scholarly journals Factors Affecting Latent Infection of Prune Fruit by Monilinia fructicola

2001 ◽  
Vol 91 (9) ◽  
pp. 864-872 ◽  
Author(s):  
Yong Luo ◽  
Themis J. Michailides
Keyword(s):  
Growth Stage ◽  
Latent Infection ◽  
Developmental Stages ◽  
Seasonal Pattern ◽  
Brown Rot ◽  
Effect Of Temperature ◽  
Monilinia Fructicola ◽  
Inoculum Concentration ◽  
Factors Affecting ◽  
Commercial Harvest

Experiments were conducted in three prune orchards in California. In each orchard, inoculations with Monilinia fructicola, the causal agent of brown rot of stone fruits, were performed on branches of trees at bloom and fruit developmental stages. Five inoculum concentrations were used in each inoculation. Six and four wetness durations were created for each inoculum concentration at bloom and fruit developmental stages, respectively. Fruit were harvested 3 weeks before commercial harvest. The overnight freezing incubation technique was used to promote sporulation and to determine incidence of latent infection (ILI) of fruit brown rot. No differences in ILI among locations were found. A seasonal pattern of bloom and fruit susceptibility to latent infection was determined. Susceptibility to latent infection at bloom stage was at a moderate level and increased to reach the highest level at pit hardening stage. Subsequently, fruit susceptibility to latent infection decreased, reaching the lowest level in early June at embryo growth stage. Thereafter, the susceptibility increased again with fruit development and maturity until harvest. Linear relationships between ILI and inoculum concentration were obtained for most combinations of growth stage and wetness duration. Incidence of latent infection increased linearly with increased wetness duration at bloom stage and increased exponentially with increased wetness duration at early and late fruit developmental stages. The optimum temperatures for latent infection at pit hardening stage ranged from 14 to 18°C, but the effect of temperature on latent infection was reduced at resistant stages. The temperature range favorable to latent infection varied for different wetness durations.

scholarly journals Threshold Conditions That Lead Latent Infection to Prune Fruit Rot Caused by Monilinia fructicola

2003 ◽  
Vol 93 (1) ◽  
pp. 102-111 ◽  
Author(s):  
Yong Luo ◽  
Themis J. Michailides
Keyword(s):  
Latent Infection ◽  
Developmental Stages ◽  
Fruit Rot ◽  
Monilinia Fructicola ◽  
Decision Support Model ◽  
Infection Level ◽  
Inoculum Concentration ◽  
Commercial Harvest ◽  
Level Ii ◽  
Threshold Conditions

Inoculations were performed six to eight times in each of 10 prune orchards located in nine counties of California. In each inoculation, branches that bore 40 to 60 blossoms or 30 to 40 fruit were inoculated with conidial suspensions of Monilinia fructicola. Three inoculum concentrations and 14 to 16 h of humidity were used for each inoculation. All inoculated fruit were maintained on trees and harvested separately 2 weeks before commercial harvest. The incidence of latent infection (ILI) and percentage of branches with fruit rot (PBFR) were determined for each inoculation in each orchard. As the ILI increased, the PBFR also increased linearly. Five conditions that lead latent infection to fruit rot include (i) latent infection level; (ii) fruit developmental stage; (iii) inoculum concentration; (iv) total hours of relative humidity greater than 90% (hRH); and (v) total hours of dew period (hDEW) from mid-July to mid-August. Three levels of PBFR, 1, 5, and 10% were assigned, and threshold conditions that lead to these levels were determined based on the experimental results. The relative probabilities that lead latent infection to fruit rot (r_PBFR) at different fruit developmental stages were calculated. A preliminary decision support model to guide fungicide application was developed based on the above results. One of the four recommendations, safe, wait, check historical weather as a reference, and apply a fungicide immediately, could be provided based on the level of latent infection and the decision process developed through this study.

scholarly journals Analysis of Factors Affecting Latent Infection and Sporulation of Monilinia fructicola on Prune Fruit

Plant Disease ◽  
2001 ◽  
Vol 85 (9) ◽  
pp. 999-1003 ◽  
Author(s):  
Yong Luo ◽  
Zhonghua Ma ◽  
Themis J. Michailides
Keyword(s):  
Latent Infection ◽  
Secondary Infection ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Latent Infections ◽  
Inoculum Concentration ◽  
Factors Affecting ◽  
Plastic Bags ◽  
Causal Pathogen ◽  
Significant Factors

