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The article discusses the results of a 2015 survey of almond growers, which is the first survey to outline basic components of pollination contracts. Highlights include honey bee colony shipments into California by state of origin, the tendency for forward contracting in the industry, and timeline of almond pollination events and honey bee colony population dynamics.

The article reports on the growth of almond production in California and its impact on commercial beekeeping in the U.S. Topics mentioned include concerns over pollination services becoming highly expensive in 2006, efforts of growers and researchers to reduce almond pollination costs, and a graph showing bearing and non-bearing acreages for almonds with simple trend projections from 1995 to 2020.

The Gram-negative bacterium Xylella fastidiosa causes disease in a number of important crops and plants within natural ecosystems. Most notable among these diseases are Pierce's disease of grapevine, Citrus Variegated Chlorosis, Almond Leaf Scorch, Oleander Leaf Scorch and Olive Quick Decline Syndrome. In response to substantial economic losses, extensive research efforts have been underway over the past several decades in North and South America. Recently, X. fastidiosa has been detected in several countries of Europe and Asia, likely appearing as a result of global trading of plant material. Once established in a new region, X. fastidiosa spread is dependent on the obligate transmission by xylem-sap feeding insects. Sharpshooter leafhoppers (Hemiptera: Cicadellidae: Cicadellinae) are the best-studied group of vectors of this bacterium; however the list of known vector species is expanding. As X. fastidiosa moves into new regions, the combination of an introduced pathogen with existing or introduced vectors carries the potential of increasing economically important disease problems in the local context. By reviewing ecological and biological information of known X. fastidiosa vectors and the epidemiology of local X. fastidiosa outbreaks, this paper aims at increasing our understanding of vector- X. fastidiosa interactions. [ABSTRACT FROM AUTHOR]

Xylella fastidiosa (Xf), the causal agent of Pierce's disease (PD), has long been considered a major threat to prosperous European viticulture. In May of 2017, PD was officially detected on a grapevine in Mallorca. To better understand the epidemiology of the first established outbreak of PD in Europe, the disease incidence and severity were assessed, vector transmission experiments were performed, and cultivar responses to Xf infections both in the field and in inoculation experiments were monitored. The genetic structure of Xf local populations was also investigated by multilocus sequence typing analysis, and their whole genome sequences and phylogenetic positions compared with respect to PD strains worldwide. Disease incidence was moderately low (0.07) and highly variable, ranging from 0.0 to 0.99. Its economic impact on wine production was considered low. Vineyards managed under conventional viticulture were significantly less infected than organic farming. Under greenhouse conditions, the insect Philaenus spumarius efficiently transmitted the pathogen from infected to healthy grapevines. In the inoculation experiments, Xf infected, to some degree, 29 of the 30 cultivar × rootstock combinations (n = 239). Cultivars Viura, Gorgollasa and Sauvignon Blanc were the most susceptible ones. All Xf isolates from grapevines belonged to sequence type ST1; they phylogenetically clustered within the Californian ST1 clade, with which they shared a 99.94% identity and the same plasmid. In addition, ST1 caused almond leaf scorch disease, where notably its incidence (0.78) and severity was much higher than PD. The likely reasons for these wide differences are discussed in the context of a 20‐year Xf introduction scenario. [ABSTRACT FROM AUTHOR]

Horticulture nitrogen (N) runoffs are major environmental and health concerns, but current farming practices cannot detect ineffective N applications. Hence, we set to recognize high N conditions and characterize their effects on the physiology of almond trees grown in drainage lysimeters. Water and nutrients mass balances exhibited that N benefitted almond trees in a limited range (below 60 mg N L−1 in irrigation), while higher N conditions (over a 100 mg N L−1) reduced evapotranspiration (ET) by 50% and inherently constrained N uptake. Respectively, whole-tree hydraulic conductance reduced by 37%, and photosynthesis by 17%, which implied that high N concentrations could damage trees. Through gas-chromatography, we realized that high N conditions also affected components of the citric acid cycle (TCA) and carbohydrates availability. Such changes in the metabolic composition of roots and leaves probably interfered with N assimilation and respiration. It also determined the proportions between N and starch in almond leaves, which formed a new index (N:ST) that starts at 0.4 in N deficiency and reaches 0.6–0.8 in optimal N conditions. Importantly, this index continues to increase in higher N conditions (as starch reduces) and essentially indicates to excessive N applications when it exceeds 1.1. • Current mineral diagnoses cannot support precise farming as it will not detect high nitrogen availability. • Disproportionate nitrogen applications compromise the hydraulic conductivity and photosynthetic productivity of trees. • Biochemical functionalities exhibit that nitrogen availability affects the composition and allocation of photosynthates. • Metabolic and mineral analyses form a new nitrogen and starch index (N:ST) to excessive nitrogen fertilization. [ABSTRACT FROM AUTHOR]

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The objective of this work was to evaluate the effect of repeated traffic with a light-weight tractor on the physical/mechanical properties of an Aridisol soil from eastern Almería (Spain). The soil has been used for almond (Prunus amigdalus L.) production for the past 29 years. A light modal tractor (≈15 kN overall load) and different traffic frequencies or treatments; namely, 0 (control, no traffic), and 1, 5, 7, and 10 passes, respectively, were used. The following variables were measured: cone Index (CI); bulk density (BD); total soil porosity (TSP); water infiltration into soil (I), and ruth depth (RD). The results showed that, only treatments 7 and 10 led to significant increases in CI and BD throughout the soil profile (0-450 mm). Changes in TSP in those treatments were consistent with changes in soil bulk density. No significant differences in RD were found when the tractor passed 1 or 5 times. All traffic treatments resulted in significant compaction in the topsoil layer (0-150 mm) and soil physical conditions that would be regarded as unsuitable for establishment of most arable crops. [ABSTRACT FROM AUTHOR]

