Percentage Of Infected Fruit Research Articles

Assessment of Tuta absoluta yield loss in Iranian tomato crops

• The South American tomato pinworm, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae) is a major invasive pest of tomato. • The weight and percentage of infected fruits was negatively related to different initial infestation levels of Tuta absoluta . • Investigating crop loss of T. absoluta in the farm is essential for enhancing integrated pest management programs. The South American tomato pinworm, Tuta absoluta Meyrick (Lepidoptera: Gelechiidae), a devastating pest of tomato plants, originates from South America but it has been considered an invasive pest for Iran since 2010. To assess crop loss caused by this pest, a study was conducted in a 600 m 2 field under a randomised complete block design. The impact of different initial densities of T. absoluta , including control (without infestation), one, two, four, and eight T. absoluta eggs on each host plant in the first and second year was investigated with an additional treatment (16 pinworm eggs per host plant) used in the second year. Yield attributes including length and width of fruits, numbers of infested and intact fruits along with their weights were sampled and assessed on a weekly basis. In addition, the correlation between the number of galleries and these characteristics was also investigated. Crop loss data demonstrated that the effect of different infestation levels on fruit size and the weight of intact fruits was not significant over both years. However, the effect of treatment on the percentage and weight of infested fruits was shown to be significantly different in 2014 and 2015. Furthermore, there was a negative significant correlation between the number of galleries and weight of infested fruits in both years. Collectively, these results will be useful for enhancing pest management programs of T. absoluta in Iran.

Distribution of stem-end rot on the canopy in ‘Hass’ avocado trees in two coastal areas in Peru

Stem-end rot (SER) of avocado is caused by several fungal species, and it is presented worldwide. This plant disease currently affects several avocado producer regions in Peru, causing fruit rot, impacting the industry negatively. Research about SER distribution in the canopy of avocado trees is limited. Thus, the present study aimed to compare which areas in the canopy are prone to have more SER in ‘Hass’ avocado harvested fruit in two different coastal areas in Peru. The experiment was conducted in the northern (Barranca) and southern (Cañete) of Lima. ‘Hass’Avocado fruits from both producer areas were collected to identify the causal agent; Lasiodiplodia theobromae was isolated from infected fruits. Identification was conducted based on morphological features and a partial DNA sequence of the translation elongation factor 1-α gene (tef1-α). The results showed that fruits inside the tree canopy were prone to have a higher disease incidence than the fruits located in the external site (P<0.001). Besides, internal-site fruits displayed a higher percentage of infected fruit for each grade disease (P<0.001) than external-site fruits, except for grade 0 (fruits without symptoms) and grade 1. Finally, the results suggested that the altitude where the fruit is positioned on the canopy could influence the incidence of SER, where fruits located in the high part revealed less incidence than the low section. The results are valuable for enhancing management strategies and avoiding postharvest loss of avocado fruits in our region.

Alternative products against anthracnose affect selected primary and secondary metabolites in strawberry fruit

Introduction. Anthracnose disease causes severe economic losses in strawberry (Fragaria × ananassa ) production. Plant response to the pathogen attack is closely linked to its content and composition of polyphenols. In order to reduce the damage caused by pathogens, organic and inorganic fungicides are applied. The aim was to determine the influence of selected fungicides on various metabolites in strawberry fruit. Materials and methods. The efficiency of potassium bicarbonate (PBC) and acetic acid (AA) was compared with the control and a fungicide treatment in the strawberry cv. Elsanta. To examine the possible effects of these fungicides, artificial inoculation was performed in all treatments except for the control. The percentage of infected fruits and the content of selected primary and secondary metabolites in non-infected and infected fruits were determined. Results and discussion. Both analyzed inorganic fungicides proved effective against anthracnose. AA treated fruits were the least infected (only 4%), followed by PBC, fungicide and control. The highest percentage (9.26%) of infected fruits was determined following artificial infection treatment. Total sugar content decreased for 32% in infected control and AA treated fruits. PBC treatment exhibited a positive effect on the organic acid content in comparison with other treatments. The content of phenolic compounds was higher in PBC treated fruits and did not change significantly after infection. Infection increased the total flavonol content of the fruit. Conclusion. The use of PBC and AA potentially present a prospective protection in the strawberry orchards especially for controlling anthracnose in organic fruit crops.