Two studies were conducted to determine the effects of water content (WC) on sporulation on thinned fruit and the effects of wetness duration, inoculum density, and temperature on secondary infection of prune fruit by Monilinia fructicola, the main causal pathogen of brown rot in California. In the first study, sporulation intensity and duration of sporulation of the pathogen were tested on inoculated thinned fruit with five levels (67.2, 53.8, 40.3, 26.9, and 13.4%) of WC. Regression analyses showed that both sporulation intensity and duration of sporulation increased as WC of thinned fruit increased. The predicted difference in duration of sporulation between fruit with 13.4 and 67.2% WC was about 3 days. In the second study, three inoculum concentrations (8,000, 16,000, and 24,000 conidia per milliliter) of M. fructicola were atomized onto prune fruit on trees in an orchard. Inoculated fruit and shoots were covered with plastic bags to maintain wetness duration for 4, 8, 12, or 16 h. An overnight freezing and incubation technique was used after harvest to determine the proportion of fruit with latent infection. Regression analysis demonstrated that inoculum concentration and wetness duration were significant factors affecting secondary infection. Temperature was less important. Increased inoculum concentration and wetness duration increased the percentage of fruit with latent infections. Increased temperature decreased the percentage of fruit with latent infections.

scholarly journals Risk Analysis for Latent Infection of Prune by Monilinia fructicola in California

2001 ◽  
Vol 91 (12) ◽  
pp. 1197-1208 ◽  
Author(s):  
Yong Luo ◽  
Themis J. Michailides
Keyword(s):  
Risk Analysis ◽  
Latent Infection ◽  
Developmental Stages ◽  
Brown Rot ◽  
Low Risk ◽  
Weather Data ◽  
Risk Level ◽  
Monilinia Fructicola ◽  
Inoculum Potential ◽  
Risk Levels

The quantitative relationships between incidence of latent infection (ILI) of prune by Monilinia fructicola and wetness duration (WD) for different bloom and fruit developmental stages and different inoculum concentrations were obtained. Three levels of ILI were considered as criteria for low, moderate, and high risks of latent infection, respectively. Seasonal patterns of WD leading to different risk levels of latent infection were obtained for low (IPL) and high (IPH) inoculum potential conditions in orchards. Longer WD was needed at a resistant than at a susceptible fruit developmental stage to induce similar levels of latent infection. The curves of WD leading to different levels of ILI over the growing season (risky WD curves) were used in risk analysis for latent infection. Multi-year historical WD data from 10 prune-growing locations in California were compared with risky WD curves. The percentage of days (P) with WD leading to a certain risk level of latent infection was calculated for each month from historical weather data. Under the IPL condition, the P distributions for low risk of latent infection were higher in March and April than in May and were the lowest in June for most locations. Under the IPH condition, the number of days that WD leading to low risk of latent infection in May increased compared with those under the IPL condition. The risk analysis approach was evaluated by using separate experimental data as incidence of fruit brown rot obtained from different prune orchards over years. Consistency between predicted overall risk levels of latent infection and observed incidence of fruit brown rot was obtained. The results demonstrated the usefulness of the risk analysis in decision support system for disease management.

scholarly journals Effect of Temperature on the Discharge and Germination of Ascospores by Apothecia of Monilinia fructicola

Plant Disease ◽  
1998 ◽  
Vol 82 (2) ◽  
pp. 195-202 ◽  
Author(s):  
Chuanxue Hong ◽  
Themis J. Michailides
Keyword(s):  
Management Strategies ◽  
Brown Rot ◽  
Effect Of Temperature ◽  
Monilinia Fructicola ◽  
Stone Fruits ◽  
Warning Systems ◽  
Fresno County ◽  
Ascospore Germination ◽  
Daily Discharge ◽  
Germ Tubes

Naturally growing apothecia of Monilinia fructicola were collected from two commercial plum orchards near Reedley and Sanger, both in Fresno County, California. Ascospore discharges from 90 (1996) and 86 (1997) apothecia were monitored individually using spore traps at four constant temperatures. The period of discharge decreased as temperature increased from 10 to 25°C. However, daily discharge increased as temperature increased from 10 to 15°C and remained high at 20 and 25°C. The greatest discharge occurred with apothecia at 15°C, followed by those incubated at 20, 10, and 25°C. The germination of ascospores of M. fructicola and the length of germ tubes increased as temperature increased from 7 to 15°C; however, increasing temperatures above 15°C did not increase either ascospore germination or length of germ tubes. This information may help in the development of warning systems and management strategies for brown rot blossom blight of stone fruits.

