Reduction In Forage Yield Research Articles

Acceptable Salinity Level for Saline Water Irrigation of Tall Wheatgrass in Edaphoclimatic Scenarios of the Coastal Saline–Alkaline Land around Bohai Sea

Saline water irrigation contributes significantly to forage yield. However, the acceptable salinity levels for saline water irrigation of tall wheatgrass remains unclear. In this study, field supplemental irrigations of transplanted-tall wheatgrass with saline drainage waters having salinities of electrical conductivity (ECw) = 2.45, 4.36, 4.42, and 5.42 dS m−1 were conducted to evaluate the effects of saline water irrigation on forage yield and soil salinization. In addition, the effects of plastic film mulching, fertilization, and saline water irrigation on sward establishment of seed-propagated tall wheatgrass were determined. Finally, a pot experiment was carried out to confirm the above field results. The results showed that two irrigations with ECw = 2.45 and 4.36 dS m−1 saline waters produced the highest dry matter yield, followed by one irrigation with ECw = 4.42 or 5.42 dS m−1. After rainfall leaching, the soil EC1:5 was reduced by 41.7–79.3% for the saline water irrigation treatments. In combination with saline water irrigation, plastic film mulching promoted sward establishment and enhanced the plant height and dry matter yield of seed-propagated tall wheatgrass, while fertilization played a marginal role. However, two irrigations with ECw = 7.13 and 4.36 dS m−1 saline waters resulted in rates of 3.2% and 16.0% of dead plants under the mulching and no mulching conditions, respectively. Furthermore, a pot experiment demonstrated that irrigation with ECw = 5.79 dS m−1 saline water led to the lowest reduction in forage yield and the highest crude protein content in leaves. However, the plants irrigated with ECw ≥ 6.31 dS m−1 saline water enhanced soil salinity and reduced the plant height, leaf size, and gas exchange rate. Conclusively, one irrigation with ECw ≤ 5.42 dS m−1 and SAR ≤ 36.31 saline water at the end of April or early May could be acceptable for tall wheatgrass production and minimize the soil salinization risk in the coastal saline–alkaline land around the Bohai Sea.

Enhancing resource use efficiency of alfalfa with appropriate irrigation and fertilization strategy mitigate greenhouse gases emissions in the arid region of Northwest China

With the increasing global warming concerns, appropriate agronomic practices for improving crop yields while reducing greenhouse gases (GHGs) emissions are essential for sustainable agricultural production. However, little information is available if these benefits can be achieved simultaneously in arid pastoral agriculture systems with irrigation and nitrogen (N) management. We assumed that the local practiced irrigation (600 mm) and N (300 kg ha −1 ) applications for spring wheat in the arid regions of Northwest China are excessive, and optimizing irrigation-N rates would improve the resource use efficiency of alfalfa and reduce GHGs emissions. A two-year field study (2015–2016) was conducted to investigate the effects of irrigation regimes (I L , 300 mm; I M , 450 mm; and I H , 600 mm) and N application rates (F 0 , 0; F L , 150; F M , 225; and F H , 300 kg ha −1 ) on forage yield, resource use efficiency, and GHGs emissions from alfalfa fields. The GHGs emissions during alfalfa growing seasons were assessed by analyzing gas samples using the static chamber-gas chromatography method. High irrigation and N application (I H F H ) was associated with elevated GHGs emissions, global warming potential, and greenhouse gas intensity, but lower irrigation water productivity (IWP) and partial factor productivity of N (PFP N ). Reducing the irrigation and N rates decreased the GHGs emissions but differently affected alfalfa yield and resource use efficiencies. Among all the treatments, I M F L and I H F L resulted in the highest alfalfa yields, IWP, and PFP N . However, I M F L showed a good trade-off between yield benefits and environmental performance manifested by lower GHGs emissions, GWP, and GHGI. The I M F L reduced the cumulative emissions of nitrous oxide by 67.83% and 67.16%, carbon dioxide by 31.05% and 34.60%, GWP by 61.72% and 70.40%, and GHGI by 74.37% and 79.78%, while increased alfalfa yield by 49.24% and 46.45%, IWP by 99.05% and 94.97%, and PFP N by 198.44% and 192.90% compared to I H F H . Regardless of all the treatments, the alfalfa field acted as a CH 4 sink during both crop-growing seasons. Our results suggest that the application of 450 mm irrigation and 150 kg N ha −1 could be used as an appropriate management strategy for enhancing resource use efficiencies and mitigating GHGs emissions, GHGI, and GWP from alfalfa fields. The findings can provide an opportunity for greenhouse gas mitigation without alfalfa forage yield reduction following the proper irrigation and fertilization regimes in the arid region of northwest China and areas with similar agro-climatic conditions. • Intensive irrigation and fertilization increase GHGs emissions and global warming potential. • Enhancing resource use efficiency with suitable irrigation and N rates mitigate GHGs emissions. • Soil moistures and inorganic N contents are the major factors regulating GHGs emissions. • 450 mm irrigation and 150 kg N ha –1 maintain high alfalfa yields and minimize environmental impacts.

