Mycobacterium fortuitum abortion in a sow

Two aborted Chester White pig fetuses were presented to a veterinary diagnostic laboratory in Illinois. Postmortem examination identified no gross abnormalities. Histologic evaluation revealed multifocal necrosis of chorionic epithelial cells, coalescing areas of mineralization in the placenta, and focal accumulations of viable and degenerate neutrophils in the lung. Intra- and extracellular acid-fast bacilli were identified in the lesions in both the placenta and lungs. Bacterial culture of stomach contents yielded heavy growth of Mycobacterium fortuitum, a rapidly growing nontuberculous mycobacterium (NTM), which was further confirmed through whole-genome sequencing. NTM are opportunistic pathogens commonly found in the soil and in contaminated water supplies. In animals, M. fortuitum is typically introduced through cutaneous wounds leading to infections limited to the skin, with systemic infection being uncommon. To our knowledge, abortion caused by M. fortuitum has not been reported previously.     

Trends in natural resource use and prospects for sustainable resource management in Kenya's Arid and Semiarid Lands

This paper describes the environmental problems facing the development of Kenya's Arid and Semiarid lands (ASAL) today. The problems arise because of a rapidly declining resource base in the ASAL as a result of overexploitation and misuse, following basic land use conflicts. The extent of the overutilization or resource damage is not well known and varies a great deal from one agroecological zone to another and from resource to resource in the ASAL; those most affected include: soil, water, range, forest, livestock and wildlife. As a result of increased population growth in the ASAL, these resources are under stress. This paper argues that many of the environmental problems in the ASAL cannot be solved if the development programme does not address the needs of the people who live in the ASAL. There is a need to shift the objective of ASAL development from a preoccupation with economic growth and the idea that the ASAL should make a contribution to GNP through interregional trade and export to sustainable development that enables the communities in the ASAL to support themselves at as good a standard of living as possible. The last part of this paper outlines a strategy to promote such sustainable development.     

Meta-analysis of fungicide efficacy on soybean target spot and cost–benefit assessment

Target spot of soybean has spread in Brazil, the southeastern United States and Argentina in the last decade. A collaborative network of field Uniform Fungicide Trials (UFT) in Brazil was created in 2011 to study the target spot control efficacy of fungicides, including azoxystrobin + benzovindiflupyr (AZ_BF), carbendazim (CZM), fluxapyroxad + pyraclostrobin (FLUX_PYRA), epoxiconazole + FLUX_PYRA (EPO_FLUX_PYRA), mancozeb (MZB) and prothioconazole + trifloxystrobin (PROT_TRIF). Network meta-analysis was used to conduct a quantitative synthesis of UFT data collected from 2012 to 2016 and to evaluate the effects of disease pressure (DP, low ≤ 35% target spot severity in the nontreated control < high) and year of experiment on the overall mean efficacy and yield response to each of the tested fungicides. Based on mean percentage control of target spot severity, the tested fungicides fall into three efficacy groups (EG): high EG, FLUX_PYRA (76.2% control relative to the nontreated control) and EPO_FLUX_PYRA (75.7% control); intermediate EG, PROT_TRIF (66.5% control) and low EG, MZB (49.6% control), AZ_BF (46.7% control) and CZM (32.4% control). DP had a significant effect on yield response. At DP_Low, the highest response was due to PROT_TRIF (+342 kg ha⁻¹, +12.8%) and EPO_FLUX_PYRA (+295.5 kg ha⁻¹, +11.2%), whereas at DP_High, EPO_FLUX_PYRA and FLUX_PYRA outperformed the other treatments, with yield responses of 503 kg ha⁻¹ (+20.2%) and 469 kg ha⁻¹ (+19.1%), respectively. The probability of a positive return on fungicide investment ranged from 0.26 to 0.56 at DP_Low and from 0.34 to 0.66 at DP_High.     

