Current-season Shoots Research Articles

Determination of Maturity Indices for Harvesting of ber (Ziziphus mauritiana Lamk.)

Indian jujube or ber (Ziziphus mauritiana Lamk.) is an important hardy underutilised fruit crop of arid and semi-arid regions of India, symbolizing the production at a minimal cost. Ber fruits are potent source of nutritional as well as medicinal values and are generally consumed fresh. Ber fruits follow non-climacteric respiratory pattern. Fruits that are allowed to ripen on the tree typically have a limited shelf life and the ideal results are obtained if they are picked before the onset of ripening. Fruit harvesting at the appropriate stage of maturity is critical for both quality control and marketing. The time taken by ber fruit to mature from fruit set to maturity depends upon cultivar as well as location. Immature fruits lack desirable sweetness and flavour while over ripe fruits quickly lose their attractiveness and crispiness with slimy texture. Hence, an experiment was conducted to determine the optimum maturity indices for harvesting Indian jujube during 2019-20. Cultivar selected for this experiment was Narendra Ber Selection-2. The fruits on tagged current season shoots were harvested 21, 36, 51, 66, 81, 96, 111, 126, 141, 156, 171 and186 days after fruit setting. Fruit colour, shape, specific gravity, total soluble solids (%), T.S.S.: Acid ratio and organoleptic score of fruits were recorded at 15 days interval after fruit set. The results revealed that ber fruit of cultivar NBS-2 matures for harvesting between 171 to186 days after fruit setting i.e., between 29th February to 15th March when fruits attain yellowish to green colour, 0.95-0.92 specific gravity, ovate shape,17.29-17.94 T.S.S. and 123.72-128.37 T.S.S.: Acid ratio with organoleptic score of 7.5 to 8.0 range.

Apple Autotetraploids—Phenotypic Characterisation and Response to Drought Stress

Polyploidization is an important source of variability for plant breeding. Polyploids are often characterised by increased resistance to biotic and abiotic stresses. Since drought and pathogen attack are the main threats to apple cultivation, obtaining new sources of resistance is an important issue for apple breeding. The newly obtained autotetraploid clones of apple cv. ‘Redchief’ showed superior resistance to fire blight. The aim of the presented research was the in-depth phenotypic characterisation of ‘Redchief’ tetraploids and assessment of their response to drought at the physiological and genetic level. The growth of own-rooted five-year-old trees of ‘Redchief’ tetraploids was poor compared with diploids; all growth parameters—the number and length of current season shoots, the total length of current season shoots per tree and the cross-section area of the trunk—were reduced in tetraploid clones. Grafting on M9 rootstock improved the growth characteristics of ‘Redchief’ tetraploids. Compared with diploid plants, the leaves of tetraploids were thicker, with altered shape, higher chlorophyll content, and larger stomata, but the stomatal density decreased. The leaf anatomical structure of tetraploids was changed, the adaxial and abaxial epidermis and both types of mesophyll were significantly thicker than in diploids. Moreover, the pollen grains of tetraploids were larger, but their viability and germination were reduced. Under conditions of limited water supply, the reduction in growth parameters was smaller and the physiological parameters were higher in the ‘Redchief’ tetraploid clone 4x-25 than in diploid plants. The expression of APX gene was higher in tetraploids than in diploids 15 days after drought stress induction. The results suggest the enhanced drought tolerance of the studied ‘Redchief’ autotetraploid clone compared with its diploid counterpart.

Studies on changes in biochemical attributes during growth and development of ber (Zizyphus mauritiana Lamk.) fruit cv. (Narendra ber selection-2)

The Studies on changes in biochemical attributes during growth and development of ber (Zizyphus mauritiana Lamk.) fruit cv. (Narendra Ber Selection-2) was conducted during growing season of 2019-20. The fruits on tagged current season shoot were harvested at 21, 36, 51, 66, 81, 96, 111, 126, 141, 156, 171 and 186 days after fruit set. Samples were collected from Main Experiment Station, Horticulture and transported to the post graduate laboratory of Department of Fruit Science, College of Horticulture and Forestry, ANDUA&T, Kumarganj, Ayodhya, Uttar Pradesh. The objective was to probe the pattern of biochemical changes in developing ber fruits. The outcomes reveal that total soluble solids increased from 1.04% to 17.94% during 186 days of fruit growth and development whereas acidity content continuously decreased and recorded 0.39% on 21th day and 0.14% on 186th day of growth and development. Ascorbic acid content increased from 3.29 mg/100g to 90.26 mg /100g of fruit. Reducing, Non-reducing and total sugar content significantly increased from 0.22% to 4.76%, 0.11% to 5.77% and 0.35% to 10.87%, respectively. Moisture content showed decreasing trend and was maximum 71.12% on 21st day and minimum 65.79% on 186th day of observation. An abrupt decrease in chlorophyll content was recorded with growth and development of the fruit.

