scholarly journals Investigations on the Timing of Fruit Infection by Fungal Pathogens Causing Fruit Rot of Deciduous Holly

Plant Disease ◽  
2019 ◽  
Vol 103 (2) ◽  
pp. 308-314 ◽  
Author(s):  
Shan Lin ◽  
Francesca Peduto Hand
Keyword(s):  
Disease Incidence ◽  
Fruit Rot ◽  
Host Susceptibility ◽  
Plant Production ◽  
Mature Fruit ◽  
Flower Bud ◽  
Fungal Isolation ◽  
Susceptibility To Infection ◽  
First Case ◽  
Fruit Maturity

Fruit rot of deciduous holly is an emerging fungal disease that is affecting plant production across midwestern and eastern U.S. nurseries. To determine the growth stage(s) of host susceptibility to infection by the major pathogens associated with the disease, Alternaria alternata and Diaporthe ilicicola, and minor pathogens such as Colletotrichum fioriniae and Epicoccum nigrum, we conducted two sets of experiments over two consecutive seasons. In the first case we monitored the presence of the pathogens as well as disease progression in a commercial nursery under natural conditions by collecting plant tissues from the flower bud stage until fruit maturity. The target pathogens were consistently isolated from asymptomatic samples at all stages of fruit development and from symptomatic samples at fruit maturity across the 2 years of collection. A significant increase in fungal isolation frequency, primarily species of Alternaria and Colletotrichum, was observed right after flowering, but fruit rot symptoms only developed on mature fruit. In the second case we artificially inoculated containerized plants maintained outdoor at our research farm with individual or combined pathogens at different fruit developmental stages, and we assessed disease incidence on mature fruit to determine the time of host susceptibility to infection and, indirectly, whether pathogens in the fungal complex carry out latent infections. D. ilicicola could cause latent infection on deciduous holly fruit when inoculated at the full bloom and petal fall stages, and all inoculations made on wounded mature fruit resulted in fruit rot. These findings suggest that flowering represents a critical period to manage D. ilicicola infections and that mature fruit should be protected from any injury to avoid disease. In both experiments a negative correlation between disease incidence and temperature was found; however, the decrease in temperature also coincided with fruit ripening. The effects of temperature and changes in physiological properties of the fruit during maturation on disease development should be further investigated to fully interpret these findings.

scholarly journals Determining the Sources of Primary and Secondary Inoculum and Seasonal Inoculum Dynamics of Fungal Pathogens Causing Fruit Rot of Deciduous Holly

Plant Disease ◽  
2019 ◽  
Vol 103 (5) ◽  
pp. 951-958
Author(s):  
Shan Lin ◽  
Francesca Peduto Hand
Keyword(s):  
Leaf Spot ◽  
Fungal Pathogens ◽  
Disease Incidence ◽  
Fruit Rot ◽  
Plant Production ◽  
Mature Fruit ◽  
Average Temperature ◽  
Leaf Spots ◽  
Maximum Minimum

Fruit rot of deciduous holly, caused by species of the genera Alternaria, Colletotrichum, Diaporthe, and Epicoccum, is affecting plant production in Midwestern and Eastern U.S. nurseries. To determine the sources of inoculum, dormant twigs and mummified fruit were collected, and leaf spot development was monitored throughout the season from three Ohio nurseries over two consecutive years. Mummified fruit was the main source of primary inoculum for species of Alternaria and Epicoccum, whereas mummified fruit and bark were equally important for species of Colletotrichum and Diaporthe. Brown, irregular leaf spots developed in the summer, and disease incidence and severity increased along with leaf and fruit development. Coalesced leaf spots eventually resulted in early plant defoliation. When tested for their pathogenicity on fruit, leaf spot isolates were able to infect wounded mature fruit and induce rot symptoms, which indicated that leaf spots could serve as a source of secondary inoculum for fruit infections. In addition, spore traps were used to monitor seasonal inoculum abundance in the nurseries. Fruit rot pathogens were captured by the spore traps throughout the season, with peak dissemination occurring during flowering. In this study, we also attempted to understand the role of environmental factors on leaf spot development. Although leaf spot incidence and severity were negatively correlated to mean maximum, minimum and average temperature, a decrease in temperature also coincided with leaf senescence. The role of temperature on leaf spot development should be further studied to fully interpret these results.

