Vaccinium Angustifolium Research Articles

Fall-bearing Year Herbicides and Spring-nonbearing Year Foramsulfuron Applications for Hair Fescue Management in Lowbush Blueberry

Hair fescue (Festuca filiformis) is a tuft-forming perennial grass that reduces yields in lowbush blueberry (Vaccinium angustifolium) fields. Nonbearing year foramsulfuron applications suppress hair fescue, but there is interest in increasing suppression through foramsulfuron use in conjunction with fall-applied herbicides. The objective of this research was to determine the main and interactive effects of fall-bearing year herbicide applications and spring-nonbearing year foramsulfuron applications on hair fescue. The experiment was a 5 × 2 factorial arrangement of fall-bearing year herbicide (none, terbacil, pronamide, glufosinate, dichlobenil) and spring-nonbearing year foramsulfuron application (0, 35 g·ha−1) arranged in a randomized complete block design at lowbush blueberry fields in Portapique and Stewiacke, Nova Scotia, Canada. Spring-nonbearing year foramsulfuron applications did not reduce total tuft density or consistently reduce flowering tuft density, flowering tuft inflorescence number, or flowering tuft seed production. Fall-bearing year pronamide applications reduced hair fescue density for the 2-year production cycle, although additional bearing year density reductions occurred when pronamide was followed by spring-nonbearing year foramsulfuron applications at Stewiacke. Fall-bearing year dichlobenil applications reduced total and flowering tuft density at each site, although reductions in flowering tuft inflorescence number and seed production were most consistent when followed by spring-nonbearing year foramsulfuron applications at Stewiacke. Suppression extended into the bearing year at each site, and dichlobenil should be examined further for hair fescue control. Fall-bearing year glufosinate applications reduced hair fescue total tuft density at each site and flowering tuft density and flowering tuft seed production at Stewiacke. Fall-bearing year glufosinate applications followed by spring-nonbearing year foramsulfuron applications also reduced nonbearing year flowering tuft inflorescence number and bearing year hair fescue seedling density at Stewiacke, indicating that this treatment may reduce hair fescue seedling recruitment at some sites. Fall-bearing year terbacil applications did not suppress hair fescue and are not recommended for hair fescue management in lowbush blueberry.

Evaluation of terbacil-based herbicide treatments for hair fescue (Festuca filiformis) management in lowbush blueberry

AbstractHair fescue is a common tuft-forming perennial grass weed that reduces yields and hinders mechanical harvest in lowbush blueberry fields. PRE terbacil applications traditionally controlled hair fescue but currently only provide suppression in most fields. Terbacil use has not, however, been evaluated in conjunction with other currently registered herbicides in lowbush blueberry. The objective of this research was to evaluate a range of terbacil-based herbicide treatments for hair fescue management in lowbush blueberry. The experiment was conducted at three lowbush blueberry fields in Nova Scotia, Canada. Spring nonbearing-year terbacil applications (2,000 g ai ha–1) exhibited variable efficacy on hair fescue with reduced total tuft density at one site and reduced flowering-tuft density and flowering-tuft inflorescence number at two sites. Suppression was limited to the year of application only. Terbacil followed by (fb) foramsulfuron (35 g ai ha–1) did not improve suppression. A terbacil tank mixture with glufosinate (750 ai ha–1), however, reduced flowering-tuft density and flowering-tuft inflorescence number at each site and reduced total tuft density at one site, suggesting improved suppression with terbacil + glufosinate relative to terbacil alone. Terbacil + glufosinate fb foramsulfuron gave additional reductions in total tuft density at two sites and reduced bearing-year flowering-tuft density at two sites, indicating that hair fescue suppression with this herbicide combination extends into the bearing year. Although less effective than the industry standard pronamide applications, terbacil + glufosinate or terbacil + glufosinate fb foramsulfuron could be used as part of a weed management program for hair fescue in lowbush blueberry.