From 2004 to 2012, the incidence and severity of the four most common almond aerial diseases were evaluated in ten experimental fields in the main almond-growing areas of Andalusia, southern Spain. The studied experimental fields were representative of the different geographic locations, agronomic characteristics and farming systems in Andalusia. A total of 14 early-flowering and 26 late-flowering cultivars (cvs.) currently grown in the new almond plantings of Andalusia and the Mediterranean basin were evaluated. The incidences of red leaf blotch (RLB), shot hole (SH), blossom blight (BB), and leaf curl (LC), which were caused by Polystigma amygdalinum , Thyrostroma carpophilum , Monilia laxa and Taphrina deformans , respectively, were monitored in each field and year. RLB was the most prevalent disease, although its severity varied markedly among fields and years. BB caused the higher outbreaks, but this was only the case when rainfall coincided with flowering, and fungicide treatments were not applied. The early-flowering cvs. were more affected than the late-flowering cvs. by BB, although most of the early-flowering cvs. were less susceptible than the reference cv. Marcona to BB. However, 'Marcona' was less susceptible than most of the early-flowering cvs. to RLB. Among the late-flowering cvs., the reference cv. Guara was susceptible to the four monitored diseases. The responses of the cvs. to the diseases varied markedly among fields and years, with significant differences among cvs. for all diseases. This work represents the first study to evaluate a broad range of almond cvs. infected with the main almond foliar diseases in natural field conditions, making an important contribution to the understanding of varietal susceptibility of almonds to four significant foliar diseases. Moreover, this study highlights the need to consider cultivar resistance in the development and selection of plant material for new almond plantings and in integrated pest management. • Understanding of varietal susceptibility of almonds to foliar diseases. • Red leaf blotch, caused by Polystigma amygdalinum , was the most prevalent disease. • The responses of the cultivars varied markedly among different fields, years, and diseases. • This work highlights the need to consider cultivar resistance for new almond plantings. [ABSTRACT FROM AUTHOR]

• Signal MDS was unaffected for water stress conditions. • TGR was a sensitive indicator to water stress. • McCutchan and Shackel baseline could be a useful tool in full irrigated conditions. Irrigation needs in mature almond orchards are very high. Although almond trees grow in rainfed conditions, the yield response is very sensitive to irrigation. Continuous monitoring of the water status could be an adequate tool to optimize deficit irrigation. In this sense, trunk diameter fluctuations appeared as a very promising indicator at the beginning of the century, but few data have been published. The aim of this work is to check threshold values of maximum daily shrikage (MDS) and identify possible limitations to their use in commercial orchards. The experiment was performed in a commercial farm in Dos Hermanas (Seville, Spain) during the 2017 season on a 7-years-old orchard (cv Vairo). The irrigation treatments were Control (100% ETc), sustained deficit irrigation (SDI) with a maximum seasonal irrigation of 100 mm and two regulated deficit treatments (RDI). Both RDI treatments (RDI-1 and RDI-2) were scheduled using the signal of maximum daily shrinkage (signal) and the midday stem water potential (SWP). In RDI-1, full irrigation conditions were provided before kernel filling and during postharvest, using the threshold values suggested in the bibliography. During kernel filling, the water stress level was designed to be -1.5 MPa (SWP) and 1.75 (signal). RDI-2 trees were irrigated using the same scheduling as RDI-1, but target water stress values were higher in kernel filling (-2 MPa and 2.75) and with a maximum seasonal amount of water of 100 mm. SWP in Control trees was near the McCutchan and Shackel baseline for most of the season. None of the deficit treatments reached the signal values suggested. Moreover, the signal values were almost equal between treatments, with no water stress effect. The trunk growth rate (TGR) presented clear differences depending on the water status. [ABSTRACT FROM AUTHOR]

Highlights • Dry-farmed almond orchard showed a marked alternate-fruiting pattern. • Foliar application of nitrogen or boron failed to improve almond yield. • Dry-farmed almond orchards did not respond to more than 25 kg N hm−2 yr-1 applied as a fertilizer. • Sufficiency ranges established for almond proved to be inadequate to diagnose nutritional disorders in rainfed orchards. Abstract Rainfed orchards have huge social importance in territories of low agro ecological potential. Research on almond is limited for dry-farmed orchards in particular for crop nutrition and fertilization. This makes difficult to implement a cropping practice adjusted to the ecological constraints of these agrosystems. It is known that nitrogen (N) and boron (B) are determining nutrients for dicot tree crops such as olive and vineyards grown under these environmental conditions. Thus, this study aims to test at what level the crop responds to soil-applied N and B, and whether the foliar sprays can supplement or replace the application of the nutrients to the soil. It is also important to check if the sufficiency ranges set for the almond, which have been based on irrigated orchards, are adjusted for rainfed farming. The N rates applied to the soil were 0 (N0), 25 (N25), 50 (N50) and 100 (N100) kg hm−2 and those of B 0 (B0), 1 (B1), 2 (B2) and 3 (B3) kg hm−2. The foliar sprays consisted of three annual applications of N (two in 2017) and two applications of B (one in 2017), the last ones of 2015 and 2016 applied at post-harvest. Foliar N and B sprays were respectively applied at the concentrations of 0.5% N and 0.036% B. The experiment was arranged as a split-plot design with soil applied N or B assigned to the main plots and foliar N or B as subplots. Kernel yield showed a marked alternate-fruiting, with two years of good crops (2015 and 2017) and a year of practically no production (2016), likely due to adverse ecological conditions for almond growth and cropping practices incorrectly performed. Soil-applied N significantly increased kernel yield in comparison to the control but the differences were not significant in N rates higher than 25 kg N hm−2. The application of B to the soil improved tissue B concentrations but did not increase productivity. In general, foliar applications of N or B failed to improve plant nutritional status and kernel yield. The current sufficiency ranges for almond seem to be unnecessarily narrow for several nutrients such as N, potassium (K), calcium (Ca), manganese (Mn) and iron (Fe), since several results were found to be out of the sufficiency range with no apparent negative consequences for the trees. The laboratories carrying out soil testing and plant analysis should take this into account in diagnosing the nutritional status of almond orchards. [ABSTRACT FROM AUTHOR]