Effect of potassium and zinc on growth, physiological and yield attributes in sweet orange (Citrus sinensis Osbeck) cv. “mosambi” under high density planting

The present investigation was carried out to study the effect of potassium and zinc on Sweet orange (Citrus sinensis Osbeck) cv. “Mosambi” during the year 2018. Eight years old uniformly grown Mosambi Sweet orange plants, grafted on Karna Khatta rootstock and planted at a distance of 3.0 x 2.5m were used in this investigation. The investigation was carried out in high density planting area of Bihar Agricultural College, Sabour, Bhagalpur, under the Department of Fruit & Fruit Technology. Twelve different treatments of K and Zn in a simple randomized block design were used. Various treatments showed significant effect on physiological, vegetative and yield parameters. The maximum leaf area (23.53cm2), total chlorophyll content (3.04mg/g), leaf relative water content (75.82%), specific leaf weight (0.0164g/cm2) were observed in T12 (K2O @500g +Zinc sulphate @200 g) whereas minimum in T1(control). The maximum increase in current season shoot length (13.22cm), canopy spread (64.17cm), trunk girth (1.93cm) and plant height (36.67cm) were also recorded in T12 (500g K2O and 200g ZnSO4) whereas minimum in control. The maximum number of fruits per tree was counted (92.67) in T8.

Effects of Deficit Irrigation and Mulching on Morpho-physiological and Biochemical Characteristics of Konservolia Olives

The present study aimed at investigating the effect of deficit irrigation and mulching on morpho-physiological and biochemical characteristics of 15-year-old Konservolia olive trees in Dallaho Olive Research Station in Kermanshah province, Iran, in 2014 and 2015. The experiments were conducted in factorial randomized complete block design with three replications. The first factor included irrigation treatments (100% irrigation [control], 75% deficit irrigation, and 50% deficit irrigation) and the second one included mulches (polyethylene, organic [straw], and no mulch). The results clarified that there is a significant difference between deficit irrigation and mulch treatments due to their effects on the characteristics measured in this study. The highest current season shoot growth and diameter was observed in presence of 100% irrigation and straw and polyethylene mulches. Increasing water stress decreased relative water content and chlorophyll content, while using straw and polyethylene mulches increased them, compared with the mulch-free condition. Increasing water stress enhanced ionic leakage, proline content, soluble sugars, phenol content, and malondialdehyde, while using mulches reduced these characteristics. As a result, deficit irrigation can be performed without any damages to the trees if it is accompanied with straw and polyethylene mulches and this can save irrigation water in olive orchards.

Prognosis of the nutritional status of apple trees based on prebloom leaves and flowers

The utilization of prebloom tissues to predict nutrition of apple (Malus domestica Borkh.) trees is limited. Therefore, the aim of this study was to assess the possible use of mineral analyses of the prebloom spur leaves and flowers to forecast the nutrition of ‘Idared’ apple trees in the mid-summer (based on the leaves from current-season shoots). The prebloom leaf concentrations of phosphorus, potassium, magnesium, boron and manganese were positively correlated with those in the summer leaves. The significant relationships between nitrogen, calcium, boron, and manganese in the flowers and those in the mid-summer leaves were also found. However, only the relationship between boron in the prebloom spur leaves and in the summer leaves was sufficiently strong. The calculated optimal range of boron in the prebloom spur leaves was 20–25 mg kg−1.

Influence of Paclobutrazol on Shoot Growth and Flowering in a High-density Pecan Orchard

Paclobutrazol (PBZ) was applied to 6-year-old pecan (Carya illinoinensis) trees as a basal trunk drench (0, 30, 90, and 150 mg·cm−2 trunk cross-sectional area) in Dec. 2012. Terminal shoot growth was retarded for 1 year after a single application of PBZ. The total number of current season shoots showed a significant increase with 30- and 90-mg·cm−2 PBZ treatments. After PBZ application at 30, 60, and 90 mg·cm−2, the percentage of very short shoots (<5 cm) was 32.3%, 36.3%, and 32.3%, respectively, compared with 22.4% on control trees; the percentage of short shoots (5–15 cm) increased to 36.0%, 38.1%, and 43.5%, respectively. The percent of long shoots (>30 cm) was decreased to 7.4%, 5.1%, and 7.6%, respectively, after PBZ application, compared with 18.7% with control. Shoots varying from 5 to 30 cm in length accounted for at least 63.3% of all pistillate inflorescences the following spring.