Effects of fall bearing-year glufosinate applications, spring nonbearing-year glufosinate applications, and spring nonbearing-year foramsulfuron applications on hair fescue (Festuca filiformis) in lowbush blueberry

AbstractHair fescue is a common perennial grass that reduces yields in lowbush blueberry fields. This grass is suppressed with nonbearing-year foramsulfuron applications, though suppression may be improved through use of sequential glufosinate and foramsulfuron applications. The objective of this research was to determine the main and interactive effects of fall bearing-year glufosinate applications, spring nonbearing-year glufosinate applications, and spring nonbearing-year foramsulfuron applications on hair fescue. The experiment was a 2 by 2 by 2 factorial arrangement of fall bearing-year glufosinate application (0, 750 g ai ha–1), spring nonbearing-year glufosinate application (0, 750 g ai ha–1), and spring nonbearing-year foramsulfuron application (0, 35 g ai ha–1) arranged in a randomized complete block design at lowbush blueberry fields located in Parrsboro and Portapique, NS, Canada. Fall bearing-year glufosinate applications, spring nonbearing-year glufosinate applications, and spring nonbearing-year foramsulfuron applications alone provided inconsistent hair fescue suppression. Fall bearing-year glufosinate applications followed by spring nonbearing-year foramsulfuron applications, however, reduced nonbearing-year total tuft density, flowering-tuft density, and flowering-tuft inflorescence number at each site and reduced seed production at Portapique. Sequential fall bearing-year and spring nonbearing-year glufosinate applications or sequential spring nonbearing-year glufosinate and foramsulfuron applications reduced flowering-tuft density and flowering-tuft inflorescence number at each site but did not consistently reduce total tuft density. Sequential herbicide treatments reduced bearing-year seedling density and may therefore contribute to hair fescue seed bank management in lowbush blueberry.

Morphological and anatomical insights into de novo shoot organogenesis of in vitro ‘Delite’ rabbiteye blueberries

Blueberries are valued for their taste and their high nutritional benefits, including their antioxidant and anti-inflammatory properties. In vitro culturing is an alternative method for clonal propagation, and has been used in many biotechnological studies. Most blueberry research is concentrated on highbush and lowbush taxa (Vaccinium corymbosum and Vaccinium angustifolium respectively), with only limited investigations of rabbiteye cultivars (Vaccinium virgatum) that are more suitable for subtropical climates and regions with warmer winters as a result of climate change. There is therefore a need to determine in vitro protocols for that species and group of cultivars. We examined here adventitious shoot regeneration in the ‘Delite’ rabbiteye blueberry cultivar. Leaf explants were cultured in vitro in Woody Plant Medium (WPM), and the effects of different thidiazuron (TDZ) concentrations, the orientation of the leaf (adaxial or abaxial surface in contact with the medium), and two portions of the leaf segment (basal or apical) were examined. De novo shoot development was studied using light and scanning electron microscopy. All concentrations of TDZ used showed similar survival and regeneration rates; 0.5 μM TDZ showed high efficiency in regenerating adventitious shoots (100%, with 57 adventitious shoots/explant), as did the adaxial surface in contact with the medium using either the apical or the basal portion of the leaf (97% shoot regeneration, 47.5 adventitious shoots/explant). Anatomical analyses showed direct and indirect organogenesis. The shoots developed leaf primordia with stomata, trichomes, and well-developed vascular tissues, with further elongation and rooting of the plants. We therefore describe here a high-efficiency regeneration method through de novo shoot organogenesis using TDZ in foliar explants of rabbiteye blueberry, with direct and indirect organogenesis.

