Does hut climate matter for piglet survival in organic production?

Piglet mortality in outdoor production systems varies across the year, and a reason for this variation could be fluctuations in hut climate, as ambient temperature might influence piglet survival, both directly and indirectly. Therefore, the aim of the current study was to investigate the impact of farrowing hut climate and year variation on stillbirth and liveborn mortality. A large-scale observational study was conducted at five commercial organic pig-producing herds in Denmark from June 2015 to August 2016. Both year variation (F 3,635=4.40, P=0.004) and farrowing hut temperature (F 2,511=6.46, P=0.002) affected the rate of stillbirths. The risk of stillborn piglets was lowest in winter and during this season larger changes in hut temperature between day 1 prepartum and the day of farrowing increased the risk of stillbirths (F 1,99=6.39, P=0.013). In addition, during the warm part of the year stillbirth rate increased at temperatures ⩾27°C. Year variation also affected liveborn mortality (F 3,561=3.86, P=0.009) with a lower rate of liveborn deaths in spring. However, the hut climate did not influence liveborn deaths. Consequently, other factors than hut climate may explain the influence of year variation on liveborn mortality. These could be light differences causing seasonality in reproduction and lactation.

Conceptualizing patient-reported outcome measures for use within two Danish psychiatric clinical registries: description of an iterative co-creation process between patients and healthcare professionals.

BACKGROUND: Denmark has national clinical indicator programs for adult patients diagnosed with depression and schizophrenia, respectively. Within each program, the responsible steering group (SG) decided to add some indicators based upon patient-reported outcome measures (PROMs). AIMS: The primary aim was to describe the process of selecting PROMs and defining a national measurement concept for use in clinical practice and for indicator monitoring and the secondary aim s to collect patient recommendations for implementation. METHODS: An interdisciplinary SG of healthcare professionals and a Patient Peer Board (PPB) representing both patient groups co-created the output in an iterative process. The work included literature search, PPB workshops, SG meetings, ratings of PROM topics and items, and a pilot. The PPB discussed the following: item relevance, mode of data collection, graphical format of the online PROMs, and display of results. Finally, requirements for PROM patient information were identified. Based upon input from the PPB, the SG selected the items and specified the measurement concept. RESULTS: The PPB prioritized 20 of 53 suitable items and suggested alternative wording and answer categories. A pilot was performed and 19 items covering well-being, lack of well-being, impairment of functioning, and overall health were selected for clinical testing. The patients recommended concrete, unambiguous, easily understandable information and procedures for data collection and display of results. CONCLUSIONS: The iterative co-creation process based upon a high degree of patient involvement resulted in a set of PROMs, a national measurement concept, and patient recommendations for implementation. The cooperation between patients and professionals was successful.

Evidence for Systemic Infection by Puccinia horiana, Causal Agent of Chrysanthemum White Rust, in Chrysanthemum.

Puccinia horiana, causal agent of the disease commonly known as chrysanthemum white rust (CWR), is a quarantine-significant fungal pathogen of chrysanthemum in the United States and indigenous to Asia. The pathogen was believed to have been eradicated in the United States but recently reappeared on several occasions in northeastern United States. The objective of the study presented here was to determine whether P. horiana could systemically infect chrysanthemum plants, thus providing a means of survival through winters. Scanning and transmission electron microscopy revealed the development of P. horiana on the surface and within leaves, stems, or crowns of inoculated chrysanthemum plants artificially exposed to northeastern U.S. winter temperatures. P. horiana penetrated leaves directly through the cuticle and then colonized the mesophyll tissue both inter- and intracellularly. An electron-dense material formed at the interface between fungal and host mesophyll cells, suggesting that the pathogen adhered to the plant cells. P. horiana appeared to penetrate mesophyll cell walls by enzymatic digestion, as indicated by the absence of deformation lines in host cell walls at penetration sites. The fungus was common in vascular tissue within the infected crown, often nearly replacing the entire contents of tracheid cell walls. P. horiana frequently passed from one tracheid cell to an adjacent tracheid cell by penetration either through pit pairs or nonpitted areas of the cell walls. Individual, presumed, fungal cells in mature tracheid cells of the crown and stems arising from infected crowns suggested that the pathogen might have been moving at least partially by means of the transpiration stream. The demonstration that chrysanthemum plants can be systemically infected by P. horiana suggests that additional disease control measures are required to effectively control CWR.

