Fruit Susceptibility Research Articles

Effect of hot water treatment on chilling injury incidence and antioxidative responses of mature green mume (Prunus mume) fruit during low temperature storage

Mume (Prunus mume Sieb. et Zucc.) fruit are harvested and consumed at the mature green stage and have a short storage life at ambient temperature. The current handling and storage temperatures, below 6 °C, extend the storage life to a week, but chilling injury (CI) occurs after a longer storage. A pre-storage hot water treatment, dipping ‘Nankou’ fruit in 45 °C water for 5 min, substantially reduced susceptibility of fruit to CI at 6 °C storage, and extended storage life for three-fold. This research was conducted to reveal the antioxidantive responses of fruit to pre-heat treatment and chilling storage. Hot water treatment inhibited the increases in malondialdehyde and hydrogen peroxide levels, and delayed the decreases in ascorbate contents and total antioxidant capacity levels compared with the control fruit during storage. The activities of antioxidant-related enzymes including ascorbate peroxidase and monodehydroascorbate reductase were higher in hot water treated fruit than in the control fruit during cold storage. These results indicate that the alleviation of CI in mature green fruit by hot water treatment might be due to the protection and enhancement of the antioxidant system by increased activity of related enzymes.

Incidence of blossom-end rot in elongated tomato fruit

Blossom-end rot (BER) is a physiological disorder that can affect 100% of the fruit crop depending on the genotype. Tomato varieties with elongated fruit usually have a greater susceptibility to BER than other varieties. To evaluate and identify the possible physiological and morphological characteristics related to the onset of BER development, four varieties of long-shape tomato fruit with different susceptibility to BER: ‘San Marzano,’ ‘Banana Legs,’ ‘Roma,’ and ‘Mini-Roma’ were examined. Our results show that ‘San Marzano’ and ‘Banana Legs’ (elongated fruit) had a higher incidence of BER and lower Ca2+ concentration in the distal fruit tissue. ‘San Marzano’ (the most elongated fruit) presented higher electrolyte leakage in the distal fruit tissue. By comparison, ‘Roma’ and ‘Mini-Roma’ (less elongated fruit) were less susceptible to BER and had a higher ratio for proximal/distal fruit Ca2+ and a lower distal cell-wall bound content of Ca2+. Additionally, xylem functionality (vessels transporting water and solutes) in the distal fruit tissue was also higher in these more-tolerant varieties. These results support the theory that total fruit content of Ca2+ is not the only factor determining fruit susceptibility to BER, but rather a balance between physiological and morphological factors that influence Ca2+ transport and allocation in the fruit.

Does increased nutritional carbon availability in fruit and foliar hosts contribute to modulation of pathogen colonization?

High losses due to postharvest pathogens call for an understanding of the processes modulating fungal colonization in comparison to leaf pathogens. Pathogens can penetrate fruit and foliar plants directly through the cuticle following the development of appressoria, or through wounds during fruit growth and postharvest life. In both cases, disease symptoms may not occur until long after infection. Maturation (when plant or fruit has attained maximum growth and size) and ripening (the process by which mature fruit become ready for consumption) are critical factors in fruit susceptibility to postharvest pathogens. During these periods, fruit undergo physiological and metabolic changes that affect nutritional composition and cause a decline in resistance mechanisms. Recent research suggests that host nutrients during ripening may modulate signaling processes in the pathogen that lead to metabolic responses, triggering the accumulation of pH-modulating molecules. The pH shift in the surrounding host tissue induces optimal gene-expression conditions for the fungus to use specific pathogenicity factors at each particular pH. Leaf pathogens usually penetrate via appressoria and also respond to carbon-regulation signaling. This review describes our understanding of the importance of carbon regulation in fruit and leaf tissue, and its contribution to pathogen colonization via facilitation of the transition from quiescent to necrotrophic lifestyle.

Epidemiology of apple bitter rot caused by Colletotrichum acutatum sensu lato

Apple bitter rot caused by Colletotrichum acutatum sensu lato results in fruit decay before and after harvest. We investigated the epidemiology of the disease in terms of conidial formation and dispersal as well as the change in susceptibility of fruits in Iwate, Japan. Conidia of C. acutatum were detected in rainwater collected from inside the tree canopy from May to August with peaks in production in mid-May to early June and mid- to late July. The first peak corresponded to the most conidia being produced on fruit scars, but the second peak was due to conidiation on mummified fruitlets and peduncles collected in July. Inoculation experiments revealed that fruits were susceptible to the pathogen between 20 and 90 days after petal fall and that immature fruits infected as early as 20 days after petal fall frequently developed lesions on the lower fruit half as growth progressed. These results suggest that C. acutatum sporulates on infested fruit scars to infect immature fruits, resulting in bitter rot and that the fungus also colonizes mummified fruitlets and peduncles, contributing to survival of the pathogen on fruit scars. Thus, infested fruit scars represent the primary source of inoculum.