Timing and order of different insecticide classes drive control of Drosophila suzukii; a modeling approach

The spotted-wing drosophila, Drosophila suzukii Matsumura, is an invasive pest causing significant damage to soft skinned fruits. Control of D. suzukii is critical since there is no tolerance for infested fruit in the market. While most insecticides control one or more D. suzukii life-stages (e.g., egg, larvae, and adult), the impact of insecticides that are toxic to immature stages is unclear on the subsequent generation of a field population. Insecticides were applied at field recommended rates on cherries and blueberries in the laboratory to determine immature D. suzukii mortality. Spinetoram, cyantraniliprole, malathion, methomyl, spinosad, and phosmet resulted in relatively high mortality of all immature life stages. Zeta-cypermethrin, cyclaniliprole, and fenpropathrin resulted in lower mortality of egg and all larval instars. Malathion was also applied to lowbush blueberries with different fruit sizes (small, medium, and large) in the laboratory and there was no statistical difference in mortality rates depending on fruit sizes. Mortality data from the laboratory experiments were used to parameterize a refined D. suzukii population model. The model revealed that the timing and order of different insecticide classes are important to control D. suzukii population. Model runs that included early applications of more effective insecticides resulted in high immature mortality and greater reduction of D. suzukii populations compared to treatments applied later.

Conditioning Machine Learning Models to Adjust Lowbush Blueberry Crop Management to the Local Agroecosystem.

Agroecosystem conditions limit the productivity of lowbush blueberry. Our objectives were to investigate the effects on berry yield of agroecosystem and crop management variables, then to develop a recommendation system to adjust nutrient and soil management of lowbush blueberry to given local meteorological conditions. We collected 1504 observations from N-P-K fertilizer trials conducted in Quebec, Canada. The data set, that comprised soil, tissue, and meteorological data, was processed by Bayesian mixed models, machine learning, compositional data analysis, and Markov chains. Our investigative statistical models showed that meteorological indices had the greatest impact on yield. High mean temperature at flower bud opening and after fruit maturation, and total precipitation at flowering stage showed positive effects. Low mean temperature and low total precipitation before bud opening, at flowering, and by fruit maturity, as well as number of freezing days (<−5 °C) before flower bud opening, showed negative effects. Soil and tissue tests, and N-P-K fertilization showed smaller effects. Gaussian processes predicted yields from historical weather data, soil test, fertilizer dosage, and tissue test with a root-mean-square-error of 1447 kg ha−1. An in-house Markov chain algorithm optimized yields modelled by Gaussian processes from tissue test, soil test, and fertilizer dosage as conditioned to specified historical meteorological features, potentially increasing yield by a median factor of 1.5. Machine learning, compositional data analysis, and Markov chains allowed customizing nutrient management of lowbush blueberry at local scale.

In vitro bioaccessibility and antioxidant activity of black plum (Syzygium caryophyllatum).

Influence of drying, juice processing, and simulated enteric digestion on bioactive constituents and bioactivity of Syzygium caryophyllatum fruit was assessed and compared with fresh blueberry (Vaccinium angustifolium). Methanolic extracts of fresh fruits and processed products and digesta at different digestion phases were analyzed for phenolics, flavonoids, anthocyanin, β-carotene, lycopene, and ascorbic acid contents, and antioxidant activities. The results indicated that fresh black-plum possesses higher bioactives content and antioxidant activities compared to processed black plum. The contents of bioactives and antioxidant activities reduced gradually due to gastrocolic digestion. Bioaccessibility and bioavailability of bioactives from blueberry, black-plum, and its products showed significant variations. These results highlighted that the alterations in contents of bioactives and antioxidant activities of black-plum due to drying, juice processing, and gastrocolic digestion could potentially influence on bioaccessibility and dialysis or potential bioavailability of bioactives found in black-plums. PRACTICAL APPLICATIONS: The present research produced a comprehensive cognition regarding alterations in the contents of bioactive constituents and antioxidant activity of black plum due to drying, juice processing, and gastrointestinal digestion, which can function as a new source of functional food.

