scholarly journals New sources of partial resistance to bacterial spot race T2 in processing tomatoes

2016 ◽  
Vol 34 (3) ◽  
pp. 326-332
Author(s):  
María C Berrueta ◽  
Gustavo Giménez ◽  
Guillermo A Galván ◽  
Alejandra Borges
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Leaf Spot ◽  
Partial Resistance ◽  
Genetic Resistance ◽  
Bacterial Spot ◽  
Bacterial Leaf Spot ◽  
Rapid Spread ◽  
Xanthomonas Species ◽  
Processing Tomatoes

ABSTRACT Bacterial leaf spot of tomato is caused by four Xanthomonas species, among which Xanthomonas vesicatoria race T2 predominates in Uruguay. Difficulties in integrated disease management and the rapid spread of the pathogen led to investigations of genetic resistance. This study aimed to identify resistance sources to bacterial leaf spot race T2 in tomato for processing. Twelve genotypes were evaluated under field conditions in 2010 and 2011. Plants were spray-inoculated with a suspension of bacteria (108 cfu/mL) 15 days after transplantation. Incubation period, disease severity on leaves, and the percentage of fruits with symptoms at harvest were determined. The incubation period did not differ among the genotypes. The genotype 'Hawaii 7981' had the lowest leaf severity on the leaves, followed by 'Loica'. The lines (derived from the cultivar 'Loica') LB97, LB99, LB60, and LB76, and the cultivar 'Ohio 8245' showed intermediate levels of severity on leaves, whereas 'H9997', 'Cuyano', LB85, and 'NUN6011' presented higher severities. The differences in disease severity of the leaves were similar over the years, while incidence of symptoms in fruit was more variable. Next to 'Hawaii 7981', the cultivars 'Loica' and 'Ohio 8245' were identified as new sources of partial resistance to bacterial spot race T2.

scholarly journals Epidemiology and management of bacterial leaf spot on watermelon caused byPseudomonas syringae

Plant Disease ◽  
2017 ◽  
Vol 101 (7) ◽  
pp. 1222-1229 ◽  
Author(s):  
E. A. Newberry ◽  
L. Ritchie ◽  
B. Babu ◽  
T. Sanchez ◽  
K. A. Beckham ◽  
...  
Keyword(s):  
Disease Severity ◽  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Negative Relationship ◽  
Disease Outbreaks ◽  
Field Trials ◽  
Multiple Regression Model ◽  
Bacterial Leaf Spot ◽  
Progress Curve ◽  
Cool Conditions

Bacterial leaf spot of watermelon caused by Pseudomonas syringae has been an emerging disease in the southeastern United States in recent years. Disease outbreaks in Florida were widespread from 2013 to 2014 and resulted in foliar blighting at the early stages of the crop and transplant losses. We conducted a series of field trials at two locations over the course of two years to examine the chemical control options that may be effective in management of this disease, and to investigate the environmental conditions conducive for bacterial leaf spot development. Weekly applications of acibenzolar-S-methyl (ASM) foliar, ASM drip, or copper hydroxide mixed with ethylene bis-dithiocarbamate were effective in reducing the standardized area under the disease progress curve (P < 0.05). Pearson’s correlation test demonstrated a negative relationship between the average weekly temperature and disease severity (–0.77, P = 0.0002). When incorporated into a multiple regression model with the square root transformed average weekly rainfall, these two variables accounted for 71% of the variability observed in the weekly disease severity (P < 0.0001). This information should be considered when choosing the planting date for watermelon seedlings as the cool conditions often encountered early in the spring season are conducive for bacterial leaf spot development.

scholarly journals Heritability of peach tree resistance to bacterial leaf spot

2017 ◽  
Vol 52 (5) ◽  
pp. 366-369 ◽  
Author(s):  
André Luiz Varago ◽  
Idemir Citadin ◽  
Marcos Robson Sachet ◽  
Gener Augusto Penso ◽  
Maria do Carmo Bassols Raseira
Keyword(s):  
Leaf Area ◽  
Disease Severity ◽  
Leaf Spot ◽  
Field Conditions ◽  
Broad Sense Heritability ◽  
Peach Tree ◽  
Bacterial Leaf Spot ◽  
Tree Resistance ◽  
Leaf Area Duration ◽  
Xanthomonas Arboricola

Abstract: The objective of this work was to evaluate the broad-sense heritability reaction to bacterial leaf spot (Xanthomonas arboricola pv. pruni), in peach tree populations obtained from directed crosses. Disease severity and defoliation of the genotypes were evaluated in field conditions, with posterior measurement of the healthy leaf area duration (HAD). The observed average heritability (0.51) indicates that the use of the evaluated genitors can be effective for the development of cultivars with higher resistance to the disease.

scholarly journals Pathogenicity and copper tolerance in Australian Xanthomonas species associated with bacterial leaf spot