Trichoderma species associated with green mould disease of Pleurotus ostreatus and their sensitivity to prochloraz

Green mould disease causes serious economic losses in Pleurotus ostreatus crops worldwide, including in Italy, where prochloraz is the only chemical fungicide allowed to control the disease. The effectiveness of the doses 0.01, 0.05, 0.25 and 1.25 μL L⁻¹ (field dose) of prochloraz (Sponix Flow, 450 g L⁻¹), against colony growth rate and spore germination of Trichoderma pleuroti, T. pleuroticola and T. guizhouense strains on wheat straw extract agar plates were evaluated. Complete inhibition of Trichoderma pleuroti and T. pleuroticola growth was shown by the field dose of prochloraz, and also by the 0.25 μL L⁻¹ dose for T. pleuroti. Complete inhibition of spore germination occurred for all Trichoderma strains at field dose, and at 0.25 μL L⁻¹ for T. pleuroti strains. In in vivo assays, the effect of prochloraz doses 0.05, 0.25 and 1.25 μL L⁻¹ on colonization of straw substrate by T. pleuroti, T. pleuroticola and T. guizhouense inoculated at two spore densities (10² and 10⁵ spores mL⁻¹) immediately after P. ostreatus spawn was studied. Trichoderma pleuroti and T. pleuroticola were both responsible for green mould disease, whereas T. guizhouense was not pathogenic. Trichoderma pleuroti was more aggressive than T. pleuroticola. Prochloraz was effective against T. pleuroti at the field dose, and against T. pleuroticola at 0.25 and 1.25 μL L⁻¹. The study on Trichoderma × Pleurotus interaction type showed that Trichoderma species were active against the mycelial growth of P. ostreatus by competition for space and nutrients, and neither hyphal interaction nor effect by volatile or nonvolatile metabolites occurred.     

Phytophthora urerae sp. nov., a new clade 1c relative of the Irish famine pathogen Phytophthora infestans from South America

An unknown Phytophthora species was discovered in the central Peruvian Andes on blighted foliage of the native South American plant species Urera lacineata. Urera is a genus of native flowering shrubs in the nettle family Urticaceae. This new taxon Phytophthora urerae sp. nov. is herewith formally described based on extensive morphological analysis, phylogenetic analysis of nuclear and mitochondrial loci, and AFLP analysis. Phytophthora urerae sp. nov. is a close relative of the Irish famine pathogen, Phytophthora infestans, and only the third clade 1c taxon described from South America to date. In contrast to the clade 1c taxon Phytophthora andina, first described in South America as a hybrid, P. urerae does not appear to be a hybrid based on cloning and sequencing nuclear loci. Findings of new species in South America may provide novel insights into the origin and evolutionary history of clade 1c Phytophthora species.     

An isolate of Wheat streak mosaic virus from foxtail overcomes Wsm2 resistance in wheat

Wheat streak mosaic virus (WSMV) is an economically important pathogen of wheat (Triticum aestivum) causing major yield losses in regions where severe infection occurs. To detect the presence of any new virus or new WSMV isolates, green foxtail (Setaria viridis) plants exhibiting virus-like symptoms were sampled in a summer-fallowed wheat field at the Agricultural Research Center-Hays, Kansas State University, Hays, Kansas. These plants were tested serologically for four wheat viruses: WSMV, Triticum mosaic virus (TriMV), High Plains wheat mosaic virus (HPWMoV) and Foxtail mosaic virus (FoMV). Among 38 plant samples exhibiting virus-like symptoms, 29 contained WSMV as indicated by ELISA. Four isolates from samples with relatively strong reactions were transferred to healthy wheat seedlings by mechanical inoculation in a growth chamber for pathogenicity testing. Three isolates were avirulent to a wheat variety RonL, which contains Wsm2, a gene providing temperature-sensitive resistance to currently prevalent isolates of WSMV. However, one isolate, KSH294, was able to infect RonL and showed more virulence on two other varieties/lines containing Wsm2. Further sequence and phylogenetic analysis of KSH294 confirmed that this isolate displays a sequence homology with WSMV, but has sequence differences making it distinct from previously identified WSMV isolates included in the phylogenetic analysis.     