Relationship of the firm with plant organ with aggressiveness oh Phytophthora capsici

Resumo - The aim of this work was to relate the susceptibility of fruits, roots and stems of vegetables infected by P. capsici to the firmness of the pulp. The treatments were represented by 18 genotypes (carrot, papaya, chayote, apple, sweet pepper, kaki, sweet potato, gherkim, melon, tomato, Solanum gilo, potato; two genotypes of cucumber and three genotypes of pumpkim), in three replications in a delineation completely randomized designed, resulting 18*3 experimental units (EU). At the first day, with the support of a probing (tip 5 mm), the firmness of the fruits were evaluated. After that stabs of micelium of 5 mm of diameter (Pcp 42, sweet pepper) were inoculated in the wound provoked by the probing (early measured). During 7 days after the inoculating, the lesion length was evaluated, allowing the calculation of the area under the lesion progress curve (AUCPL). The incubation period was also estimated (between the inoculation and the emergence of the symptoms) and determinated the isolated pathogenicity to the genotypes in study. Cucumber (conserve and green), eggplant and sweet pepper had had the highest averages of ABCIP (F17,36=28,76**), differing statistically from the other. Tomato, gala apple and pepper had had the lowest scores of firmness (F17,36=46,81**), also differing statistically from the other. The relationship among the values of firmness and AUCPL demonstrated that as the fruit’s firmness increases the susceptibility reduces in up to 58 % (r**=-0,5796). That is the first work the relates firmness of fruits to susceptibility of P. capsici in Brazil.

Mechanisms regulating fruit calcium content and susceptibility to bitter pit in cultivars of apple

This work was carried out to investigate the mechanisms regulating fruit calcium (Ca) content and susceptibility to bitter pit (BP) in 'Fuji' and 'Catarina' apples (cultivars with low and high susceptibility to BP, respectively). Fruit of both cultivars were harvested at commercial maturity in an orchard located in southern Brazil, and assessed for xylem functionality and lenticels pore area (mm2 mm-2 of skin) at the distal end. Fruits were also cold stored for four months (0.0±0.5°C/95% RH) and then separated in lots without and with BP. Fruits of both cultivars without and with BP were assessed at the distal (blossom end), middle (equatorial region) and proximal (peduncle end) portions for pectin methylesterase (PME) activity in the skin and flesh tissues, and at distal portion for peroxidase (POD) and ascorbate peroxidase (APX) activities and Ca content in the flesh tissue. At harvest, 'Catarina' apples had lower xylem functionality and lower lenticels pore area at the distal end than 'Fuji' apples. 'Catarina' had higher incidence of BP after cold storage (12.7%) than 'Fuji' (2.3%). In both cultivars, fruit with BP had lower Ca content in the flesh at the distal end. Fruits with BP showed at the distal region higher POD activity in the flesh in 'Fuji' and higher PME activity in the skin in 'Catarina' than fruit without BP. Only in 'Fuji', fruits with BP had higher PME activity in the flesh tissue at the middle and distal portion than fruits without BP. The results show that impairment of xylem functionality, and reduced lenticels pore area and high PME activity in the skin tissue at the distal portion of the fruit might reduce fruit Ca content and increase the incidence of BP, especially in 'Catarina', a cultivar highly susceptible to the disorder.

Mature Larval Dispersal and Adult Emergence of the Economically Significant Pest, Scirtothrips aurantii Faure (Thysanoptera: Thripidae), in Commercial Citrus.