Culturable bacterial microflora associated with nectarine fruit and their potential for control of brown rot

2010 ◽  
Vol 56 (6) ◽  
pp. 480-486 ◽  
Author(s):  
Wojciech J. Janisiewicz ◽  
Jeffrey S. Buyer
Keyword(s):  
Pseudomonas Syringae ◽  
Early Stage ◽  
Acid Methyl Ester ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Frequency Of Occurrence ◽  
Bacterial Strains ◽  
Inoculum Concentration ◽  
Stage Of Development ◽  
Acid Methyl

Microflora of fruit surfaces have been the best source of antagonists against fungi causing postharvest decay of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grape, apple, and citrus. We characterized bacterial microflora on nectarine fruit surfaces from the early stage of development until harvest. Identification of bacterial strains was made using MIDI (fatty acid methyl ester analysis) and Biolog systems. Biolog identified 35% and MIDI 53% of the strains. Thus results from MIDI were used to determine the frequency of occurrence of genera and species. The most frequently occurring genera were Curtobacterium (21.31%), followed by Pseudomonas (19.99%), Microbacterium (13.57%), Clavibacter (9.69%), Pantoea (6.59%), and Enterobacter (4.26%). The frequency of isolations of some bacteria — for example, the major pseudomonads (Pseudomonas syringae, Pseudomonas putida, and Pseudomonas savastanoi) or Pantoea agglomerans — tended to decline as fruit developed. As Pseudomonas declined, Curtobacterium became more dominant. Time of isolation was a significant factor in the frequency of occurrence of different bacteria, indicating succession of the genera. Throughput screening of the bacterial strains against Monilinia fructicola on nectarine fruit resulted in the detection of strains able to control brown rot. The 10 best-performing antagonistic strains were subjected to secondary screening. Four strains reduced decay severity by more than 50% (51.7%–91.4% reduction) at the high pathogen inoculum concentration of 105conidia/mL.

scholarly journals Risk Analysis of Brown Rot Blossom Blight of Prune Caused by Monilinia fructicola

2001 ◽  
Vol 91 (8) ◽  
pp. 759-768 ◽  
Author(s):  
Y. Luo ◽  
D. P. Morgan ◽  
T. J. Michailides
Keyword(s):  
Environmental Conditions ◽  
Brown Rot ◽  
Stochastic Simulations ◽  
Monilinia Fructicola ◽  
Prunus Domestica ◽  
Inoculum Concentration ◽  
Different Temperatures ◽  
The Relationship ◽  
Late Stages ◽  
Linear Regressions

Experiments under controlled environmental conditions were conducted during bloom of prune (Prunus domestica, L.) in 1999 and 2000 to assess the effects of inoculum concentration (IC), wetness duration (WD), temperature, and bloom stages on development of brown rot blossom blight of prunes. Branches from trees of a prune orchard were inoculated with Monilinia fructicola at different bloom stages and incubated at different temperatures with different periods of WD. The proportion of blighted blossoms (PBB) for each inoculated branch was determined. Bloom stage, IC, temperature, and WD significantly affected blossom blight of prunes. PBB at popcorn and full bloom stages was significantly greater than PBB at later bloom stages (P ≤0.05). The optimal temperatures for blossom blight development were 22 to 26°C, and Gaussian functions were used to describe the relationship between PBB and temperature. PBB linearly increased with increased IC. Linear regressions of PBB on WD were obtained for each combination of bloom stage, IC, and temperature. The parameters of these regressions were used in a computer program to produce the possible maximum PBB with 90% probability (PBB90) using stochastic simulations. Early bloom stages with a higher IC at temperatures from 20 to 25°C were associated with more severe blossom blight than late stages with a lower IC at nonoptimal temperatures. Blossom blight did not occur at <10 or >30°C and less than 4-h WD. However, longer than 4-h WD linearly increased incidence of blossom blight. A risk assessment table of blossom blight was produced for different environmental conditions to guide the control of prune brown rot.