Effect of Carum copticum essential oil on growth and aflatoxin formation by Aspergillus strains

The objectives of this study were to determine the antiaflatoxin B1 activity in vitro of the essential oil (EO) extracted from the seeds of Carum copticum and to evaluate its antifungal activity in vivo as a potential food preservative. The C. copticum EO exhibited noticeable inhibition on dry mycelium and synthesis of aflatoxin B1 (AFB1) by Aspergillus flavus, completely inhibiting AFB1 production at 4 μL/mL. C. copticum EOs showed the lowest percentages of decayed cherry tomatoes for all fungi compared with the control at 100 μL/mL with values of 5.01 ± 67% for A. flavus and 5.98 ± 54% for Aspergillus niger. The results indicated that the percentage of infected fruits is significantly (p < 0.01) reduced by the EO at 16°C for 30 days. In this case, the oil at 100 μL/mL concentration showed the highest inhibition of fungal infection with a value of 80.45% compared with the control. Thus, the EO of dill could be used to control food spoilage and as a potential source of food preservative.

Active label-based packaging to extend the shelf-life of “Calanda” peach fruit: Changes in fruit quality and enzymatic activity

A new active packaging, consisting of a label with cinnamon essential oil incorporated and attached to plastic packaging, was used to extend the shelf-life of late-maturing peach fruit. After 12 days of storage at room temperature, the percentage of infected fruit in the active label packaging was 13% vs. 86% in the non-active packaging. Significant differences were obtained for weight loss (3.4% less at 12 days of storage) and firmness (more than 15.9 N at 12 days) during storage. The influence of the active packaging on the in vivo activity of lipoxygenase (LOX), polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and of malondialdehyde (MDA) content as an indicator of lipid oxidation, was studied. The active agent, cinnamon essential oil, also reduced in vitro activity of LOX. Sensory analysis of the peaches was performed over the storage time. Most of positive descriptors were not significantly different from the optimum quality level (day 0) for peaches stored in the active package after 12 days at room temperature.

LOW OXYGEN EFFECT ON PENICILLIUM EXPANSUM MOULD IN STORED APPLE

Penicillium expansum causing blue mould is a serious postharvest pathogen in all growing pome fruit areas. Physical treatments, including storage atmosphere manipulation, have been developed to control postharvest fungal decay. The present study aimed to determine the influence of oxygen (O 2 ) levels on growth of P. expansum (P37 strain). Pathogen enzymatic production at low oxygen levels was also tested in in vitro trials by agarose diffusion assay. In in vitro trials, 100 μl of conidial suspension (10 3 conidia per ml) was spread on MEA dishes, stored for 30 days at 0°C with 0.7, 1.5, 3, 6 and 21% O 2 . The concentration of carbon dioxide was 1%. In in vivo trials, fruit were wounded and inoculated with 20 μl of a conidial suspension (10 3 conidia per ml) of P. expansum and stored with the same oxygen concentrations for five months at 0°C plus 3 days at 20°C. No significant differences were observed, within the different oxygen concentrations, on P. expansum growth in vitro. The percentage of infected fruit was significantly greater at low oxygen concentrations (0.7, 1.5, 3%) than at 6 or 21%. However, the dimensions of decay lesions, on apples exposed to 21 and 6% of O 2 , were significantly larger than those of apples stored at 0.7, 1.5 and 3% O 2 . In addition, O 2 levels greatly influenced the enzymatic activity. Polygalacturonase, protease and amylase activities were increased by low oxygen level (0.7%), whereas cellulases were reduced by the same oxygen concentration. More investigations are required to better elucidate the interactions between pathogen-fruit-oxygen level and the role of the enzymes in pathogenicity.

Control effect of bactericides on bacterial shot hole disease caused by Xanthomonas campestris pv. pruni in peach in relation to severity of infection

We investigated the control effect of bactericides, mainly antibiotics, on bacterial shot hole disease caused by Xanthomonas campestris pv. pruni in peach from 1998 to 2005 in relation to the severity of infection. The antibiotic streptomycin was effective giving a protective value of 63-67 in the untreated plots when the percentage of infected fruit was 5.5-9.8%. At a higher rate of infection, however, the protective value decreased. Streptomycin was as effective as the other bacteriocides (oxytetracycline, validamycin and dithianon) when the rate of infection in the untreated plot was low. The efficacy of streptomycin was not improved by combined administration with ziram-thiram compounds.

Effect of short hypobaric treatments on postharvest rots of sweet cherries, strawberries and table grapes

The effectiveness of short hypobaric treatments against postharvest rots was investigated by exposing sweet cherries, strawberries and table grapes to sub-atmospheric pressures (0.25, 0.50, and 0.75 atm) for different times (from 1 to 24 h). Postharvest rots of sweet cherries and strawberries arose from natural infections, whereas small table grape bunches and artificially wounded single berries were inoculated with Botrytis cinerea after hypobaric treatment. Sweet cherries exposed to 0.50 atm for 4 h had the lowest incidence of gray mould, brown rot and total rots, while a 1 h treatment was not effective. On strawberries, the greatest reductions of gray mould and Rhizopus rot were observed on fruits treated for 4 h at 0.25 and 0.50 atm, respectively. On table grape bunches treatment with 0.25 atm applied for 24 h significantly reduced the incidence of gray mould. In experiments performed with artificially wounded single table grape berries exposed to 0.50 atm for 24 h and then inoculated, the percentage of infected fruits and the diameter of the lesions were significantly reduced, in comparison with the controls. As a sub-atmospheric pressure of 0.25 atm did not affect radial growth of B. cinerea and Monilinia laxa, induced resistance was likely to be responsible for the observed reduction in decay.