Antifungal polyketides from the Picea rubens and Vaccinium angustifolium endophyte Lachnellula calyciformis

As part of a survey of foliar endophytes of conifers in the Acadian forest, we isolated a strain of Lachnellula calyciformis from a healthy Picea rubens needle. From this fungus, the new natural products deoxylachnellulone (3) and lachnelluloic acid B (5), and the known metabolite lachnellulone (1), were isolated and structurally characterized. Isolachnellulone (2) and isodeoxylachnellulone (4) occurred as isomers resulting from the facile isomerization of lachnellulone (1) and deoxylachnellulone (3), respectively. The natural products lachnellulone (1) and deoxylachnellulone (3) were also confirmed from two strains of L. calyciformis isolated as leaf and stem endophytes of Vaccinium angustifolium in eastern Canada, representing the first record of this species from a non-conifer host. All isolated compounds displayed moderate antifungal and antibiotic activity. This study of biologically active natural products from a conifer endophyte highlights the increasing apparent complexity of their collective life histories.

Evaluation of currently registered herbicides for fall bearing year red sorrel (Rumex acetosella L.) management in lowbush blueberry (Vaccinium angustifolium Aiton)

Red sorrel is a common creeping herbaceous, perennial weed species in lowbush blueberry fields and reproduces asexually via ramets from creeping roots. Ramets emerge throughout the season but remain vegetative due to a vernalisation requirement for flowering. This weed may therefore be managed with fall herbicide applications, but few currently registered herbicides have been evaluated for fall red sorrel management in lowbush blueberry. The objectives of this research were to (i) determine the effect of various herbicide treatments on red sorrel shoot and root biomass in the greenhouse, (ii) determine the effect of fall bearing year herbicide applications on overwintered red sorrel ramet density in the field, (iii) determine if reduced overwintered ramet density reduces flowering ramet density in the field, and (iv) estimate the potential for red sorrel to recover from fall bearing year herbicide applications. Dicamba, tribenuron-methyl, and glufosinate reduced red sorrel shoot and root biomass in the greenhouse and reduced overwintered ramet density in the field. Clopyralid, sulfentrazone, and flumioxazin reduced shoot and root biomass in the greenhouse but exhibited limited efficacy in the field. Nicosulfuron + rimsulfuron and glyphosate were ineffective in both the greenhouse and field. Dichlobenil and pronamide reduced overwintered ramet density in the field. Reduction of overwintered ramet density did not consistently reduce flowering ramet density. Dichlobenil reduced seedling density at two sites, but no herbicide consistently reduced summer non-bearing year ramet density. Fall herbicide applications alone, therefore, do not appear to maintain red sorrel suppression in lowbush blueberry fields.

Analysis of Pollination Services Provided by Wild and Managed Bees (Apoidea) in Wild Blueberry (Vaccinium angustifolium Aiton) Production in Maine, USA, with a Literature Review

Maine is the largest producer of wild blueberry (Vaccinium angustifolium Aiton) in the United States. Pollination comes from combinations of honey bees (Apis mellifera (L.)), commercial bumble bees (Bombus impatiens Cresson), and wild bees. This study addresses (1) previous research addressing wild-blueberry pollination, (2) effects of wild-bee and honey-bee activity densities on fruit set, yield, and crop value, (3) the economic value of wild-bee communities, and (4) economic consequences of pollinator loss. Bee communities were sampled in 40 fields over three years (2010–2012) and bee activity densities were estimated for bumble bees, honey bees, and other wild bees. These data were applied to an economic model to estimate the value of bee taxa. Bumble bees and honey bees predicted fruit set and reduced its spatial heterogeneity. Other wild bees were not significant predictors of fruit set. Yield was predicted by fruit set and field size, but not pest management tactics. Our analysis showed that disruption in supply of honey bees would result in nearly a 30% decrease in crop yield, buffered in part by wild bees that provide “background” levels of pollination. Honey-bee stocking density and, thus, the activity density of honey bees was greater in larger fields, but not for wild bees. Therefore, a decrease in crop yield would be greater than 30% for large fields due to the proportionally greater investment in honey bees in large fields and a relatively lower contribution by wild bees.

First report of Godronia cassandrae as a major cranberry fruit rot pathogen in Eastern Canada.