Intestinal microbiota balance modulates host susceptibility to infection with enteric pathogenss

2007 ◽  
Vol 30 (4) ◽  
pp. 93
Author(s):  
I Sekirov ◽  
N Tam ◽  
M Robertson ◽  
C Lupp ◽  
B Finlay
Keyword(s):  
Intestinal Microbiota ◽  
Small Animal ◽  
Host Susceptibility ◽  
Morphological Development ◽  
Future Design ◽  
Susceptibility To Infection ◽  
Colonic Microbiota ◽  
Food Borne ◽  
Serovar Typhimurium ◽  
Intestinal Pathogens

Background: During our lifetimes we develop a very complex set of interactions with the multitude of microorganisms colonizing our bodies. In the gastrointestinal system, the microbiota is highly important for morphological development, nutrition, and protection against infectious diseases. The gastrointestinal pathogens, enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC) and Salmonella enterica serovar Typhimurium (ST) are food-borne pathogens that cause much morbidity and mortality worldwide. Citrobacter rodentium (Cr) is a mouse pathogen that is used in small animal models to mimic EHEC and EPEC infections. Methods: We began to characterize the contribution of intestinal microbiota to the progression of these infections. Two main phyla comprise the majority of mouse intestinal microbiota: Bacteroidetes and Firmicutes. Bacteria from a number of additional phyla are also present in smaller numbers; among them γ-Proteobacteria class, belonging to Proteobacteria phylum, is note-worthy as this class harbours many intestinal pathogens, such as ST and Cr. The mouse intestinal microbiota was perturbed using tetracycline (Tet) and streptomycin (Sm) to increase the proportion of Bacteroidetes in the colonic microbiota, and using vancomycin (Vanc) to create a predominance of Firmicutes. The mice with this perturbed microbiota were infected with ST to investigate the resultant pathology and virulence characteristics, and any additional shifts in microbiota as a result of infection. Results: Treatment of mice with Sm and Vanc was found to decrease the resistance of mice to colonization with ST, while Tet-treated mice exhibited unchanged colonization resistance. Treatment of mice with gradually increasing doses of Sm, which gradually augmented the proportion of CFB bacteria in the microbiota, resulted in progressively increasing colonization of mice by ST, as well as a step-wise increase in the ST-induced typhlitis, associated with higher levels of inflammatory markers IL-6 and KC. The increasing levels of ST colonization following both Sm and Vanc treatment were associated with an increase in the proportion of γ-Proteobacteria in the cecal and colonic microbiota, as well as a decrease in the total bacterial numbers in both organs. Conclusions: It is evident that the intestinal microbiota plays a significant role in the host’s response to infection with enteric pathogens, and its composition and numbers are also affected by the offending bacteria. Elucidation of the details regarding the contribution of the microbiota to infectious disease progression will offer novel targets for the future design of superior prevention and treatment methods.

scholarly journals Effect of Compost Amendments on Disease Severity and Yield of Tomato in Conventional and Organic Production Systems

Plant Disease ◽  
2002 ◽  
Vol 86 (2) ◽  
pp. 156-161 ◽  
Author(s):  
P. A. Abbasi ◽  
J. Al-Dahmani ◽  
F. Sahin ◽  
H. A. J. Hoitink ◽  
S. A. Miller
Keyword(s):  
Disease Severity ◽  
Production Systems ◽  
Disease Incidence ◽  
Organic Production ◽  
Fruit Rot ◽  
High Rate ◽  
Bacterial Spot ◽  
Marketable Yield ◽  
Tomato Production ◽  
Compost Amendments

Field trials were conducted over 2 years to assess the effects of compost amendments on disease development in organic and conventional processing tomato (Lycopersicon esculentum L.) production systems. The incidence of anthracnose fruit rot was reduced in organic tomato plots amended with a high rate of composted cannery wastes compared with the incidence in nonamended control plots in 1998 when disease incidence was high. Marketable yield was increased by 33% in compost-amended organic plots. Plots amended with a high compost rate had more ripe fruit than the nonamended control. The incidence of anthracnose and of total disease on fruit was less on the cultivar OH 8245 than on Peto 696. Total fruit yield of OH 8245 but not Peto 696 in organic plots was increased by amendment with composted cannery wastes. In conventional tomato production, composted yard wastes increased disease severity on foliage both years but reduced bacterial spot incidence on fruit in 1997, when disease pressure was high. The incidence of anthracnose was not affected by composted yard wastes. Marketable and total fruit yields of Peto 696 were not increased in compost-amended conventional plots. The plant activator Actigard reduced foliar disease severity and the incidence of bacterial spot and anthracnose on fruit, while increasing yield of marketable fruit.