Scirtothrips aurantii Faure (Thysanoptera: Thripidae) is a major pest of citrus fruit in subtropical southern Africa. Population monitoring is an important aspect of S. aurantii control, but additional information is required on its phenology. Dispersal of mature larvae onto the soil surface from the tree canopy, and emergence of adults, were assessed using dispersal/emergence (D/E) traps in an untreated citrus orchard in South Africa. Overall, 90.7% of adult Thysanoptera emerging from soil / leaf litter beneath the citrus trees were S. aurantii, of which 35.7% were males, and 64.3% were females. Female S. aurantii having survived winter as adults oviposited on the early spring flush. This resulted in the first population peak of larvae dropping to the ground to pupate and adults emerging in spring, September to early October, as the first vegetative flush of the citrus-growing season hardened, and fruit was set as blossoming ended. Initial infestation of young fruit occurred after a build-up of larval numbers on the soft citrus flush late July to early August. The second generation larval and adult peak occurred late November to early December, whether there was new flush or not, as young fruit could support the S. aurantii population. A third peak occurred mid-December to late January, depending on year. Thus, there were three generations of S. aurantii during the period of citrus fruit susceptibility to thrips damage (September–January). After the autumn flush in April, another peak of larvae and adults occurred before the population declined to a minimum from May to July.

Aerated Steam Sanitization of Whole Fresh Cantaloupes Reduces and Controls Rind-Associated Listeria but Enhances Fruit Susceptibility to Secondary Colonization.

Water vapor (steam) at a high temperature can be used to sanitize the surface of fresh, whole cantaloupe melons in a continuous-feed manner. Both Listeria bacteria and spoilage organisms are markedly reduced from initial levels and survivor outgrowth severely restricted during subsequent refrigerated storage. This approach to microorganism control is likely most applicable in situations where rinds and flesh are to be separated immediately via further processing.

Evaluation of Host Resistance to Botrytis Bunch Rot in Vitis spp. and Its Correlation with Botrytis Leaf Spot

Botrytis cinerea, the causal agent of Botrytis bunch rot and gray mold, is the number one postharvest disease of fresh grapes in the United States. Fungicide applications are used to manage the disease, but fungicide-resistant isolates are common and postharvest losses occur annually. Host resistance is needed for long-term management of the disease. Sources of resistance in grape have been identified, but often have poor fruit quality. In this study, 27 grape lines (cultigens and species), including high fruit–quality Vitis vinifera, were evaluated for fruit and leaf susceptibility to two isolates of B. cinerea. No significant differences in virulence or pathogenicity were detected between the two isolates, but differences in disease incidence were evident among lines in leaves and berries. Most V. vinifera cultivars evaluated had high disease incidence in berries, whereas complex hybrids, Vitis aestivalus and Vitis arizonica, had low- to moderate disease incidence. Two V. vinifera breeding lines had moderate susceptibility (<50% disease) to Botrytis bunch rot when inoculated with either isolate. Only one V. vinifera line had little (<5%) to no berry or leaf disease when inoculated with either isolate. Moderate resistance (10% to 25%) was detected in Vitis spp., and a single V. vinifera line. Correlations were examined among soluble solids, leaf susceptibility, and fruit susceptibility. No correlations between soluble solids and disease susceptibility (leaves or berries) were identified, but moderate correlations between leaf and berry susceptibility were observed. Moderate resistance to Botrytis bunch rot and leaf spot were detected in Vitis breeding lines, suggesting these may be useful for developing grape cultivars with high fruit quality and resistance to B. cinerea.

The Crop Load Affects Brown Rot Progression in Fruit Orchards: High Fruit Densities Facilitate Fruit Exposure to Spores but Reduce the Infection Rate by Decreasing Fruit Growth and Cuticle Cracking

Brown rot, triggered by Monilinia spp., causes significant economic losses in fruit crop and it is mainly controlled by chemicals with inherent environmental costs. Controlling brown rot spreading by diminishing fruit susceptibility to the disease, via sustainable cultural practices, is a promising approach. In a two years experiment (2014-2015) on a peach (Prunus persica) orchard, we controlled fruit growth rates by varying the fruit load. Fruit thinning practices enhanced the fruit growth and laboratory analyses showed that, in both 2014 and 2015 samples, fast growing fruits were more susceptible to infection when in contact with conidia suspension of Monilinia laxa. In the field, brown rot infection took place in 2014 and not in 2015. In 2014, trees subject to moderate thinning intensities had the highest brown rot incidence. We argue that this is due to the fact that, for null thinning, slow growing fruits are less susceptible to the infection while, for intense thinning, even if faster growing fruits are more susceptible to infection, the lower fruits density reduces per-contact probability of infection. We compared meteorological data of 2014 and 2015 and we argue that brown rot did not spread in 2015 due to an absence of favorable conditions, summarized as the number of rainy days with mean temperature between 22 and 26 °C , in the period of fruit susceptibility.

