Plant Pathology

Conventional methods to detect and assess the viability of plant pathogenic bacteria are usually based on plating assays or serological techniques. Plating assays provide information about the number of viable cells, expressed as colony-forming units, but are time-consuming and laborious. Serological methods, such as the enzyme-linked immunosorbent assay (ELISA) and immunofluorescence microscopy (IF), can be performed in a shorter timespan than most plating assays, but they do not discriminate between live and dead cells. Flow cytometry (FCM) in combination with fluorescent probe technology is a rapid, sensitive, and quantitative technique to detect microorganisms and assess their viability. Quantitative information on the presence and viability of plant pathogenic microorganisms is valuable for risk assessment regarding disease transmission and disease development. FCM has been applied successfully in the fields of food microbiology, veterinary science, and medical research to dete...

Ascochyta blight of chickpea (Cicer arietinum L.) caused by Ascochyta rabiei(Pass.) Labr. has been recorded for the first time in Erbil province . The results of field surveys conducted in five locations in the province during March, April, and May of 2002, showed that the disease exists in all these locations. The disease incidence ranged between 40-100%, while disease score range was 0.45-5.00 using 0-5 scale and some fields were completely devastated and not harvested. The presence of chickpea debris of the previous season and sowing infested seeds are mainly the reasons behind increasing of disease incidence in the fields that were sown in early spring.

Diseases are a significant limiting factor for papaya production. The nature and frequency of these diseases depend on local conditions and effective management depends on a thorough knowledge of the pathogen, host plant, environment, and their interaction. The precise identity of the causal agent is of paramount importance, and disease management options must be economical. Assessment of disease incidence or severity, and fruit loss are the key factors in determining the economics of disease management. In general, disease management strategies involve different practices that include plant resistance, and prophylactic and curative measures. The papaya diseases related have diverse etiologies, divided into those with biotic (infectious) and abiotic (noninfectious) etiologies that affect the fruit and those affecting the plant. We have attempted to emphasize procedures for diagnosis and control with detailed information on each. Descriptions of pathogens are provided in sufficient detail to assist professional diagnosticians in making accurate diagnosis. Fungicides used to control many of the diseases described in this chapter are mentioned for information proposes only. Legal restrictions and regulations of fungicide use vary among countries, and regulations within any country are subject to change over time. The information reported has been extracted from the available scientific literature and the authors’ experience, and we hope that this publication will provide a helpful reference to growers, students, and professionals working with papaya.

The ability of Brevibacillus brevis to influence development of disease on tomato caused by Fusarium oxysporum f.sp. lycopersici was investigated using plants raised in Petri dish microcosms and in pots in the glasshouse. Development of symptoms on both microcosm-and ...

In the 2013-2014 growing season, field surveys were conducted in native corn fields located in high altitude agricultural communities in the 'Sierra Norte de Puebla' in Mexico. Symptoms typical of maize bushy stunt (MBS) disease were observed and DNA extracted from symptomatic native corn plants was used as template to confirm the presence of phytoplasmas. Amplification and sequencing of 16S rRNA-encoding sequences and chaperonin 60 universal target (cpn60 UT) sequences followed by in vitro restriction fragment length polymorphism and phylogenetic analyses revealed that the phytoplasma detected belongs to the subgroup 16SrI-B, 'Candidatus Phytoplasma asteris'. Based on 16S rRNA-encoding gene sequence analysis and on a single nucleotide polymorphism within the cpn60 UT sequence, two MBS strains, MBS-Puebla and MBS-Veracruz, were identified. This is the first detection of MBS phytoplasma (MBSP) affecting native corn and the first molecular survey made in corn fields in Mexico to detect and characterize MBSP. We discuss these results in light of the potential evolutionary relationship between corn and MBSP.

Sweet corn, silage and grain crops have been facing the threat of severe corn disease for many years, spreading to various parts of Israel. Over the past few years, we conducted a series of field experiments, with the assistance of Netafim Israel, growers' associations and farmers from the Galilee region. In 2017-2018, this research led to a historic breakthrough: for the first time, 60 years since its discovery, an economically feasible solution was found for late wilt disease of corn in Israel. The successful treatment protocol is based on changing the cultivation method, changing the traditional irrigation method used in most corn growing areas in Israel, and the sophisticated integration of pesticide mixtures in a schedule adapted to key points in the development of the disease. This method can now be widely applied in commercial fields for the protection of sensitive corn varieties.

Late wilt disease in corn is caused by the fungus Harpophora maydis, which is found in the soil and seeds. It penetrates the plant and blocks the water supply to its upper parts. The disease, considered to be the most severe corn disease in our region, was first discovered in Egypt in 1960, where it still persists and causes serious damage. The disease is now reported in 11 countries. In Israel, it has existed for 40 years in the Upper Galilee, especially in the Hula Valley, and in the past decade, has spread to the south of the country. In heavily contaminated fields and in sensitive maize cultivars, the pathogen can cause 100% infection and total yield loss. The disease is characterized by a rapid wilt of the corn plant, which usually occurs two to three weeks before harvesting. In the past, attempts had been made to control the pathogen using different methods, including agricultural (balanced soil fertility and flood fallowing), chemical, biological, physical (solar heating) and plant compounds. Despite the potential of some of these methods, the only means applied in Israel to date to restrict the disease is the use of resistant corn varieties. However, in Egypt and Spain, virulent pathogen strains that threaten resistant maize cultivars have been found.

