scholarly journals Peach Rusty Spot Epidemics: Temporal Analysis and Relationship to Fruit Growth

Plant Disease ◽  
2003 ◽  
Vol 87 (4) ◽  
pp. 366-374 ◽  
Author(s):  
Laura A. Furman ◽  
Norman Lalancette ◽  
James F. White
Keyword(s):  
Disease Progression ◽  
Fruit Development ◽  
Disease Incidence ◽  
Fruit Size ◽  
Temporal Analysis ◽  
Logistic Function ◽  
Fruit Growth ◽  
Data Sets ◽  
Growing Seasons ◽  
Physical Changes

Incidence and severity of peach rusty spot were monitored throughout the growing seasons of 1999 to 2001. Graphical and statistical analysis revealed that disease increased from the shuckoff stage of fruit development until 60 days after full bloom; epidemics typically lasted from 17 to 30 days. An analysis of fruit growth indicated that the early-season epidemic coincided with the first stage of stone fruit development, physiologically characterized as the period of cell division. During this period, as fruit growth slowed and approached initiation of pit-hardening, the rate of disease increase slowed. Since fruit infection was greatest during the period of fruit growth, disease progression was modeled as a function of plant growth instead of time. Temporal analysis revealed that the logistic function was appropriate for describing both growth processes, and a synchronous logistic/logistic composite disease progression/fruit growth model was fit to all data sets. No change in disease levels occurred during midseason, which coincided with the second stage of fruit development, a period of slow growth. Subsequently, disease incidence and severity significantly declined on average by 26% and 1.3 lesions per fruit, respectively, during the 20 to 30 days prior to harvest. This decline phase coincided with the third stage of fruit growth, the period of cell enlargement and coloration. These disease reductions may be related to physical changes in fruit size and pigmentation, as opposed to resistance development, causing younger, less established lesions to become undetectable.

scholarly journals Fruit Development in Saskatoon (Amelanchier alnifolia Nutt.)

HortScience ◽  
1996 ◽  
Vol 31 (4) ◽  
pp. 682f-682
Author(s):  
Roisin McGarry ◽  
Jocelyn A. Ozga ◽  
Dennis M. Reinecke
Keyword(s):  
Fruit Development ◽  
Fruit Size ◽  
Fruit Weight ◽  
Growth Patterns ◽  
Fruit Growth ◽  
Seed Number ◽  
Fresh Weight ◽  
Canadian Prairies ◽  
Developmental Patterns ◽  
Growing Seasons

Saskatoon fruits, an emerging horticultural crop across the Canadian prairies, vary greatly in size among cultivars. In this study, we compare fruit development patterns among large, medium, and small fruited cultivars of saskatoon, and assess the role of seed number and pedicel diameter on fruit size. Fruit growth patterns of four cultivars (Thiessen, Northline, Regent, and Smoky) were determined from weekly measurements of fruit diameters and fresh and dry flower/fruit weights during two consecutive growing seasons. The developmental patterns of fruit growth determined using the above criteria were similar among cultivars and between years. At maturity, the largest fruits (fresh weight) obtained were from cv. Thiessen, followed by `Northline', `Smoky', and `Regent', in descending order. Pedicel diameters (one week prior to maturity) correlated linearly with increasing fruit diameter and fresh weight. At maturity, seed number per fruit correlated linearly with increasing fruit weight. Thiessen contained significantly more seeds per fruit (4.6) than `Northline' (3.7), `Smoky' (3.2), and `Regent' (3.2).

scholarly journals Spatial and Temporal Analysis of Squash vein yellowing virus Infections in Watermelon

Plant Disease ◽  
2014 ◽  
Vol 98 (12) ◽  
pp. 1671-1680 ◽  
Author(s):  
William W. Turechek ◽  
Pamela D. Roberts ◽  
Philip A. Stansly ◽  
Craig G. Webster ◽  
Chandrasekar S. Kousik ◽  
...  
Keyword(s):  
Disease Incidence ◽  
Management Strategies ◽  
Temporal Analysis ◽  
Virus Infections ◽  
Average Value ◽  
Disease Progress ◽  
Growing Seasons ◽  
Progress Curve ◽  
Temporal Rate ◽  
Yellowing Virus

