In-orchard population dynamics of Erwinia amylovora on apple flower stigmas

2022 ◽  
Author(s):  
Suzanne Slack ◽  
Jeff Schachterle ◽  
Emma Sweeney ◽  
Roshni Kharadi ◽  
Jingyu Peng ◽  
...  
Keyword(s):  
Population Dynamics ◽  
Wind Speed ◽  
Relative Humidity ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Field Studies ◽  
Post Inoculation ◽  
Time Period ◽  
Weather Parameters ◽  
Frequent Sampling

Populations of the fire blight pathogen Erwinia amylovora Ea110 on apple flower stigmas were tracked over the course of apple bloom in field studies conducted between 2016 and 2019. In 18 of 23 experiments, flower stigmas inoculated on the 1st day of opening were found to harbor large (106-107 cells / flower) populations of E. amylovora when assessed three to five days post-inoculation. However, populations inoculated on stigmas of flowers that were already open for three days did not reach 106 cells / flower, and populations inoculated on stigmas of flowers that were already open for five days never exceeded 104 cells / flower. During this study, >10-fold increases in E. amylovora stigma populations in a 24-hr time period (termed population surges) were observed on 34.8%, 20.0%, and 4.0% of possible days on 1-day, 3-day, and 5-day open flowers, respectively. Population surges occurred on days with average temperatures as high as 24.5°C and as low as 6.1°C. Experiments incorporating more frequent sampling during days and overnight revealed that many population surges occurred between 10:00 PM and 2:00 AM. A Pearson’s correlation analysis of weather parameters occurring during surge events indicated that population surges were significantly associated with situations where overnight temperatures either increased or remained constant, where wind speed decreased, and where relative humidity increased. This study refines our knowledge of E. amylovora population dynamics and further indicates that E. amylovora is able to infect flowers during exposure to colder field temperatures than previously reported.

Effect of kasugamycin, oxytetracycline, and streptomycin on in-orchard population dynamics of Erwinia amylovora on apple flower stigmas

Plant Disease ◽  
2020 ◽  
Author(s):  
Suzanne Slack ◽  
Kellie J Walters ◽  
Cory Outwater ◽  
George W. Sundin
Keyword(s):  
Population Dynamics ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Disease Incidence ◽  
Population Data ◽  
Antibiotic Activity ◽  
The Other ◽  
Control Efficacy ◽  
Weather Parameters

We assessed the effect of three antibiotics (streptomycin, oxytetracycline, and kasugamycin) on populations of the fire blight pathogen Erwinia amylovora on apple flower stigmas during three field seasons. Timing of application relative to E. amylovora presence on flower stigmas had little impact on both population dynamics and subsequent disease incidence. While E. amylovora populations on water-treated flowers increased to 106-7 cfu flower-1 after 4-5 days in each experiment, the antibiotics streptomycin and kasugamycin caused statistically-significant reductions of stigma populations by as many as 4-5 logs over a 4-5 day period in two of the three experiments. In contrast, the effect of oxytetracycline on E. amylovora populations on stigmas was more variable, with reductions in E. amylovora populations only observed in one of the three experiments. In agreement with the population data, disease incidence was significantly higher on oxytetracycline-treated flowers compared to the other antibiotic treatments in two of three years. Statistical analyses of effects of weather parameters on antibiotic activity revealed that solar radiation and temperature negatively impacted the activity of both kasugamycin and oxytetracycline. We further assessed the potential for photodegradation of formulated kasugamycin (Kasumin 2L, Arysta LifeSciences), and found that Kasumin 2L was susceptible to degradation in vitro after exposure to a 16-hr photoperiod of daily light integrals (DLIs) varying from 6 to 35 mol·m–2·d–1. We further determined that exposure to three consecutive 16-hr photoperiods of DLIs of 23 or 35 mol·m–2·d–1 reduced the available concentration of Kasumin 2L (assessed using a bioassay) from 100 g ml-1 to 10-20 g ml-1. Our results correlate the superior blossom blight control efficacy of kasugamycin and streptomycin to significant population reductions of E. amylovora on apple flower stigmas but indicate that, similar to oxytetracycline, kasugamycin is vulnerable to photodegradation which would suggest that further considerations should be made when applying this antibiotic.