The complex etiology of cranberry fruit rot (CFR) (Oudemans et al., 1998) has made it difficult to precisely identify the fungi involved in CFR and their relative importance in North America. To remedy this situation, a multiplex PCR approach targeting the 12 most commonly reported fungi in CFR was recently developed (Conti et al., 2019). However, in surveys conducted in Eastern Canada, the molecular tool revealed the presence of an unknown fungus in more than 30% of the collected samples. Analyses were thus undertaken to identify this species. From 117 rotten fruit collected at harvest in 2017, 34 samples of the unknown fungus, all morphologically similar, were isolated but not detected using the molecular tool. Their ITS ribosomal regions were sequenced using universal primers (Vilgalys and Hester, 1990; White et al., 1990) and searched against the GenBank database using the Blastn tool (Altschul et al., 1990). The top match was obtained with Godronia cassandrae (accession number: MH855281 (Vu et al., 2019), 98-100% of identity and an E-value of 0.0), even though some isolates had minor nucleotide differences, as presented in the tree. Sequences were deposited in GenBank as accession numbers MT599989 to MT600022. Since G. cassandrae had been reported, albeit rarely, on cranberry in Michigan (Olatinwo et al., 2003), it was supposed to amplify with the molecular tool developed from the strain DAOM C216021 (AAFC, Ottawa, ON) identified in 1993 on Vaccinium angustifolium as G. cassandrae. Analysis of the sequences used to build the specific primers from this strain confirmed the DAOM strain as being Neocucurbitaria juglandicola, which was never diagnosed in our cranberry samples. To confirm this revised diagnosis, a multi-sequence alignment (MSA) was performed on the ITS regions of the isolates from rotten cranberries and sequences available for the genus Godronia in the NCBI nucleotide database (NCBI txid269064). This MSA allowed us to find discriminant regions between Godronia spp. A pair of PCR primers specific to G. cassandrae found on cranberry fruit was then designed (the forward and reverse sequences are AAT CAG TGG CGG TGC CTG TC and TAC CGC TTC ACT CGC CGT TAC, respectively), generating 196 bp amplicons, with an annealing temperature of 65°C. The diagnosis of 7,835 fruit sampled at three time points (harvest, after three and after six weeks of storage) in 2018, from four cranberry farms located in Québec (CA) and Nova Scotia (CA), detected G. cassandrae in 2350 samples (30%). To assess the pathogenicity of four specimens from 2017, Koch's postulates were completed on two healthy fruit per isolate. The fruit were wounded with a sterilized pick and individually inoculated; two fruit were used as control. Based on our observations, the fungi isolated from cranberry fruit displayed a pale lemon yellow mycelium and black pycnidia. Conidia are hyaline, cylindrical and divided by a single septum. These morphological characters are similar to the ones described in the literature for G. cassandrae (Polashock et al., 2017). Rot symptoms appear as a discoloration from the firm, red and healthy cranberry fruit to a yellowish-orange softer fruit. Molecular characterization of the re-isolated fungus confirmed the presence of G. cassandrae. We report Godronia cassandrae for the first time as a major cause of CFR in Eastern Canada. Its prevalence in cranberry fields of Québec and Nova Scotia suggests that it supplants Physalospora as the main fungus involved in CFR in Eastern Canada.

Field Perimeter Trapping to Manage Rhagoletis mendax (Diptera: Tephritidae) in Wild Blueberry.

Rhagoletis mendax Curran (the blueberry maggot fly) is a major pest of wild blueberry. It is a direct pest of the fruit. Females lay eggs in fruit resulting in infestations of larvae unacceptable to most consumers. Three field perimeter interception tactics were tested for control of R. mendax in wild blueberry, Vaccinium angustifolium Aiton (Ericales: Ericaceae), between 2000 and 2010. We investigated field perimeter deployment of baited, insecticide-treated, green spheres (2000-2005), baited, yellow Trécé PHEROCON AM traps (2005 and 2006), and baited, Hopper Finder, sticky barrier tape (2008-2010). Only the Hopper Finder tape provided significant reduction in R. mendax adults and fruit infestation over the 3-yr field study. However, the reduction in fruit infestation compared with control plots was only 48.2 ± 7.3%, a level of reduction in damage that would be unsuitable for many commercial wild blueberry growers as a stand-alone tactic, but could be an important reduction as part of a multiple tactic IPM strategy. In addition, we constructed an agent-based computer simulation model to assess optimal trap placement between three patterns: 1) a single row of traps along field perimeter; 2) a double row of traps along the field perimeter at half the density of the single row; and 3) a grid of traps spread throughout the field but with the largest distance between traps. We found that the single row deployment pattern of traps was the best for reducing immigration of R. mendax adults into simulated fields.