Pathogenesis and pathology of shoulder ulcerations in sows with special reference to peripheral nerves and behavioural responses to palpation.

Shoulder ulcerations are common in breeding sows in production systems but the consequences for the animals in terms of pain or discomfort are not well-described. This study presents data from a histopathological examination of shoulders of sows, specially focusing on the peripheral nerves in the region and the behavioural responses towards palpation of animals with traumatic neuromas but without ulcers. The study included 155 sows from seven Danish herds initially screened and stratified according to absence/presence and size of shoulder ulcers 3-4 weeks post-partum, out of which 71 were free of ulcerations and 84 had different stages of ulceration. Before collection, sows were subjected to shoulder palpation and behavioural responses were registered. From the consecutive pattern of development of ulcerations it is evident that shoulder ulcerations develop from top-to-bottom. A high frequency of traumatic neuromas was found in both healed and unhealed lesions. The observation of viable nerve-ends in shoulder ulcerations makes it likely that ulcerations are associated with pain. Moreover, the presence of traumatic neuromas in healed ulcerations indicates that there is discomfort even after the lesions have healed. This is further supported by the behavioural finding that rubbing behaviour in response to palpation was increased on the day of sample collection of the shoulders in sows with traumatic neuromas but without shoulder ulcers (P=0.053). Further studies are needed for final confirmation but these results suggest that shoulder ulcers may be associated with pain even after healing.

Effects of frequency of "extreme" temperature highs on development of soybean rust.

Previously, we hypothesized that summer "extreme" diurnal temperature highs in the southeastern United States were responsible for the yearly absence or delay of soybean rust development until fall. Utilizing temperature-controlled growth chambers, a diurnal temperature pattern of 33°C high and 20°C low reduced urediniospore production by 81%. However, that study did not consider the influence of frequency of extreme temperatures on soybean rust. We now report that a temperature high of 35°C for 1 h on three consecutive days, initiated 15 days after inoculation, when lesions had formed, reduced urediniospore production by 50% and required 9 to 12 days for sporulation to resume once the extreme temperature highs ceased. Furthermore, three consecutive days in which the temperature high was 37°C, beginning immediately after inoculation and subsequent dew period, reduced lesion numbers by 60%. The combined effects of reduced numbers of lesions and urediniospores per lesion caused by extreme temperature highs can account for observed absence or delay of soybean rust development in the southeastern United States until fall. A comparison of frequency of extreme temperature highs with numbers of counties reporting presence of soybean rust from 2005 to 2012 verified that extreme temperature highs may be largely responsible for absence or delay of soybean rust development. This is the first report showing the effect of frequency of extreme temperature highs on development of soybean rust. Because the south-to-north progression of soybean rust is required for the disease to occur in the major soybean-production regions of the United States, temperatures in the southeastern United States have a major effect on the entire U.S. soybean industry.

Effects of daily temperature highs on development of Phakopsora pachyrhizi on soybean.

Although considerable information exists regarding the importance of moisture in the development of soybean rust, little is known about the influence of temperature. The purpose of our study was to determine whether temperature might be a significant limiting factor in the development of soybean rust in the southeastern United States. Soybean plants infected with Phakopsora pachyrhizi were incubated in temperature-controlled growth chambers simulating day and night diurnal temperature patterns representative of the southeastern United States during the growing season. At 3-day intervals beginning 12 days after inoculation, urediniospores were collected from each plant and counted. The highest numbers of urediniospores were produced when day temperatures peaked at 21 or 25°C and night temperatures dipped to 8 or 12°C. When day temperatures peaked at 29, 33, or 37°C for a minimum of 1 h/day, urediniospore production was reduced to 36, 19, and 0%, respectively, compared with urediniospore production at the optimum diurnal temperature conditions. Essentially, no lesions developed when the daily temperature high was 37°C or above. Temperature data obtained from the National Climatic Data Center showed that temperature highs during July and August in several southeastern states were too high for significant urediniospore production on 55 to 77% of days. The inhibition of temperature highs on soybean rust development in southeastern states not only limits disease locally but also has implications pertaining to spread of soybean rust into and development of disease in the major soybean-producing regions of the Midwestern and northern states. We concluded from our results that temperature highs common to southeastern states are a factor in the delay or absence of soybean rust in much of the United States.