Infestation level and population dynamics of aphid on mustard

2018 ◽  
Vol 43 (4) ◽  
pp. 611-618 ◽  
Author(s):  
E Mandal ◽  
MR Amin ◽  
H Rahman ◽  
AM Akanda
Keyword(s):  
Population Dynamics ◽  
Regression Analysis ◽  
Relative Humidity ◽  
Linear Regression ◽  
Light Intensity ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Lipaphis Erysimi ◽  
Infestation Level ◽  
Weather Parameters

Mustard (Brassica juncea) variety BARI Shorisha-11 was cultivated during September 2016 to March 2017 in Gazipur, Bangladesh to find out the population dynamics of aphid and its infestation level on mustard. The aphid Lipaphis erysimi (Homoptera: Aphididae) was abundant in the field and caused infestation. The population of aphid in the mustard field showed fluctuation and reached to the peak at 22 December which was 289 per plant. Inflorescence had significantly higher level of infestation compared to individual siliqua and leaf. The daily mean temperature had significant negative, light intensity had insignificant negative and relative humidity had insignificant positive correlation with the abundance of aphid. The multiple linear regression analysis showed that the weather parameters namely temperature, light intensity and relative humidity individually as well as combindly contributed on the abundance of aphid, but the temperature had greater effect than other factors.Bangladesh J. Agril. Res. 43(4): 611-618, December 2018

scholarly journals Blackberry and raspberry are alternative resistance sources to fire blight

2017 ◽  
Vol 97 (1) ◽  
pp. 12-16 ◽  
Author(s):  
Ozer Calis ◽  
Cetin Cekic ◽  
Serhat Kara ◽  
Demet Celik Ertekin
Keyword(s):  
Bacterial Growth ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Bacterial Pathogen ◽  
Post Inoculation ◽  
Resistance Sources ◽  
Pathogenicity Tests ◽  
Susceptibility And Resistance ◽  
Resistant Genotypes ◽  
Moderate Susceptibility

Erwinia amylovora causes fire blight mainly on pear, apple and quince trees. This bacterial pathogen also infects other Rosaceous plants, such as blackberry and raspberry. A race structure was established between an isolate of E. amylovora and berries using 40 wild blackberry and 7 wild raspberry genotypes. In pathogenicity tests, wild blackberry and raspberry genotypes had three phenotypic reactions: enhanced susceptibility, moderate susceptibility and resistance. We noted a higher bacterial growth of over 300 × 109 cfu mL-1 in plants with enhanced susceptibility, with resistant genotypes showing a bacterial growth of around 150 × 109 cfu mL-1. These results are also associated with symptoms observed at 29 days post-inoculation. This resistance is being evaluated to control fire blight.

scholarly journals Epiphytic Bacteria and Yeasts on Apple Blossoms and Their Potential as Antagonists of Erwinia amylovora

2009 ◽  
Vol 99 (5) ◽  
pp. 571-581 ◽  
Author(s):  
P. Lawrence Pusey ◽  
Virginia O. Stockwell ◽  
Mark Mazzola
Keyword(s):  
Relative Humidity ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Acid Methyl Ester ◽  
Washington State ◽  
Microbial Populations ◽  
Acid Methyl ◽  
Population Sizes ◽  
Average Relative Humidity ◽  
Cryptococcus Spp