Spatial Distribution of Highland Cattle in Alnus viridis Encroached Subalpine Pastures

Green alder (Alnus viridis) is a shrub species that has expanded over former pastures in Central Europe due to land abandonment, leading to negative agri-environmental impacts, such as a reduction in forage yield and quality and an increase in nitrate leaching. Robust livestock breeds such as Highland cattle could be used to control A. viridis encroachment. The objectives of this study were to investigate the impact of A. viridis encroachment on plant community composition and diversity and to map the spatial distribution of Highland cattle in A. viridis-encroached pastures. During the summer of 2019, three different Highland cattle herds were placed along an A. viridis encroachment gradient. A total of 58 botanical surveys were carried out before grazing to assess plant community composition, pastoral value, and ecological indicator values. The spatial distribution of cattle was studied during the whole grazing period by monitoring six to eight cows equipped with GPS collars in each herd. Plant species associated with higher pastoral values of the vegetation were found in areas with lower A. viridis cover, while highly encroached areas were dominated by a few nitrophilus and shade-tolerant broad-leaved species and by ferns. Cattle spent more time in areas with higher pastoral value but did not avoid areas with high cover of A. viridis, on steep slopes or far from water. These results show that Highland cattle are able to tolerate harsh environmental conditions and that they can exploit A. viridis-encroached pastures. This suggests that they have a high potential to reduce A. viridis encroachment in the long-term.

Salicylic Acid Counteracts Aluminum Stress-induced Growth and Biomass Yield Reduction in <i>Medicago sativa</i> L.

Salicylic acid (SA) is an essential plant growth regulator that functions as a signaling molecule in plants. The purpose of this study was to clarify how the exogenous application of SA counteracts aluminum stress-induced growth and biomass yield reduction in alfalfa exposed to aluminum (Al) stress. Two-week-old alfalfa seedlings were exposed to a combination of AlCl3 (0 μM, 50 μM and 100 μM, respectively) and SA (0.1 mM) for 72 hours. We observed, Al stress-induced plant growth inhibition and forage yield reduction are Al stress-dependent manner. A significant reduction of plant height (42.0-52.9%), leaf relative water content (13.0-21.4%), root length (35.4-48.7%), shoot fresh weight (31.2-25.9%), root fresh weight (15.4-23.3%), shoot dry weight (12.7-22.2%), roots dry weight (47.3 -53.5%), were observed in alfalfa. In contrast, SA alleviated the Al-stress and enhanced growth and biomass yield in alfalfa. This study provides useful information concerning the role of SA that counteracts aluminum stress-induced growth and yield reduction in alfalfa.

Effect of irrigation with detergent-containing water on foxtail millet shoot biomass and ion accumulation.

Water shortage leads farmers to use sewages for irrigation. Sewages contain a large amount of laundry detergent. In this study the impact of irrigation by contaminated water on shoot biomass and seed germination of foxtail millet (Setaria italica) was investigated. The research was conducted as laboratory and pot experiments. Iso-potentials (- 0.042, - 0.077, and - 0.415MPa) of polyethylene glycol (PEG, water deficit treatment) and laundry detergent (contamination treatment) made the laboratory experiment treatments. The pot experiment included contamination factor (0, 0.1, 1, and 10gL-1 of laundry detergent) and deficit irrigation factor (irrigation interval of 1, 2, and 3days). Results of this study showed that at the iso-potential, laundry detergent had more negative effect on seed germination traits when compared with PEG. There was no germination at - 0.415MPa of laundry detergent. Both drought and contamination reduced dry forage yield, plant height, leaf number, leaf area, leaf dry and fresh weight, stem dry, and fresh weight. Detergent concentration of 10gL-1 with irrigation interval of 3days had a forage yield reduction of 63% compared to control (laundry detergent concentration of 0gL-1 with irrigation interval of 1day). Detergent concentration of 10gL-1 with irrigation interval of 1day had a sodium increase of 1847% compared to control. Based on the results of this study, it is recommended not to irrigate foxtail millet farm by contaminated water with laundry detergent higher than 1gL-1.