Explaining variability in parasite aggregation levels among host samples

Parasitology ◽  
2013 ◽  
Vol 140 (4) ◽  
pp. 541-546 ◽  
Author(s):  
ROBERT POULIN
Keyword(s):  
Body Size ◽  
Strong Relationship ◽  
Host Susceptibility ◽  
Helminth Parasites ◽  
Susceptibility To Infection ◽  
Host Body ◽  
Parasite Aggregation ◽  
Using Data ◽  
Species Specific ◽  
Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

scholarly journals Human Babesiosis in Europe

Pathogens ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 1165
Author(s):  
Anke Hildebrandt ◽  
Annetta Zintl ◽  
Estrella Montero ◽  
Klaus-Peter Hunfeld ◽  
Jeremy Gray
Keyword(s):  
Clinical Management ◽  
Diagnostic Tools ◽  
Genetic Characteristics ◽  
Susceptibility To Infection ◽  
First Case ◽  
The Usa ◽  
Life Threatening ◽  
History Of ◽  
Etiological Agents ◽  
Human Babesiosis

Babesiosis is attracting increasing attention as a worldwide emerging zoonosis. The first case of human babesiosis in Europe was described in the late 1950s and since then more than 60 cases have been reported in Europe. While the disease is relatively rare in Europe, it is significant because the majority of cases present as life-threatening fulminant infections, mainly in immunocompromised patients. Although appearing clinically similar to human babesiosis elsewhere, particularly in the USA, most European forms of the disease are distinct entities, especially concerning epidemiology, human susceptibility to infection and clinical management. This paper describes the history of the disease and reviews all published cases that have occurred in Europe with regard to the identity and genetic characteristics of the etiological agents, pathogenesis, aspects of epidemiology including the eco-epidemiology of the vectors, the clinical courses of infection, diagnostic tools and clinical management and treatment.

scholarly journals High Susceptibility of Olive Cultivar FS-17 to Alternaria alternata in Southern Spain

Plant Disease ◽  
2008 ◽  
Vol 92 (8) ◽  
pp. 1252-1252 ◽  
Author(s):  
J. Moral ◽  
R. De la Rosa ◽  
L. León ◽  
D. Barranco ◽  
T. J. Michailides ◽  
...  
Keyword(s):  
Alternaria Alternata ◽  
Disease Incidence ◽  
Southern Spain ◽  
Fruit Rot ◽  
Planting Density ◽  
High Susceptibility ◽  
Olive Cultivar ◽  
White Skin ◽  
Olive Cultivars ◽  
Olive Trees

Traditional olive orchards in Spain have been planted at a density of 70 to 80 trees per ha with three trunks per tree. During the last decade, the hedgerow orchard, in which planting density is approximately 2,000 trees per ha, was developed. In 2006 and 2007, we noted a severe outbreak of fruit rot in FS-17, a new cultivar from Italy, in an experimental hedgerow planting in Córdoba, southern Spain. The incidence of fruit rot in ‘FS-17’ was 80% in January of 2006 and 24% in January of 2007. Cvs. Arbosana, IRTA-i18 (a selected clone from ‘Arbequina’), and Koroneiki had no symptoms in either year of the study. Disease incidence in ‘Arbequina’ was <0.1% only in 2006. Affected fruits were soft with gray-white skin and they eventually mummified. Black-green sporodochia were observed on the surface of diseased fruits. A fungus was isolated from diseased fruits on potato dextrose agar (PDA) and incubated at 22 to 26°C with a 12-h photoperiod. After 8 days of growing on PDA, fungal colonies formed conidial chains having a main axis with up to 10 conidia and secondary and tertiary short branches with two to four conidia. Conidia were obpyriform, ovoid, or ellipsoidal, without a beak or with a short beak, had up to four transverse septa, and measured 11.7 to 24.7 (mean 19.6) μm long and 7.7 to 13.0 (mean 9.6) μm wide at the broadest part of the conidium. The length of the beak of conidia was variable, ranging from 0 to 28.6 (mean 5.5) μm. The fungus was identified as Alternaria alternata (1). Pathogenicity tests were performed by spraying 40 mature fruits of ‘FS-17’ with a spore suspension (1 × 106 spores per ml). The same number of control fruits was treated with water. After 21 days, inoculated fruit developed symptoms that had earlier been observed in the field. A. alternata was reisolated from lesions on all infected fruits. The fungus was not isolated from any of the control fruits. The experiment was performed twice. The new growing system and the high susceptibility of some olive cultivars, such as FS-17, may result in a high incidence of disease caused by a pathogen that is generally characterized as weakly virulent. To our knowledge, this is the first report of A. alternata causing a severe outbreak of fruit rot on olive trees in the field. References: (1) B. M. Pryor and T. J. Michailides. Phytopathology 92:406, 2002.