Preharvest factors influencing bruise damage of fresh fruits – a review

Abstract Bruise damage of fresh fruits is a major problem in the horticultural industry, potentially occurring during preharvest, harvest and at all stages of postharvest handling chain. This damage can cause considerable postharvest and economic losses, reduce produce quality and result in serious food safety concerns. Understanding the factors influencing susceptibility or resistance of produce to bruising is important in developing strategies for reducing the problem. This review discusses main preharvest factors that could be manipulated by producers prior to harvest in attempts to reduce bruise damage of fresh fruits during postharvest handling. These factors include: (1) genetic (species/genotype); (2) climatic and environmental; (3) seasonal variation; (4) orchard management practices; and (5) effect of fruit properties. A critical discussion of these factors and their relative influence on bruise susceptibility of fresh fruits is presented. Among other factors, orchard management practices such as irrigation and fertilization could be an important strategy to manipulate fruit mechanical strength to enhance resistance to bruising. Future research directions are discussed.

Compression damage susceptibility of apple fruit packed inside ventilated corrugated paperboard package

Abstract Ventilated corrugated paperboard (VCP) packages are used widely in the fruit industry cold chain and are designed to reduce produce damage while still maintaining adequate air distribution needed to ensure optimum heat transfer from produce to cold air. The packages may experience mechanical failure due to excessive compression load under such cold chain conditions, which may lead to bruising of the packed fresh produce, particularly apple fruit that are susceptible to mechanical damage during postharvest handling. The objectives of this study were to investigate the compression bruise susceptibility of apples packed inside two ventilated corrugated paperboard packages (MK4 and MK6). The MK4 package design has higher length-to-height, longer trays and higher vent area compared to the MK6 package design. Results showed that the susceptibility to bruise damage was affected significantly by package design. Fruit bruise damage inside the MK6 package design was more than the apple fruit bruise damage inside the MK4 package design, with differences of about 63% and 43% in apple bruise area and apple bruise volume, respectively. Irrespective of package design, fruit placed towards the bottom of the package incurred lesser damage.

Predicting bruise susceptibility in apples using Vis/SWNIR technique combined with ensemble learning

Bruise susceptibility in fruits is an important indicator in evaluating risk factors for bruising caused by external factors. Prediction of the bruising susceptibility of fruit can provide useful information for proper postharvest handling and storage operations. In this study, visible and shortwave near-infrared (Vis/SWNIR) technique was used to develop nondestructive method for predicting the bruise susceptibility of apples. Vis/SWNIR spectra covering 400-1100 nm were collected for 300 ‘Golden Delicious’ apples over a time period of three weeks after harvest. A pendulum-like device was used to simulate impact bruise at three impact energy levels of 1.11 J, 0.66 J and 0.33 J. Bruise volumes were estimated from the digital images of the bruised apples by using the bruise thickness model. Three prediction models, i.e. partial least squares model (PLS), partial least squares model combined with successful projection algorithm (SPA-PLS), and selective ensemble learning based on feature selection (SELFS), for bruise susceptibility were developed for each impact energy level as well as for the pooled data. Compared with PLS and SPA-PLS model, SELFS gave the better prediction results for bruise susceptibility, with the correlation coefficient of Rp=0.800-0.886 for the prediction set, the root-mean-square error of 38.7- 62.1 mm3/J for the prediction set (RMSEP), and the residual predictive deviation (RPD) of 1.78-2.14 for three impact energy level. For three impact energy levels, the RMSEP and RPD value obtained by SELFS model improved by 14.8%-20.0% and 15.0%-24.5% compared to PLS model, and 11.4%-21.2% and 11.5%-27.1% compared to SPA-PLS model, respectively. The SELFS model achieved relatively lower prediction accuracies for the pooled data, with the Rp values of 0.731, RMSEP of 85.46 mm3/J, and RPD of 1.46, which were also better than that of PLS model and SPA-PLS model. This research demonstrated that Vis/SWNIR technique combined with ensemble learning is promising technique for rapid assessment of bruise susceptibility of fruit, which would be useful for postharvest handling of fruit. Keywords: apple, nondestructive detection, bruise susceptibility, visible/short-wave near-infrared technique, ensemble learning DOI: 10.25165/j.ijabe.20171005.2888 Citation: Yao J, Guan J Y, Zhu Q B. Predicting bruise susceptibility in apples using Vis/SWNIR technique combined with ensemble learning. Int J Agric & Biol Eng, 2017; 10(5): 144–153.

Mechanical Models of Compression and Impact on Fresh Fruits.