2020 ◽  
Vol 127 ◽  
pp. 104923 ◽  
Author(s):  
R. Roach ◽  
R. Mann ◽  
C.G. Gambley ◽  
R.G. Shivas ◽  
T. Chapman ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Copper Tolerance ◽  
Bacterial Leaf Spot ◽  
Xanthomonas Species

scholarly journals Temperature and incubation period affect Septoria pistaciarum conidium germination: disease forecasting and validation

2021 ◽  
Vol 60 (1) ◽  
pp. 113-117
Author(s):  
Thomas THOMIDIS ◽  
Konstantinos MICHOS ◽  
Fotis CHATZIPAPADOPOULOS ◽  
Amalia TAMPAKI
Keyword(s):  
Incubation Period ◽  
Disease Severity ◽  
Leaf Spot ◽  
Disease Risk ◽  
Generic Model ◽  
High Disease Severity ◽  
Conidium Germination ◽  
Effects Of Temperature ◽  
Important Disease ◽  
Septoria Leaf Spot

Septoria leaf spot is an important disease of pistachio trees in Greece. This study aimed to determine effects of temperature and the incubation period on germination of conidia of Septoria pistaciarum, and to evaluate a generic model to forecast pistachio leaf spot under the field conditions of Aegina Island, Greece. The optimum temperature for conidium germination was 23°C, and germination was inhibited at 35 and 4°C. At constant temperature of 23°C, conidia commenced germination after 9 h. The predictive model indexed disease risk close to 100 at 10 May at two locations (Rachi Moschona and Vigla) in 2017, and first leaf spot symptoms were observed on 17 May. Moderate to high disease severity (>25% leaves infected) were observed in unsprayed trees at the end of May. In 2018, the model indexed risk close to 100 on 9 May at Rachi Moschona, and first symptoms were observed on 18 May. Moderate to high disease severity (>25% leaves infected) were observed in unsprayed trees on 25th of May. This study has shown that the forecasting model can be used in Aegina Island, Greece, to predict the severity of Septoria leaf spot of pistachio.

scholarly journals Multiple resistance to bacterial halo blight and bacterial leaf spot in Coffea spp.*

2019 ◽  
Vol 86 ◽  
Author(s):  
Lucas Mateus Rivero Rodrigues ◽  
Suzete Aparecida Lanza Destéfano ◽  
Irene Maria Gatti de Almeida ◽  
Luís Otávio Saggion Beriam ◽  
Masako Toma Braghini ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Leaf Spot ◽  
Low Cost ◽  
Durable Resistance ◽  
Genetic Resistance ◽  
Causal Agent ◽  
Limiting Factor ◽  
Bacterial Leaf Spot ◽  
Halo Blight ◽  
Moisture Conditions

ABSTRACT Breeding for genetic resistance is an important method of crop disease management, due to the numerous benefits and low cost of establishment. In this study, progenies of 11 Coffea species and 16 wild C. arabica accessions were tested for their response to Pseudomonas syringae pv. garcae, the causal agent of bacterial halo blight, a widespread disease in the main coffee-producing regions of Brazil and considered a limiting factor for cultivation in pathogen-favorable areas; and also to P. syringae pv. tabaci, causal agent of bacterial leaf spot, a highly aggressive disease recently detected in Brazil. Separate experiments for each disease were carried out in a greenhouse, with artificial pathogen inoculations and ideal moisture conditions for disease development. The results showed that C. canephora, C. congensis, C. eugenioides, C. stenophylla, and C. salvatrix progenies, the wild C. arabica accessions Dilla & Alghe and Palido Viridis, and cultivar IPR 102 contain satisfactory levels of simultaneous resistance against bacterial halo blight and bacterial leaf spot. These results are useful in breeding programs for durable resistance to multiple biotic agents, providing new combinations of resistance alleles by hybridization, as well as for phytopathological studies, to identify infraspecific variability of the pathogens.

scholarly journals Evaluation of a Light-activated Nanoparticle Formulation of Titanium Dioxide with Zinc for Management of Bacterial Leaf Spot on Rosa ‘Noare’

HortScience ◽  
2013 ◽  
Vol 48 (2) ◽  
pp. 189-192 ◽  
Author(s):  
Mathews L. Paret ◽  
Aaron J. Palmateer ◽  
Gary W. Knox
Keyword(s):  
Titanium Dioxide ◽  
Leaf Spot ◽  
No Reduction ◽  
Basic Research ◽  
Economic Losses ◽  
Bacterial Spot ◽  
Bacterial Leaf Spot ◽  
The Past ◽  
Industry Standard ◽  
Nanoparticle Formulation

Bacterial leaf spot on roses caused by a Xanthomonas sp. is a new disease affecting commercial rose production with the potential to cause major economic losses. In the past few decades, antimicrobial photocatalyst technology has emerged from basic research and development to provide convenient formulations of titanium dioxide (TiO2) nanoparticles, which have the ability to destroy bacteria on surfaces in the presence of light. In this study, a TiO2 nanoparticle formulation containing zinc (TiO2/Zn) was tested for management of bacterial leaf spot on Rosa ‘Noare’. TiO2/Zn caused significant reduction in the survival of Xanthomonas sp. strain Xr-1 on glass coverslips coated with the nanoparticles on exposure to light at 3 × 104 lux for 10 minutes. There was no reduction of bacterial viability in non-coated or non-illuminated controls. Field applications of TiO2/Zn at ≈500 to 800 ppm on Rosa ‘Noare’ significantly reduced bacterial spot severity compared with the untreated control. TiO2/Zn activity was better or on par with the ornamental industry standard for management of rose diseases.