Penetration and establishment of Phakopsora pachyrhizi in soybean leaves as observed by transmission electron microscopy.

For over 30 years, it has been known that Phakopsora pachyrhizi is unusual in that it penetrates from urediniospores directly through the leaf cuticle without entering stomates. This unusual mode of penetration suggests that disease resistance mechanisms might exist for soybean rust that do not exist for most rust diseases. As a result, we decided to conduct a histological study using transmission electron microscopy to further elucidate the mechanisms of penetration and early establishment of P. pachyrhizi in soybean leaves. Based on our study, it was concluded that P. pachyrhizi utilizes primarily mechanical force, perhaps with the aid of digestive enzymes, to penetrate the cuticle on the leaf surface. However, the lack of deformation lines in micrographs indicated that digestive enzymes, without mechanical force, are used by the penetration hypha to penetrate the outer and inner epidermal cell walls. Digestive enzymes, again indicated by the lack of deformation lines, are used by haustorial mother cells to breach the walls of mesophyll cells to form haustoria. The possibility exists for eventual determination of the precise roles of pressure and digestive enzymes in the development of soybean rust and elucidation of some of the determinants of resistance and susceptibility to this important plant disease.

Decubital shoulder ulcers in sows: a review of classification, pain and welfare consequences.

Decubital shoulder ulcers are lesions on the shoulders of sows kept in production systems, reported to have a relatively high prevalence, and to some extent be comparable with human pressure ulcers. In sows, the ulcers are caused by pressure inflicted by the flooring, leading to oxygen deficiency in the skin and the underlying tissue. This paper reviews existing knowledge about decubital shoulder ulcers in sows, focusing on the pathogenesis, classification and consequences in terms of pain and animal welfare. On the basis of available human as well as animal literature, we describe the primary causal factors, underlying mechanisms, suggested direction of progression as well as temporal development. We review suggested scales for the classification of decubital shoulder ulcers, and argue that none of these are useful for the classification of decubital shoulder ulcers in live sows. The knowledge of the welfare consequences of decubital shoulder ulcers is limited. On the basis of the tissue structures that are involved, we assume that the development and presence of decubital shoulder ulcers in sows are a painful and prolonged condition. It is concluded that the extent of the welfare problem related to decubital shoulder ulcers cannot be fully determined until a valid ante-mortem classification system is available, and knowledge about the duration of the condition (including the various stages), as well as the possible consequences in terms of pain or discomfort have been established.

Characterizing Resistance to Phakopsora pachyrhizi in Soybean.

Resistance in soybean to Phakopsora pachyrhizi, the cause of soybean rust, is characterized by either reddish-brown (RB) lesions or an immune response. The RB type of resistance can be incomplete, as evidenced by the presence of sporulating uredinia within lesions. Susceptibility, on the other hand, is exemplified by tan-colored (TAN) lesions, and can be expressed in gradations of susceptibility or partial resistance that are less well defined. This study evaluated traits associated with incomplete or partial resistance to P. pachyrhizi in soybean by comparing 34 soybean accessions inoculated with four P. pachyrhizi isolates. Six accessions produced RB lesions to all four isolates, while 19 accessions produced TAN lesions, including plant introduction (PI) 200492 (Rpp1) and the susceptible check 'Williams'. Williams had among the largest area under the disease progress curve (AUDPC) values and area under the sporulating uredinia progress curve (AUSUPC) values, while eight accessions had lower AUSUPC values. Of the known sources of single-gene resistance, only PI 230970 (Rpp2), PI 459025B (Rpp4), and PI 594538A (Rpp1b) had lower AUDPC and AUSUPC values than Williams. PI 594538A and PI 561356 had RB lesions and had the lowest AUDPC and AUSUPC values. Of the known sources of single-gene resistance, only PI 230970 (Rpp2) and PI 594538A (Rpp1b) produced fewer and smaller-diameter uredinia than Williams. This study characterized reactions to P. pachyrhizi in 34 accessions based on lesion type and sporulation, and defined incomplete resistance and partial resistance in the soybean-P. pachyrhizi interaction.

beta-Arrestin 1 and 2 stabilize the angiotensin II type I receptor in distinct high-affinity conformations.