Sparse‐Flowering Orchardgrass is Stable Across Temperate North America

ABSTRACTOrchardgrass (Dactylis glomerata L.) is a major component of many pastures in temperate North America. Early and profuse flowering in pastures is problematic due to livestock refusal to consume flowering stems. The objective of this research was to determine the stability and agronomic impact of recently developed sparse‐flowering orchardgrass populations across temperate North America. Six cultivars, three sparse flowering and three normal flowering, were grown at 21 locations in temperate North America and evaluated for panicle density, heading date, and forage yield. Sparse‐flowering cultivars had 57% fewer panicles than normal‐flowering cultivars, but this effect was highly dependent on mean winter temperature, with normal‐flowering cultivars showing twice as much temperature sensitivity compared to sparse‐flowering cultivars. Forage yield of sparse‐flowering cultivars was reduced by approximately 24 to 32% for first harvest and 2 to 9% for regrowth harvests compared to normal‐flowering cultivars and this reduction in forage yield was independent of mean winter temperature. The forage yield reduction associated with sparse flowering is most likely due to a combination of physiological load (loss of stems) and opportunity cost (lack of selection pressure for yield), suggesting an opportunity to improve forage yield potential of this sparse‐flowering germplasm pool.

Reduced dairy grassland yields in Central Norway after a single springtime grazing event by pink‐footed geese

AbstractPopulations of migratory geese overwintering in Europe have risen rapidly during recent decades, leading to increased pressure on available forage resources and more grazing on agricultural lands. Farmers throughout Europe have complained of yield losses due to goose grazing. In spring, the Svalbard‐breeding population of pink‐footed goose (Anser brachyrhynchus) migrates through specific staging sites in Norway, where the geese graze on dairy grasslands and other types of agricultural lands in the early growing season. Despite this, little is known of the impacts of goose grazing on hay biomass and quality in Norway. An experiment using exclosures to prevent goose grazing, and plots that were open for grazing, was established in Central Norway to test the effects of variable grazing intensity on dairy grassland yields. A single spring‐grazing event had severe negative impact at the site with the highest grazing intensity, leading to a 25% reduction in forage yield (milk feed units per hectare) as compared to ungrazed areas. The impacts on the sites with lower grazing intensity were more subtle. The overall reduction (across all sites) of biomass yield was 26%. Forage quality, in terms of milk feed units per kg, was not much affected. Grazing increased the proportion and diversity of weeds, as evidenced by a 49% increase of the Shannon biodiversity index, and there was a 1·3% decrease in the proportion of herbage biomass of sown species. Hence, we have confirmed farmer reports on yield losses, gaining an increased understanding of the overall farmer costs associated with goose grazing in this northern latitude region.

Drought-tolerance indices in a tall fescue population and its polycross progenies

Development of drought-tolerant cultivars is hampered by a lack of effective selection criteria. In this research, drought tolerance of 75 genotypes of tall fescue in three sets (25 parental, 25 early, 25 late-flowering progenies) was evaluated under no soil moisture stress and soil moisture stress in the field during 2009 and 2010. Five drought-tolerance indices were calculated: stress tolerance (TOL), mean productivity (MP), geometric mean productivity (GMP), stress susceptibility index (SSI), and stress tolerance index (STI). These calculations were based on forage yield (dry matter basis) under drought (Ys) and non-drought (Yp) conditions. Soil moisture stress caused significant reduction in forage yield. Considerable genetic variation for drought tolerance was found among genotypes. A moderately high relationship was found between Yp and Ys using regression analysis, with a clear relationship in the second year. Indices GMP and STI were found to be valuable aids in the selection of drought-tolerant, high-yielding genotypes. Plots of the first and second principal components identified drought-tolerant genotypes in each set. Results indicated that selection for drought-tolerant genotypes should be planned separately for first year (establishment stage) and second year (productive stage) in tall fescue.

