Evaluation of Sticky Traps for Monitoring Scolothrips sexmaculatus (Thysanoptera: Thripidae) and Stethorus punctum (Coleoptera: Coccinellidae) as Predators of Spider Mites in California Almonds
Changes in almond production practices have caused sixspotted thrips, Scolothrips sexmaculatus Pergande, and the coccinellid beetle, Stethorus punctum LeConte, to replace phytoseiid mites as the dominant predators of spider mites in California almonds. We conducted a series of field studies to evaluate nine commercially available adhesive traps for S. sexmaculatus and S. punctum and found that the yellow strip trap was the most effective, least expensive, and easy to use. At peak population levels, individual cards routinely caught >1,000 S. sexmaculatus and >100 S. punctum trap-1 week-1. We documented that larger traps collected more S. sexmaculatus, and more S. sexmaculatus per square area, suggesting that the trap surface was attractive. We determined the number of traps needed to have 50, 70, and 90% confidence that the averages of trap captures were within 10, 30, and 50% of the population mean. Two yellow strip traps per orchard provided 90% confidence that trap captures were within 50% of the population mean if there were an average of 16.0 S. sexmaculatus trap-1 week-1 or 7.9 S. punctum trap-1 week-1. Populations required to attain the same levels of confidence using four traps per orchard were 3.9 S. sexmaculatus and 2.9 S. punctum trap-1 week-1. We conclude that use of the yellow strip trap to monitor for natural enemies, in combination with leaf samples for spider mites, has the potential to improve integrated pest management programs for spider mites, and assist future research to understand the biology and phenology of both predator species.
Evaluation of pruning wound protection products for the management of almond canker diseases in California
Almond trunk and branch canker diseases constitute a major cause of tree mortality in California. Numerous fungal pathogens have been associated with these canker diseases and pruning wounds act as major infection courts. Prior to this study, there were no products registered in California for the management of these diseases. In this study, fungicidal products including synthetic chemistries, biocontrols, paint and a sealant were evaluated for preventing fungal pathogen infection via pruning wounds. In four field trials conducted over two dormant seasons, sixteen pruning wound treatments were tested using hand-held spray applications, against five almond canker pathogens, namely Botryosphaeria dothidea, Neofusicoccum parvum, Cytospora sorbicola, Ceratocystis destructans, and Eutypa lata. The fungicide thiophanate-methyl (Topsin M) provided 82% overall disease prevention against four fungal pathogens. The biological control agent, Trichoderma atroviride SC1 (Vintec), tested at three application rates, resulted in 90 to 93% protection of pruning wounds in field trials, and for individual pathogens ranged from 81-100% protection for the three rates. At the time of this publication, Vintec is being considered for registration as a biological control product for the prevention of almond canker diseases, while Topsin M is recommended to growers for the prevention of almond canker diseases. This research indicates that effective protection of pruning wounds from infection by almond canker pathogens can be achieved with a one-time spray application of thiophanate-methyl or the biocontrol, T. atroviride SC1 (recommended 2 g/liter) after pruning.
Phosphorus fertilization induces nectar secretion for honeybee visitations and cross-pollination of almond trees
Precise phosphorus (P) application requires a mechanistic understanding of mineral effects on crops' biology and physiology. Photosynthates assimilation, metabolism, and transport require phosphorylation, and we postulated that P is critical for the bloom and fruit-set of almond trees that rely on stored carbohydrate reserves. Hence, we studied the growth-physiology and carbohydrate dynamics in two-year-old almond trees irrigated with P concentrations between 1 and 20 mg L -1. Almond trees attained maximal photosynthesis, transpiration, and growth by 6 mg P L -1 in irrigation. Nevertheless, almond trees continued to extract P in 10 and 15 mg P L -1 irrigations, which corresponded to bigger starch reserves and yields. We attributed the augmented productivity to increased fruit-set (59% between 6 and 15 mg L -1 P), caused by more frequent (29%) honeybee visits. High P improved pollinators' visitation by enabling almond trees to utilize more of their starch reserves for nectar secretion (which increased by ~140% between 6 and 15 mg P L -1). This work illuminates P fertilization's benefits to plant-pollinator mutualism, critical to almond productivity, and reveals novel indices for optimal P application in almond orchards.