Highlights • The Non-Water Stress Baseline (NWSB) for an almond orchard was developed. • The CWSI was closely related to the transpiration rate and the ratio kT/GC. • A model that relates the seasonal average of CWSI and nut yield was developed. • The model was applied to aerial imagery to plot a map of estimated crop yield. Abstract This paper evaluates the usefulness of the Crop Water Stress Index (CWSI) for monitoring transpiration and water status in almond trees, and proposes a methodology for assessing crop yield derived from the relation between canopy temperature and transpiration. For this purpose, a Non-Water Stress Baseline (NWSB) was developed from canopy temperature measurements taken with Infrared Thermometers (IRT) installed permanently over well-watered trees for three years. Tree transpiration was measured continuously with sap flow probes installed in the same trees than the IRT sensors. The calculated CWSI was closely related to water potential and stomatal conductance measured during kernel filling, as well as with transpiration and the ratio kT/GC (the transpiration coefficient over the ground cover). Taking into consideration this relation and the water production function recently published, the seasonal CWSI was compared to final yield and the regression yielded good results (R2 = 0.80). An empirical relationship between the CWSI acquired remotely from two flights performed during the kernel filling stage and crop yield was determined for this orchard. The estimated yield from the proposed methodology was compared to ground-truth measurements of crop yield measured in 80 trees during 2014 and 2015. The result obtained a RMSE that yielded 1.54 kg/tree. This study thus demonstrates that CWSI is closely related to the transpiration and the ratio kT/GC. This relation settles the basis for the development of methodologies for estimating water-limited crop yield from thermal derived information. [ABSTRACT FROM AUTHOR]

Almond yields vary between rainfed and intensively irrigated systems, but how to match irrigation to potential productivity is unclear. Hence, we compared almond physiology under deficit (600 mm) and full (1300 mm) irrigation to identify stress indices and determine the production overheads of mismanaged watering. We hypothesized that trees alter their growth to conserve resources during drought and mitigate their hydraulic stress responses. Thus, we monitored stem water potential and stomatal conductance to characterize the hydraulic responses of trees to deficient and hydrated water conditions. Adapting the seasonal relationship between irrigation coefficients and tree water potential was also tested. Finally, soil water status and trunk development were considered physical stress indices for field conditions. Soil water depletion in deficit irrigation reduced stem water potential below − 2 MPa and checked stomatal conductance at 0.15 mol m-2 s-1 for most of the growing season. An empirical productivity model determined that, under deficit irrigation, almond trees suffer from chronic stress that limits their photosynthetic capacity to ∼14 µmol m-2 s-1. Consequently, nominal assimilation limitations (10%) in early summer manifested to 4 kg C tree-1 metabolic losses by autumn. The inter-annual vegetative limitations in deficit irrigation resulted in significant yield reductions (35%) by the second experimental season. Temporal changes in the correlations between stem water potential, stomatal conductance, and trunk contractions made it difficult to use water stress indices to make irrigation decisions. However, normalizing tree performance by phenology indicated a 960 mm irrigation that supported high yields. Further, integrating the variability in soil water with trunk dendrometry illustrated that trees could maintain constant growth between irrigation days under well-watered conditions. Hence, in commercial operations, variable growth rates and trunk contraction measures signal insufficient irrigation and could guide practical irrigation adaptations. • Global yield discrepancies in almond farms relate to water allocations. • Almonds mask stress indices as they exhaust water and energy resources. • Adapting irrigation via transient drought indices saves water without stress. • Productivity losses in deficit irrigation may not be sustainable. [ABSTRACT FROM AUTHOR]

Almond seed extraction from whole kernel recovery is a process which is usually performed manually thus making it laborious and time consuming. The purpose of this paper is to investigate a means for almond seed extraction for whole kernel recovery to close the gap in domestic, commercial and industrial demand of almond seeds for food and industrial processing. The machine comprises of four units: the hopper; the cracking chamber which embeds the shaft, the hammer and electric motor. SolidWorks software was used to determine the responses of the machine critical elements. The sample of almond fruit used was picked from the premises of the University of Ilorin, Kwara State. The fruit (almond) was properly prepared by removing the fleshy parts from it and subjecting its seeds to a drying period of 7 days to 10 days at an average temperature of 35°C before was loaded into the extractor where cracking of the seeds was effected. Performance evaluation of the machine was conducted; its efficiency was found to be 82% with a throughput capacity of 42 kg h-1 and whole kernel recovery of 70%. The machine is affordable to both peasant farmers and process industries. [ABSTRACT FROM AUTHOR]

Agricultural landscapes offer unique habitats for many species. Because agriculture is a major land use worldwide, changes in farming practices can have major repercussions for biodiversity. Particularly in Western Europe, ongoing intensification and scale enlargement but also land abandonment and poor agricultural practices leading to land degradation form a major threat to agrobiodiversity. Agro-ecological farming practices are suggested as an alternative way of farming in order to conserve and enhance biodiversity. Yet knowledge about what factors explain farmers' adoption of agro-ecological farming practices is fragmented and incomplete. In this paper, we offer a holistic framework that specifies these factors and how they are interconnected. The framework is illustrated and refined by means of a case study analysis of almond farming in Andalusia. The chosen case represents a specific localized farming practice that currently negatively impacts biodiversity but for which agro-ecology forms an attractive alternative regarding biodiversity. The case study demonstrates that our framework offers a useful tool to systematically identify the different factors that affect agro-ecological farming adoption, interlinkages between factors and particularly the more structural barriers to agro-ecology. [ABSTRACT FROM AUTHOR]