BACKGROUND AND PURPOSE: The angiotensin II type 1 (AT(1)) receptor belongs to family A of 7 transmembrane (7TM) receptors. The receptor has important roles in the cardiovascular system and is commonly used as a drug target in cardiovascular diseases. Interaction of 7TM receptors with G proteins or beta-arrestins often induces higher binding affinity for agonists. Here, we examined interactions between AT(1A) receptors and beta-arrestins to look for differences between the AT(1A) receptor interaction with beta-arrestin1 and beta-arrestin2. EXPERIMENTAL APPROACH: Ligand-induced interaction between AT(1A) receptors and beta-arrestins was measured by Bioluminescence Resonance Energy Transfer 2. AT(1A)-beta-arrestin1 and AT(1A)-beta-arrestin2 fusion proteins were cloned and tested for differences using immunocytochemistry, inositol phosphate hydrolysis and competition radioligand binding. KEY RESULTS: Bioluminescence Resonance Energy Transfer 2 analysis showed that beta-arrestin1 and 2 were recruited to AT(1A) receptors with similar ligand potencies and efficacies. The AT(1A)-beta-arrestin fusion proteins showed attenuated G protein signalling and increased agonist binding affinity, while antagonist affinity was unchanged. Importantly, larger agonist affinity shifts were observed for AT(1A)-beta-arrestin2 than for AT(1A)-beta-arrestin1. CONCLUSION AND IMPLICATIONS: beta-Arrestin1 and 2 are recruited to AT(1A) receptors with similar ligand pharmacology and stabilize AT(1A) receptors in distinct high-affinity conformations. However, beta-arrestin2 induces a receptor conformation with a higher agonist-binding affinity than beta-arrestin1. Thus, this study demonstrates that beta-arrestins interact with AT(1A) receptors in different ways and suggest that AT(1) receptor biased agonists with the ability to recruit either of the beta-arrestins selectively, would be possible to design.

The interrelationships between clinical signs and their effect on involuntary culling among pregnant sows in group-housing systems.

Sows suffering from clinical signs of disease (e.g. lameness, wounds and shoulder ulcers) are often involuntarily culled, affecting the farmer's economy and the welfare of the animals. In order to investigate the interrelationships between clinical signs of individual pregnant group-housed sows, we performed an explanatory factor analysis to identify factors describing the patterns of variation of clinical signs. Moreover, we investigated how these emerging factors affected the probability of a sow to be either (i) euthanized, (ii) suddenly dead, (iii) sent to slaughter due to clinical signs of disease such as claw lesions or wounds or (iv) involuntarily culled (representing a pool of sows that were either euthanized, dead or sent to slaughter due to disease). Data from 2.989 pregnant sows in group-housing systems from 33 sow herds were included in the study. A thorough clinical examination was performed for each sow by using a protocol including 16 different clinical signs. Farmers recorded all cullings and deaths and the reasons for these actions in a 3-month period after the clinical examination. Among the observed sows, 4.2% were involuntarily culled during the 3-month period. From the explanatory factor analysis, we identified three factors describing the underlying structure of the 16 clinical variables. We interpreted the factors as 'pressure marks', 'wounds' and 'lameness' Logistic analyses were performed to investigate the effect of the three factors and the parity number of each sow on the four outcomes: (i) euthanized, (ii) suddenly dead, (iii) sent to slaughter due to clinical signs of disease and (iv) involuntarily culled. The analyses showed that 'lameness' significantly increased the risk of sows to be involuntarily culled (P = 0.016) or sent to slaughter due to clinical signs of disease (P = 0.026). Lameness is generally considered to be an important welfare problem in sows, which could explain the increased risk seen in this study. By contrast, 'pressure marks' and 'wounds' did not have any significant effect on the four outcomes (P > 0.05).

Comparative Susceptibility of Kudzu Accessions from the Southeastern United States to Infection by Phakopsora pachyrhizi.