Cuticular Fractures Promote Postharvest Fruit Rot in Sweet Cherries.

Preharvest cuticular fractures in sweet cherry fruit have been suggested to facilitate pathogen invasion, and a method to classify the mount of cuticular fracturing into five categories (from 1 = no visible fractures to 5 = severe fracturing) has previously been proposed. Sweet cherry fruit of the four cultivars Early Burlat, Lapins, Van, and Vista were sorted into these five categories of cuticular fracturing and inoculated with conidial suspensions of either Botrytis cinerea or Monilinia laxa. After incubating the fruit at 20°C and 100% relative humidity for 4 to 7 days, they were assessed for visible fungal growth. Due to quiescent infections of M. laxa, fruit treated with B. cinerea developed more brown rot than gray mold. However, a significant linear relation (P < 0.05) between the amount of cuticular fracturing and fungal infections was obtained in five of seven trials with B. cinerea and in two of four trials with M. laxa, indicating that fungal infections in sweet cherry fruit may be facilitated by cuticular fractures. Independent of cultivar and year, a significant linear relation was found between the category of cuticular fracturing and percentage of infected fruit after inoculation with both B. cinerea and M. laxa, and in control fruit (P = 0.0001, 0.0183, and 0.0182, respectively). This is the first report quantifying an increase in fungal infection with increasing amount of cuticular fracturing. The mean difference in fruit rot (%) ± standard deviation among fruit in fracturing categories 1 and 5, expressed as the linear contrast of amount of fruit rot in category 5 minus amount of fruit rot in category 1, was 37.2 ± 7.4 (P = 0.0001), 35.4 ± 11.0 (P = 0.0022), 17.0 ± 6.7 (P = 0.0135), and 29.8 ± 4.7 (P = 0.0001), after treatments with B. cinerea, M. laxa, water control, and for all data pooled, respectively.

ON FARM APPROACH OF PINEAPPLE FRUITLET CORE ROT DISEASE IN MARTINIQUE

Fruitlet Core Rot is one on the main disease that affects pineapple fruit development in the world. However, factors promoting the disease are not well known. A large survey, including soil, climatic, physiological and pathological variables at a field scale, and including spatial heterogeneity and temporal variability, was designed and conducted in the pineapple production area in Martinique. This on farm-approach allowed the identification and specification of the main factors responsible for the disease. Fruit sampling analysis revealed the Penicillium funiculosum was involved in 95 % of the observer cases. However, although P. funiculosum was widespread in the soils of the survey, no quantitative relation was established between the quantity of inoculum in the soil or on the plant and the development of P. funiculosum in fruits. Fruit observations at harvest time showed a high level of variation between fruits within a field. However, significant correlations between the percentage of infected fruits within a field, the average number of spots per fruit and their size were established. A global analysis of the data showed that average ascorbic acid content in fruits at harvest is negatively linked with the percentage of infected fruits. The nutritional status of the plants, especially low levels of calcium and magnesium, and/or high levels of nitrogen, is also a significant promoting factor for the development of the disease. It is concluded that Fruitlet Core Rot in Martinique is promoted by a combination of factors which determine the sensitivity of fruits. Climatic conditions before harvest, acid content, and nutritional status are the main factors. (Resume d'auteur)

Influence of Leaf Removal, Fungicide Applications, and Fruit Maturity on Incidence and Severity of Grape Powdery Mildew

Vineyard plots were established in 1988 and 1989 to examine the effects of basal leaf removal, timing of fungicide applications and fruit maturity on incidence and severity of powdery mildew on <i>Vitis vinifera</i> cv. Chardonnay. In plots receiving a single prebloom fungicide application, basal leaf removal reduced disease severity (the percentage of infected fruit per cluster) from 15.3% to 4.2% in 1988 and from 46.1% to 21.0% in 1989. When basal leaf removal was combined with one prebloom and two postbloom fungicide applications in 1988 and three postbloom fungicide applications in 1989, disease incidence (the percentage of infected clusters per vine) and severity was reduced to levels similar to adjacent commercial plots receiving 12 and 11 fungicide applications in 1988 and 1989, respectively. In 1989, significant levels of rachis infection were observed in all plots except those receiving 11 fungicide applications. Healthy fruit removed over the course of the season was inoculated in the laboratory under controlled conditions. A negative exponential relationship was observed between susceptibility of fruit and accumulation of soluble solids, with fruit above 7°Brix rarely infected.