Apple blossoms were sampled for indigenous epiphytic populations of culturable microorganisms during different stages of bloom at two locations in central Washington State and one site in Corvallis, OR. Frequencies and population sizes of bacteria on stigmas of apple were lower in Washington than at Corvallis, where average relative humidity was higher and possibly favored greater colonization; however, bacteria at Corvallis were mainly pseudomonads, whereas those in Washington were diverse, composed of several genera. In Washington, yeast as well as bacteria were isolated from both stigmatic and hypanthial surfaces. Sampled blossoms were processed immediately to assess microbial populations, or after a 24-h incubation at 28°C and high relative humidity, which broadened the range of detectable taxa evaluated as potential antagonists. Identifications were based on fatty acid methyl ester profiles and rDNA sequence analyses. Yeasts or yeastlike organisms were detected at frequencies similar to or greater than bacteria, particularly in hypanthia. When microbial isolates were tested for their capacity to suppress Erwinia amylovora on stigmas of detached crab apple flowers, many were ineffective. The best antagonists were the bacteria Pantoea agglomerans and Pseudomonas spp. and a few yeasts identified as Cryptococcus spp. Further evaluation of these taxa on flowers could lead to the discovery of additional biocontrol agents for fire blight.

scholarly journals Long term monthly and inter-seasonal weather variability analysis for the lower Shivalik foothills of Punjab

MAUSAM ◽  
2022 ◽  
Vol 73 (1) ◽  
pp. 173-180
Author(s):  
NAVNEET KAUR ◽  
M.J. SINGH ◽  
SUKHJEET KAUR
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Minimum Temperature ◽  
Maximum Temperature ◽  
Linear Regression Method ◽  
Post Monsoon ◽  
Sunshine Hours ◽  
Annual Minimum Temperature ◽  
Weather Parameters

This paper aims to study the long-term trends in different weather parameters, i.e., temperature, rainfall, rainy days, sunshine hours, evaporation, relative humidity and temperature over Lower Shivalik foothills of Punjab. The daily weather data of about 35 years from agrometeorological observatory of Regional Research Station Ballowal Saunkhri representing Lower Shivalik foothills had been used for trend analysis for kharif (May - October), rabi (November - April), winter (January - February), pre-monsoon (March - May), monsoon (June - September) and post monsoon (October - December) season. The linear regression method has been used to estimate the magnitude of change per year and its coefficient of determination, whose statistical significance was checked by the F test. The annual maximum temperature, morning and evening relative humidity has increased whereas rainfall, evaporation sunshine hours and wind speed has decreased significantly at this region. No significant change in annual minimum temperature and diurnal range has been observed. Monthly maximum temperature revealed significant increase except January, June and December, whereas, monthly minimum temperature increased significantly for February, March and October and decreased for June. Among different seasons, maximum temperature increased significantly for all seasons except winter season, whereas, minimum temperature increased significantly for kharif and post monsoon season only. The evaporation, sunshine hours and wind speed have also decreased and relative humidity decreased significantly at this region. Significant reduction in kharif, monsoon and post monsoon rainfall has been observed at Lower Shivalik foothills. As the region lacks assured irrigation facilities so decreasing rainfall and change in the other weather parameters will have profound effects on the agriculture in this region so there is need to develop climate resilient agricultural technologies.

scholarly journals Modelling Agro-Met Station Observations Using Genetic Algorithm

2014 ◽  
Vol 2014 ◽  
pp. 1-8
Author(s):  
Prashant Kumar ◽  
Bimal K. Bhattacharya ◽  
C. M. Kishtawal ◽  
Sujit Basu
Keyword(s):  
Genetic Algorithm ◽  
Wind Speed ◽  
Relative Humidity ◽  
Data Fitting ◽  
Prediction Methods ◽  
Training Algorithm ◽  
Near Surface ◽  
The Past ◽  
Forecast Models ◽  
Weather Parameters