Squash vein yellowing virus (SqVYV) is a whitefly-transmitted ipomovirus infecting watermelon and other cucurbits that was recently introduced to Florida. Effects on watermelon are devastating, with total vine collapse, often near harvest, and fruit rendered unmarketable by brown, discolored flesh. The epidemiology of SqVYV was studied in a 1-ha field of ‘Fiesta’ watermelon over six growing seasons (I to VI) to characterize the spatial patterning of disease and temporal rate of disease progress, as well as its association with Cucurbit leaf crumple virus (CuLCrV) and Cucurbit yellow stunting disorder virus (CYSDV), two additional whitefly-transmitted viruses that often occur with SqVYV. The field was scouted at regular intervals for the length of the season for incidence of virus and number of whiteflies. Incidence of SqVYV reached 100% during seasons I, II, and V and 20% during season III. SqVYV did not occur during seasons IV and VI. SqVYV progressed in a characteristic logistic fashion in seasons I, II, and V but less so in season III. The rate of disease progress was similar for the three seasons with high disease incidence, with an average value of 0.18. A positive correlation between the area under the disease progress curve and whitefly-days was found, where both progress curves were calculated as a function of thermal time (degree days, base 0°C). SqVYV displayed significant but variable levels of aggregation, as indicated by its fit to the β-binomial distribution, the binary power law, and ordinary runs analysis. Association analysis indicated that the viruses were largely transmitted independently. Results of this study provide epidemiological information that will be useful in the development of management strategies for SqVYV-induced vine decline, and provide new information for CuLCrV and CYSDV.

scholarly journals Thinning and Diametric Fruit Growth Response of Apple Trees Treated with Benzyladenine and GA4+7 (Accel®), Carbaryl, and NAA

HortScience ◽  
1995 ◽  
Vol 30 (4) ◽  
pp. 787E-787
Author(s):  
John A. Cline ◽  
Mary Bom ◽  
Donald C. Elfving
Keyword(s):  
Growth Response ◽  
Additional Data ◽  
Fruit Size ◽  
Fruit Growth ◽  
Sharp Decline ◽  
Fruit Thinning ◽  
Growing Seasons ◽  
Fruit Maturity ◽  
Cluster Rate ◽  
Number Of Seeds

A series of seven fruit thinning experiments with benzyladenine (BA), benzyladenine and GA4+7 (10:1 BA:GA4+7, Accel), carbaryl (CB), and NAA were conducted at the Horticultural Experiment Station, Simcoe, during the 1993 and 1994 growing seasons. In 1993, BA and Accel at 0, 100, 200, and 300 mg of BA/liter were applied to mature `Redspur Delicious'/M.26 and `Empire'/M.26 trees when fruit were ≈10 mm in diameter. In one set of experiments in 1994, Accel was applied at 0, 25, 50, 100, 150, and 200 mg of BA/liter to mature `McIntosh'/M.26 and `Empire'/M.7 trees. In a second set of experiments in 1994, Accel was applied at 0, 50, and 100 mg of BA/liter to mature `Idared'/M.26, `Empire'/M.26, and `Marshall McIntosh'/Mark trees when fruit were ≈10 mm in diameter. Additional treatments included bloom sprays of Accel at 50 mg of BA/liter, and sprays of BA at 50 mg a.i/liter, NAA at 10 mg a.i./liter, CB at 1000 mg a.i./liter, and a “low” (two fruit remaining/flower cluster) and `”high” (one fruit remaining/flower cluster) rate of hand thinning. In all experiments, thinning response to BA and Accel increased with concentration. Concentrations below 50, 100, and 300 mg BA/liter were generally ineffective for thinning `Empire', `Idared', and `McIntosh', and `Delicious', respectively. Fruit size of `Idared' and `Empire' was increased at rates of 50 mg BA/liter, whereas rates of 100 mg BA/liter were needed to increase fruit size of `McIntosh'. Accel applied to `Empire' at 150 mg BA/liter decreased the number of seeds per fruit and increased fruit length:diameter (L:D) ratios. Concentrations of Accel exceeding 100 mg BA/liter in `Red Delicious' decreased the number of seeds per fruit, while having little effect on fruit L:D ratios even though lower concentrations increased fruit L:D ratios. Diametric fruit growth measurements in 1994 indicated a temporary, but sharp, decline in growth rate immediately following treatment imposition for trees that responded positively to thinning. Additional data describing treatment effects on fruit size distribution, vegetative growth, and fruit maturity will be presented and discussed in relation to crop load.