Almond ( Prunnus dulcis Mill.) has been traditionally associated to marginal land cultivation and rain-fed agriculture in South Spain. However, in the last years, this crop is being progressively introduced in more productive agricultural areas within the Guadalquivir river basin, where the available water resources are not enough to satisfy the adequate crop-water requirements. Considering this limitation, a more precise irrigation scheduling to maximize the yield is required. Infrared thermal imaging emerges as alternative to other traditional methodologies to assess the crop-water status, especially when deficit irrigation (DI) strategies are being applied. The aim of this study was to define the methodology to assess the almond water status by means of thermal information. The trial was conducted during 2014, during the kernel-filling period, in an almond experimental orchard (SW Spain), with 5-year-old trees, subjected to three irrigation regimes: i) a full-irrigation treatment (C-100), which received 100% of ET C ; ii) a regulated deficit irrigation (RDI-50), which received 100% of ET C except during the kernel filling period, when this treatment was irrigated with 50% of ET C ; iii) and a low-frequency deficit irrigation treatment (LFDI), which received 100% of ET C except during the kernel filling period, when it was subjected to continuous periods of irrigation-restriction, defined in terms of the threshold values of shaded leaf water potential ( Ψ leaf ). Three daily curves of canopy temperature ( T C ), stomatal conductance to water vapour ( g s ) and Ψ leaf with measurements at 8:00, 11:00, 14:00, 17:00 and 20:00 were developed. Additionally, Crop Water Stress Index ( CWSI ), temperature difference between canopy and the surrounding air (Δ T canopy-air ), and the relative index to stomatal conductance ( I G ) obtained at different scales (canopy and row) were estimated. Significant correlations of infrared thermal information vs. Ψ leaf and g s were obtained (p ≤ 0.05 and p ≤ 0.01), in particular, by using the thermal readings taken at 11:30, 14:30 at 17:30 h, especially robust were the relationships obtained between T C and CWSI with Ψ leaf at 11:30 h; and between T C and CWSI with g s , and Ψ leaf at 14:30 h. Finally, considering the infrared thermal monitoring procedure (readings at tree and row level), similar values of T C were obtained, and therefore, the images taken at row level offered a better information with a higher feasibility in terms of image processing. [ABSTRACT FROM AUTHOR]

European red mite (ERM), Panonychus ulmi (Koch) is a major pest of fruit crops (apple and almond) in Kashmir Valley, India. Investigations were carried out at ICAR-Central Institute of Temperate Horticulture, Srinagar, Jammuand Kashmir to study the population dynamics, biology and efficacy of acaricides against P. ulmi on almond and apple. In both the crops highest population (31.56 and 6.46 mites/leaf), respectively, was observed in the 29th standard week (SW) and significantly correlated with the temperature. Biology of ERM was also studied on almond: eggs hatched in 6.50 ± 0.29 days; larval development took 2.00 ± 0.00 days; protonymphal and deutonymphal stages lasted for 1.75±0.25 days each. Longevity of adult males and females was 4.25 ± 0.25 and 8.25 ± 0.48 days, respectively. The efficacies of some of the acaricides were evaluated against ERM on almond. Among these, fenazaquin 10 EC (0.004 %) was found to be excellent with 94.92 % mortality of ERM on almond. [ABSTRACT FROM AUTHOR]

The present study estimated almond nut weight using flower, nut and kernel characteristics of almond’s cultivars and genotypes by multivariate analysis. The nut traits had heritability from 20.73 to 80.60%, while the kernel traits heritability ranged from 35.16 to 88.23%. Although the nut related traits influenced the nut weight significantly, but kernel weight had the most standardized beta (0.712). The most important variables which affect nut weight, were kernel weight, kernel thickness, kernel length and the nut width respectively. Nut weight estimation using kernel characteristics had the most R2 (0.993). [ABSTRACT FROM AUTHOR]

Pierce's disease of grapevine and almond leaf scorch disease are both caused by the bacterial pathogen Xylella fastidiosa Wells et al. In the Central Valley of California, Draeculacephala minerva Ball (Hemiptera: Cicadellidae) is the most common vector of X. fastidiosa. As alfalfa fields and pastures are considered source habitats for D. minerva, it is recommended that almond orchards and vineyards should be distanced from alfalfa and pastures. Here, risk of alfalfa and pastures serving as sources of D. minerva was compared to the potential benefit of alfalfa and pastures serving as sources of generalist natural enemies belonging to the families Chrysopidae and Coccinellidae. Populations of D. minerva were greatest in pastures, whereas chrysopids were least abundant in pastures, and coccinellids were only moderately more abundant in pastures than in vineyards or almond orchards. Accordingly, risk of pastures serving as a source of D. minerva was not offset by any potential benefit of pastures serving as a source of chrysopids or coccinellids. Abundance of D. minerva in alfalfa was low, whereas abundance of chrysopids and coccinellids in alfalfa was high. Thus, well-maintained alfalfa fields were a minor source of D. minerva that may contribute chrysopids and coccinellids to surrounding habitats. Spissistilus festinus (Say) (Hemiptera: Membracidae), a recently identified vector of grapevine red blotch virus, was abundant in alfalfa fields and was observed in vineyards. Thus, a full evaluation of the risk of planting vineyards near alfalfa may require considering risk associated with movement of S. festinus. [ABSTRACT FROM AUTHOR]

Pollination services provided by managed bees are essential for California almond (Prunus dulcis Mill.; Rosales: Rosaceae) production. Currently, pollination needs are met by rented or owned Apis mellifera L. (Hymenoptera: Apidae; honey bee) colonies. Excessive demand on a challenged A. mellifera industry to provide strong colonies in early spring has caused sharp increases in rental prices over the past decade, inviting the consideration of alternative pollinators in addition to, or in place of, A. mellifera. Osmia lignaria Say (Hymenoptera: Megachilidae; the blue orchard bee) is an excellent pollinator of fruit and nut trees, but its pollination impacts when used in tandem with A. mellifera have yet to be evaluated in commercial almond orchards. A 2-yr study was conducted in California orchards to compare almond pollination and production using A. mellifera as sole pollinator to an alternative practice of adding O. lignaria as a co-pollinator with A. mellifera. Almond orchard managerial decisions, such as for pesticide use and irrigation intensity, vary between almond growing regions because of local climates. Therefore, both north-central and southern sites of California's San Joaquin Valley are represented. We compared bee visitation, nut set, and nut yield between orchards and between tree rows within orchards. Also, O. lignaria reproductive success was recorded to assure that these bees remained in the orchards as pollinators and to assess the ability to sustain these bees under regional orchard conditions. We demonstrated that augmenting large commercial almond orchards with O. lignaria can significantly increase nut set and sometimes nut yield in both regions evaluated. [ABSTRACT FROM AUTHOR]

