identified. Study Description This study involved growing six lentil cultivars at the four main slope positions (topslope, backslope, footslope, and toeslope) determining their production potential at each. The experiment was conducted at three different locations over 3 yr (1984, 1985, and 1986). Samples of the mature crop were harvested from a 4 ft segment of the middle two rows in each plot. Total biomass, seed, and residue yields were recorded for each cultivar and harvest index was calculated by dividing seed yield by total biomass yield. Applied Questions How can lentil residues be increased to a sufficient level on the upper slope positions to significantly reduce erosion? This may be accomplished through site specific farming. Farmers would grow high residue producing cultivar on the upper slope positions while growing a cultivar that produced less residue on the lower positions. One caution with thi approach is that the two cultivars have to mature at nearly the same time. Often the crop on the upper positions will mature earlier than those on the lower posi tions due to lower moisture reserves. Can future cultivars be developed to produce adequate levels of residue? Lentil breeding programs should consider using residue production as a selection criteria when developing new cultivars. Recommendation Growers may consider site specific farming where a cultivar producing large amounts of residue are planted on the upper slope positions while a cultivar producing less residue could be planted on the lower slope positions where smaller amounts are needed.

Thermoluminescence dating of late Pleistocene loess and tephra from eastern Washington and southern Oregon and implications for the eruptive history of Mount St. Helens

The first numeric dating of late Pleistocene loess from the Palouse region of eastern Washington is reported. This loess is interbedded with thin, distal tephra layers, some identified as Mount St. Helens products. Both the interbedded tephra layers and thick paleosols that have developed in the loess have previously been correlated across the region. A thicker correlative of one of these tephra layers (Mount St. Helens set C) was collected from Summer Lake, Oregon, for direct dating by thermoluminescence (TL). Polymineral, fine grain TL ages for loess from three chosen sections in Washington range from 17 to 83 ka. These imply ages for some tephra beds that are significantly older than implied by earlier radiocarbon (14C) dating. For example, TL ages of 17–21 ka for loess bracketing a tephra layer correlated to Mount St. Helens set S suggests a somewhat older age for this ash than the previously accepted 14C age of ∼15.5±0.5 ka cal yr (corrected to calendar years). TL ages of 46±6 (1σ) ka and 57±7 ka for loess above, and of 53 ± 7 ka and &lt;75±6 ka below a tephra bed correlated to a Mount St. Helens set Cw layer, along with a TL age of 46±5 ka for fine‐silt‐sized glass from a Mount St. Helens set Cy bed in Oregon, revise upward from ∼38 ka cal yr (14C age is ∼36 ka B.P.) to ∼50 ka the age of this regionally important marker ash set. Several TL ages, taken together, imply a much longer eruptive history for Mount St. Helens than previously thought. A TL age of 83±8 ka just below a previously undated tephra layer from Mount St. Helens (EMSH ash) suggests that the eruptive history of the mountain extends back to at least 80 ka. Furthermore, age depth extrapolation through our sections to an ash (WA‐5C) probably correlated to Mount St. Helens suggests an eruptive history of at least 120 ka.

Varying Winter Wheat Seeding Rates among Landscape Positions

Recent research in the Palouse region of eastern Washington has suggested that traditional seeding rates may not be adequate to maximize winter wheat (Triticum aestivum L.) yield on all landscape positions. Low spike densities due to reduced light intensities, longer snow cover, and cool temperatures result in lower than expected yields on north-backslope (N-backslope) landscape positions. The objective of this experiment was to determine if higher seeding rates could increase spike density and yield. Three seeding rates, 1.0X standard grower rate (1.0X), 1.5X standard rate (1.5X), and 2.0X standard rate (2.0X), were tested on toeslope, south-backslope (S-backslope), shoulder, and N-backslopes at two locations, Farmington and Pullman, WA, in 1992 and 1993. The 1.5X and 2.0X treatments were established with an additional seeding operation perpendicular to the 1.0X drill passes. Increasing seeding rates resulted in greater spike density on all landscape positions. Spike density of wheat seeded at the 2.0X rate was from 11% greater on the S-backslope to 24% greater on the N-backslope in comparison with the 1.0X rate. Yield, however, only increased on the N-backslope with wheat seeded at the 2.0X rate yielding 10.3% more than wheat seeded at the 1.0X rate. On the three other landscape positions, a reduction in kernel number per spike resulted in no yield increase. Based on expected costs, the 2.0X seeding rate would increase net return on the N-backslope by $2.35/acre given $3.55/bu wheat. Research is needed to determine if similar yield increases could be achieved without making a perpendicular drill pass to double the seeding rate, which would increase net returns by $13.23/acre.

Winter Wheat Yield and Grain Protein across Varied Landscape Positions

AbstractWinter wheat (Triticum aestivum L.) yield varies greatly among landscape positions in the Palouse region of eastern Washington, yet N fertilizer is typically applied uniformly. Varying N fertilizer rates within fields to match site‐specific N requirements can increase fertilizer use efficiency; however, spatially variable N management programs are limited by their ability to predict site‐specific yield potentials and the resultant N requirements. The objective of this study was to ascertain the role of yield components and soil properties in determining soft white winter wheat grain yield and protein when N application rates are varied among landscape positions. Nitrogen fertilizer (0 to 140 kg N ha−1) was fall‐applied on footslope, south‐backslope, shoulder, and north‐backslope landscape positions at each of two farms in 1989 and in 1990. Grain yield among landscapes varied by up to 55% in 1990 and by up to 33% in 1991. Landscape position grain yields increased by 199 kg ha−1/(cm precipitation + soil water reduction) (r2 = 0.51) and by 706 kg ha−1 per 100 spikes m‐2 (r2 = 0.76). Grain protein concentration among landscapes increased by 2.7 g kg−1 per each increase of 10 kg residual soil NO3−N ha−1 (r2 = 0.82). The large differences in grain yield among landscape positions may justify spatially variable N application. Improved N management should favorably reduce soft white winter wheat protein concentrations by minimizing high residual N levels as well as improve net returns and reduce environmental degradation. The basis for this improved N management may be site‐specific yield estimates calculated from soil water availability and spike density.

