These results agreed with previous studies on the relationships between grapevine water status and yield components . However, leaf area and crown porosity were not affected by applied water amount treatments in 2020. This might havebeen resulted from the remarkably high air temperature at the experimental site, diminishing the grapevine vegetative growth despite the water compensation from irrigation . Consequently, berry quality parameters were slightly affected by irrigation treatments, with only TSS being higher with greater water stress in the harvest of the first season due to berry dehydration and potential promotion in sugar accumulation .There were two flavonoid classes monitored in this study, anthocyanins and flavonols. They are highly sensitive towards environmental conditions . This study evidenced that SH increased berry skin anthocyanin and flavonol concentrations compared to the other trellis systems over the two seasons. SH might have had more advancement in berry development due to more efficient leaf area to fruit ratio achieved in this trellis system . Furthermore, low round pots the crown porosity of SH was ranging from 0.20 to 0.30, a window of inferred solar radiation exposure identified in previous works for `Cabernet Sauvignon´.
As for VSPs, anthocyanin degradation was unlikely to be the reason why VSPs had lower anthocyanin concentration since the greater leaf area could have provided berries some degree of protection from receiving excessive solar radiation . This can be confirmed by the fact that TSS and berry skin anthocyanin concentration were still synchronized in 2020. However, there was a decoupling of TSS and berry skin anthocyanin concentration in 2021, where the VSPs had higher TSS but lower skin anthocyanin content. Unlike the first season, the leaf area and canopy crown porosity showed no difference among the trellises, but the effective leaf area that can provide protection against excessive solar radiation might differ between SH and HQ from the other trellis systems. Hence, even with similar leaf areas, the VSPs still exposed clusters to the environmental stresses, which promoted TSS accumulation due to dehydration but greater anthocyanin degradation, similar to what was observed in previous studies . Although the TSS levels in this study were not at the level for reaching the tipping point of anthocyanin degradation as previously reported , compared to the SH and HQ with greater height from the vineyard floor, the VSPs might have been more easily affected by the solar radiation and heat reflected from soil surface, causing hotter and drier canopy microclimate and inevitably lead to greater anthocyanin degradation .
Additionally, some previous studies have shown negative relationships between yield and berry composition . Similar observations in this study might be due to source organs of the VSPs were not distributed widely enough to be as efficient as those of the SH and HQ, resulting in lower photosynthetic capacity in their canopies, which further reduced the translocation of photosynthates flowing into berries to promote TSS accumulation and flavonoid biosynthesis. As for flavonols, previous studies have shown that flavonols are very sensitive to solar radiation, especially UV radiation, where more light will often increase flavonol concentration in berry skins . The results from this work corroborated previous observations that less leaf area with more crown porosity would increase solar radiation inside the canopy, and further increase flavonol concentrations in berry skins . Additionally, SH and HQ showed greater concentrations in di-hydroxylated flavonols as well as some tri-hydroxylated flavonol derivatives. Water deficits, achieved by manipulating applied water amounts through irrigation, can significantly improve flavonoid concentrations in grape berries . Similar results were observed in our findings as well, where 25% ETc was able to increase anthocyanin and flavonol concentrations in grape berries. One previous study at the same experimental site showed that 25% ETc could potentially increase the possibility for flavonoid degradation and decrease the wine antioxidant capacity .
However, we did not see such effects in this study. This might be because berry sugar accumulation was not affected among the three applied water amounts, and the overall TSS levels did not exceed the tipping point . It was repeatedly been noticed that, beyond this TSS level, skin anthocyanins and even flavonols would start to significantly degrade in a hot climate . Hence, in our study, all the treatments might have ended up having similar advancements in berry flavonoid accumulation because of the similar levels of TSS without any promoted accumulation or degradation among the three irrigation strategies , but 25% ETc was able to decrease berry weights, which resulted in higher concentrations in anthocyanins and flavonols.Positive relationships between flavonols and solar radiation, especially UV-B, have been consistently observed in previous research, clearly indicating that more solar radiation penetrating into the canopy interior promotes flavonol concentration in berry skins . Further, flavonol content and derivative proportions exhibited strong relationships with solar radiation , which was confirmed in this study, where quercetin proportion and both total flavonol concentration correlated strongly with leaf area and crown porosity especially with VSP types. When the high air temperature or drought conditions became extreme, flavonoids in berry skins started to degrade . For all six trellis systems in 2020, the relationships between flavonols and canopy architecture were strong. These relationships between leaf area/crown porosity and flavonols can provide a feasible way of assessing canopy architecture in terms of the canopy’s contribution towards berry composition and vice versa. This approach is not limited only to red cultivars and can also be applied to white cultivars since flavonols are still synthesized in their skin tissues . Also, for quercetin specifically, it is the most abundant flavonol derivative in grape berry skins. Hence, the compound would be unchallenging to isolate and extract, offering an easy assessment of the effects of solar radiation on berry flavonol profiles. Interestingly, in this study, the VSPs did not result in higher quercetin or total flavonol concentrations, indicating that these trellis systems might not be suitable for accumulating or maintaining flavonoids in berry skins in a hot climate regardless of TSS levels compared to other trellis systems. Although the relationships between canopy architecture and flavonols were strong in this study and align with previous reports, the influence of canopy structure imposed by trellis system on berry chemical development needs more investigation to understand the contributions of trellis systems to canopy architecture and canopy microclimate.Commerce via global trade and transport provides a mechanism for introduction of invasive species to new territories, extending pest habitats outside of their native regions . Invasive species threaten biodiversity, habitat, nutritious food, clean water, resilient environments, sustainable economies, and human health . Agricultural production systems are continuously challenged by invasive species that attack high-value crops, plastic pots 30 liters thereby significantly hampering the ability of food industries to maintain profitability . The geographic range of agricultural crops provides the potential for invasive species to colonize regions on a global scale . Factors that aid expansion include short life cycle, fast growth rate, high plasticity, and resiliency to a wide range of environmental conditions . Such factors are drivers of rapid evolutionary change, population increase, and global colonization . Practitioners and stakeholders should aim to implement new strategies to manage such new invasive species in agricultural production . Drosophila suzukii Matsumura is an invasive species native to Southeast Asia. Passive transportation is the main reason of the dispersal of this species .