The research team led by Dr. Ofir Degani from Migal – The Galilee Research Institute and Tel-Hai College, funded and supported by Netafim Israel, the Extension Service of the Israel Ministry of Agriculture and Rural Development, and growers' associations, has recently led to a breakthrough development of historical significance. For the first time, 60 years since the discovery of the late wilt disease, an efficient and economically feasible solution has been found that can be used on a large scale to protect sensitive corn varieties in commercial fields.

This solution, published in December 2018 in the leading scientific journal PloS ONE, saves about 40% of irrigation costs and combines antifungal mixtures with different mechanisms to prevent resistance development. The new application was tested in field trials in 2017-2018 and included the injection to the irrigation system of  the substances Difenoconazole + Azoxystrobin (of which the commercial name is 'Ortiva-Top', manufactured by Syngenta, Basel ,Switzerland, supplied by Adama Makhteshim, Airport City, Israel), at intervals of 15, 30 and 45 days from sowing, or other fungicide mixtures. Savings in the deployment of irrigation lines was acquired by using a dripline for two adjacent rows (a row spacing of 50 cm instead of 96 cm), a row space that maintains the effective concentration of the fungicide in the soil. A recently developed real-time PCR-based molecular detection system showed that following the treatment of 'Ortiva-Top', the amount of pathogen DNA in the host tissue decreased to near zero levels. The successful treatments using 'Ortiva-Top' resulted in a 100% decrease in dehydration symptoms and a 100% increase in crop yield, together with an approximately 40% increase in crop quality (the yield classified as A class that had a cob weight exceeding 250 g). These results were also obtained in an alternative protocol– the replacement of pesticides based on 'Ortiva-Top' in the first application and the application of pesticides harboring a different mechanism of action in the second and third applications. A remote sensing evaluation of the efficacy of the treatments using a quadcopter equipped with a thermal infra-red sensitive camera carried out by Dr. Assaf Chen’s research team (Migal - Galilee Research Institute) supported the results and showed its effectiveness as a research tool for diagnosing infected fields.

These results are the fruits of a decade of research (since 2008), in which a fundamental understanding of the pathogen H. maydis and the generation and development of late wilt disease in Israel was established. During this period, new research methods such as sensitive molecular tests (PCR and qPCR) were developed in order to diagnose fungal virulence and in order to detect the pathogen inside the host plant tissue. In addition, a link was found to plant hormones that regulate the development of the pathogen. Complex field trials that were carried out annually over a full growing season (about 80 days) since 2009 led to this important discovery.
However, the work on late wilt disease does not end here. In the past two years, Dr. Degani's research team identified the presence of H. maydis in secondary hosts, such as cotton, watermelon and green foxtail (Setaria viridis), which could support the survival of the pathogen, developed an environmentally friendly biological control method to control the pathogen, and established a new bio-assay for examining soils suspected of being infected with the pathogen. These new findings, which are currently in the process of being prepared for scientific publication, are encouraging the continuation and enhancement of the research.

Four DNA citrus plant tissue extraction protocols and three methods of DNA extraction from vector psyllid  Diaphorina citri  Kuwayama (Hemiptera: Psyllidae) were compared as part of the validation process and standardization for detection of huanglongbing (HLB). The comparison was done using several criterias such as integrity, purity and concentration. The best quality parameters presented in terms of extraction of DNA from plant midribs tissue of citrus, were cited by Murray and T hompson (1980) and  Rodríguez  et  al.  (2010), while for the DNA extraction from psyllid vectors of HLB, the best extraction method was suggested by Manjunath  et al.  (2008).

Curly top disease is caused by a complex of curtoviruses (family Geminiviridae), and it continues to plague tomato production in California. To better understand the etiology of curly top of tomatoes in California, polymerase chain reaction (PCR)-based methods were developed and used to characterize the curtoviruses involved, and to monitor for these viruses in the beet leafhopper vector, Circulifer tenellus. From 2002 to 2008, 86 processing and fresh market tomato fields in the Central Valley of California were surveyed for the incidence of curly top symptoms. Representative samples with curly top symptoms were collected from the surveyed fields, as well as from another 24 fields. The incidence of curly top symptoms in most fields ranged from trace (<1%) to low (1 to 5%); however, in 2002, 2003, and 2008, some fields had medium (5 to 20%) or high (>20%) incidences. PCR with general and species-specific primers was used to establish that the predominant species associated with...