scholarly journals Association between Fruit Development and Mature Fruit Drop in Huanglongbing-affected Sweet Orange

HortScience ◽  
2020 ◽  
Vol 55 (6) ◽  
pp. 851-857
Author(s):  
Lisa Tang ◽  
Sukhdeep Singh ◽  
Tripti Vashisth
Keyword(s):  
Fruit Development ◽  
Sweet Orange ◽  
Water Status ◽  
Fruit Size ◽  
Substantial Reduction ◽  
Fruit Growth ◽  
Mature Fruit ◽  
Callose Deposition ◽  
Immature Fruit ◽  
Fruit Drop

In the past decade, FL citrus industry has been struck by Huanglongbing (HLB), a disease caused by the phloem-limited bacterium Candidatus Liberibacter asiaticus (CLas). Besides tree decline, HLB causes a sharp increase in mature fruit drop before harvest, leading to a substantial reduction in citrus production. The aim of the study was to provide insights in HLB-associated mature fruit drop. For HLB-affected ‘Valencia’ and ‘Hamlin’ sweet orange (Citrus sinensis), trees exhibiting severe symptoms (“severe trees”) had a significantly higher rate of mature fruit drop compared with mildly symptomatic ones (“mild trees”). Interestingly, dropped fruit were smaller than those still attached to tree branches regardless of the symptom levels of trees; overall, fruit of severe trees were smaller than mild trees. The result suggests a negative effect of HLB on fruit growth that may lead to a high incidence to drop subsequently at maturity. This possibility is further supported by the difference in immature fruit size as early as 2 months after bloom between severe and mild trees. Although HLB-triggered phloem plugging due to callose deposition in citrus leaves, which results in disrupted carbohydrate transport, has been documented in literature, the results of the histological analysis demonstrated no consistent pattern of callose deposition in the mature fruit pedicel in relation to the drop incidence. Additionally, sugar concentration in juice was not significantly different between dropped and attached fruit, providing evidence that carbohydrate shortage is not the case for dropped fruit and thus not the predominant cause of HLB-associated mature fruit drop. Notably, the midday water potential was significantly lower for severe than mild trees during the preharvest period (2 weeks before harvest of the current crop) in late March, which was also the second week after full bloom of return flowering. This suggests that altered tree water status due to HLB might limit fruit growth during the initial stage of fruit development (immediately after flowering) and/or increase the incidence of mature fruit abscission, leading to elevated preharvest fruit drop. Together, the results suggest that in the presence of HLB, strategies to increase fruit size and minimize additional stresses (especially drought) for the trees may improve mature fruit retention.

scholarly journals Interlinked regulatory loops of ABA catabolism and biosynthesis coordinate fruit growth and ripening in woodland strawberry

2018 ◽  
Vol 115 (49) ◽  
pp. E11542-E11550 ◽  
Author(s):  
Xiong Liao ◽  
Mengsi Li ◽  
Bin Liu ◽  
Miaoling Yan ◽  
Xiaomin Yu ◽  
...  
Keyword(s):  
Fruit Ripening ◽  
Fruit Development ◽  
Fruit Size ◽  
Fruit Growth ◽  
P450 Monooxygenase ◽  
Woodland Strawberry ◽  
Rate Limiting Step ◽  
Aba Catabolism ◽  
Repressive Effect ◽  
Rate Limiting