scholarly journals Distribution of stem-end rot on the canopy in ‘Hass’ avocado trees in two coastal areas in Peru

2021 ◽  
Vol 5 (2) ◽  
pp. 60-70
Author(s):  
Alejandro Kepler Llanos Melo ◽  
Walter Eduardo Apaza-Tapia
Keyword(s):  
Disease Incidence ◽  
Management Strategies ◽  
Elongation Factor ◽  
Fungal Species ◽  
Coastal Areas ◽  
Tree Canopy ◽  
Fruit Rot ◽  
Internal Site ◽  
External Site ◽  
Hass Avocado

Stem-end rot (SER) of avocado is caused by several fungal species, and it is presented worldwide. This plant disease currently affects several avocado producer regions in Peru, causing fruit rot, impacting the industry negatively. Research about SER distribution in the canopy of avocado trees is limited. Thus, the present study aimed to compare which areas in the canopy are prone to have more SER in ‘Hass’ avocado harvested fruit in two different coastal areas in Peru. The experiment was conducted in the northern (Barranca) and southern (Cañete) of Lima. ‘Hass’Avocado fruits from both producer areas were collected to identify the causal agent; Lasiodiplodia theobromae was isolated from infected fruits. Identification was conducted based on morphological features and a partial DNA sequence of the translation elongation factor 1-α gene (tef1-α). The results showed that fruits inside the tree canopy were prone to have a higher disease incidence than the fruits located in the external site (P<0.001). Besides, internal-site fruits displayed a higher percentage of infected fruit for each grade disease (P<0.001) than external-site fruits, except for grade 0 (fruits without symptoms) and grade 1. Finally, the results suggested that the altitude where the fruit is positioned on the canopy could influence the incidence of SER, where fruits located in the high part revealed less incidence than the low section. The results are valuable for enhancing management strategies and avoiding postharvest loss of avocado fruits in our region.

scholarly journals Prior exposure to long-day photoperiods alters immune responses and increases susceptibility to parasitic infection in stickleback

2020 ◽  
Vol 287 (1930) ◽  
pp. 20201017
Author(s):  
James R. Whiting ◽  
Muayad A. Mahmud ◽  
Janette E. Bradley ◽  
Andrew D. C. MacColl
Keyword(s):  
Immune Responses ◽  
Parasitic Infection ◽  
Population Variation ◽  
Host Susceptibility ◽  
Day Length ◽  
Previous Exposure ◽  
Parasite Abundance ◽  
Susceptibility To Infection ◽  
Long Day ◽  
Host Parasite

Seasonal disease and parasitic infection are common across organisms, including humans, and there is increasing evidence for intrinsic seasonal variation in immune systems. Changes are orchestrated through organisms' physiological clocks using cues such as day length. Ample research in diverse taxa has demonstrated multiple immune responses are modulated by photoperiod, but to date, there have been few experimental demonstrations that photoperiod cues alter susceptibility to infection. We investigated the interactions among photoperiod history, immunity and susceptibility in laboratory-bred three-spined stickleback (a long-day breeding fish) and its external, directly reproducing monogenean parasite Gyrodactylus gasterostei . We demonstrate that previous exposure to long-day photoperiods (PLD) increases susceptibility to infection relative to previous exposure to short days (PSD), and modifies the response to infection for the mucin gene muc2 and Treg cytokine foxp3a in skin tissues in an intermediate 12 L : 12 D photoperiod experimental trial. Expression of skin muc2 is reduced in PLD fish, and negatively associated with parasite abundance. We also observe inflammatory gene expression variation associated with natural inter-population variation in resistance, but find that photoperiod modulation of susceptibility is consistent across host populations. Thus, photoperiod modulation of the response to infection is important for host susceptibility, highlighting new mechanisms affecting seasonality of host–parasite interactions.