Four phenotypic xanthomonad groups have been identified that are pathogenic to pepper, tomato, or both hosts. These include groups A and C which are found in Xanthomonas axonopodis pv. vesicatoria, group B found in X. vesicatoria, and group D found in 'X. gardneri'. We present DNA:DNA hybridization data in which X. axonopodis pv. vesicatoria group A and C strains have less than 70% DNA relatedness with each other, with the type strain of X. axonopodis, and with the currently classified species within Xanthomonas and, therefore, should be removed from this species and given species status. We present information that the A strains most closely resemble the strains originally isolated by Doidge in 1921. In an attempt to avoid confusion in nomenclature as stated in Principle 1 of the Bacteriological Code, we propose that the A strains of X. axonopodis pv. vesicatoria be renamed as X. euvesicatoria (ATCC11633 T = NCPPB2968 T = ICMP 109 T = ICMP 98 T). Use of the euvesicatoria epithet should be reserved for strains originally identified by Doidge, which she designated Bacterium vesicatorium (Ann. Appl. Biol. 7: 407-430, 1921) in the original description when she referred to those strains as being feebly amylolytic. The name X. perforans sp. nov. is proposed for the C group of strains previously designated as X. axonopodis pv. vesicatoria (ATCC BAA-983 T = NCPPB 4321 T). We also propose that 'X. gardneri', which has less than 70% DNA relatedness with any of the Xanthomonas species and which has never had taxonomic status, be named X. gardneri (ATCC 19865 T = NCPPB 881 T) to reflect the specific epithet proposed by Sutic [17] in 1957.

Diseases induced by Fusarium, like damping-off and wilt on cucumber, are serious problems around the world. Samples of cucumber seeds were collected from commercial markets in Egypt and tested for seed-borne fungi. In order to detect the maximum number of internal and external seed-borne fungi, agar plate examination of disinfected and non-disinfected seeds were used. Two species of Fusarium were the most frequent and predominant fungi. Facultative parasites of the genera Alternaria, Rhizoctonia, Helminthosporium and Penicillium were also found. A total 33 isolates of Fusarium spp. were obtained using Komada’s selective medium. Fusarium oxysporum and F. solani were highly frequent. Pathogenicity test indicated that, F. oxysporum isolate (Fem8) was the main causal organism of pre- and post-emergence damping off. Furthermore, it occurred in all seed parts tested. Some infected seeds germinate, but they were either rapidly overgrown by F. oxysporum or they developed into a diseased see...

The leaf properties and construction costs (CC) are reported for eight indigenous heath (kerangas) forest species and three invasive (exotic) species of Acacia. Both groups of species co-occur and colonise disturbed lowland tropical heath rainforest habitats in Brunei, Borneo Island. Across species, CC mass-based increased with nitrogen (N) and heat of combustion (H C ), and decreased with ash content. CC area-based showed similar trends (although weaker in strength) in addition to significant positive correlation with leaf mass per unit area (LMA). Within the native species, the CCs of the shrub and small tree species were lower and significantly different from those of medium-sized tree species. Given the invasive success of the three acacias, it is hypothesised that these species may require less energy for biomass construction than do the native species. Within similar life growth form, no difference in CC mass-based was detected between the native trees and the invasive acacias. For CC area-based, the invasive Acacia species had a higher value. These findings failed to uphold our hypothesis. LMA and leaf N and phosphorus (P), but not potassium (K), were higher in the invasive acacias. The higher N and LMA could have been the cause of higher CC area-based in the invasive acacias. From the ordination of 11 species on the basis of leaf properties, the invasive and native species are more likely to be found in different groupings-although some native species seem more affiliated with the invasive than with their own guild, especially Alphitonia and Macaranga.

The efficacy of eight plant extracts (garlic, clove, garden quinine, Brazilian pepper, anthi mandhaari, black cumin, white cedar and neem) in controlling leaf rust disease of wheat was investigated in vitro and in vivo. In vitro, all treatments inhibited spore germination by more than 93%. Neem extract recorded 98.99% inhibition of spore germination with no significant difference from the fungicide Sumi-8 (100%). Under greenhouse conditions, seed soaking application in neem extract (at concentration of 2 ml/L) resulted in 36.82% reduction in the number of pustules/leaf compared with the untreated control. Foliar spraying of plant extracts on wheat seedlings decreased the number of pustules/leaf. Foliar spraying of plant extracts four days after inoculation led to the highest resistance response of wheat plants against leaf rust pathogen. Spray application of wheat seedlings with neem, clove and garden quinine extracts, four days after inoculation with leaf rust pathogen completely prevented rust development (100% disease control) and was comparable with the fungicide Sumi-8. Foliar spray application of wheat plants at mature stage with all plant extracts has significantly reduced the leaf rust infection (average coefficient of infection, ACI) compared with the untreated control and neem was the most effective treatment. This was reflected on grain yield components, whereas the 1000-kernel weight and the test weight were improved whether under one-or two-spray applications, with two-spray application being more effective in this regard. Thus, it could be concluded that plant extracts may be useful to control leaf rust disease in Egypt as a safe alternative option to chemical fungicides.