Tractor Speed and Spray Application Volume in Tall Pecan Trees: Effect on Spray Coverage at Different Heights in the Canopy
Scab (caused by Venturia effusa) is the most important disease of pecan in the southeastern U.S.A. The yield losses in susceptible cultivars, combined with costs of control amount to tens of millions of dollars annually. It is known that fungicide coverage from air-blast sprayers declines with height in the canopy, and conversely, disease severity increases. But how application volume (L/ha) and speed (km/h) affect spray coverage at different heights is unknown. Coverage was quantified using kromekote cards and Vision Pink™ dye at heights of 5.0, 7.5, 10.0, 12.5 and 15.0 m in pecan canopies. An orchard air-blast sprayer was operated at 2.4 and 3.2 km/h applying 468, 935 or 1871 L/ha. Nozzles were selected to provide proportionally similar volumes to the upper and lower canopy positions at set speeds. Speeds tested did not affect spray coverage consistently. However, greater volumes resulted in significantly greater spray coverage, but most of that increase was at heights ≤12.5 m. Although there were significant differences among volumes applied at 12.5 m, they were numerically small. Card orientation had a profound effect on spray coverage at heights ≤12.5 m, with most spray being detected on the cards facing horizontally downwards, and least on those facing vertically backwards. The study demonstrates that higher volumes result in more coverage, but the effect declines rapidly with height. If disease control achieved with 470 L/ha is no different (or is more efficacious) compared to >470 L/ha and is the same at higher speeds (3.2 km/h), savings may be possible in terms of operating time and equipment costs.
Effects of drying and extraction methods on bioactive properties of plums
Plums are a popular fruit whose large quantities are subjected to processing, which contributes to changes in the physicochemical parameters, and the magnitude of these changes is determined by the technology applied. The study aimed to analyse the bioactive compound content and the antioxidant capacity of plums of the Bluefree, Stanley and Sweet Common Prune (Wegierka Zwykla) varieties, depending on the drying and extraction processes applied. Significant differences in the bioactive compound content and the antioxidant capacity were found between the varieties under study. The convection drying process resulted in the greatest significant decrease in both the anthocyanin pigment content (by an average of 82%) and the total polyphenol content (by an average of 41%). The average losses of phenolic acids reached 34%, and the greatest decrease was noted for chlorogenic acid (an average of 69%). As regards flavan-3-ols and flavonols, the drying processes caused their losses by an average of 56%. The vacuum drying and lyophilisation processes applied were softer for the tested bioactive compounds. Moreover, these processes reduced the ABTS and FRAP antioxidant capacity. The ultrasound- and microwave-assisted extraction increased the total anthocyanin content by an average of 29%. These methods yielded significantly greater amounts of all four determined anthocyanins in the tested fruit. The results show that the search for a safe, inexpensive raw material drying method is still a current research issue.
Peanut and linseed oil emulsion gels as potential fat replacer in emulsified sausages
The study aimed to highlight the utilization of gelled emulsion (GE) systems containing peanut and linseed oils to replace beef fat partially or completely in emulsified sausages. Total fat content was reduced by up to 40% and energy content was lowered by up to 27% in reformulated products. Saturated fatty acids and cholesterol were successfully decreased while noticeable increments were provided in mono and poly-unsaturated fatty acids in sausages containing GE. Moreover, the reformulation procedure presented a good potential for increasing n-3 content, while lowering atherogenicity index, thrombogenicity index, and n-6/n-3 ratios. Although the incorporated GE resulted in color and texture alterations, it was effective to improve the technological attributes in terms of emulsion stability and cooking behaviors. In GE added samples, oxidative stability of final products decreased; however sensory features were acceptable. Overall results pointed out that GE systems could be successfully conveyed to emulsified sausage formulations to ensure a healthier lipid profile with good technological and sensory quality.