Evaluation of acetolactate synthase/acetohydroxyacid synthase – inhibiting herbicide spot applications and mesotrione tank mixtures for narrow-leaved goldenrod management in lowbush blueberry

Narrow-leaved goldenrod is a common creeping herbaceous perennial weed in lowbush blueberry that is difficult to manage due to limited control from pre-emergence hexazinone applications and incomplete control from post-emergence mesotrione applications. The objectives of this research were to (1) evaluate a range of summer and fall non-bearing year acetolactate synthase/ acetohydroxyacid synthase (ALS/AHAS) – inhibiting herbicide spot applications for narrow-leaved goldenrod control, and (2) evaluate broadcast applications of mesotrione applied alone or in tank mixture with foramsulfuron, nicosulfuron + rimsulfuron, flazasulfuron, and clopyralid for crop tolerance and management of narrow-leaved goldenrod in lowbush blueberry. Summer non-bearing year spot applications of glyphosate and flazasulfuron caused &gt;90% visual injury to narrow-leaved goldenrod and reduced both non-bearing and bearing year shoot density. Spot applications of tribenuron methyl, foramsulfuron, nicosulfuron + rimsulfuron, halosulfuron, and pyroxsulam caused variable injury and did not consistently reduce narrow-leaved goldenrod shoot density. Results were similar in the fall non-bearing year experiment and they indicate that flazasulfuron could be used as an alternative to glyphosate for spot applications to narrow-leaved goldenrod due to lower crop injury from this herbicide relative to glyphosate. Broadcast mesotrione applications injured narrow-leaved goldenrod but did not reduce shoot density. Broadcast foramsulfuron, nicosulfuron + rimsulfuron, and clopyralid applications caused &lt;60% narrow-leaved goldenrod injury and did not reduce shoot density. Tank mixture of these herbicides with mesotrione did not improve narrow-leaved goldenrod control. Broadcast flazasulfuron applications caused &gt;60% visual injury to narrow-leaved goldenrod and reduced non-bearing year and bearing year shoot density. Flazasulfuron efficacy was reduced when applied in tank mixture with mesotrione.

The impact of planting buckwheat strips along lowbush blueberry fields on beneficial insects

Pollination and pest control are important in many agroecosystems. Beneficial insects that provide these services (e.g., bees and natural enemies) often require floral resources beyond crop bloom. Planting floral resources along crop field margins may be a useful tactic to support communities of beneficial insects in agroecosystems. We examined the effect of planting buckwheat (Fagopyrum esculentum Moench) along lowbush blueberry (Vaccinium angustifolium Aiton) field margins on beneficial insect abundance and generic richness. We found that bee abundance was higher in buckwheat transects than control transects in 2014 and 2015, but not 2016, and that bee generic richness was higher in buckwheat transects than in control transects in 2015 only. High variability occurred across years. All bee genera recorded during blueberry bloom were also collected in buckwheat transects, suggesting buckwheat is a useful resource for the bee community involved in blueberry pollination. The effect of buckwheat on natural enemies was variable and inconsistent. We conclude that buckwheat influenced bee and natural enemy communities during certain years, but field edges in the lowbush blueberry fields studied may already adequately support beneficial insects. Thus, not all habitat management efforts with augmentative floral plantings may consistently boost communities of beneficial insects.

The Ecology of Autogamy in Wild Blueberry (Vaccinium angustifolium Aiton): Does the Early Clone Get the Bee?