A B S T R A C T Coffee (Coffea arabica L.) bean quality can be affected by a number of factors of which storage fungi are one of the major ones. In Ethiopia coffee is a number one export commodity supporting the national economy but there was little information about the association of mycoflora with coffee beans. Therefore, the objective of this study was to assess the associations of mycoflora with coffee seeds and their effect on coffee infection at Limmu Coffee Plantation. The comparison was done using two coffee berry disease resistant selections (74112 and 74110) with and without parchment and with and without surface treatment of coffee beans with 5% sodium hypochlorite and storing under two storage conditions (local cold house and corrugated iron warehouse). Thus, the experiment was laid down as 2×2×2×2 factorial experiment with four replications. The study showed the association of four fungal species (Fusarium spp., Aspergillus spp., Penicillium spp. and Mucor spp.) and some unidentified species in both blotting and agar plating techniques. In general, significantly higher infection percentage was found in coffee seeds without parchment and surface disinfection irrespective of the storage type and coffee selection. Thus, keeping coffee beans with parchment and disinfecting by disinfectants may reduce the association and prevalence of mycoflora on coffee and minimize postharvest problems.

Eight isolates of Sclerotium rolfsii from four strategically geographical sites of Bangladesh were characterized and their cultural properties like average linear mycelial growth, colony colour, colony consistency, growth pattern and sclerotia formation were studied. Isolates varied in mycelial growth and other growth characteristics and were grouped into three. The highest linear growth was displayed by S8. DNA concentration of eight isolates varied from 1150-7200 ng/µl. DNA fingerprinting by RAPD prompted the grouping of isolates. Selected 3 primers generated 20 bands with size ranging from 100-1500 bp. Out of the 20 bands, 9 bands (45%) were polymorphic and 11 bands (55%) were monomorphic among the eight isolates of Sclerotium rolfsii. The coefficient of gene differentiation (Gst) was 1.000 reflecting the existence of high level of genetic variations among the 8 isolates. The lowest genetic distance and highest inter isolate similarity was found in S1 and S2 which would be homogeneous. The highest genetic distance and lowest inter isolate similarity found in S3, S7 and S3, S8 pair which would be most divergent isolates. The cluster analysis also revealed that S3, S7 and S8 belong to different clusters. All five varieties of eggplant and tomatoes were graded as susceptible when inoculated with eight isolates. Plant mortality 93.33% was recorded in S4, S6 and in S8. Considering the isolate factor the most virulent isolate would be S8 whereas the less virulent isolate would be S2 and S7. Host plant of S8 was tomato collected from Thakurgaon. S2 and S7 were collected from BAU farm and Dinajpur and host plants were lentil and tomato respectively. It is evident that Sclerotium rolfsii from Thakurgaon on host tomato is more virulent.

The 21 st century has already seen a major paradigm shift in our understanding of the biology, evolution, and genetics of the genus Phytophthora as well as the tools and approaches used to develop novel approaches for disease management. The combination of novel tools and approaches provided by the convergence of genome sequencing, computing power and novel genomic/biotechnological tools paints a promising picture of the future of Phytophthora disease management. At the same time Phytophthora pathogens continue to emerge at an accelerated rate due to increased global travel and trade. This article provides a brief review of the impact, biology and the current genome-enabled era that will characterize progress in the 21 st century. 9 10

Navas-Cortés, J. A., Landa, B. B., Méndez-Rodríguez, M. A., and Jiménez-Díaz, R. M. 2007. Quantitative modeling of the effects of temperature and inoculum density of Fusarium oxysporum f. sp. ciceris races 0 and 5 on development of Fusarium wilt in chickpea cultivars. Phytopathology 97:564-573.

The total proteins of four strawberry cultivars with differing resistance and/or susceptibility
to grey mould were extracted by two different methods, phenol and
sodium dodecyl sulphate (SDS). Compared to phenol extraction, SDS extraction produced
higher protein yields but poor quality protein bands with a high degree of
streaking indicating possible contamination. In contrast, the total proteins obtained
by phenol extraction could be used in two-dimensional polyacrylamide gel electrophoresis
(2-DE) because of their higher quality, and the protein spots were well separated
for all tested genotypes. From all the cultivars studied in this research, we
obtained 89 differential (unmatched) protein spots that may be related to fruit disease
resistance or susceptibility. Using the SPSS 11.0 software, we obtained a cluster of
the four strawberry cultivars. The cultivars “APF029-4” and “SJ8976-1” were in the
same subcluster with the highest Pearson correlation coefficient (0.705). Afterwards,
they were amalgamated into the second group with “Joliette”, a disease-resistant
cultivar, which means that they might have a similar resistance to grey mould.

Genetic resistance to Meloidogyne incognita in pepper (Capsicum annuum) has been well characterised for the N and Me3 resistance genes. However, there are no studies comparing the effects of these two genes directly or investigating the combined effects when both genes are present together. Several studies were undertaken to investigate the relationship of the N and Me3 gene systems to one another and to assess whether these two genes are allelic or truly separate genes. Two genotypes homozygous for the N gene ('Carolina Wonder' and 'Charleston Belle') and two genotypes homozygous for the Me3 gene (HDA 149 and PM 687) were compared in a replicated greenhouse test for reaction to M. incognita race 3. There were no significant differences between the resistant reactions of genotypes possessing the N or Me3 gene. Allelism tests were performed using the F2 populations of the parental genotypes HDA 149 × 'Charleston Belle' and HDA 149 × 'Carolina Wonder'. The results of these studies clearly show the N and Me3 genes to be distinct, separate dominant resistance genes conferring resistance to M. incognita race 3 and not alleles of the same gene.

