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 Reaction of peach tree genotypes to bacterial leaf spot caused by Xanthomonas arboricola pv. prunis

2011 ◽  
Vol 68 (1) ◽  
pp. 57-61 ◽  
Author(s):  
José Gilberto Sousa Medeiros ◽  
Idemir Citadin ◽  
Idalmir dos Santos ◽  
André Paulo Assmann
Keyword(s):  
Leaf Spot ◽  
Prunus Persica ◽  
Field Conditions ◽  
Peach Tree ◽  
Bacterial Leaf Spot ◽  
Severity Rating ◽  
Detached Leaf ◽  
Greenhouse Evaluation ◽  
The World ◽  
Xanthomonas Arboricola

Bacterial leaf spot (BLS), caused by Xanthomonas arboricola pv. pruni, is one of the most important diseases in Brazilian peach [Prunus persica (L.) Batsch] orchards and all over the world. The main objective of this study was to evaluate for BLS sensitivity of peach genotypes. Evaluations of thirty genotypes were carried out during the onset of the disease, for incidence, severity and defoliation, in field conditions. Pearson's correlations between the percentage of defoliation and leaf severity rating were performed. Genotypes 'Conserva 985', 'Conserva 871', 'Conserva 1129', and 'Tropic Snow', as resistance sources, and 'Conserva 1153', 'Bonão', 'Conserva 1125', and 'Atenas', as susceptible to BLS, were submitted to detached-leaf bioassay and greenhouse evaluation. The peach genotypes showed different reactions to the BLS, and none was immune to the pathogen. 'Conserva 985' and 'Conserva 1129' confirmed resistance responsiveness while 'Conserva 1153', 'Conserva 1125' and 'Atenas' were found susceptible for the detached-leaf bioassay.

scholarly journals Reaction of Peach Genotypes to Bacterial Leaf Spot: Correlations with Environmental Conditions, Leaf Phenology, and Morphology

HortScience ◽  
2013 ◽  
Vol 48 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Marcos R. Sachet ◽  
Idemir Citadin ◽  
Silvia Scariotto ◽  
Idalmir dos Santos ◽  
Pedro H. Zydek ◽  
...  
Keyword(s):  
Leaf Area ◽  
Leaf Spot ◽  
Dry Matter ◽  
Leaf Length ◽  
Bacterial Leaf Spot ◽  
Breeding Programs ◽  
Healthy Leaf ◽  
Growing Seasons ◽  
Selection Environment ◽  
Leaf Area Duration

In breeding programs, it is essential to understand how characteristics are expressed by the germplasm in relation to the selection environment. The reactions of 15 peach genotypes to bacterial leaf spot (BLS) during three growing seasons (2008–09, 2009–10, and 2010–11) were investigated. Quantitative assessments were made from three plants per genotype through a modified healthy leaf area duration (HAD) method. None of the genotypes were immune to the disease. The most resistant were ‘Cascata 1055’, ‘Conserva 985’, ‘Cascata 967’, and ‘Cascata 1065’. There was a reduction in HAD with increased precipitation. The leaf dry matter (g/leaf), leaf blade length, leaf length (with petiole), and leaf area (cm2/leaf) were inversely correlated with genotype resistance to BLS. The HADs of susceptible genotypes were influenced by the number of wet days regardless of temperature. The most susceptible genotypes were those with earlier budburst and fruit ripening. A shorter duration of healthy leaf area was related to earlier budburst and flowering in the subsequent year. We found no relationship between HAD and productivity.

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 Photosynthesis of Blueberry Leaves as Affected by Septoria Leaf Spot and Abiotic Leaf Damage

Plant Disease ◽  
2004 ◽  
Vol 88 (4) ◽  
pp. 397-401 ◽  
Author(s):  
I. Roloff ◽  
H. Scherm ◽  
M. W. van Iersel
Keyword(s):  
Leaf Area ◽  
Disease Severity ◽  
Leaf Spot ◽  
Abiotic Factors ◽  
Lesion Size ◽  
Leaf Conductance ◽  
Yield Potential ◽  
Leaf Spots ◽  
Virtual Lesion ◽  
Septoria Leaf Spot