Wild blueberry, Vaccinium angustifolium Aiton, for the most part requires cross-pollination. However, there is a continuum across a gradient from zero to 100% in self-compatibility. We previously found by sampling many fields that 20–25% of clones during bloom have high levels of self-compatibility (≥50%). In 2009–2011, and 2015 we studied the ecology of self-pollination in wild blueberry, specifically its phenology and bee recruitment and subsequent bee density on bloom. We found that highly self-compatible clones were predominantly early blooming genotypes in the wild blueberry population. On average, fruit set and berry weight were highest in self-compatible genotypes. The bumble bee community (queens only early in the spring) was characterized by bees that spent large amounts of time foraging in self-compatible plant patches that comprised only a small proportion of the blueberry field, the highest density in the beginning of bloom when most genotypes in bloom were self-compatible. As bloom proceeded in the spring, more plants were in bloom and thus more land area was occupied by blooming plants. The absolute density of bumble bee queens per m2 declined, as a dilution effect, and this probably resulted in lower fruit set throughout the field.

Into the wild blueberry (Vaccinium angustifolium) rhizosphere microbiota.

The ability of wild blueberries to adapt to their harsh environment is believed to be closely related to their symbiosis with ericoid mycorrhizal fungi, which produce enzymes capable of organic matter mineralization. Although some of these fungi have been identified and characterized, we still know little about the microbial ecology of wild blueberry. Our study aims to characterize the fungal and bacterial rhizosphere communities of Vaccinium angustifolium (the main species encountered in wild blueberry fields). Our results clearly show that the fungal order Helotiales was the most abundant taxon associated with V. angustifolium. Helotiales contains most of the known ericoid mycorrhizal fungi which are expected to dominate in such a biotope. Furthermore, we found the dominant bacterial order was the nitrogen-fixing Rhizobiales. The Bradyrhizobium genus, whose members are known to form nodules with legumes, was among the 10 most abundant genera in the bacterial communities. In addition, Bradyrhizobium and Roseiarcus sequences significantly correlated with higher leaf-nitrogen content. Overall, our data documented fungal and bacterial community structure differences in three wild blueberry production fields.

Natural products and polysorbates: Potential Inhibitors of biofilm formation in Pseudomonas aeruginosa.

With all the challenges super bugs are imposing, biofilm formation opens the door against various more complicated challenges. Such issue may be highlighted with the ability of the latter to render the antibiotics hardly accessible to bacterial cells and sheds the light on the importance of finding antibiofilm formers. Therefore, we assessed the inhibitory effect of natural product extracts (ginger, wild blueberry) and polysorbates (PS20, PS80) on biofilm formation at the molecular level. Growth inhibition assay was performed to test the effect of ginger (Zingiber Officinale), wild blueberry (Vaccinium Angustifolium), and polysorbates on Pseudomonas aeruginosa (PAN14) growth. Transcription levels of biofilm exopolysaccharides encoding genes (ndvB, pelC, algC) and quorum sensing genes (lasI, lasR, rhlI, rhlR) for LasI/LasR and RhlI/ RhlR systems were evaluated by RT qPCR. The polysorbates and the extracts of both ginger and wild blueberry had no effect on the growth of P. aeruginosa. Biofilms' examination has unraveled the effectiveness of treatments used in reducing its formation. Moreover, a significant reduction in the expression of all genes tested for biofilm exopolysaccharides and its quorum sensing system was observed. The decrease in the relative gene expression of the exopolysaccharides and quorum sensing encoding genes sheds the light on the mechanism of action of ginger and wild blueberry's constituents as well as polysorbates 20 and 80 on P. aeruginosa biofilm formation. Future studies need to assess the antibiofilm effect of each fraction of herbal extracts separately.

Wild Blueberry Fruit Drop: A Consequence of Seed Set?