Water use and salinity dynamics in the soils are the crucial management factors influencing the productivity and long-term sustainability of almond and associated environment. In this study, HYDRUS-2D was calibrated and validated on measured spatial and temporal water contents and soil salinities ( EC e ) distributions under almond irrigated with different water qualities ( EC iw ) at different physiological stages. During two irrigation seasons (2014–15 and 2015–16), less saline irrigation water (average EC iw 0.78 dS/m) was substituted for recycled irrigation water (average EC iw 1.9 dS/m) in three phenologically different growth stages; pre-pit hardening, kernel growth, and post-harvest, along with no and full substitution during the entire season. Graphical and statistical comparisons (RMSE, MAE, ME, the Nash and Sutcliffe model efficiency, and the coefficient of determination) between measured and simulated values of water contents and EC e in the soil showed a close agreement in all treatments. The water balance data revealed that the seasonal crop evapotranspiration of almond ( ET c ) varied from 850 to 955 mm in different treatments over the two seasons which represented 68–79% of the water application. Trees irrigated with only less saline water through the two seasons (average EC iw 0.78 dS/m) showed 10% higher plant water uptake as compared to those irrigated with recycled water only (average EC iw 1.9 dS/m). Substituting less saline irrigation during the kernel growth phase, between pit-hardening and harvest, showed greater water uptake by almond and lower salinity buildup in the soil as compared to treatments that substituted less saline irrigation early or late in the season. For all treatments, the average daily root zone EC e (2.4–3.7 dS/m) remained above the level of the almond salinity tolerance threshold ( EC e  = 1.5 dS/m) throughout the period of investigation. Water use efficiency of almonds varied in a narrow range (0.21–0.25 kg m −3 ) for different treatments. Deep drainage below the root zone (2 m) varied from 22.4–31.1% of the total water application (Rainfall + Irrigation), which was episodic and insufficient to contain the salinity below the almond threshold. This study provided a greater understanding of soil water and salinity dynamics under almond irrigated with waters of varying qualities. [ABSTRACT FROM AUTHOR]

In almonds, and the genus prunus in general, there is little research directly relevant to improvement of zinc foliar uptake. In our lab, we have worked for several years to better understand Zn uptake, especially in almonds. This study highlights two experiments that together better elucidate this phenomenon. The first experiment included two field trials to study how Zn retranslocation from mature leaves is affected by fruiting in almonds. The second experiment was a targeted field validation of different zinc formulations, including nitrogen, in a commercially managed almond orchard for three growing seasons. Results indicate that the presence of almond fruit can increase Zn export from adjacent vegetative and woody tissue. It was also demonstrated that leaves from bearing spurs have lower Zn concentration than non-bearing spurs and that long-term Zn adequacy of bearing spurs required that applications of foliar Zn be repeated annually. [ABSTRACT FROM AUTHOR]

Irrigation optimization under limited water supply requires knowledge of the relation between consumptive use and production. The recent expansion of almond production is highly dependent on irrigation which may be limited by water scarcity in the future. A 3-year experiment was conducted in Cordoba, Spain, to determine the yield and water productivity (WP) responses of almond (cv. Guara) to irrigation deficits. Maximum yields of 2508.4 kg/ha (3-year average) were obtained when the crop evapotranspiration (ETC) was fully met. Three deficit irrigation treatments that supplied 66.9, 69.7 and 43.2% of the full irrigation requirements yielded 2147.5, 2038.2, and 1496.9 kg/ha, respectively. Assessment of the consumptive use (ETC) and its components, ES and T, yielded seasonal values of 1088, 887, 894 and 699 mm of ETC, of which T represented 831, 640, 648 and 479 mm, for the four different treatments, respectively. The relations between yield and irrigation, ETC, and T were used to determine the WP values as affected by water. Although values varied from year to year, the WPET averaged 0.23 kg/m3 for the 3 years and did not differ among treatments. The transpiration efficiency (WPT) had a value of 0.32 kg/m3 and was roughly the same for all treatments. [ABSTRACT FROM AUTHOR]

Many high-value tree crops are dependent on soil fumigation for control of plant-parasitic nematodes and diseases for successful orchard replanting. Due to detrimental impacts on the environment, fumigants are under stringent regulations. The study investigated if a commercially available totally impermeable film (TIF) such as VaporSafe ® and reduced fumigant rates can achieve emission reduction while providing good control of plant-parasitic nematodes and improving tree establishment. Two field trials were conducted in almond orchards on a sandy soil or a sandy loam to test the effects of Telone ® C-35 (containing 63% 1,3-dichloropropene and 35% chloropicrin) on fumigant movement, nematode survival, and tree performance. In the trials, Telone ® C-35 was applied at various rates: 100% (610 kg ha −1 ), 66%, or 33%; with three surface sealing methods: bare, standard polyethylene film (PE), and TIF. The TIF greatly reduced emissions compared to PE or bare soil with very low off-edge emissions. Both 100% and 66% rates of the fumigant promoted similar tree growth regardless of surface sealing methods. The 66% rate under TIF and PE also provided 100% control of resident nematodes as the 100% rate at or above 100 cm soil depth in both trials. Fumigation at the sandy soil site was able to reduce or eliminate the nematode population at the 120-150 cm soil depth. However, none of the treatments provided 100% control of nematodes at this depth in the sandy loam soil indicating the effects of soil texture on fumigation efficacy. Thus, TIF and reduced rates of Telone ® C-35 can be used to reduce the environmental impacts of soil fumigation and fumigant expenses. [ABSTRACT FROM AUTHOR]

Delineating geographic shifts in crop cultivation under future climate conditions provides information for land use and water management planning, and insights to meeting future demand. A suitability modeling approach was used to map the thermal niche of almond cultivation and phenological development across the Western United States (US) through the mid-21st century. The Central Valley of California remains thermally suitable for almond cultivation through the mid-21st century, and opportunities for expansion appear in the Willamette Valley of western Oregon, which is currently limited by insufficient heat accumulation. Modeled almond phenology shows a compression in reproductive development under future climate. By the mid-21st century, almond phenology in the Central Valley showed ~ 2-week delay in chill accumulation and ~ 1- and ~ 2.5-week advance in the timing of bloom and harvest, respectively. Although other climatic and non-climatic restrictions to almond cultivation may exist, these results highlight opportunities for shifts in the geography of high-value cropping systems, which may influence growers’ long-term land use decisions, and shape regional water and agricultural industry discussions regarding climate change adaptation options. [ABSTRACT FROM AUTHOR]