The present work discusses the development of a nonlinear data-fitting technique based on genetic algorithm (GA) for the prediction of routine weather parameters using observations from Agro-Met Stations (AMS). The algorithm produces the equations that best describe the temporal evolutions of daily minimum and maximum near-surface (at 2.5-meter height) air temperature and relative humidity and daily averaged wind speed (at 10-meter height) at selected AMS locations. These enable the forecasts of these weather parameters, which could have possible use in crop forecast models. The forecast equations developed in the present study use only the past observations of the above-mentioned parameters. This approach, unlike other prediction methods, provides explicit analytical forecast equation for each parameter. The predictions up to 3 days in advance have been validated using independent datasets, unknown to the training algorithm, with impressive results. The power of the algorithm has also been demonstrated by its superiority over persistence forecast used as a benchmark.

scholarly journals Influence of Weather Parameters and Thermal Time Approach on Green Gram at Coimbatore, Tamil Nadu

2020 ◽  
pp. 1-5
Author(s):  
S. A. Naveen ◽  
S. Kokilavani ◽  
S. P. Ramanathan ◽  
G. A. Dheebakaran ◽  
S. Anitta Fanish
Keyword(s):  
Wind Speed ◽  
Relative Humidity ◽  
Tamil Nadu ◽  
Green Gram ◽  
Research Centre ◽  
Maximum Temperature ◽  
Sowing Dates ◽  
Sunshine Hours ◽  
Diurnal Range ◽  
Weather Parameters

An investigation was carried out at the Agro Climate Research Centre, Tamil Nadu Agricultural University, on the effect of weather parameters on the green gram yield sown at various sowing dates during the rabi season of 2019. At various sowing dates, two green gram cultivars, VBN 4 and ADT 3, were sown. For both cultivars, the phonological crop length decreased with delays in sowing dates beyond October 23rd. The yield of green gram sown on 23rd October was significantly higher than the crops sown on 30th October and 6th November. The weather parameters Maximum Temperature (Tmax), Diurnal Range (Trange), Bright Sunshine Hours (BSS), Relative Humidity (RH I), Wind Speed (WS) were found to be negatively correlated with seed yield whereas Minimum Temperature (Tmin), Relative Humidity (RH II), Vapour Pressure (VP) were found to be positively correlated with the yield of green gram. The accurate prediction of green gram yield could be done with the maximum temperature, bright sunshine hours, wind speed and with thermal indices especially hygrothermal unit II with 82 percent, accuracy level.

scholarly journals Effectiveness of Kasugamycin Against Erwinia amylovora and its Potential Use for Managing Fire Blight of Pear

Plant Disease ◽  
2011 ◽  
Vol 95 (4) ◽  
pp. 448-454 ◽  
Author(s):  
J. E. Adaskaveg ◽  
H. Förster ◽  
M. L. Wade
Keyword(s):  
Fire Blight ◽  
Erwinia Amylovora ◽  
Field Studies ◽  
The United States ◽  
Mean Value ◽  
Natural Occurrence ◽  
Baseline Sensitivity ◽  
Inhibition Of Growth ◽  
Industry Standards

Comparative field studies on the management of fire blight were conducted in California on Asian and Bartlett pear using single-bactericide, mixture, and rotation treatments of selected compounds. Treatment efficacy was evaluated based on the natural occurrence of the disease or after inoculation with Erwinia amylovora. Kasugamycin at 100 mg/liter demonstrated similar or higher pre- and post-infection activity than the industry standards, streptomycin and oxytetracycline. Phytotoxicity caused by kasugamycin was observed only when five or six sequential weekly applications were done. In a six-spray rotation program including three bactericides (copper, kasugamycin, and oxytetracycline), with each being used twice, phytotoxicity was minor. Baseline sensitivity concentrations for kasugamycin were established for growth of 376 isolates of E. amylovora from California. Values for the lowest concentration where a reduction in growth on nutrient agar was observed ranged from 3.5 to 18.3 mg/liter, with a mean value of 8.7 mg/liter. Values for ≥95% inhibition of growth ranged from 6.9 to 46.7 mg/liter, with a mean value of 18.5 mg/liter. These inhibitory values for kasugamycin were higher than those for streptomycin or oxytetracycline. The in vitro activity of all three compounds was highly dependent on the agar medium used in the sensitivity assay. The activity of kasugamycin was also highly dependent on the pH of the medium and was significantly higher at pH 5.1 than pH 7.3. With the planned registration in the United States, kasugamycin represents the first new, highly effective bactericide for managing fire blight in over 40 years.