Well-designed and well-operated postharvest mechanical handling processes are vital if fresh fruits are to enter markets with minimal damage. The susceptibility of fruit to quality loss during handling is largely determined by mechanical contact and damage. This article reviews current understanding concerning the effect of impact and other mechanical contacts on fruits. It also discusses the major mechanical models that represent the interaction between fruits or a fruit and a surface. In total, 25 mechanical models associated with compression and impact behaviors of fresh fruits, mainly characterizing such behavior between 2 deformable spherical bodies and between a deformable spherical body and a rigid plate are reviewed. Finally, possible future research directions are discussed. The main challenge in fruit handling is to recognize and prevent microscopic damage to fruits, especially internal tissue/cell damage and microcracks resulting from multiple/repetitive impacts and compressions.

Investigation of Potential Causes of Peach Skin Streaking.

Peach skin streaking is a previously undescribed skin discoloration affecting red-blush peach cultivars in Georgia and South Carolina. Streaked peach fruit have been observed in the field close to harvest. The cause of streaking is still unknown but one hypothesis is that atmospheric pollutants may be involved. The goal of this study was to establish proof of concept that commonly found air pollutants can produce streaks on peach skin similar to those observed in commercial orchards and investigate the susceptibility of peach fruit during maturation. Common reactive byproducts of atmospheric pollutants, including sulfuric acid (H2SO4), nitric acid (HNO3), and hypochlorite acid (HCl), at concentrations up to 10 μg/ml did not produce streaking under field conditions when applied at week 3, 2, and 1 prior to commercial harvest. However, sodium hypochlorite (NaClO) in the form of Clorox solution and chlorine dioxide (ClO2) at 100 μg/ml generated from the Aquamira water treatment solution produced streaking symptoms on detached peach fruit under controlled conditions and in the field. Peach fruit were most susceptible to streaking closest to harvest, suggesting that NaClO and ClO2 interfere with pigment formation.

Susceptibility of Cold-Climate Wine Grape Cultivars to Downy Mildew, Powdery Mildew, and Black Rot.

Lack of knowledge regarding the susceptibility of cold-climate hybrid wine grape cultivars may be leading to the overuse of fungicides and underutilization of plant host resistance to combat disease in the northern United States. To provide new insights on diseases of cold-climate cultivars and to update management recommendations, disease was evaluated in three vineyards containing eight cultivars that were not sprayed with fungicides in 2015 and 2016. Disease severity or incidence of downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator), and black rot (Guignardia bidwellii) were measured from bud break until 2 weeks after harvest. Cold-climate cultivars ranged widely in susceptibility to different diseases and, although several cultivars were relatively resistant to two diseases, no cultivar was highly resistant to all three diseases. Additionally, a difference between foliar and fruit susceptibility for all three diseases was noted in several cultivars. These data provide a foundation for developing low-spray and certified organic disease management strategies for cold-climate wine grape cultivars based on susceptibility to disease.

Transcriptomic and metabolomic analyses of cucumber fruit peels reveal a developmental increase in terpenoid glycosides associated with age-related resistance to Phytophthora capsici

The oomycete, Phytophthora capsici, infects cucumber (Cucumis sativus L.) fruit. An age-related resistance (ARR) to this pathogen was previously observed in fruit of cultivar ‘Vlaspik’ and shown to be associated with the peel. Young fruits are highly susceptible, but develop resistance at ~10–12 days post pollination (dpp). Peels from resistant (16 dpp) versus susceptible (8 dpp) age fruit are enriched with genes associated with defense, and methanolic extracts from resistant age peels inhibit pathogen growth. Here we compared developing fruits from ‘Vlaspik’ with those of ‘Gy14’, a line that does not exhibit ARR. Transcriptomic analysis of peels of the two lines at 8 and 16 dpp identified 80 genes that were developmentally upregulated in resistant ‘Vlaspik’ 16 dpp versus 8 dpp, but not in susceptible ‘Gy14’ at 16 dpp. A large number of these genes are annotated to be associated with defense and/or specialized metabolism, including four putative resistance (R) genes, and numerous genes involved in flavonoid and terpenoid synthesis and decoration. Untargeted metabolomic analysis was performed on extracts from 8 and 16 dpp ‘Vlaspik’ and ‘Gy14’ fruit peels using Ultra-Performance Liquid Chromatography and Quadrupole Time-of-Flight Mass Spectrometry. Multivariate analysis of the metabolomes identified 113 ions uniquely abundant in resistant ‘Vlaspik’ 16 dpp peel extracts. The most abundant compounds in this group had relative mass defects consistent with terpenoid glycosides. Two of the three most abundant ions were annotated as glycosylated nor-terpenoid esters. Together, these analyses reveal potential mechanisms by which ARR to P. capsici may be conferred.