scholarly journals First Report of Fruit Rot of Melon Caused by Fusarium asiaticum in China

Plant Disease ◽  
2020 ◽  
Author(s):  
Fangmin Hao ◽  
Quanyu Zang ◽  
Weihong Ding ◽  
Erlei Ma ◽  
Yunping Huang ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Elongation Factor ◽  
Morphological Characteristics ◽  
Its Region ◽  
Fruit Rot ◽  
Post Inoculation ◽  
Basal Cells ◽  
First Report ◽  
Fusarium Asiaticum ◽  
Sterile Needle

Melon (Cucumis melo L.) is a member of the Cucurbitaceae family, an important economical and horticultural crop, which is widely grown in China. In May 2020, fruit rot disease with water-soaked lesions and pink molds on cantaloupe melons was observed in several greenhouses with 50% disease incidence in Ningbo, Zhejiang Province in China. In order to know the causal agent, diseased fruits were cut into pieces, surface sterilized for 1 min with 1% sodium hypochlorite (NaClO), 2 min with 75% ethyl alcohol, rinsed in sterile distilled water three times (Zhou et al. 2018), and then placed on potato dextrose agar (PDA) medium amended with streptomycin sulfate (100 μg/ml) plates at 25°C for 4 days. The growing hyphae were transferred to new PDA plates using the hyphal tip method, putative Fusarium colonies were purified by single-sporing. Twenty-five fungal isolates were obtained and formed red colonies with white aerial mycelia at 25°C for 7 days, which were identified as Fusarium isolates based on the morphological characteristics and microscopic examination. The average radial mycelial growth rate of Fusarium isolate Fa-25 was 11.44 mm/day at 25°C in the dark on PDA. Macroconidia were stout with curved apical and basal cells, usually with 4 to 6 septa, and 29.5 to 44.2 × 3.7 to 5.2 μm on Spezieller Nährstoffarmer agar (SNA) medium at 25°C for 10 days (Leslie and Summerell 2006). To identify the species, the internal transcribed spacer (ITS) region and translational elongation factor 1-alpha (TEF1-α) gene of the isolates were amplified and cloned. ITS and TEF1-α was amplified using primers ITS1/ITS4 and EF1/EF2 (O’Donnell et al. 1998), respectively. Sequences of ITS (545 bp, GenBank Accession No. MT811812) and TEF1-α (707 bp, GenBank Acc. No. MT856659) for isolate Fa-25 were 100% and 99.72% identical to those of F. asiaticum strains MSBL-4 (ITS, GenBank Acc. MT322117.1) and Daya350-3 (TEF1-α, GenBank Acc. KT380124.1) in GenBank, respectively. A phylogenetic tree was established based on the TEF1-α sequences of Fa-25 and other Fusarium spp., and Fa-25 was clustered with F. asiaticum. Thus, both morphological and molecular characterizations supported the isolate as F. asiaticum. To confirm the pathogenicity, mycelium agar plugs (6 mm in diameter) removed from the colony margin of a 2-day-old culture of strain Fa-25 were used to inoculate melon fruits. Before inoculation, healthy melon fruits were selected, soaked in 2% NaClO solution for 2 min, and washed in sterile water. After wounding the melon fruits with a sterile needle, the fruits were inoculated by placing mycelium agar plugs on the wounds, and mock inoculation with mycelium-free PDA plugs was used as control. Five fruits were used in each treatment. The inoculated and mock-inoculated fruits were incubated at 25°C with high relative humidity. Symptoms were observed on all inoculated melon fruits 10 days post inoculation, which were similar to those naturally infected fruits, whereas the mock-inoculated fruits remained symptomless. The fungus re-isolated from the diseased fruits resembled colony morphology of the original isolate. The experiment was conducted three times and produced the same results. To our knowledge, this is the first report of fruit rot of melon caused by F. asiaticum in China.

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