Fruit growth and ripening are controlled by multiple phytohormones. How these hormones coordinate and interact with each other to control these processes at the molecular level is unclear. We found in the early stages of Fragaria vesca (woodland strawberry) fruit development, auxin increases both widths and lengths of fruits, while gibberellin [gibberellic acid (GA)] mainly promotes their longitudinal elongation. Auxin promoted GA biosynthesis and signaling by activating GA biosynthetic and signaling genes, suggesting auxin function is partially dependent on GA function. To prevent the repressive effect of abscisic acid (ABA) on fruit growth, auxin and GA suppressed ABA accumulation during early fruit development by activating the expression of FveCYP707A4a encoding cytochrome P450 monooxygenase that catalyzes ABA catabolism. At the onset of fruit ripening, both auxin and GA levels decreased, leading to a steep increase in the endogenous level of ABA that drives fruit ripening. ABA repressed the expression of FveCYP707A4a but promoted that of FveNCED, a rate-limiting step in ABA biosynthesis. Accordingly, altering FveCYP707A4a expression changed the endogenous ABA levels and affected FveNCED expression. Hence, ABA catabolism and biosynthesis are tightly linked by feedback and feedforward loops to limit ABA contents for fruit growth and to quickly increase ABA contents for the onset of fruit ripening. These results indicate that FveCYP707A4a not only regulates ABA accumulation but also provides a hub to coordinate fruit size and ripening times by relaying auxin, GA, and ABA signals.

scholarly journals Differences in Fruit Development among Large- and Small-fruited Cultivars of Saskatoon (Amelanchier alnifolia)

2001 ◽  
Vol 126 (4) ◽  
pp. 381-385 ◽  
Author(s):  
Roisin McGarry ◽  
Jocelyn A. Ozga ◽  
Dennis M. Reinecke
Keyword(s):  
Fruit Development ◽  
Developmental Stages ◽  
Fruit Size ◽  
Cell Number ◽  
Fruit Growth ◽  
Stage I ◽  
Canadian Prairies ◽  
Amelanchier Alnifolia ◽  
Minimum Number ◽  
Harvest Maturity

Fruit growth in saskatoons (Amelanchier alnifolia Nutt.), an emerging horticultural crop across the Canadian prairies, results from development of the mesocarp and the endocarp-locular-ovular structure which includes the developing seeds. Contribution of these tissues to fruit size was assessed using transverse sections of ovaries sampled at six developmental stages among large- and small-fruited cultivars. Mesocarp development was similar among the larger-fruited cultivars (Thiessen, Northline, and Smoky); the number of cells increased rapidly through Stage I [162 to 293 growing degree days (GDDs)] of fruit growth, and cell number increase was minimal during Stages II (293 to 577 GDDs) and III (577 to 747 GDDs). In `Regent' fruit (a small-fruited cultivar), the maximal rate of cell division was delayed until Stage II and the mesocarp contained fewer cells than the larger-fruited cultivars at harvest maturity. Mesocarp cell enlargement was similar among all of the cultivars studied where cell expansion was maximal during Stage I and continued at a slower rate during Stages II and III. The area of the endocarp-locular-ovular structure was greatest for `Thiessen' and `Northline', midrange for `Smoky', and smallest for `Regent'. Data suggest that a minimum number of mesocarp cells early in fruit development is required to attain maximal mesocarp size, and that differences in cultivar fruit size are a function of both the mesocarp and the endocarp-locular-ovular structure.

Interaction Between CPPU and NAA on Fruit Thinning and Fruit Development in Selected Apple Cultivars

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 513c-513 ◽  
Author(s):  
Martin J. Bukovac ◽  
Jerome Hull ◽  
John C. Neilsen ◽  
Michael Schroeder ◽  
Georg Noga
Keyword(s):  
Total Yield ◽  
Fruit Size ◽  
Frost Damage ◽  
Fruit Growth ◽  
Soluble Solids ◽  
Seed Number ◽  
Crop Load ◽  
Fruit Thinning ◽  
Carpel Development ◽  
Return Bloom

NAA is used extensively for fruit thinning of apples to increase fruit size and to promote return bloom. In some cultivars, even if thinning is achieved, fruit size at harvest may be less than expected based on crop load. CPPU, N-(2-chloro-4-pyridinyl)-N.-phenylurea, has been shown to increase fruit growth in apples, grapes, and kiwi. We evaluated combinations of NAA and CPPU on thinning, fruit growth and return bloom in Redchief `Delicious', `Elstar', and `Gloster'. CPPU was applied at 5 mgμL–1 (based on 0 to 10 mgμL–1 response curve) in combination with 15 mgμL–1 NAA as high-volume sprays at 7 to 10 mm KFD. Yield and fruit size distribution (on total yield) were used as index of response. In `Delicious', CPPU (3-year study) increased % large (70 mm+) fruit, but in the presence of NAA % large fruit was reduced 2 of the 3 years. CPPU did not induce significant thinning. There were no significant effects on color or soluble solids; firmness was increased slightly and seed number reduced. The L/D ratio was increased and uneven lobe and carpel development was common. CPPU had no significant effect on return bloom in presence or absence of NAA, but NAA increased bloom in both the presence and absence of CPPU. With `Elstar' (2-year study) there was no significant thinning with either chemical, but CPPU increased mean fruit size and % large (70–80 mm) fruit over nonthinned, but not significantly greater than NAA alone. There were no significant differences in firmness, color, soluble solids or seed number. NAA + CPPU did not inhibit fruit growth or cause excessive uneven carpel development. Frost damage reduced crop load in `Gloster' where results were similar to `Elstar' except seed number was reduced by the NAA + CPPU combination.