Modified insulated punnets and conventional packaging films for retail storage of robusta banana fruits

The application of poor consumer packaging technology to Banana fruits can increase fruit susceptibility to diseases which affect quality and shelf-life. Understanding the use of appropriate consumer packages is crucial in developing packages for the fresh produce sector. In this study, four different consumer packages and Control Samples (CT) which included Perforated Insulated Punnet (PP), Non-perforated Punnet (NP), Perforated Films (PF) and Non-perforated Films (NF) were used. Fruits in packages were stored at 27°C for 7 days where rate of ripening, weight loss, total soluble solids, taste, pulp texture and consumer acceptance were assessed. The results demonstrated that the use of perforated punnets was better in reducing the rate of ripening. The changes in TSS was progressive in all the treatments but the control sample produced the highest Brix at 16% compared with Brix 15% for fruits in PP, NP. PF and NF. Weight loss was more pronounced in the control sample 11.7% compared with the least weight loss of 0.7% for fruits in NF. Except, Sweetness and TSS without dilution all the parameters assessed were statistically significant at P ≤ 0.05. Based on the results obtained in this research, it can be shown that the use of insulation and perforations of punnets demonstrated appropriateness which offers a promise and can be adopted for consumer use in the fresh produce sector.

Yield and fruit quality of strawberry cultivars grown in organic farming in the mid-Adriatic area

Organic fruit and vegetable productions in Marche Region, the main Italian Region of the mid-Adriatic area, are still rising. The interest for the production of organic strawberries is also increasing and brings about the need to identify strawberry cultivars with higher adaptability to open field and protected organic cultivation in this area. With this aim, thanks to a collaboration started between D3A-UNIVPM and the Regional Extension Service Agency (ASSAM), a two years experimental trial was set, comparing sixteen cultivars of strawberries; thirteen of these cultivars were short day cultivars ('Alba', 'Aprica', 'Asia', 'Brilla', 'Clery', 'Cristina', 'Garda', 'Joly', 'Madeleine', 'Premy', 'Romina', 'Sibilla', and 'Syria'), while three were day neutral ('Albion', 'Malga' and 'Monterey'). Among these cultivars, only four were already recommended for strawberry integrated crop production in the Marche Region, while all the other were identified from different national and international programs. The experimental trial, set in 2014, was prepared following a randomized design with three blocks of sixteen plots, of twenty plants each, for both cultivation conditions (open field and protected-Veronese tunnel). At harvest time, data on plant and fruit susceptibility to fungal and pest diseases were detected and vegetative (vigor of the plant, number of crowns), productive (total plant production, total discard for rot and deformed fruit and fruit average weight) and quality (texture, color, content sugars and titratable acidity) parameters were measured. The results showed a significant difference in adaptability, yield and satisfactory quality of some cultivars. Of greatest interest resulted 'Romina', 'Sibilla' and 'Cristina', as short day, and 'Monterey' as day neutral. The 'Veronese tunnel' resulted as a flexible and easy way to manage protected cultivation system that helped to increase yields of different cultivars, highlighting how this technique is essential for the success of strawberry organic production in this area.

Influence of boron applications on preharvest and postharvest nectarine fruit rot caused by brown rot

Brown rot is a very important disease of stone fruit causing mainly postharvest damages on fruit, although preharvest fruit rots and shoot blight are also important. With recent public concerns regarding pesticide residues on fruit, there is a need for alternative disease management practices that will reduce health risks resulting from occupational exposure and from residues in food and drinking water. The main aim of this study was the investigation of the effects of boron on the susceptibility of nectarine (cv Tasty Free) on preharvest and postharvest fruit rots. The results demonstrated the fungicidal activity of organic chemical structure of boron to the mycelial growth of M. laxa in vitro. This product inhibited the mycelial growth and conidia germination of M. laxa at concentration of 1000 and 1600 μl/l respectively. The EC 50 value was 690.9 μl/l for the mycelial growth and 985 μl/l for the conidia germination respectively. Spray applications of nectarine trees reduced the susceptibility of fruit on preharvest and postharvest fruit rots caused by brown rot. Generally, boron application is an effective, alternative method to improve the resistance of nectarine to brown rot.