Claviceps cynodontis is a widespread parasite of Cynodon spp. (Bermuda grass) in the paleotropical and subtropical regions. The sphacelial stage of ergot on Cynodon dactylon in México and Texas was identified as that of Claviceps cynodontis by comparison of conidial morphology, rDNA sequence, and random amplified polymorphic DNA (RAPD) patterns with an African isolate of this species. Sequence of internal transcribed spacers ITS1-5.8S-ITS2 of Claviceps cynodontis clustered phylogenetically with those of Claviceps maximensis, Claviceps rhynchelytri, and Claviceps sp. SG (from Setaria geniculata). This is the first record of the identification of Claviceps cynodontis in the Americas.

Rice (Oryzae sativa L.) is the most important staple food in the world today. Nigeria is the highest producers and importer of rice in the West Africa. Its production is threatened by several diseases causing grain yield losses of staggering dimension. Previous attempts to increase rice production through the use of improved varieties without proper regard for plant protection measures were unsuccessful. Hence, the objectives of this study were, to screening rice lines for resistance to false smut and blast (leaf and panicle blast) under natural conditions and determine yield loss to the diseases. The experiment was conducted at the Research Farm of National Cereal Research Institutes, Ibadan Out-Station in 2017 planting season. It was laid out in a randomized complete block design with three replications. Ten upland rice lines and 3 checks were screened, twenty plants were randomly selected from a sampling area of 1 m 2 quadrant. Leaf blast (LB), panicle blast (PB) and False Smut (FSm) incidence scoring was carried-out at 2-12 weeks after planting, using a visual scale of 0-9, The resistance level (RL) was also determined; following the standard evaluation scale (SES) of International Rice Research Institute (IRRI). All the data collected were analysed using ANOVA. The results indicated that ART3-8L14P3-2-B-2 (6.33) and FARO 63 (5.67) had significantly (p<0.05) higher incidence of FSm than all other lines evaluated.

Plant breeders have used disease resistance genes (R genes) to control plant disease since the turn of the century. Molecular cloning of R genes that enable plants to resist a diverse range of pathogens has revealed that the proteins encoded by these genes have several features in common. These findings suggest that plants may have evolved common signal transduction mechanisms for the expression of resistance to a wide range of unrelated pathogens. Characterization of the molecular signals involved in pathogen recognition and of the molecular events that specify the expression of resistance may lead to novel strategies for plant disease control.

Canopy-stored seed banks are a common trait among members of several plant families in sclerophyllous woodlands of Australia and South Africa, with their fruits usually opening in response to damage or fire. Unknown is whether the degree of dormancy and of germination differs among age cohorts in seeds stored on the mother plant. We examined the extent and speed of germination from two intensely serotinous myrtaceous species, Callistemon glaucus and Calothamnus quadrifidus, for seed held in capsules for up to 9 years. Germination of both species differed significantly among age cohorts (P < 0.0001). However, no consistent increase in germination over a range of temperatures with storage was found, suggesting that no after-ripening occurred and that seeds were non-dormant at maturity. Differences among cohorts may be due to pre-conditioning. Significant (P 0.0214) differences occurred between the small-seeded Callistemon and the large-seeded Calothamnus. Germination was (1) optimum at !20 C for Callistemon but at <20 C for Calothamnus, (2) 9-12 days earlier for Callistemon than for Calothamnus, and (3) higher in light than in darkness for Callistemon but equal in both light conditions for Calothamnus. While germination of the species differed in important features, we would expect synchronous germination of all age cohorts to occur following fire and the onset of regular rainfall.

ABSTRACT Guava (Psidium guajava) fruit is vulnerable to postharvest diseases, such as anthracnose. In the present study, molecular characterisation and pathogenicity of Colletotrichum associated with antharcnose disease of guava fruit were conducted. From anthracnose lesion of guava, 20 isolates were successfully recovered. Based on colony colours, conidia, appressoria and presence or absence of setae, and ITS regions and ß-tubulin gene sequences, the isolates were identified as Colletotrichum gloeosporioides. Phylogenetic analysis based on combined data-sets using neighbour-joining method showed that C. gloeosporioides isolates did not group with C. gloeosporioides epitype strain, and thus the isolates were referred to as C. gloeosporioides species complex or C. gloeosporioides sensu lato. Pathogenicity tests using wounded treatment showed that C. gloeosporioides isolates from guava were pathogenic causing anthracnose on the fruits. The present study showed that C. gloeosporioides sensu lato is the most common species causing antharcnose disease of guava fruit.