Leaf spots caused by fungal pathogens or abiotic factors can be prevalent on southern blueberries after harvest during the summer and fall, yet little is known about how they affect physiological processes that determine yield potential for the following year. In this study, we measured CO2 assimilation and leaf conductance on field-grown blueberry plants affected by Septoria leaf spot (caused by Septoria albopunctata) or by edema-like abiotic leaf blotching. Net assimilation rate (NAR) on healthy leaves varied between 6.9 and 12.4 μmol m-2 s-1 across cultivars and measurement dates. Infection by S. albopunctata had a significant negative effect on photosynthesis, with NAR decreasing exponentially as disease severity increased (R2 ≥0.726, P < 0.0001). NAR was reduced by approximately one-half at 20% disease severity, and values approached zero for leaves with >50% necrotic leaf area. There was a positive, linear correlation between NAR and leaf conductance (R2 ≥ 0.622, P < 0.0001), suggesting that the disease may have reduced photosynthesis via decreased CO2 diffusion into affected leaves. Estimates of virtual lesion size associated with infection by S. albopunctata ranged from 2.8 to 3.1, indicating that the leaf area in which photosynthesis was impaired was about three times as large as the area covered by necrosis. For leaves afflicted by edema-like damage, there also was a significant negative relationship between NAR and affected leaf area, but the scatter about the regression was more pronounced than in the NAR-disease severity relationships for S. albopunctata (R2 = 0.548, P < 0.0001). No significant correlation was observed between leaf conductance and affected area on these leaves (P = 0.145), and the virtual lesion size associated with abiotic damage was significantly smaller than that caused by S. albopunctata. Adequate carbohydrate supply during the fall is critical for optimal flower bud set in blueberry; therefore, these results document the potential for marked yield losses due to biotic and abiotic leaf spots.

scholarly journals First Report of Bacterial Leaf Spot Caused by Xanthomonas arboricola Infecting Saucer Magnolia in Tennessee

Plant Disease ◽  
2020 ◽  
Vol 104 (10) ◽  
pp. 2724-2724
Author(s):  
Cansu Oksel ◽  
Farhat A. Avin ◽  
Terri Simmons ◽  
Fulya Baysal-Gurel
Keyword(s):  
Leaf Spot ◽  
Bacterial Leaf Spot ◽  
First Report ◽  
Xanthomonas Arboricola

scholarly journals Optimum Sample Size for Determining Disease Severity and Defoliation Associated with Septoria Leaf Spot of Blueberry

Plant Disease ◽  
2006 ◽  
Vol 90 (9) ◽  
pp. 1209-1213 ◽  
Author(s):  
P. S. Ojiambo ◽  
H. Scherm
Keyword(s):  
Sample Size ◽  
Leaf Area ◽  
Disease Severity ◽  
Total Variation ◽  
Leaf Spot ◽  
Variance Components ◽  
Optimum Sample Size ◽  
The Mean ◽  
Time Required ◽  
Optimum Sample

In a 3-year field study, Premier rabbiteye blueberry plants were sampled at three hierarchical levels (leaf, shoot, and bush) to assess severity of Septoria leaf spot (caused by Septoria al-bopunctata) and incidence of defoliation. A positive linear relationship (R 2 = 0.977, P < 0.0001, n = 2127) was observed between the number of spots per leaf and percent necrotic leaf area, both assessed on individual leaves in mid- to late October. For data summarized at the shoot level, percent defoliation increased nonlinearly (R 2 = 0.729, P < 0.0001, n = 224) as disease severity increased, with a rapid rise to an upper limit showing little change in defoliation above 60 spots per leaf. Variance components were calculated for disease severity to partition total variation into variation among leaves per shoot, shoots per bush, and bushes within the field. In all cases, leaves per shoot and shoots per bush accounted for >90% of the total variation. Based on the variance components and linear cost functions (which considered the time required to assess each leaf and select new shoots and bushes for assessment), the optimum sample size for assessing disease severity as number of spots per leaf (with an allowable variation of 20% around the mean) was 75 leaves, one each selected from three shoots per bush on 25 bushes (total time required for assessment: 36.1 min). For disease severity expressed as percent necrotic leaf area, the corresponding values were 144 leaves, two each sampled from three shoots per bush on 24 bushes (total time required: 21.7 min). Thus, given the strong correlation between the two disease variables demonstrated in this study, visual assessment of percent necrotic area was the more efficient method. With an allowable variation of 10% around the mean, a sample of 27 shoots from nine bushes was the optimum sample size for assessing defoliation across the 3 years.

Stability of bacterial leaf spot resistance in peach regenerants under in vitro, greenhouse and field conditions

Euphytica ◽  
1994 ◽  
Vol 76 (1-2) ◽  
pp. 101-106 ◽  
Author(s):  
F. A. Hammerschlag ◽  
D. J. Werner ◽  
D. F. Ritchie
Keyword(s):  
Leaf Spot ◽  
Field Conditions ◽  
Bacterial Leaf Spot

scholarly journals First Report of Bacterial Leaf Spot Caused by the Quarantine Pathogen Xanthomonas arboricola pv. pruni on Peach in Hungary

Plant Disease ◽  
2018 ◽  
Vol 102 (8) ◽  
pp. 1654-1654 ◽  
Author(s):  
I. Schwarczinger ◽  
Z. Bozsó ◽  
Á. Szatmári ◽  
S. Süle ◽  
Z. Szabó ◽  
...  
Keyword(s):  
Leaf Spot ◽  
Bacterial Leaf Spot ◽  
First Report ◽  
Quarantine Pathogen ◽  
Xanthomonas Arboricola

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.

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