scholarly journals Spatial Heterogeneity of the Incidence of Powdery Mildew on Hop Cones

Plant Disease ◽  
2006 ◽  
Vol 90 (11) ◽  
pp. 1433-1440 ◽  
Author(s):  
David H. Gent ◽  
Walter F. Mahaffee ◽  
William W. Turechek
Keyword(s):  
Powdery Mildew ◽  
Spatial Heterogeneity ◽  
Power Law ◽  
Binomial Distribution ◽  
Disease Incidence ◽  
Disease Assessment ◽  
Cluster Sampling ◽  
Data Sets ◽  
Ratio Test ◽  
Frequency Distributions

The spatial heterogeneity of the incidence of hop cones with powdery mildew (Podosphaera macularis) was characterized from transect surveys of 41 commercial hop yards in Oregon and Washington from 2000 to 2005. The proportion of sampled cones with powdery mildew ( p) was recorded for each of 221 transects, where N = 60 sampling units of n = 25 cones assessed in each transect according to a cluster sampling strategy. Disease incidence ranged from 0 to 0.92 among all yards and dates. The binomial and beta-binomial frequency distributions were fit to the N sampling units in a transect using maximum likelihood. The estimation procedure converged for 74% of the data sets where p > 0, and a loglikelihood ratio test indicated that the beta-binomial distribution provided a better fit to the data than the binomial distribution for 46% of the data sets, indicating an aggregated pattern of disease. Similarly, the C(α) test indicated that 54% could be described by the beta-binomial distribution. The heterogeneity parameter of the beta-binomial distribution, θ, a measure of variation among sampling units, ranged from 0.01 to 0.20, with a mean of 0.037 and a median of 0.015. Estimates of the index of dispersion ranged from 0.79 to 7.78, with a mean of 1.81 and a median of 1.37, and were significantly greater than 1 for 54% of the data sets. The binary power law provided an excellent fit to the data, with slope and intercept parameters significantly greater than 1, which indicated that heterogeneity varied systematically with the incidence of infected cones. A covariance analysis indicated that the geographic location (region) of the yards and the type of hop cultivar had little effect on heterogeneity; however, the year of sampling significantly influenced the intercept and slope parameters of the binary power law. Significant spatial autocorrelation was detected in only 11% of the data sets, with estimates of first-order autocorrelation, r1, ranging from -0.30 to 0.70, with a mean of 0.06 and a median of 0.04; however, correlation was detected in only 20 and 16% of the data sets by median and ordinary runs analysis, respectively. Together, these analyses suggest that the incidence of powdery mildew on cones was slightly aggregated among plants, but patterns of aggregation larger than the sampling unit were rare (20% or less of data sets). Knowledge of the heterogeneity of diseased cones was used to construct fixed sampling curves to precisely estimate the incidence of powdery mildew on cones at varying disease intensities. Use of the sampling curves developed in this research should help to improve sampling methods for disease assessment and management decisions.

scholarly journals Sequential Sampling for Estimation and Classification of the Incidence of Hop Powdery Mildew II: Cone Sampling

Plant Disease ◽  
2007 ◽  
Vol 91 (8) ◽  
pp. 1013-1020 ◽  
Author(s):  
David H. Gent ◽  
William W. Turechek ◽  
Walter F. Mahaffee
Keyword(s):  
Powdery Mildew ◽  
Binomial Distribution ◽  
Disease Incidence ◽  
Sequential Sampling ◽  
Model Construction ◽  
Data Sets ◽  
Data Set ◽  
Sampling Plans ◽  
Simulated Sampling