The recent emergence of wheat stem rust Ug99 and evolution of new races within the lineage threatens global wheat production because they overcome widely deployed stem rust resistance (Sr) genes that had been effective for many years. To identify loci conferring adult plant resistance to races of Ug99 in wheat, we employed an association mapping approach for 276 current spring wheat breeding lines from the International Maize and Wheat Improvement Center (CIMMYT). Breeding lines were genotyped with Diversity Array Technology (DArT) and microsatellite markers. Phenotypic data was collected on these lines for stem rust race Ug99 resistance at the adult plant stage in the stem rust resistance screening nursery in Njoro, Kenya in seasons 2008, 2009 and 2010. Fifteen marker loci were found to be significantly associated with stem rust resistance. Several markers appeared to be linked to known Sr genes, while other significant markers were located in chromosome regions where no Sr genes have been previously reported. Most of these new loci colocalized with QTLs identified recently in different biparental populations. Using the same data and Q + K covariate matrices, we investigated the interactions among marker loci using linear regression models to calculate P values for pairwise marker interactions. Resistance marker loci including the Sr2 locus on 3BS and the wPt1859 locus on 7DL had significant interaction effects with other loci in the same chromosome arm and with markers on chromosome 6B. Other resistance marker loci had significant pairwise interactions with markers on different chromosomes. Based on these results, we propose that a complex network of gene–gene interactions is, in part, responsible for resistance to Ug99. Further investigation may provide insight for understanding mechanisms that contribute to this resistance gene network.

Background: Abnormal uterine bleeding (AUB) is considered one of the most common and challenging problems presenting to the gynecologist. Histopathological examination of endometrial biopsy is gold standard diagnostic tool in evaluation of AUB. Our study is aimed at determining the spectrum of endometrial pathologies in different age group patients presenting with AUB at our hospital which caters largely to women living in rural area. Methods: This was a retrospective study done on patients presenting with AUB over the period Jan 2013-Dec.2015, in Department of Pathology, Ashwini rural medical college and research centre, Kumbhari, Tq. South Solapur, in Western Maharashtra(India). The histopathological findings of AUB were categorized into functional and organic causes. A detailed histological study was carried out and the findings were noted. A statistical analysis between age of presentation and a specific endometrial cause was done using chi-square test. Results: The most common age group presenting with AUB was 41-50 yrs (42%). Mean age for women presented with AUB was 44.2 years. The commonest pattern in these patients was normal cyclical endometrium (33.9%): Proliferative and secretory phase. The commonest pathology was endometrial hyperplasia (22.2%). Other causes identified were disordered proliferative endometrium(13.7%), atrophic endometrium(13.2%), benign endometrial polyp(8%), deficient secretory phase(3.3%), chronic endometritis(2.4%), and endometrial carcinoma(2.3%). It has been observed that, there was highly significant association between age group and histopathological diagnosis (p<0.01). Conclusions: Histopathological examination of endometrium is gold standard diagnostic tool in evaluation of AUB and there is an age specific association of endometrial lesions.

Efficacy of Trichoderma spp. to reduce sunflower head rot caused by Sclerotinia sclerotiorum was evaluated in the field. A mixture of six isolates, including Trichoderma koningii , T. aureoviride and T. longibrachiatum , was tested in five field trials at Balcarce, Argentina. Trichoderma formulation (TF) included Trichoderma conidia and viable hyphal fragments, industrial talc and milled corn kernels. Honeybees ( Apis mellifera ) were used to disperse TF for six weeks from the onset of flowering. Two days after the first TF delivery, sunflower heads were inoculated with S. sclerotiorum ascospores. When 100 g TF was taken by honeybees in a 10-h per day period, head rot incidence was significantly reduced. This approach was successful in reducing disease incidence until physiological maturity of the crop, in environments highly conducive to head-rot development.

SUMMARY To collect information on the incidence of Verticilli- um wilt of olive in Apulia (southern Italy), about 6,000 woody samples from 1,390 young and old olive or- chards were analysed. Moreover, 565 soil samples from commercial orchards and nurseries located all over Apulia region were tested for the presence of V. dahliae microsclerotia. Verticillium wilt was found in the

Over the past decade, the emergence of anthracnose disease has newly challenged the health of turfgrasses on North American golf courses, resulting in considerable economic loss. The fungus responsible for the outbreaks, Colletotrichum cereale, has also been identified from numerous natural grasses and cereal crops, although disease symptoms are generally absent. Here we utilize phylogenetic and population genetic analyses to determine the role of ecosystem in the advancement of turfgrass anthracnose and assess whether natural grass and/or cereal inhabitants are implicated in the epidemics. Using a four-gene nucleotide data set to diagnose the limits of phylogenetic species and population boundaries, we find that the graminicolous Colletotrichum diverged from a common ancestor into distinct lineages correspondent with host physiology (C3 or C4 photosynthetic pathways). In the C4 lineage, which includes the important cereal pathogens Colletotrichum graminicola, C. sublineolum, C. falcatum, C. eleusines, C. caudatum and several novel species, host specialization predominates, with host-associated lineages corresponding to isolated sibling species. Although the C3 lineage--C. cereale--is comprised of one wide host-range species, it is divided into 10 highly specialized populations corresponding to ecosystem and/or host plant, along with a single generalist population spread across multiple habitat types. Extreme differentiation between the specialized C. cereale populations suggests that asymptomatic nonturfgrass hosts are unlikely reservoirs of infectious disease propagules, but gene flow between the generalist population and the specialized genotypes provides an indirect mechanism for genetic exchange between otherwise isolated populations and ecosystems.