Transcriptome Analysis Reveals Significant Difference in Gene Expression and Pathways Between Two Peanut Cultivars under Al Stress
Aluminum (Al) toxicity is an important factor in limiting peanut growth on acidic soil. The molecular mechanisms underlying peanut responses to Al stress are largely unknown. In this study, we performed transcriptome analysis of the root tips (0-1 cm) of peanut cultivar ZH2 (Al-sensitive) and 99-1507 (Al-tolerant) respectively. Root tips of peanuts that treated with 100 μM Al for 8 hours and 24 hours were analyzed by RNA-Seq, and a total of 8,587 differentially expressed genes (DEGs) were identified. GO and KEGG pathway analysis excavated a group of important Al-responsive genes related to organic acid transport, metal cation transport, transcription regulation and programmed cell death (PCD). These homologs were promising targets to modulate Al tolerance in peanuts. It was found that the rapid transcriptomic response to Al stress in 99-1507 helped to activate effective Al tolerance mechanisms. Protein and protein interaction analysis indicated that MAPK signal transduction played important roles in the early response to Al stress in peanuts. Moreover, weighted correlation network analysis (WGCNA) identified a predicted EIL (EIN3-like) gene with greatly increased expression as an Al-associated gene, and revealed a link between ethylene signaling transduction and Al resistance related genes in peanut, which suggested the enhanced signal transduction mediated the rapid transcriptomic responses. Our results revealed key pathways and genes associated with Al stress, and improved the understanding of Al response in peanut.
Salicylic acid and kaolin effects on pomological, physiological, and phytochemical characters of hazelnut (Corylus avellana) at warm summer condition
Climate change and population increase are two challenges for crop production in the world. Hazelnut (Corylus avellana L.) is considered an important nut regarding its nutritional and economic values. As a fact, the application of supporting materials as foliage sprays on plants will decrease biotic and abiotic stresses. In this study, the effects of salicylic acid (0, 1 mM and 2.5 mM) and kaolin (0, 3% and 6%) sprays were investigated on morphological, physiological, pomological, and biochemical characteristics of hazelnut. The results showed that 1 mM salicylic acid and 6% kaolin had the best effects on nut and kernel weight compared to control. Biochemical parameters such as chlorophyll a, b, a + b, and carotenoid contents showed that salicylic acid and kaolin improved pigment concentration. Proline and antioxidant contents such as phenolic acids, SOD, APX, and CAT enzyme activities increased by these applications. On the other hand, lipid peroxidation, protein content, and H2O2 content were decreased. Based on the tolerance index result, Merveille de Bollwiller cultivar showed the highest tolerance while 'Fertile de Coutard' had the lowest value. Therefore, hazelnut performance may be improved through exogenous application of the signaling (salicylic acid) and particle film (Kaolin) compounds in warmer climates.
Developmental transcriptome profiling uncovered carbon signaling genes associated with almond fruit drop
Almond is one of the most featured nut crops owing to its high nutritional value. However, due to three different waves of flower and fruitlet drop, fruit drop is a major concern for growers. In this study, we carried out a time-course transcriptome analysis to investigate gene expression differences between normal and abnormal fruitlet development. By de novo assembly analysis, we identified 33,577 unigenes and provided their functional annotations. In total, we identified 7,469 differentially expressed genes and observed the most apparent difference between normal and abnormal fruits at 12 and 17 days after flowering. Their biological functions were enriched in carbon metabolism, carbon fixation in photosynthetic organisms and plant hormone signal transduction. RT-qPCR validated the expression pattern of 14 representative genes, including glycosyltransferase like family 2, MYB39, IAA13, gibberellin-regulated protein 11-like and POD44, which confirmed the reliability of our transcriptome data. This study provides an insight into the association between abnormal fruit development and carbohydrate signaling from the early developmental stages and could be served as useful information for understanding the regulatory mechanisms related to almond fruit drop.
Recent progress in determination of ochratoxin A in foods by chromatographic and mass spectrometry methods
Ochratoxin A is a highly toxic mycotoxin and has posed great threat to human health. Due to its serious toxicity and wide contamination, great efforts have been made to develop reliable determination methods. In this review, analytical methods are comprehensively summarized in terms of sample preparation strategy and instrumental analysis. Detailed method is described according to the food commodities in the order of cereal, wine, coffee, beer, cocoa, dried fruit and spice. This review mainly focuses on the recent advances, especially reported in the last decade. At last, challenges and perspectives are also discussed to achieve better advancement and promote practical application in this field.