Sequential sampling models for estimation and classification of the incidence of powdery mildew (caused by Podosphaera macularis) on hop (Humulus lupulus) cones were developed using parameter estimates of the binary power law derived from the analysis of 221 transect data sets (model construction data set) collected from 41 hop yards sampled in Oregon and Washington from 2000 to 2005. Stop lines, models that determine when sufficient information has been collected to estimate mean disease incidence and stop sampling, for sequential estimation were validated by bootstrap simulation using a subset of 21 model construction data sets and simulated sampling of an additional 13 model construction data sets. Achieved coefficient of variation (C) approached the prespecified C as the estimated disease incidence, [Formula: see text], increased, although achieving a C of 0.1 was not possible for data sets in which [Formula: see text] < 0.03 with the number of sampling units evaluated in this study. The 95% confidence interval of the median difference between [Formula: see text] of each yard (achieved by sequential sampling) and the true p of the original data set included 0 for all 21 data sets evaluated at levels of C of 0.1 and 0.2. For sequential classification, operating characteristic (OC) and average sample number (ASN) curves of the sequential sampling plans obtained by bootstrap analysis and simulated sampling were similar to the OC and ASN values determined by Monte Carlo simulation. Correct decisions of whether disease incidence was above or below prespecified thresholds (pt) were made for 84.6 or 100% of the data sets during simulated sampling when stop lines were determined assuming a binomial or beta-binomial distribution of disease incidence, respectively. However, the higher proportion of correct decisions obtained by assuming a beta-binomial distribution of disease incidence required, on average, sampling 3.9 more plants per sampling round to classify disease incidence compared with the binomial distribution. Use of these sequential sampling plans may aid growers in deciding the order in which to harvest hop yards to minimize the risk of a condition called “cone early maturity” caused by late-season infection of cones by P. macularis. Also, sequential sampling could aid in research efforts, such as efficacy trials, where many hop cones are assessed to determine disease incidence.

scholarly journals NONLINEAR AGROMETEOROLOGICAL MODELS FOR ESTIMATING LYCHEE FRUIT GROWTH

2017 ◽  
Vol 39 (2) ◽  
Author(s):  
LUCAS EDUARDO DE OLIVEIRA APARECIDO ◽  
RAFAEL BIBIANO FERREIRA ◽  
GLAUCO DE SOUZA ROLIM ◽  
BIANCA SARZI DE SOUZA ◽  
PAULO SERGIO DE SOUZA
Keyword(s):  
Fruit Development ◽  
Dry Matter ◽  
Potential Evapotranspiration ◽  
Climatic Conditions ◽  
Fruit Growth ◽  
Multivariate Models ◽  
Degree Days ◽  
Fresh Matter ◽  
Meteorological Elements ◽  
Fruit Diameter

ABSTRACT The influence of climate on the development of lychee fruit is complex, but few studies have discussed the problem. We developed agrometeorological models for simulating the development of fruit fresh matter (FM), fruit dry matter (DM), fruit length (LE), fruit diameter (DI), fruit volume (VO), and fruit number per cluster (FN) of the “Bengal” lychee cultivar as functions of climatic conditions. We conducted three analyses: (a) the influence of mean meteorological elements on the rates of fruit growth, (b) estimation of fruit development by the agrometeorological models using sigmoidal adjustments, and (c) simulation of fruit development using multiple nonlinear regression of two meteorological elements to improve the accuracy. A rate of water deficit (WD) near 5 mm d-1 maximised FM, DM, LE, DI, and VO. Increases in potential evapotranspiration (PET), degree days (DD), and actual evapotranspiration (AET) were correlated with increases in VO and decreases in LE and NF. Models estimating fruit development indicated that the accumulation of WD, PET, AET, and DD had sigmoidal relationships with all variables of fruit growth except FN. FN decreased as WD, PET, AET, and DD increased. The adjusted multivariate models were accurate, with the largest error of 6.45 cm3 (VO). The best models were: FM = f(SWD, DD), LE = f(SAET, DD), DI = f(SWD, DD), VO = f(SWD, DD), and FN = f(SAET, WD).

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