Wild blueberry is a native plant managed as a crop in northeastern North America. Fruit drop in wild blueberry, Vaccinium angustifolium Aiton, was studied over 6 years (1996–1999, 2008 and 2011). Three hypotheses were tested regarding fruit drop mechanisms from plants (clones) sampled in the field: (1) proportional fruit drop; (2) constant or uniform fruit drop; and (3) pollen or resource limitation. In addition, the temporal rate of fruit drop was measured between the end of pollination (petal fall) and fruit maturity just prior to harvest (2008 and 2011). The dynamics of fruit drop were different in the two years. The role of pollination intensity in fruit drop was also assessed. Evidence for both proportional fruit drop and resource limitation at the clone level was found but only proportional drop at the field level. Low levels of seed set are associated with fruit drop. In a four-year study (1996–1999), fruit drop ranged from 23.3 to 49.4% of the total set fruit. Partitioning the variance in fruit drop between years, fields and clones (plant genotypes) showed that the highest variation is between stems within clones (37.4%) and clones (plant genotype) within fields (35.4%), followed by between fields (19.8%) and between years (7.4%).

Phenology and spatial distribution of spotted-wing drosophila (Diptera: Drosophilidae) in lowbush blueberry (Ericaceae) in Saguenay-Lac-Saint-Jean, Québec, Canada

AbstractDrosophila suzukii (Matsumura) (Diptera: Drosophilidae), the spotted-wing drosophila, is an invasive pest of fruit crops, which appeared in eastern Canada in 2010. It represents a major threat to lowbush blueberry (Vaccinium angustifolium Aiton; Ericaceae) in the Saguenay-Lac-Saint-Jean region, Québec, Canada, at the northern limits of its distribution. The dynamics, overwintering capacity, population fluctuations, and damage to lowbush blueberry of D. suzukii are unknown in Saguenay-Lac-Saint-Jean. We aimed to 1) document D. suzukii abundance and phenology in lowbush blueberry in separate localities; 2) evaluate the potential of D. suzukii to overwinter and examine population dynamics over three seasons; and 3) study the spatial distribution of D. suzukii in lowbush blueberry fields with respect to forested borders. Drosophila suzukii is abundant in lowbush blueberry fields of Saguenay-Lac-Saint-Jean. In spring, D. suzukii were absent until late June, when few summer-morph females appeared. Drosophila suzukii densities started to increase regularly in August, with increasing male proportions, to culminate in fall at high levels with balanced sex ratios. Overwintering remains uncertain, D. suzukii being undetectable in spring despite intensive trapping. Appearance of diapausing winter morphs at high densities indicates that D. suzukii responds appropriately to local conditions preceding cold winter. Models of variation of D. suzukii densities and lowbush blueberry fruit infestation with distance from borders indicate that forest borders are favoured habitats over lowbush blueberry fields and the source of D. suzukii moving to some extent into lowbush blueberry fields.

Diversity and nutritional value of pollen harvested by honey bee (Hymenoptera: Apidae) colonies during lowbush blueberry and cranberry (Ericaceae) pollination

AbstractThe growth of the commercial pollination industry raises important concerns regarding honey bee (Apis mellifera Linnaeus; Hymenoptera: Apidae) health and development. While providing such services, honey bees are often exposed to undiversified pollen sources that may contribute to nutritional deficiencies, notably in protein and amino acids. To understand how honey bees are affected during provision of pollination services, we compared honey bee colonies that pollinated lowbush blueberry (Vaccinium angustifolium Aiton; Ericaceae) and/or cranberry (Vaccinium macrocarpon Aiton; Ericaceae) crops (management strategies) with control colonies in a diversified farmland environment. We identified the floral species of pollen collected by honey bee colonies in those crops compared to pollen collected by control colonies. We also analysed the protein and essential amino acid content of collected pollen and bee bread and measured the nutritional impact of pollination services on honey bee colonies. We found that honey bees providing blueberry and/or cranberry pollination services are exposed to a less diversified pollen diet than colonies located in a farmland environment, especially in a cranberry field. There was a significantly lower proportion of crude protein content in collected and stored pollen during provision of blueberry pollination services, which led to a smaller brood population. Many nutritional deficiencies were measured with regards to essential amino acids.