scholarly journals Primary Inoculum Sources of Monilinia spp. in Spanish Peach Orchards and Their Relative Importance in Brown Rot

Plant Disease ◽  
2010 ◽  
Vol 94 (8) ◽  
pp. 1048-1054 ◽  
Author(s):  
M. Villarino ◽  
P. Melgarejo ◽  
J. Usall ◽  
J. Segarra ◽  
A. De Cal
Keyword(s):  
Latent Infection ◽  
Brown Rot ◽  
Monilinia Fructicola ◽  
Relative Importance ◽  
Inoculum Sources ◽  
Primary Inoculum ◽  
Ebro Valley ◽  
Growing Seasons ◽  
Fruit Orchards ◽  
Peach Orchard

Immediately following the identification of Monilinia fructicola in a Spanish peach orchard in the Ebro Valley in 2006, this orchard and two other orchards in the same valley were intensively sampled for potential tree and ground sources of primary Monilinia inoculum before and during three growing seasons between 2006 and 2008. Overwintered Monilinia spp. produced inoculum from only mycelium, and no apothecia were found in any of the three orchards over the three growing seasons. Mummies on trees were the main source of primary inoculum. More than 90% of Monilinia isolates on all fruit mummies were M. laxa. Positive relationships were found between (i) the number of mummified fruit and the incidence of postharvest brown rot (P = 0.05, r = 0.75, n = 8), and (ii) the number of mummified fruit and nonabscised aborted fruit in the trees and the number of conidia on the fruit surface (P = 0.04, r = 0.71; P = 0.01, r = 0.94, respectively, n = 8) and the incidence of latent infection (P = 0.03, r = 0.75; P = 0.001, r = 0.99; respectively, n = 8). In addition, the numbers of mummified fruit and pruned branches on the orchard floor were correlated with the number of airborne conidia in the orchard. Based on the results of these surveys, the control of brown rot in stone fruit orchards is discussed.

scholarly journals Incidence of Latent Infection of Immature Peach Fruit by Monilinia fructicola and Relationship to Brown Rot in Georgia

Plant Disease ◽  
2000 ◽  
Vol 84 (8) ◽  
pp. 853-857 ◽  
Author(s):  
K. M. Emery ◽  
T. J. Michailides ◽  
H. Scherm
Keyword(s):  
Latent Infection ◽  
Disease Risk ◽  
Brown Rot ◽  
Biological Indicator ◽  
Fruit Rot ◽  
Monilinia Fructicola ◽  
Latent Infections ◽  
Ripening Stage ◽  
Peach Fruit ◽  
Immature Fruit

Peach fruit are most susceptible to infection by Monilinia fructicola during the preharvest ripening stage. Although various sources of inoculum for preharvest infection have been characterized, the role of latent infection of immature fruit in the carryover of M. fructicola from the spring (blossom blight phase) to the preharvest period (fruit rot phase) is unknown for the southeastern United States. From 1997 to 1999, immature peach fruit were collected at 14-day intervals from orchards in middle and northern Georgia. Fruit were surface disinfested and treated with paraquat (1997) or frozen overnight (1998 and 1999) to induce tissue senescence and activate latent infections. Across sites and years, the incidence of latent infection remained low until the final sampling date 7 to 12 days before harvest. The incidence of latent infection on the final sampling date ranged from 0 to 22.0% and correlated significantly with both the incidence of blossom blight earlier in the season (r = 0.9077, P = 0.0332) and the incidence of fruit rot at harvest (r = 0.9966, P = 0.0034). There also was a significant association between the incidence of latent infection at the onset of pit hardening (between 7 and 10 weeks before harvest) and subsequent fruit rot incidence (r = 0.9763, P = 0.0237). Weather variables (cumulative rainfall or rainfall frequency) alone did not correlate with fruit rot incidence (P > 0.05), whereas combined latent infection-rainfall variables did. The results suggest that latent infections can serve as a source of inoculum for subsequent fruit rot in peach orchards in Georgia. Despite its significant association with fruit rot incidence, the potential for using latent infection incidence as a biological indicator of disease risk at harvest may be limited; the assessment of latent infection during the fruit ripening stage (similar to the timing of the final sampling date in this study) would not provide sufficient lead time for preharvest disease management decisions, whereas an earlier assessment (e.g., at the onset of pit hardening) would require large sample sizes due to the low incidence of latent infection present during that period.

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