Native managed bees can improve crop pollination, but a general framework for evaluating the associated economic costs and benefits has not been developed. We conducted a cost-benefit analysis to assess how managing blue orchard bees (Osmia lignaria Say [Hymenoptera: Megachildae]) alongside honey bees (Apis mellifera Linnaeus [Hymenoptera: Apidae]) can affect profits for almond growers in California. Specifically, we studied how adjusting three strategies can influence profits: (1) number of released O. lignaria bees, (2) density of artificial nest boxes, and (3) number of nest cavities (tubes) per box. We developed an ecological model for the effects of pollinator activity on almond yields, validated the model with published data, and then estimated changes in profits for different management strategies. Our model shows that almond yields increase with O. lignaria foraging density, even where honey bees are already in use. Our cost-benefit analysis shows that profit ranged from -US$1,800 to US$2,800/ acre given different combinations of the three strategies. Adding nest boxes had the greatest effect; we predict an increase in profit between low and high nest box density strategies (2.5 and 10 boxes/acre). In fact, the number of released bees and the availability of nest tubes had relatively small effects in the high nest box density strategies. This suggests that growers could improve profits by simply adding more nest boxes with moderate number of tubes in each. Our approach can support grower decisions regarding integrated crop pollination and highlight the importance of a comprehensive ecological economic framework for assessing these decisions. [ABSTRACT FROM AUTHOR]

The degree of coupling to the environment of almond ( Prunus dulcis ) orchards during periods of transient water stress was investigated in a two-year study in California. Plant water status was monitored weekly, before and/or after irrigation, measuring midday stem water potential (Ψ stem ) that ranged from −0.5 to −2 MPa, while actual evapotranspiration (ET a ) was measured with an eddy covariance tower. Irrigation was applied weekly following common commercial practice, resulting in weekly cycles of Ψ stem . Despite Ψ stem reaching levels shown to induce substantial stomatal closure, the ratio actual to reference evapotranspiration (ET a /ET o = K a ) did not show a decrease during weekly periods of low Ψ stem in the two years of the study. Midday average canopy surface resistance (r cmid ), computed by reversing the Penman-Monteith equation from eddy covariance ET data, yielded a statistically significant increase with a decrease in Ψ stem , but just in the first year of the study. However, r cmid did not show a significant relationship with stomatal resistance measured at the leaf level with porometry and scaled-up to the canopy level. In the first year, r cmid showed a sharp increase after harvest, when K a also decreased, perhaps produced by the composite effect of defoliation associated with harvest and stomatal closure associated with water stress. During the growing season, r cmid ranged from 0 to 100 s m −1 and midday average aerodynamic resistance (r amid ) ranged between 0 and 50 s m −1 . Despite r cmid being generally larger than r a , the midday average decoupling factor (Ω) averaged 0.7 during the irrigation season, indicating decoupled conditions. However, there was a large day to day fluctuation of midday Ω ranging from 0.16 to 0.98 mostly associated with r cmid and wind speed. This study indicated that tall and rough canopies can be relatively decoupled depending on the effect of wind speed and canopy resistance on the decoupling factor. From a water management point of view, this result suggests that inducing transient mild to moderate water stress may not produce substantial water savings in areas having low to moderate winds. [ABSTRACT FROM AUTHOR]

• Estimate almond bloom density from aerial images using deep learning U-Net model. • High accuracy achieved: 81% precision, 65% recall, NRMSE < 1%. • Significant correlation between bloom density and crop load confirmed. • Valuable tool to determine in field variability for Nitrogen management. • Enables early in-season yield estimation for almond growers. Our study aims to measure bloom density in almond trees and, in turn, predict crop load at the tree level from aerial RGB images. Almond yield forecasting early in the season has become necessary in California due to the new legislation that requires growers to determine their nitrogen fertilizer rate based on soil tests and crop yield forecasts. Predicting almond yield by estimating crop load from bloom density would be the earliest in-season yield estimation. It would help growers with precision management, saving inputs, and complying with the nitrogen limit mandate. Drone flights were conducted during the almond bloom period for six orchards. An end-to-end deep learning architecture, U-Net, was used to segment and determine bloom density per tree. Our model was able to achieve high levels of accuracy, with precision and recall values of 81% and 65%, respectively, which means that the model was able to identify a significant proportion of the bloom pixels with high precision. We conducted a simple linear regression analysis to compare bloom density determined by manual hue-saturation-value (HSV) thresholding (as labels) to bloom density predicted by the U-Net, which resulted in a coefficient of determination (R2) of 0.78 and a normalized root mean square error (NRMSE) of<1 percent (0.69%). The results confirmed that the model is robust and independent from lighting and environmental conditions. End-of-season yield data at the row level were collected from an experimental almond orchard for three consecutive years and used as ground truth for verifying the association between the bloom density and crop load. Our tests revealed a significant positive Pearson's correlation coefficient (R = 0.65–0.9, p < 0.05) when comparing crop load and the estimated bloom density for Nonpareil cultivar every year, which growers could use to predict expected in-field yield variability in regard to bloom density. [ABSTRACT FROM AUTHOR]

Capturing the complementary strengths of observational and experimental research methods usually requires the researcher to gather separate experimental and observational data sets. In some cases, however, commercial agricultural practices produce the spatial and temporal mixing of ‘treatments’ independently of other possibly covarying factors that is normally achieved only with formal experimentation. The resulting ‘pseudoexperiments’ can provide strong evidence for causal relationships. Here, we analyze a large observational data set that creates a series of such pseudoexperiments to assess the effect of different commercial varieties of almond, Prunus dulcis (Mill.) on the impact of two key lepidopteran pests, the navel orangeworm Amyelois transitella (Walker) (Lepidoptera: Pyralidae), and the peach twig borer Anarsia lineatella Zeller (Lepidoptera: Gelechiidae). Almonds are universally planted as polycultures of different varieties to obtain efficient cross-pollination. We find substantial differences across almond varieties in the rates of infestation of almond hulls and nutmeats by the two pests. We find no support for the hypothesis that earlier-maturing varieties sustain higher attack; for A. transitella, later-maturing varieties instead had more frequent infestation. On many almond varieties, A. lineatella reaches high infestation levels by feeding almost exclusively on the hulls, rather than nutmeats. Given the importance of these pests in directly destroying almond nuts and in promoting aflatoxin-producing Aspergillus sp. fungal infections of almonds, further work exploring the impact of these pests is warranted. Because many crops requiring cross-pollination are planted as mixtures of different varieties, commercial agricultural production data hold great potential for studying within-crop variation in susceptibility to insect attack. [ABSTRACT FROM AUTHOR]