Developing new and improved grazing systems for crop–livestock farms where crop production is the major driver of farm management decisions presents a unique research and development challenge. In southern Australia, a substantial proportion of animal production from grazing comes from regions and farms where cropping is the major enterprise. In this paper, we describe a multi-disciplinary farming-systems research approach (EverCrop) aimed at improving farm profitability, risk management and environmental impacts through the development and integration of new grazing options with an emphasis on perennial species. It has been used to analyse and target new opportunities for farmers to benefit from perennial species across dry Mediterranean-type and temperate regions of southern Australia. It integrates field experimentation, on-farm trialling, farmer participatory research, soil–plant–climate biophysical modelling, whole-farm bioeconomic analysis and evaluations of adoptability. Mult...

Fusarium oxysporum f. sp. cubense is the causal agent of Panama disease of banana. A rapid and reliable diagnosis is the foundation of integrated disease management practices in commodity crops. For this diagnostic purpose, we have developed a reliable molecular method to detect Foc race 4 isolates in Taiwan. By PCR amplification, the primer set Foc-1/Foc-2 derived from the sequence

Agriculture is highly dependent on the social sustainability inherent in rural communities. Yet too often we focus on the economic and environmental drivers relating to agricultural production, ignoring the social and community aspects that make rural livelihood not only possible but also rewarding and nurturing. In this paper I focus on climate change as yet another factor associated with rural restructuring that defrays community wellbeing. I argue that attention to social factors and a stronger role for government in assisting communities will enable greater adaptation and enhance resilience in what are essentially very uncertain times.

Species associated with Fusarium head blight are depending on the production and edaphic conditions. The differences are found in the representation of various Fusarium spp. in the diseases, which sporadically occur all over the territory of Slovakia, in all agricultural production types. We identified fifteen Fusarium species during ten years of investigation. Most of the mentioned species F. culmorum (W.G. Smith) Sacc., F. graminearum Schwabe, recently F. cerealis (Cooke) Sacc. (crookwellense Burgess, Nelson & Tousson) and F. sambucinum Fuckel in diseased caryopsis are seed transmitted. The significant differences among species and intra species in cultural and pathogenicity assays in vitro and in vivo were correlated. Some of them are able to produce toxic metabolites -deoxynivalenone, which probably play a role in the aggressiveness of the pathogen and promote disease development and pathogen colonization.

Onion downy mildew (Dm) symptoms and damage on seed production fields in southern Uruguay were quantified during two seasons as the progress of incidence, severity, and as the effect of the level of seed-stalks infections on seed yield and quality. In addition, the effects of two plantation dates and two plant densities on Dm were studied in a factorial experiment. Maximum incidence along the season ranged from 15 to 65% in four commercial fields in 2005 and two fields in 2006. Maximum severity ranged from 4.5 to 9.3% of leaf area affected in 2005, and 0.35 to 1.17% in 2006. Whereas Dm incidence varied among studied fields, disease progress as Dm severity varied mainly between studied years. Crop rotation, crop vigour and plant density were identified as major factors affecting Dm variation in the field. Intensive fungicide schedules did not control Dm when other conditions favoured the disease. A high level of Dm severity defined as large necklace spots on seed-stalks significantly reduced seed yield in comparison with healthy seed-stalks in 2005, as well as seed yield and germination in 2006. Weight of 1,000 seeds was not significantly reduced by Dm infections on seed-stalks. Six genera of fungi were recovered from seeds harvested on highly infected seed-stalks (Stemphylium, Fusarium, Alternaria, Penicillium, Aspergillus and Botrytis), but not Peronospora. Late planting date and low plant density had significantly lower Dm incidence and severity. This finding questioned the early planting dates and high densities previously recommended in order to achieve high yielding crops. The combination of several practices to reduce initial inoculum, susceptibility status of the host, and environmental conditions promoting the disease is discussed as forming a basis for effective disease control.

The planthopper Hyalesthes obsoletus, is the vector of grapevine bois noir disease, caused by stolbur phytoplasma. This hopper is widespread in Europe and the Middle East but it is not a grapevine specialist, and its host range is still controversial. This paper reports on the population dynamics, host range and infectivity of H. obsoletus in northwestern Italy. Field sampling of adults was done with yellow sticky traps and sweep nets on grapevines and in nettle beds, whereas nymphs were sought on nettle and bindweed roots. PCR and dot-blot analyses were used to detect stolbur phytoplasma. The life span of the planthopper was tested in the laboratory on broadbean, periwinkle, nettle and grapevine. Nymphs were found only on roots of Urtica dioica L., and many more adults were captured in nettle beds than on grapevine. Flight activity started in the middle of June and ended middle of September, with a flight peak at the end of July. In the laboratory, the longest life span was observed on nettle whereas broadbean and grapevine were not suitable for survival. Natural infectivity was 6-8% for nymphs and 9-50% for adults. These results confirm the strong links between H. obsoletus, Bois Noir, and U. dioica in northwestern Italy.