Chickpea Wilt Incited by Pea Streak Carlavirus

Pea streak carlavirus (PSV) incited a widespread wilting and yellowing disease of chickpea (Cicer arietinum) in commercial and experimental plantings in the Palouse region of eastern Washington and northern Idaho. Incidence of PSV usually ranged from 0.5 to 5%. Experimental host ranges of several Palouse PSV isolates were confined to the Fabaceae and one species of Amaranthaceae. Systemic necrosis developed in chickpea, lentil (Lens culinaris), pea (Pisum sativum), fenugreek (Trigonella foenum-graecum), and faba bean (Vicia faba), while alfalfa (Medicago sativa), white sweet clover (Melilotus alba), and hairy vetch (Vicia villosa subsp. villosa) were symptomless carriers of PSV

A comparison of winter wheat yield and quality under uniform versus spatially variable fertilizer management

The Palouse region of eastern Washington, USA is characterized by steep, highly erodible hills with complex patterns in soil fertility and crop productivity. Because of these patterns, there is increasing interest in applying variable, rather than uniform rates of fertilizer across the landscape. This study was conducted to determine the yield and quality of wheat at several different positions on landscapes managed with uniform vs. variable rates of nitrogen and phosphorus fertilizer. A moderately to severely eroded wheat farm in summer fallow management near St. John, Washington was intensively sampled at intervals of 15 m along several transects 655 m long and separated by 122 m. Each transect crosses a wide range of landscape position, and a variety of soil fertility and crop productivity regimes. Maximum slope steepness along the transects reached 45%, although flat portions also existed. Along the south side of each transect, fertilizer was applied at a uniform rate according to the grower's typical practice (73 kg N ha −1 and 6 kg P ha −1). Along the north side, the transects were separated into three management zones that received different rates of nitrogen and phosphorus fertilizer applications to match the existing soil fertility and crop productivity patterns. The three variably fertilized management zones received 22 kg N ha −1 and 6 kg P ha −1 (Zone 1), 90 kg N ha −1 and 6 kg P ha −1 (Zone 2), and 22 kg N ha −1 and 18 kg P ha −1 (Zone 3). Yield and quality of wheat were measured in both the uniform and variable management strips at intervals of 15 m. In spite of applying 51 kg N ha −1 less in management Zones 1 and 3 than in the adjacent uniformly fertilized strip, there were no significant differences in yield of wheat in any management zone between the variably and the uniformly fertilized strips. Grain yield was significantly different between the three fertilizer management zones, with measured yields of 4097 kg ha −1 (Zone 1), 4501 kg ha −1 (Zone 2), and 3339 kg ha −1 (Zone 3). These differences are largely due to differences between each zone in available water content and nitrate nitrogen in the profile. Protein content of wheat was significantly lower in variably fertilized strips than in uniformly treated strips, leading to significant improvements in grain quality. The parts of the landscape with the lowest available water content in the profile had the highest grain protein content due to water stress-nitrogen interactions.

Fungi Associated with the Seeds of Commercial Lentils from the U.S. Pacific Northwest

Seeds of commercial lentils (Lens culinaris) from the Palouse region of eastern Washington and northern Idaho were sampled for pathogenic seedborne fungi during 1982-1985. Ascochyta fabae f. sp. lentis, Botrytis cinerea, Fusarium acuminatum, F. avenaceum, Macrophomina phaseolina, Phoma medicaginis var. pinodella, Rhizoctonia solani, and Sclerotinia sclerotiorum were isolated. B. cinerea and P. m. pinodella were isolated most frequently (.)

OWNBEY'S TRAGOPOGONS: 40 YEARS LATER

Two of the classic examples of recent allopolyploid speciation are Tragopogon mirus and T. miscellus. Previous studies have documented that both allotetraploids originated within the past 50–60 years; the diploid parents of T. minis are T. dubius and T. porrifolius; those of T. miscellus are T. dubius and T. pratensis. It has now been 40 years since these allotetraploids were first described by Ownbey in 1950. To assess whether population size (the absolute number of plants) and population number of these species have changed during the past 40 years, we determined their distribution and numbers in the Palouse region of eastern Washington and northern Idaho in the spring of 1990. We visited 90 localities, 60 in Washington and 30 in Idaho. Tragopogon minis is found in nine locations, with eight of these sites located in eastern Whitman County, Washington. Tragopogon miscellus is much more widespread, occurring in 38 of 90 locations. The latter species is now one of the most common weeds in the vicinity of Spokane, Washington. Comparison of the current distributions of these species with historical records indicates that both allotetraploids, especially T. miscellus, have increased substantially in both geographic range and numbers. These Tragopogon species offer an excellent model system for testing questions concerning the ecology and population biology of recently derived allotetraploid species and their diploid progenitors.