P0 protein of cotton leafroll dwarf virus-atypical isolate is a weak RNA silencing suppressor and the avirulence determinant that breaks the cotton Cbd gene-based resistance

Cotton blue disease (CBD) is the most important disease present in cotton crops in South America and cotton leafroll dwarf virus (CLRDV) is the causal agent. The disease has been controlled by sowing cotton varieties resistant to CLRDV. However, in the 2009/10 growing season, an outbreak due to an atypical CLRDV isolate (CLRDV-at) occurred in northwest Argentina. Although CLRDV and CLRDV-at genomes are very closely related, the symptoms they produce in cotton plants are quite different. P0 is the most divergent protein between the isolates and in CLRDV is a silencing suppressor protein. This work characterized the silencing suppressor activity of the P0 protein encoded by CLRDV-at (P0^CL-at) and evaluated its role in Cbd-resistance break in cotton plants. It was demonstrated that P0^CL-at, despite having a mutation in the consensus of the F-box-like motif, was able to suppress local RNA silencing, but displayed lower activity than P0^CL. P0^CL and P0^CL-at showed no differences in the interaction with Gossypium hirsutum SKP1 orthologue (GSK1) and Nicotiana benthamiana SKP1 and both P0 proteins triggered destabilization of ARGONAUTE1. However, when the ability to enhance PVX symptoms was evaluated, P0^CL-at was shown to be a weaker pathogenicity factor than P0^CL in N. benthamiana. Interestingly, trans-expressed P0^CL-at enabled CLRDV to systemically infect CBD-resistant plants, and a chimeric CLRDV-P0^CL-at infectious clone succeeded in establishing infection in CBD-resistant cotton varieties with symptoms resembling those produced by CLRDV-at. These results strongly suggest that P0^CL-at is the avirulence (Avr) determinant involved in breaking cotton Cbd gene-based resistance.     

Phytophthora oleae,a new root pathogen of wild olives

Wild olive (Olea europaea subsp. europaea var. sylvestris) is an important component of Mediterranean forests and a key genetic source for olive improvement programmes. Since 2009, a severe decline caused by Phytophthora cryptogea and P. megasperma has been detected in a protected wild olive forest of high ecological value (Dehesa de Abajo, Seville, Spain). In this natural forest, sampling of roots and soil was carried out on 25 wild olives with symptoms in 2014 and 2015. Apart from the already known P. cryptogea A1 and P. megasperma, a third Phytophthora species was consistently isolated from wild olive rootlets with symptoms. These isolates conformed morphologically with the newly described species P. oleae and were confirmed by analysis of their ITS regions and cox1 sequences. Temperature–growth relationships showed a maximum growth at 19.9 °C on carrot agar medium, making it the lowest temperature Phytophthora species infecting wild olive roots. Pathogenicity was confirmed on 1-year-old healthy wild olive seedlings and was similar to the previously known pathogenic phytophthoras. As temperature requirements are quite different, the three Phytophthora species may be active against wild olive roots in different seasons. However, the prevalence of P. oleae infecting wild olives in recent years could be due to its introduction as a new invasive pathogen. The probable invasive nature of P. oleae, together with increasing rain episodes concentrated in short periods frequent in southern Spain, would allow the outbreak of infections in wild olive forests, and also put cultivated olive orchards at risk.     

Rhynchosporium leaf scald disease incidence: seed source and spatial pattern

A programme of field trials for the study of the winter barley–Rhynchosporium commune pathosystem is reported. The associated seedborne disease rhynchosporium leaf scald is regarded as having an important impact on barley yields. The analysis in this study relates to the impact of the seed source (commercial or farm-saved seed) on disease incidence and to the spatial pattern of rhynchosporium leaf scald disease incidence. Disease incidence data were calculated from field data recorded as disease severity. Mean disease incidence was higher in the crops grown from farm-saved seed than in those grown from commercial seed, although great agronomic significance cannot be attached to this result. The spatial pattern of rhynchosporium leaf scald disease incidence was characterized in terms of the binary power law (BPL) and was indicative of an aggregated pattern. Programme-wide BPL results were described using a novel phytopathological application of a random coefficients model. These results have application in field sampling for rhynchosporium leaf scald disease.