Improving nitrogen and irrigation water use efficiency through adaptive management: A case study using annual ryegrass

Nitrogen is often poorly managed in irrigated agro-ecosystems. Accumulation and leaching of N can occur due to excessive fertiliser N, high soil inorganic N carryover between seasons, rapid mineralisation in spring and poor irrigation scheduling. This can reduce forage yield, quality and N-use efficiency, and lead to pollution of soil and water resources. Experiments were conducted to test whether adaptive nitrogen and irrigation management approaches using ryegrass as a case study could (1) reduce N application without compromising yield, (2) maintain or improve forage quality, (3) improve water use efficiency, and (4) minimise potential for nitrate leaching, using the current local recommended fertiliser rates as a baseline. Adaptive management strategies based on the concentration of nitrate measured in a wetting front detector at different depths reduced fertiliser N application by 28–32% compared to the baseline recommendation, reduced residual soil N that is potentially leachable, and improved forage quality without reduction in forage yield. The essence of the adaptive approach is to set thresholds for action that are relatively easy to monitor, based on a simple conceptualisation of the system. The thresholds were defined for the depth that a strong wetting front could be passively detected under field conditions, and for the concentration of nitrate in the percolating water. These thresholds were chosen as simple integral measures of the water and N cycles. Results suggest that a good adaptive manager would improve the thresholds for action as more experience is gained.

Arbuscular mycorrhizal fungi and nematodes are involved in negative feedback on a dual culture of alfalfa and Russian wildrye

The complex biological interactions taking place in soil–plant systems may sometimes alter the functioning of an ecosystem. We examined the relationship between arbuscular mycorrhizal (AM) root colonization, nematode populations, and plant competition in an 8-year-old field experiment comparing alfalfa monoculture to dual culture of alfalfa ( Medicago sativa L.) and Russian wildrye ( Psathyostachys juncea Fisch. Nevski) (RWR) grown under different soil P fertility levels, in a Brown Chernozemic soil in Saskatchewan. The experiment included three P rates: 0, 20 and 40 kg P 2O 5 ha −1 (0P, 20P and 40P) applied annually and was sampled three times during the cropping season: 30 June, 1 September and 30 September. Higher AM symbiotic development compensated for reduced soil P fertility in alfalfa stands without RWR and forage dry matter yield was not affected by P rates. But in the presence of RWR, reduced soil P fertility at 0P and 20P led to forage yield reduction. Fertilization treatments modified the soil microbial community structure only in the presence of RWR, as revealed by discriminant analysis of the profiles of microbial phospholipids fatty acid in soil lipid extracts and functional nematode groups. Arbuscular mycorrhizal root colonization level was reduced with P fertilizer both in the presence and absence of RWR. In the presence of RWR, lower plant AM root colonization was concurrent with higher abundance of total, fungivorous and omnivorous nematodes. Our results are consistent with a model of negative feedback from the plant-associated soil microflora where the presence of RWR increased the population of fungivorous nematodes and grazing of AM hyphae. Negative impacts were larger in low P fertility soils promoting AM symbiotic development. The unexpected decrease in alfalfa–RWR dual culture yield under 0P and 20P fertilization levels was attributed to a carbon drain created by enhanced nematode feeding on AM fungi in the presence of RWR.

Considerations Related to Richardson's Ground Squirrel (Spermophilus richardsonii) Control in Montana

Alfalfa (Medicago sativa L.) production is limited in Montana due to activities associated with Richardson's ground squirrels (Spermophilus richardsonii), and control is often considered to be cost prohibitive. This study was conducted to document the economic impact of ground squirrel activities on alfalfa yield and demonstrate field efficacy of available toxicants. Montana alfalfa producers completed a survey to determine perceived severity and losses due to ground squirrels. Actual first‐harvest forage yield losses were determined at two locations in southwest Montana in 2003 and 2004 using cage exclosures. Chlorophacinone (Rozol), diphacinone (Ramik‐Green), and zinc phosphide were administered at two locations to determine the efficacy of each treatment. Survey results across Montana indicate alfalfa producers estimate a 24% average reduction in forage yield in areas known to be infested with ground squirrels. First‐cut forage yields were reduced by 31% in southwest Montana. Rozol was the most effective control agent (84% efficacy) while Ramik‐Green was the least effective control agent in our trials (29% efficacy). Landowner perceptions of ground squirrel damage are similar to actual yield reduction and possibly underestimated. The costs associated with the control of ground squirrels can be quite high, and caution must be exercised when implementing a new control program to assure these costs are offset by forage gained.