Soybean rust, caused by Phakopsora pachyrhizi, was first discovered in the continental United States in the fall of 2004. The potential for economic loss in the United States hinges largely on whether or not the pathogen can survive winters in the absence of soybean. Kudzu (Pueraria lobata) is known to be a host for P. pachyrhizi in Asia and South America and is widely distributed in the southern United States. This study examined reactions of kudzu collected from several areas of the southeastern United States to three isolates of P. pachyrhizi, one each from Alabama, Louisiana, and Brazil. Susceptible tan (TAN) lesions, resistant reddish-brown (RB) lesions, and immune (IM) response, previously described on soybean, were produced on kudzu based on the evaluation of 125 plants. However, in contrast to soybean, the RB response on kudzu was common, with approximately 50% frequency. IM responses to at least one isolate were observed on five individual plants, and two plants were immune to all three pathogen isolates used in the test. TAN lesions averaged 3.2 uredinia per lesion with an average diameter per uredinium of 121 µm. In contrast, RB lesions had an average of 0.3 uredinia per lesion with an average uredinial diameter of 77 µm. In 25 of 39 (64%) instances in which multiple plants were tested from a site, each reacted the same to the individual pathogen isolates. This suggested a tendency for plants at specific sites to be genetically identical with respect to rust reaction. Only 19 of 125 (15%) individual plants produced a different reaction to one isolate than to the other two isolates. When four kudzu plants previously shown to produce only TAN lesions to P. pachyrhizi isolates Alabama 04-1, Brazil 01-1, and Louisiana 04-1 were inoculated with eight additional isolates from several areas of the world, all 11 isolates produced only TAN lesions. Likewise, when five other plants previously shown to produce only RB lesions when inoculated with the three isolates were inoculated with the 11 isolates, all produced only RB lesions. These results suggest that susceptibility or resistance to P. pachyrhizi in individual kudzu plants often is broad, extending over a wide range of P. pachyrhizi isolates.

New Legume Hosts of Phakopsora pachyrhizi Based on Greenhouse Evaluations.

Phakopsora pachyrhizi, the causal organism of soybean rust, was first found in the continental United States in 2004 and has been found on soybean, kudzu, Florida beggarweed, and three Phaseolus species in the field. The pathogen has been reported to occur on more than 90 legume species worldwide and it is likely to infect native and introduced legume species in the United States. The objective of this study was to determine if 176 species representing 57 genera of legumes, the majority of which are either native or naturalized to soybean-growing areas of the United States, could be hosts of P. pachyrhizi. Between one and three accessions of each species, a total of 264 accessions, were inoculated with a mixture of four isolates of P. pachyrhizi. Severity and sporulation were rated on a 1-to-5 scale at 14 and 28 days after inoculation. P. pachyrhizi was confirmed by the presence of sporulating uredinia and/or immunological assay on 65 new species in 25 genera; 12 of these genera have not been reported previously as hosts. Many of the newly identified hosts grow in the southern United States, and like kudzu, could serve as overwintering hosts for P. pachyrhizi.

Comparative Susceptibilities of Legume Species to Infection by Phakopsora pachyrhizi.

Knowledge of the host range of Phakopsora pachyrhizi is important to agriculture in the United States because of the distinct possibility that economic losses could occur to crops other than soybean. Furthermore, it is possible that alternative hosts could provide a means of overwintering of the pathogen, providing inoculum to initiate epidemics in future years. To clarify the potential importance of soybean rust on nonsoybean legumes and their role in overwintering of the disease, multiple accessions of clover, cowpea, pea, kudzu, lima bean, snap bean, and single accessions of coffee senna, Florida beggarweed, hemp sesbania, hyacinth bean, partridge pea, and showy crotalaria were inoculated under greenhouse conditions with urediniospores of P. pachyrhizi; infected soybean plants served as a control. The four criteria used to assess susceptibility were lesion density, proportion of lesions with sporulating uredinia, average number of uredinia per lesion, and average uredinia diameter, each determined 2 weeks following inoculation. Based on lesion densities, percentage of lesions with sporulation, and average numbers of uredinia per lesion, soybean, kudzu, and pea were the most susceptible species, followed by snap bean. However, because infected pea plants defoliated rapidly, urediniospore production presumably was limited, lessening the potential for epidemics on pea. Cultivars of snap bean produced numerous brown to reddish-brown lesions, many of which sporulated, but numbers of uredinia per lesion were lower than on soybean, kudzu, or pea. The presence of both tan (susceptible) and reddish-brown (resistant) lesions on kudzu demonstrated physiological differentiation on that host. Some kudzu plants appeared to be potentially excellent hosts for overwintering of the disease. The average number of uredinia per lesion appeared to be a valid measurement with which to compare host susceptibilities, and may have epidemiological significance. High susceptibility of a host was characterized by numerous uredinia with a wide range of sizes within individual lesions. In contrast, low susceptibility to rust was characterized by no or a few small uredinia.