It was first detected in North America and Europe in 2008 , and later in South America in 2013 , and Northern Africa in 2017 . The long-serrated ovipositor of D. suzukii enables it to oviposit inside fresh fruit, which creates a challenging management problem . Emerged larvae burrow within fruit pulp rendering fruit unmarketable . When D. suzukii became established in the U.S. during 2008, the total annual revenue losses for the West Coast berry and cherry industries were estimated at over $500 million . Currently the situation is not changed in term of economic impact . This particular insect is challenging to manage due to its high dispersal potential, ability to survive and adapt to harsh environmental conditions, and ability to attack a wide host range. For these reasons, D. suzukii is a key pest of these fruit industries worldwide. In the last decade, conventional insecticide uses on affected crops significantly increased to manage D. suzukii fruit damage. Typically used insecticides include spinosyns, pyrethroids, and organophosphates . Intensive use of insecticides poses a tremendous risk to non-target organisms such as pollinators, natural enemies, and humans . In addition, frequent insecticide applications likely resulted in resistance development . These factors require development of an IPM program that includes alternatives to conventional insecticides for managing D. suzukii. Non-insecticidal control methods including cladding, irrigation, netting, mulching, pruning, monitoring and mass trapping have been implemented against D. suzukii . While each method provides some relief to D. suzukii pressure, they provide limited reductions in crop damage . Behavioral control of D. suzukii on susceptible fruit indicated promise for industry adoption. The food grade gum makes use of physical properties to mimic fruit, resulting in D. suzukii laying their eggs in a soft gel-like substrate, instead of the fruit itself. The food grade gum is a mixture of food-grade ingredients which is highly attractive to D. suzukii and competes with the ripening fruit throughout the season . To the best of our knowledge, the food-grade gum modifies various D. suzukii behaviors, ultimately resulting in a significant decrease in fruit damage. The product diverts D. suzukii away from ripening fruit, which results in significant retention of the pest, keeping it away from fruit. Third, the food-grade gum acts as an egg sink. Since the D. suzukii eggs laid in this medium cannot develop, this translates in a substantial reduction of the pest population growth . The aim of this work was to determine the potential of the food grade gum to reduce D. suzukii damage in large-scale commercial open-field and screen house fruit production units on blueberry, cherry, raspberry, blackberry, and wine grape. The hypothesis was that food-grade gum would reduce D. suzukii damage in small fruit, tree fruit and grapes under semi-field and small-scale field conditions. These studies were conducted during 2019 and 2020 in California and Oregon in the western United States.In all field trials, GUM dispensers were placed at least 27 meters away from untreated control plots to minimize volatile plume interaction between treatments. In the current study, cotton pads were used to apply ~1.8 g of GUM on each dispenser at the rate of 124 dispensers per hectare under commercial production conditions . Cotton pads were placed directly on the ground close to irrigation drippers to provide adequate daily moisture. Earlier work illustrated that dispensers have a field longevity of 21 days and for this reason, dispensers were therefore deployed 1 to 4 times depending on the duration of crop ripening and susceptibility. In three trials , egg laying data were collected in buffer plots that were located between UTC and GUM plots to determine the active range of released volatiles beyond treated areas. This design was implemented based on the assumption that volatiles from treatment plots may be blown or diffuse beyond treatment plots. Berries were brought to the laboratory to determine number of eggs in fruit for each of the plots using a dissecting microscope. All soft or damaged fruits were excluded when assessing presence of eggs. In some cases, at first fruit color, laboratory-reared D. suzukii flies were released in each plot with the intent to create a relatively even pest pressure in all plots. Colonies of D. suzukii used in field studies consisted of seasonally collected wild adults from multiple field sites in the Willamette Valley, Oregon, and Oxnard, California. Collected adults were released into plastic cages and reared at 24°Cand 70% relative humidity, with a 16:8 h photo period before being released in the respective field trials. Flies were constantly provided with water and artificial diet that served as both a food source and an oviposition medium. Before their use in experiments, all flies were allowed to mate for 8 d in mixed-sex cages. Some small fruit varieties were numbered since this information is proprietary.A replicated field trial on drip-irrigated Pinot noir winegrape was conducted in Yamhill County, Oregon, USA from 10 to 18 October 2019 on ~2.6 hectares. Vines were spaced at 1.5 by 5 m, and trellised on a standard four wire trellis system, supporting a ~2 m canopy.