scholarly journals Evaluation of the Effect of Seed Treatments, Bactericides, and Cultivars on Bacterial Leaf Spot of Lettuce Caused by Xanthomonas campestris pv. vitians

Plant Disease ◽  
2000 ◽  
Vol 84 (3) ◽  
pp. 295-299 ◽  
Author(s):  
O. Carisse ◽  
A. Ouimet ◽  
V. Toussaint ◽  
V. Philion
Keyword(s):  
Seed Germination ◽  
Disease Severity ◽  
Sodium Hypochlorite ◽  
Copper Sulfate ◽  
Leaf Spot ◽  
Xanthomonas Campestris ◽  
Hot Water ◽  
Seed Treatments ◽  
Bacterial Leaf Spot ◽  
Significant Difference

As a part of a broader program for management of bacterial leaf spot, the effects of lettuce-seed treatments, greenhouse application of bactericides, and cultivars were evaluated. Seed artificially inoculated with Xanthomonas campestris pv. vitians was treated with bactericides or heat treated and evaluated for the incidence of contaminated seed and seed germination. Seed soaked in 1% sodium hypochlorite for 5 and 20 min had an incidence of contaminated seed of less than 10%. Dry-heat (1 h), hot-water (50°C, 2 h), and organic-acid treatments significantly reduced seed germination. Considering both the effects on incidence of contaminated seed and seed germination, the best treatments were soaking the seeds in 1% sodium hypochlorite for 5 or 20 min. Copper sulfate, alone or mixed with Zineb or Dithane, failed to control the disease and caused phytotoxicity. All of the other bactericides significantly reduced the severity of bacterial leaf spot. However, the differences among bactericide efficacy were too small to allow comparison between the different forms of copper used, as well as the effect of adding manganese and zinc (Dithane) or zinc alone (Zineb) to the copper product. Nevertheless, copper hydroxide alone, mixed with Zineb or mixed with Dithane, and basic copper sulfate reduced disease severity by 86.89, 78.67, 80.42, and 81.82%, respectively, without causing phytotoxicity. For the two years of cultivar evaluation, no significant difference in mean disease severity was observed among the cultivars. Based on disease incidence, the most susceptible cultivar was Bellagreen. Cvs. Ideal cos, Grand Teton, Great Lakes, Paris Island, Ithaca, and Optima showed intermediate susceptibility, and the least-susceptible cultivars were Waldmann's and Grand Rapids, both green-leaf type. There was no significant difference between the three romaine (cos) cultivars and between the two crisphead cultivars, but a significant difference was observed between the two butterhead types, Bellagreen and Optima, which had 80.04 and 48.01%, respectively, of their leaves diseased at the time of harvest.

scholarly journals Inheritance of resistance against Peronospora destructor in onion cv. ‘Regia’

2020 ◽  
pp. 1999-2009
Author(s):  
Mariana Arias ◽  
Natalia Curbelo ◽  
Pablo González Rabelino ◽  
Esteban Vicente ◽  
Gustavo Giménez ◽  
...  
Keyword(s):  
Disease Severity ◽  
Partial Resistance ◽  
Agronomic Traits ◽  
Selection Process ◽  
Genetic Resistance ◽  
Transgressive Segregation ◽  
Inheritance Of Resistance ◽  
Peronospora Destructor ◽  
Loss Of Susceptibility ◽  
Onion Downy Mildew

Onion downy mildew (DM) caused by Peronospora destructor is a very destructive leaf disease. Genetic resistance is an economic and environmentally friendly way of disease control. In this research, the segregation of DM resistance was analysed in six offspring from crosses between national cultivars and the cv. ‘Regia’, a partial resistance source. F1 plants were self-fertilised, and F1S1 derived progenies were evaluated. The segregations in DM severity were skewed towards susceptibility, with transgressive segregation in five of six progenies. The recessive inheritance could be associated with loss of susceptibility mechanisms. In another experiment, the response of advanced F1S2 lines ‘Regia’ x ‘Pantanoso del Sauce’ were evaluated two times (August and November 2017) in DM disease severity, DM histological quantitative differences, and agronomic traits. F1S2 lines, which have had an earlier selection process, presented an intermediate DM severity between the parents. Disease severity was positively correlated with histological differences in the proportion of infected stomata. ‘Regia’ presented the lowest DM severity and the highest percentage of healthy stomata. Most resistant F1S2 lines did not differ from control cultivars in bulb yield, bulb quality traits and postharvest behaviour, and could be the basis to develop a DM resistant cultivar in comparison to currently grown cultivars

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