Bacterial wilt disease is a very serious problem to Tomato growers of Morogoro region. The objective of this study was to identify the status and pathogenicity of Ralstonia solanacearum causing Tomato bacterial wilt disease in Morogoro region. Most of the farmers 71.7% had a farm of less than 1 ha. Majority of the farmers 32% were growing both hybrid and OPV while the reasons for variety preference differed across the villages. Most of respondents 79% were knowledgeable with the disease and considered uprooting affected plants as the only major control measure on the disease. Most of the farmers 35.5% neither burn nor bury the remains of uprooted infected plants and the remained 32.6% bury while 31.9% burn the crop remains. The results showed the highest disease incidence and severity were 42.32% and 3.1 recorded in Kiberengeni and the lowest were 13.76% and 1.75 Nyandira respectively. Majority of the farmers are using seedbed and furrow irrigation system contrary to seedling trays and drip irrigation system. Assila F1 recorded the lowest disease scores, then Rio safari variety while Cal J recorded the highest. Root drenching+wounding inoculation technique recorded significantly highest disease scores and was fatal compared to the other inoculation techniques. Most of Tomato growing farmers84.8% don’t manage the disease properly in Morogoro. Equipping farmers with knowledge of good agronomic practices will enhance proper management techniques of the disease. The use of certified and disease free seeds, resistant or tolerant varieties, good agronomic practices can help in proper management of the disease across Morogoro region. The bacterial inoculum isolated from Morogoro was confirmed as R. solanacearum using biochemical tests, Serological test and pathogenicity test. From above such results it was observed that Assila F1 tomato variety was significantly resistant compared to Rio safari and the susceptible Cal J. The use of Asilla F1, followed by Rio safari variety with proper agronomic methods can help farmers to minimize the disease new infections and ultimately spread.

In vitro efficacy six chemical substance were evaluated against Erwinia carotovora the causal organism of potato soft rot disease. E. carotovora was isolated from diseased potato tubers by dilution plate technique and different biochemical and pathogenicity test were performed to confirm the bacterial species. Six chemicals viz. Copper Oxychloride @ 0.2%, Mancozeb @ 0.2%, Boric acid @ 0.1%, Kasugamycin @ 0.02%, Carbendazim @ 0.3% and Sodium Hypochlorite @ 0.2% were tested against E. carotovora subsp. carotovora by well diffusion method. For each treatment there were four replications and tested chemical volume was 100 μl. Data were recorded up to five days of incubation. Maximum zone of inhibition (mm) was obtained after 48 hours of incubation with Copper Oxychloride (30.35 mm), followed by Mancozeb (20.15 mm), Boric acid (19.15 mm) and Kasugamycin (16.28mm). Copper Oxychloride produced the maximum growth inhibition (33.72%) of the pathogen, on the other hand Sodium Hypochlorite (2.68%) did not efficiently inhibit the growth of E. carotovora. Copper Oxychloride proved to be the best chemical followed by Mancozeb under in-vitro management against E. carotovora subsp. carotovora.
Keywords—Soft rot, in-vitro, chemicals, zone of inhibition.

The epiphytic plant Hylocereus undatus , locally known as pitahaya, is endemic to Mexico. Recently, small-scale farming of this plant has begun and the harvested fruit exported to distant markets. In 2001 and 2002, samples of H. undatus with stem spots were collected from Mecapalapa, Xochitlan and Dolores Hidalgo in the state of Puebla. Early symptoms were small, chlorotic specks, which enlarged as they matured to a maximum of 0·5 cm in diameter. A fast-growing, mouse-grey-coloured fungus was consistently isolated from these diseased stems. After 8 days, under continuous fluorescent light at 22 -25 ° C, pycnidal fruiting bodies (180 × 150 µ m) formed on potato dextrose agar (PDA). The conidia observed in these bodies were one-celled, hyaline, ellipsoidal to fusoid with distinctly truncate bases and measured 12·15 -19·44 × 4·86 -8·51 µ m (av. 16·49 × 5·90 µ m). The isolated fungus conformed to the anamorphic Fusicoccum state of Botryosphaeria dothidea . The teleomorph was never observed in culture, but was seen on infected plants. Healthy, detached H. undatus stems were inoculated with the Fusicoccum isolate, while three control stems were inoculated with sterile PDA discs. After incubation for 3 days at 25-30 ° C, under high humidity and a 12-h day length, disease symptoms similar to those observed on naturally infected plants were observed. All inoculated stems were infected and turned brown, in contrast to the negative controls which remained unaffected. The anamorphic Fusicoccum state of B. dothidea was re-isolated from the inoculated plants, thus satisfying Koch's postulates. This fungus has been previously reported to cause panicle and shoot blight and