Almond production is not typical for Serbia however the existence of natural populations and unexpectedly suitable agro-climatic conditions initiated this kind of study. Total oil content and concentrations of the fatty acids, total phenolic content and radical-scavenging activity were determined in the kernel oil of 20 local almond selections originating from North Serbia and cultivars ‘Marcona’, ‘Texas’ and ‘Troito’. Sixteen fatty acids were identified and quantified, with the most abundant being oleic acid and linoleic acid. Nine phenolic acids and nineteen flavonoids were quantified using UHPLC-DAD MS/MS. The predominant polyphenol was catechin, followed by chlorogenic acid and naringenin. Based on oleic acid/linoleic acid ratio, levels of unsaturated fatty acids and specific polyphenols, some selections were chosen for growing and could also be recommended for breeding programs. Our investigation demonstrated that this region could be a suitable for growing almonds with chemical compositions competitive with standard cultivars. [ABSTRACT FROM AUTHOR]

Background: The almond tree (Prunus amygdalus Batsch) is an important nut tree grown in subtropical regions that produces nutrient-rich nuts. However, a paucity of genomic information and DNA markers has restricted the development of modern breeding technologies for almond trees. Results: In this study, almonds were sequenced with Illumina paired-end sequencing technology to obtain transcriptome data and develop simple sequence repeats (SSR) markers. We generated approximately 64 million clean reads from the various tissues of mixed almonds, and a total of 42,135 unigenes with an average length of 988 bp were obtained in the present study. A total of 27,586 unigenes (57.7% of all unigenes generated) were annotated using several databases. A total of 112,812 unigenes were annotated with the Gene Ontology (GO) database and assigned to 82 functional sub-groups, and 29,075 unigenes were assigned to the KOG database and classified into 25 function classifications. There were 9470 unigenes assigned to 129 Kyoto Encyclopaedia of Genes and Genomes (KEGG) pathways from five categories in the KEGG pathway database. We further identified 8641 SSR markers from 48,012 unigenes. A total of 100 SSR markers were randomly selected to validate quality, and 82 markers could amplify the specific products of A. communis L., whereas 70 markers were successfully transferable to five species (A. ledebouriana, A. mongolica, A. pedunculata, A. tangutica, and A. triloba). Conclusions: Our study was the first to produce public transcriptome data from almonds. The development of SSR markers will promote genetics research and breeding programmes for almonds. [ABSTRACT FROM AUTHOR]

The navel orangeworm, Amyelois transitella (Walker) (Lepidoptera: Pyralidae), is a key pest of almonds and pistachios and is sometimes controlled using mating disruption as part of a program of integrated management. The formulation used has a single, nonattractive compound [(11Z,13Z )-hexadecadienal] as the active ingredient that is emitted from timed aerosol dispensers. This study compared this nonattractive, single-compound formulation with two aerosol formulations also containing two additional compounds [(11Z,13Z)-hexadecadien-1-ol and (3Z,6Z,9Z,12Z,15Z)-tricosapentaene] that are found in the pheromone glands, and that in combination with the aldehyde are attractive in wind-tunnel and field-attraction trials. An experiment in pistachios found 97% to 99% suppression of males captured in female-baited traps and 82-93% suppression of mating in sentinel females. Both assays revealed a trend to greater suppression by the more complete pheromone formulations. In almonds, where the abundance of navel orangeworm was lower, all three formulations suppressed males captured in traps and mating in sentinel females by >99%. Each of the formulations significantly reduced damage to Nonpareil almonds. In almonds, there were no significant differences among the formulations in disruption of sexual communication or in damage. These findings suggest that it may be possible to make mating disruption more cost-effective and to achieve higher levels of mating disruption by using attractive aerosol formulations to reduce the number of dispenser per ha. Such a formulation, however, would be more expensive to register in the United States than pheromones meeting the definition of straight-chain lepidopteran pheromone, including the currently used aldehyde-only formulation. [ABSTRACT FROM AUTHOR]

The consumptive use of water by almond trees in California has become a controversial topic due to a worsening drought that began in 2011. The research reported herein was designed to provide information that could be used in irrigation decision-making including how to evaluate the risks/rewards of seeking/acquiring additional supplies in a drought. Ten irrigation levels ranging from 1000 to 1350 mm per season were applied in a mature southern San Joaquin Valley 'Nonpareil' almond orchard over a 5-year period. Nut load was invariant over the range of irrigation regimes with no evidence of any sustained negative impacts. Individual kernel weight was reduced commensurate with the level of deficit irrigation; the lowest irrigation resulted in a 15% lighter kernel. Maximum yield (3900 kg/ha) was achieved with 1250 mm of applied water. There was statistically significant tree stress in the 1250-mm application regime with midday shaded leaf water potential about 0.2 MPa more negative than trees receiving additional water. Maximum marginal water productivity (WP) was 0.30 kg/m at 1080 mm of applied water, falling to zero at 1290 mm. With almond prices of $8/kg, this is equivalent to water valued at $2/m. Estimated annual statewide almond orchard evapotranspiration based on this study is 1100-1350 mm which is about 25% higher than estimates made four decades ago. However, yields have increased in the 250% range since that time. This tenfold difference between yield and evapotranspiration means that WP is much higher now than in the past, and at current prices, it demonstrates that almond trees are suited for high water cost areas. [ABSTRACT FROM AUTHOR]