Companion crop establishment of short-lived perennial forage crops in Saskatchewan

Short-lived perennial forages may provide producers with a cash hay crop as a viable option to diversify annual grain rotations. Little or no information on alternative annual crops for companion crop establishment of forages is available for Saskatchewan conditions. We evaluated field pea (Pisum sativum), canola (Brassica napus), and Westerwolds ryegrass (Lolium westerwoldicum) as companion crops over 3 yr (1998–2000) at three Saskatchewan sites: Swift Current (Brown soil zone), Saskatoon (Dark Brown) and Nipawin (Dark Gray). We also compared three short-lived, vigourous grass species in mixture with two alfalfa (Medicago sativa) cultivars or monoculture. Combinations of precipitation and temperature variables combined with companion crop plant density and biomass explained 90% of the variation in forage yield loss relative to no companion crop forage yield. We conclude that companion crops can be used with low yield reductions at Nipawin, but that all three companion crops significantly reduced forage yield at Swift Current. Forage seedling density was reduced under companion crops but the decline in forage seedling density did not explain the reduction in forage yield. We speculate that yield components rather than plant density must have been affected by companion crop competition. Intermediate wheatgrass (Elytrigia intermedia) produced higher forage yield than Dahurian wildrye (Elymus dahuricus) or slender wheatgrass (Elymus trachycaulus). Grass-alfalfa mixtures produced higher forage yield than grass mono culture. Economic returns were superior if no companion crop was used to establish the forages at Swift Current and Saskatoon; but, at Nipawin economic returns were generally higher with companion crop establishment. The feasibility of companion crops for establishment of short-lived perennial forages in Saskatchewan thus depends on soil zone, with their use best suited to the more humid regions. Key words: Forage yield, plant density, weather, economics

Forage Yield and Economic Losses Associated with the Brown‐Midrib Trait in Sudangrass

Brown‐midrib genes increase digestibility due to reduced lignification in sudangrass, Sorghum bicolor subsp. drummondii (Nees ex Steud.) de Wet & Harlan. Brown‐midrib lines are known to be low in forage yield potential, but this reduction in forage yield has not been previously quantified. The objectives of this study were to quantify the increase in forage quality and decrease in forage yield and to provide an economic assessment of this dichotomy. Piper and Greenleaf (normal leaves) were compared with their brown‐midrib counterparts and to four highly selected brown‐midrib (FG) lines at two locations for 2 yr. Brown‐midrib lines averaged 9.0% lower in lignin and 7.2% higher in in vitro fiber digestibility than normal lines. The reduction in first‐harvest forage yield was highly variable across germplasms and locations. Greenleaf and the FG lines showed severe forage yield reductions in Wisconsin but not in Nebraska, whereas forage yield of Piper was uniformly reduced across locations. Reduced tillering and plant height of the brown‐midrib plants appeared to be mechanisms for reducing forage yield. The brown‐midrib phenotype of sudangrass, caused by the homozygous condition of the bmr‐6 allele, appears to be environmentally sensitive, particularly limiting production in cooler and shorter growing seasons. Conversely, uniform reductions in second‐harvest forage yield suggested a fundamental limitation to regrowth potential associated with the brown‐midrib phenotype. Predicted net returns from feeding sudangrass hay were similar for first‐harvest normal and brown‐midrib lines, but severely depressed for brown‐midrib lines in second harvest, due to the severe yield reductions.

Response of nine forage grasses to saline irrigation and its schedules in a semi-arid climate of north-west India