Effects of temperature on urediniospore germination, germ tube growth, and initiation of infection in soybean by phakopsora isolates.

ABSTRACT Temperature is a critical factor in plant disease development. As part of a research program to determine how specific environmental variables affect soybean rust, we determined temperature effects on urediniospore germination and germ tube growth of four isolates of Phakopsora pachyrhizi, one each from Brazil, Hawaii, Taiwan, and Zimbabwe, and an isolate of P. meibomiae from Puerto Rico, collected over a 25-year period. Also compared were the effects of temperature during a night dew period on initiation of disease by the P. pachyrhizi isolates. All variables were fit to a nonlinear beta function with temperature as the independent variable. Minimum, maximum, and optimum temperatures, along with shape parameters of the beta function for each variable, were statistically analyzed. All Phakopsora isolates behaved similarly as to how temperature affected urediniospore germination, germ tube growth, and initiation of disease. The results suggest that P. pachyrhizi has changed little in the past few decades with respect to how it responds to temperature and that previously collected research data continues to be valid, simplifying the development of soybean rust disease models.

Aggregation of measures to produce an overall assessment of animal welfare. Part 1: a review of existing methods.

Several systems have been proposed for the overall assessment of animal welfare at the farm level for the purpose of advising farmers or assisting public decision-making. They are generally based on several measures compounded into a single evaluation, using different rules to assemble the information. Here we discuss the different methods used to aggregate welfare measures and their applicability to certification schemes involving welfare. Data obtained on a farm can be (i) analysed by an expert who draws an overall conclusion; (ii) compared with minimal requirements set for each measure; (iii) converted into ranks, which are then summed; or (iv) converted into values or scores compounded in a weighted sum (e.g. TGI35L) or using ad hoc rules. Existing methods used at present (at least when used exclusively) may be insufficiently sensitive or not routinely applicable, or may not reflect the multidimensional nature of welfare and the relative importance of various welfare measures. It is concluded that different methods may be used at different stages of the construction of an overall assessment of animal welfare, depending on the constraints imposed on the aggregation process.

Evaluation of Virulence of Phakopsora pachyrhizi and P. meibomiae Isolates.

Asian soybean rust (ASR), caused by Phakopsora pachyrhizi and recently discovered for the first time in continental United States, has been of concern to the U.S. agricultural industry for more than 30 years. Since little soybean rust resistance is known, and resistance is often difficult to detect or quantitate, we initiated a project to develop a better, more quantitative, method. The methodology determined the average numbers and diameters of uredinia in lesions that developed on leaves of inoculated plants 14 days after inoculation. It was used to compare virulence of P. pachyrhizi isolates from Asia and Australia and P. meibomiae from Puerto Rico and Brazil, collected as many as 30 years earlier, with isolates of P. pachyrhizi recently collected from Africa or South America. Susceptible reactions to P. pachyrhizi resulted in tan-colored lesions containing 1 to 14 uredinia varying greatly in size within individual lesions. In contrast, on these same genotypes at the same time of year, resistance to other P. pachyrhizi isolates was typified by 0 to 6 small uredinia in reddish-brown to dark-brown lesions. Using appropriate rust resistant and rust susceptible genotypes as standards, examination of uredinia 14 days after inoculation allowed quantitative comparisons of sporulation capacities, one measure of susceptibility or resistance to soybean rust. The study verified the presence and ability to detect all known major genes for resistance to soybean rust in the original sources of resistance. It demonstrated that soybean lines derived from the original PI sources, and presumed to possess the resistance genes, in actuality may lack the gene or express an intermediate reaction to the rust pathogen. We suggest that a determination of numbers and sizes of uredinia will detect both major gene and partial resistance to soybean rust.

Survival of Teliospores of Tilletia indica in Soil.