In vitro efficacy of ten fungicides was evaluated against four Botryosphaeriaceae spp. (Diplodia seria-ta, Neofusicoccum luteum, N. mediterraneum and N. pnrvum) associated with branch cankers on alrnond trees. Cy-proeonazole, pyraclostrobin, tebuconazole, and thiophanate-methyl were effective for the inhibition of mycelial growtla of most of tliese fungí. An experiment on 3-year-oId almond trees evaluated boscalid, mancozeb, tliiophan-ate-methyl, pyraclostrobin and tebuconazole for preventative ability against infections caused by tire four patlro-gens. Five montlrs after pruning and fungicide application, lesión length measurements and isolation percentages showed no significant differences among the four pathogens after tlrey were inoculated onto the trees, and also between tire two inoculation times tested (1 or 7d after fungicide application). Tlriophanate-nretlryl was tire most effective fungicide, resulting in the shortest lesion lengths aird the lowest isolation percentages from artificiallv inoculated pruning wounds. This Chemical is tlrerefore a candidate for inclusion in integrated disease nranage-ment, to protect pruning wounds from infections caused by species of Botryosphaeriaceae. This study represents the first approach to developnrent of Chemical control strategies for the managenreirt of canker diseases caused by Botryosphaeriaceae fungi on almond trees. [ABSTRACT FROM AUTHOR]

Almond tree yield is a function of the number of flowers on a tree and the percentage of flowers that set fruit. Almonds are borne on spurs (short proleptic shoots that can have both leaves and flowers). Almond tree spur dynamics research has documented that previous year spur leaf area is a predictive parameter for year-to-year spur survival, spur flowering and to a lesser extent spur fruiting, while previous year fruit bearing has a negative impact on subsequent year flowering. However, a question remained about whether yields are more dependent on flower numbers or relative fruit set of the flowers that are present. The aim of the present work was to compare the importance of flower abundance with that of relative fruit set in determining the productivity of a population of tagged spurs in almond trees over a 6-year period. Overall tree yield among years was more sensitive to total number of flowers on a tree rather than relative fruit set. These results emphasize the importance of maintaining large populations of healthy flowering spurs for sustained high production in almond orchards. [ABSTRACT FROM AUTHOR]

• Calendar of reproductive phenology in almond cultivars grown in Mediterranean. • Chilling and heat requirements of almond cultivars grown in Morocco. • Correlation of reproductive phenology with agro-climatic requirements. • 'Fournat de Brézenaud' and 'Marcona' should be grown in areas with low frost risks. • Chill decline could threaten production of high chilling cultivars. Agro-climatic requirements are of crucial importance for establishment and management of nut tree orchards. In this work, we investigated timing and duration of key reproductive phenology events and their chilling units (CU) and heat requirements namely growing degree-days (GDD) and degree-hours (GDH) in five Mediterranean almond cultivars of early ('Marcona'), intermediate ('Fournat de Brézenaud'), and late flowering time ('Ferraduel', 'Ferragnès', and 'Tuono'). Field phenological observations were performed during three growing seasons (2016–2018) across five contrasting sites in northern and eastern Morocco. Phenological records consisted of timing of initial inflorescence (Inf), inflorescence duration (Inf D), initial flowering (Ini F), full flowering (Ful F), final flowering (Fin F), flowering duration (FD), ripening (Rip), fruit development period (FDP). Our outcomes reveal that 'Marcona' and 'Fournat de Brézenaud' presented low CUs. 'Tuono', 'Ferraduel', and 'Ferragnès' required higher GDD and GDH to reach flowering time. Additionally, 'Marcona' had the highest FDP and GDD and GDH for ripening. Sites of northern Morocco exhibited a delayed timing of inflorescence and flowering and longer Inf D, FD, and FDP and high GDD and GDH for different phenological events. 2016 had low CU resulting in delayed timing of inflorescence and flowering but shortened Inf D and FD. Important correlations were outlined among phenological events and agro-climatic requirements. Principal component analysis explains data variation through first principal component (PC, genotypic), the second and the third PC discriminated sites and growing seasons, respectively (environmental components). In conclusions, owing to their early flowering and fruit set, 'Fournat de Brézenaud' and 'Marcona' should be grown in areas with low frost risks. 'Marcona' is not recommended for warmer environments because of its longer FDP. Chill decline induced by global warming may threaten production of high chilling requirement cultivars ('Ferraduel', 'Ferragnès', and 'Tuono'). [ABSTRACT FROM AUTHOR]

Almond plantations are expanding worldwide, specifically in Spain; the new orchards are often designed under more intensive systems in comparison to the traditional rainfed orchards frequently found in the Mediterranean Sea basin. In these new areas, water is the main limiting factor, and therefore, the present research is aimed at quantitatively analyzing previous findings obtained in irrigation field trials carried out in Spain with mature almond trees. The goal was to derive applied water-production functions and compare sustained and regulated deficit irrigation strategies to provide robust information on the marginal water productivity and the preferred irrigation option to be applied under water scarcity conditions. This quantitative analysis reported a yield increase as water application increased, with the highest potential yield of about 2500 kg/ha achieved with around 1000 mm of irrigation water applied. Under severe water restrictions, similar responses were observed regardless of the deficit irrigation technique employed. In contrast, under moderate water stress, it seems more advantageous to apply a regulated deficit irrigation strategy rather than a sustained deficit strategy. The reported results are useful for deriving more sustainable irrigation protocols and highlight the need to optimize other inputs in addition to water to take full advantage of the irrigation intensification to be carried out in the new almond plantations. • A meta-analysis of almond tree responses to deficit irrigation (sustained and regulated) was performed. • The marginal water productivity under conditions of water scarcity was analysed. • Yield reduction was mainly caused by water stress severity, and to a lesser extent by irrigation strategy. • The marginal water productivity decreased linearly with irrigation water applied. [ABSTRACT FROM AUTHOR]

In April-August 2018, samples of galled roots with rhizosphere soil were collected from almond orchards in Atwater, Merced County and Bakersfield, Kern County, California. Almond trees ( Prunus dulcis) grafted on 'Hansen 536' and 'Brights Hybrid®5' (peach-almond hybrid) rootstocks showed strong symptoms of growth decline. Extracted root-knot nematodes were identified by both morphological and molecular methods as M. floridensis. Meloidogyne floridensis was initially found in Florida, USA, and has not been reported from any other states and countries. This is a first report of M. floridensis in California and outside of Florida. [ABSTRACT FROM AUTHOR]