Traditionally, the degraded lands in arid and semi-arid regions are left for pastures but their forage productivity is low, unstable and unremunerative. Often this results in acute shortages of fodder during the post-monsoon period that can perhaps be partly overcome if the limited saline ground-water resources are effectively utilized to supplement water supplies. Thus, a field experiment was conducted during 1993–1997 on a calcareous soil in a semi-arid part of north-west India (average rainfall 350 mm/annum) to evaluate the suitability of forage grasses to saline irrigation (ECiw 8.5–10.0 dS/m) and optimize its schedule. Grass species included in this experiment were Brachiaria mutica Stapf. Cenchrus setigerus Vahl. Chloris gayana Kunth, Cymbopogon flexuosus, Cynodon dactylon Pers. Echinochloa colonum Link. Panicum antidotale Retz., P. coloratum Linn., P. laevifolium Hack., P. maximum Jacq. (Local wild), P. maximum Jacq. (Cultivated) and P. virgatum. Species those were identified to be the most promising included Panicum laevifolium and P. maximum (both local wild and cultivated) with an annual forage production of 3.43–4.23 Mg/ha. The overall reduction in forage yield with saline irrigation equalled 29 per cent when compared with canal water (ECiw 0.4 dS/m). Scheduling saline irrigation based on climatological approach, i.e. when the ratio of depth of irrigation water (Diw) and cumulative open pan evaporation (CPE) equalled 0.4, was observed to be optimal whereas increased salt accumulation nullified the benefits of enhanced water supplies (Diw/CPE=0.8). Two of the definite advantages of irrigated forages were about three–four-fold increase in productivity as compared with natural/seeded pastures and extension of production period to those of conventional shortages, i.e. during summer months (April–June) when the most nomad populations are forced to migrate to traditionally irrigated areas. Thus, it was concluded that saline water use strategies for rehabilitating arid lands with above grass species would not only render these degraded lands be more productive but also ensure conservation and improvement for long-range ecological security of these lands.

Behaviour of cadmium in contrasting Indian soils

Adsorption behaviour, chemical speciation and plant uptake of cadmium (Cd) was studied in two contrasting soil types of India, namely, an Ultisol and a Vertisol. Results indicated that both soil types followed Freundlich adsorption isotherm; the adsorption capacity (μg Cd g‐1 soil) of Vertisol was about thirty times more than that of Ultisol. Data on chemical speciation studies have shown that the extraction of plant‐available forms of Cd (exchangeable + adsorbed + organic‐bound fractions) was considerably higher from Ultisol than from Vertisol. The results of adsorption behaviour and chemical speciation studies were well reflected in the plant‐uptake studies, where, a significant reduction in forage yield was observed at 100 ppm Cd in Ultisol and 200 ppm Cd in Vertisol due to significantly higher plant tissue concentrations of Cd grown in the Ultisol than that grown in the Vertisol.

Combining Ability Effects for Resistance to Four Insects in Selected Alfalfa Clones1

Diallel cross progenies, including reciprocals, of six alfalfa (Medicago sativa L.) clones that differed in miridinduced leaf malformation and aphid resistance were studied to obtain estimates of combining ability effect for characters associated with resistance to the spotted alfalfa aphid (SAA), Therioaphis maculata Buckton; the peaaphid (PA), Acyrthosiphon pisum Harris; and two mirids: the alfalfa plant bug (APB), Adelphocoris lineolatus Goeze, and the tarnished plant bug (TPB), Lygus lineolaris Beauv. The responses to mirid feeding were measured in the field with controlled APB and TPB infestations under cages. Aphid tests were conducted on seedlings in the greenhouse. The hypothesis that the same genetic system controlled feeding by APB and TPB was supported by the absence of significant genotype ✕ mirid species interactions. Forage yield and stem length were reduced 5 and 20%, respectively, whereas percentages of dry matter were unchanged and protein percentages increased 4% due to mirid infestation. Resistance to mirid‐induced forage yield reduction and stunting was not found. Leaf malformation, a symptom of mirid feeding, appeared to be a highly heritable trait, but was not correlated with forage yield reduction, stunting, forage quality, or aphid resistance. General combining ability effects were far more important than specific combining ability effects among single crosses for forage yield, stem length, and leaf malformation under mirid infestation, and for PA and SAA resistance.

INFLUENCE OF STEM NEMATODE INFESTATION ON BACTERIAL WILT REACTION AND FORAGE YIELD OF ALFALFA VARIETIES

Four varieties of alfalfa (Medicago sativa L.) were tested in field plots for their reactions to single and dual inoculations with the stem and bulb nematode Ditylenchus dipsaci (Kühn) Filipjev and the alfalfa wilt bacterium Corynebacterium insidiosum (McCull.) Jensen. Grimm was highly susceptible to both pathogens. Vernal maintained high resistance to C. insidiosum despite moderate nematode infestation. Lahontan remained highly resistant to both pathogens. Beaver lost much of its inherent resistance to the wilt bacterium when infested by D. dipsaci.Six varieties, including the four above, were grown in a forage-yield test in which nematode-inoculated and uninoculated plots were harvested in three successive seasons. The nematode-susceptible varieties showed marked reduction in forage yield during the second and third harvest years. Vernal, with partial nematode resistance, was less severely affected. The resistant varieties, Talent and Lahontan, showed no yield reduction.