scholarly journals Effect of rootstock clones on fire blight susceptibility in scion apple cultivars

2017 ◽  
Vol 38 (SI 2 - 6th Conf EFPP 2002) ◽  
pp. 552-554
Author(s):  
J. Korba ◽  
K. Patáková ◽  
V. Kůdela
Keyword(s):  
Relative Humidity ◽  
Fire Blight ◽  
Erwinia Amylovora ◽  
Shoot Length ◽  
High Relative Humidity ◽  
Golden Delicious ◽  
Apple Cultivars

This study was performed on 24 clonal rootstocks and 4 scion apple cultivars to evaluate rootstock/cultivar combinations for susceptibility to fire blight (Erwinia amylovora). For this aim, the clonal rootstocks were planted in plastic greenhouse in 1992 and grafted with 4 cultivars (Golden Delicious, Dulcit, Domino and Dione) in 1998. A total of 96 rootstock/cultivar combinations were tested during 1998–2001. Each year, 10 to 30 actively growing shoots per one combination were inoculated with the pathogen. The shoots were inoculated by cutting through first unfolding leaves with scissors dipped into inoculum (109 cfu/ml). The trees were misted to create a high relative humidity. The susceptibility of the test roostock/cultivar combinations was evaluated by calculating the length of necrosis to the total shoot length 40 days after inoculation. The degree of susceptibility of cultivar tested varied depending on the rootstocks and years. In order of decreasing to increasing levels of fire blight susceptibility of four cultivars tested, the pattern observed was Dulcit, Golden Delicious, Domino (moderately susceptible) and Dione (very susceptible). The lowest susceptibility of four cultivars tested was observed on TE 52 rootstock (on average, the cultivars were evaluated as intermediate), the highest susceptibility was on JTE-E and M9 rootstocks (the cultivars were very susceptible). The influence of 21 remaining rootstocks on susceptibility in scion cultivars was not marked. Thus some rootstocks can render the scion cultivars more fire blight susceptible or more resistant.

scholarly journals Effects of environmental factors on population dynamics of rice earhead bug and their management with newer insecticide combinations and sole insecticide

2019 ◽  
Vol 48 (4) ◽  
pp. 973-979
Author(s):  
Kamal Ravi Sharma ◽  
S.V.S. Raju ◽  
D. Rakshith Roshan
Keyword(s):  
Population Dynamics ◽  
Relative Humidity ◽  
Environmental Factors ◽  
Correlation Analysis ◽  
Negative Correlation ◽  
Untreated Control ◽  
Significant Negative Correlation ◽  
Average Temperature ◽  
Average Relative Humidity ◽  
Weather Parameters

An experiment was conducted to study the population dynamics of rice earhead bug and to evaluate the efficacy of newer insecticide combinations and sole insecticide along with untreated control. The rice earhead bug population was first recorded on 36th standard week as 1 nos./10 sweep nets and peak population (17 nos./10 sweep nets) was observed during 44th standard week. The correlation analysis revealed that rice earhead bug showed significant negative correlation with rainfall while the remaining weather parameters like average relative humidity and average temperature were found negative and non-significantly correlated. The overall data of efficacy revealed that all insecticidal treatments were significantly superior over untreated control. However, the plots treated with fipronil 5% + buprofezin 20% SC recorded the lowest number of rice earhead bug population (2.10 and 3.51 nos./5 sweep nets) after first and second insecticidal sprays, respectively, followed by indoxacarb 10% + thiamethoxam 10% WG (2.47 and 4.25 nos./5 sweep nets, respectively). Whereas, application of thiamethoxam 25% WG and buprofezin 25% singly SC were recorded as third and fourth best treatments, respectively.

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