This study was conducted to assess survival of Tilletia indica teliospores in a location in the northern United States. Soils differing in texture and other characteristics were collected from four locations, equilibrated to -0.3 MPa, and infested with teliospores of T. indica to give a density of 103 teliospores per gram of dry soil. Samples (22 g) of the infested soil were placed in 20-µm mesh polyester bags, which were sealed and placed at 2-, 10-, and 25-cm depths in polyvinyl chloride tubes containing the same field soil as the infested bags. Tubes were buried vertically in the ground at Bozeman, MT, in October 1997. Soil samples were assayed for recovery and germination of T. indica teliospores 1 day and 8, 20, and 32 months after incorporation of teliospores into soil. The rates of teliospores recovered from soil samples were 90.2, 18.7, 16.1, and 13.3% after 1 day and 8, 20, and 32 months after incorporation of teliospores into soil, respectively, and was significantly (P < 0.01) affected by soil source. The percentage of teliospore recovery from soil was the greatest in loam soil and lowest from a silt loam soil. The rate of teliospores recovered from soil was not significantly affected by depth of burial and the soil source-depth interaction during the 32-month period. The percentage of germination of teliospores was significantly (P < 0.01) affected by soil source and depth of burial over the 32-month period. The mean percentage of teliospore germination at 1 day, and 8, 20, and 32 months after incorporation into soils was 51.3, 15.1, 16.4, and 16.5%, respectively. In another experiment, samples of silty clay loam soil with 5 × 103 teliospores of T. indica per gram of soil were stored at different temperatures in the laboratory. After 37 months of incubation at 22, 4, -5, and -18°C, the rates of teliospore recovered from soil were 1.6, 2.0, 5.7, and 11.3%, respectively. The percentage of spore germination from soil samples was highest at -5°C. Microscopy studies revealed that disintegration of teliospores begin after breakdown of the sheath-covering teliospore. The results of this study showed that teliospores of T. indica can survive in Montana for more than 32 months and remain viable.

Survival of Teliospores of Tilletia indica in Arizona Field Soils.

The survival of teliospores of the Karnal bunt of wheat pathogen, Tilletia indica, was determined in field plots in Tucson, AZ. Two methods were used to test viability during a 48-month period in which 21-µm-pore-size polyester mesh bags of teliospore-infested soil were buried in irrigated and nonirrigated field plots at two sites. One method determined the total number of viable teliospores in a soil sample, regardless of whether or not they could be extracted from the soil using a sucrose centrifugation technique. The total number of viable teliospores declined over time in both irrigated and nonirrigated field plots and in the same soils in the laboratory. Based on nonlinear regressions, total number of viable teliospores decreased from 55.7% at time zero to 9.7 and 6.7% for nonirrigated and irrigated field soils, respectively, in 48 months. Total number of viable teliospores in soil in the laboratory decreased from 55.7 to 34.0% after 48 months. The second method determined germination percentages of teliospores extracted from the soil samples by means of a sucrose centrifugation technique. Based on linear regressions of transformed data, germination of teliospores extracted from irrigated and nonirrigated field soils, and control (laboratory) soil, significantly decreased over time. The rate of decrease in germination was significantly greater for teliospores from irrigated field plots than from nonirrigated plots and the laboratory soil. At time zero, 55.7% of teliospores germinated, and by 48 months, average germination of teliospores extracted from soil in nonirrigated plots had decreased to 13.6% compared with 4.4% in irrigated plots and 36.8% for teliospores in the laboratory control. Regression over time of total number of viable teliospores accounted for more of the overall variability than did regression over time of germination percentages of extracted teliospores. Neither field site nor soil depth had any effect on total number of viable teliospores or on teliospore germination percentages.

Survival of Tilletia indica Teliospores in Different Soils.

To determine the potential for Tilletia indica, cause of Karnal bunt of wheat, to survive and become established in new areas, a teliospore longevity study was initiated in Kansas, Maryland, Georgia, and Arizona. Soil from each location was infested with T. indica teliospores and placed in polyester mesh bags. The bags were placed within soil from the same location within polyvinyl chloride pipes. Pipes were buried in the respective plots such that the bags were at 5-, 10-, and 25-cm depths. Each pipe was open at the ends to allow interaction with the outside environment, however fitted with screens preventing possibility of teliospore escape. In the Karnal bunt-quarantine area of Arizona, bags of infested soil also were placed outside the pipes. Teliospore-infested soil from each location was maintained dry in a laboratory. During the first 2 years, viability declined more rapidly in pipes than outside pipes, and more rapidly in fields in Kansas and Maryland than in Georgia or Arizona. After 2 years, viability declined nearly equally. In the laboratory over 3 years, viability decreased significantly more rapidly in dry soil from Kansas or Maryland than in dry soil from Georgia or Arizona, while pure teliospores remained unchanged. We hypothesized that soils, irrespective of weather, affect teliospore longevity.