Novel metrics to classify fire blight resistance of 94 apple cultivars

Fire blight (Erwinia amylovora), a potentially devastating disease in apple, can cause floral, fruit and structural damage and even tree death. Most commercial apple cultivars are susceptible and the resistance/susceptibility of many modern cultivars has not been evaluated. Fire blight resistance/susceptibility is difficult to phenotype due to quantitative resistance, impacts of tree vigour and environment on susceptibility, and the erratic nature of the disease. Resistance/susceptibility levels were determined for 94 apple cultivars and important breeding parents. In 2016 and 2017, multiple actively growing shoots per tree (about three trees per cultivar) were challenged withE. amylovoraEa153n via a cut‐leaf inoculation method. Proportion of current season's shoot length blighted (SLB) was calculated for each shoot. To classify cultivar responses, estimated marginalSLBmeans were compared to four controls, representing highly susceptible (HS) to highly resistant (HR), via Dunnett's tests. Cultivar responses ranged fromHStoHRwith estimated marginalSLBmeans of 0.001–0.995 in 2016 and 0.000–0.885 in 2017. Most cultivars demonstrated similar resistance/susceptibility levels in both years (ρ = 0.657,P < 0.0001). K‐means clustering was used to classify cultivars into three resistance/susceptibility groups based on incidence, average severity (SLB), and maximum severity values (maximumSLBand age of wood infected). Sixteen cultivars were consistently moderately resistant (MR) toHRwhile the remainder ranged fromHStoMR. An updated comparison of susceptibility of important cultivars is provided. Resistance/susceptibility information gained could be used to identify genetic loci associated with resistance/susceptibility and/or inform parental selection in apple scion breeding programmes.

Winter season crop regulation in Sardar guava

A field experiment was conducted on six year old guava cv. Sardar trees subjected to ten treatments, i.e., T1-Urea spray 10% fertilizer grade at 50% bloom stage and second spray after 10 days of first spray, T2-Urea spray 15% fertilizer grade at 50% bloom stage, T3-NAA @ 1000 ppm, T4-NAD @ 80 ppm, T5-Pruning of ¾ length of current season shoot, T6-Pruning at ½ length of current season shoot, T7-Bending of upright shoots, T8-Withheld irrigation with root exposure, T9-Withheld irrigation and T10-Control. The results showed that vegetative growth parameters (number of newly emerging shoots and leaf area index) were maximum under NAD @ 80 ppm whereas, yield (plant−1 and ha−1) was better under NAA at 1000 ppm. In terms of physicochemical parameters (fruit weight, TSS, ascorbic acid content), bending (T7) and pruning at ½ length of shoot (T6) showed its superiority. As far as economics is concerned, higher net return (Rs.1, 10, 561.9 ha−1) and B: C ratio (2.82: 1) were recorded in Urea 15% fertilizer grade single spray treatment (T2). Thus, T2 treatment was economically efficient for avoiding rainy season crop load and registered significantly higher fruit yield as well as satisfactory fruit quality attributes in winter season guava under southern Rajasthan conditions.

To cut or not to cut: the role of extension growth in fruit quality

Cherries are a sweet fruit, with total soluble solids being a key determinant of quality in most fruit quality studies. It is also well known that leaves play a role in delivering assimilates to fruit, and that fruits are strong sinks. Less well known is the role of extension growth (current season shoot growth) on fruit quality. Extension growth occurs throughout the fruit growing season and has the potential to be a strong source of assimilates. However, while growing they can also be a strong sink; hence the question; to cut or not to cut? Summer pruning can be useful to reduce vigour, or promote light interception but can it also be used to reduce competition for assimilates between growing fruit and extension growth? Trials assessing fruit quality from trees ('Kordia', L'Sweetheart' and 'Satonishiki') which had been pruned at various times throughout the growing season were undertaken. Timing had a significant impact on fruit quality with pruning after, but not at, Stage II increasing fruit sugars (TSS). Pruning at most stages had no impact on sugars in newly developing buds. Pruning during Stage III increased current season fruit sugars. Pruning did not affect the uniformity of bud burst or yield in the following season. Therefore, used appropriately, summer pruning of extension growth may be a useful tool in promoting sugar assimilation. Furthermore, pruning during rainfall in the three weeks prior to harvest maturity reduced fruit cracking, while pruning prior to rainfall in the same period did not impact on cracking. This implicates a role of extension growth leaves in the supply of excess water to the fruit reducing both yield and quality such that pruning could increase both yield and quality.

Floral morphology of Eleaegnus latifolia L.

Eleaegnus latifolia L. is one of the most important life sustaining underutilized fruit crops among the tribes of the eastern Himalaya region. The fruits have several uses and all parts of the fruits including seed are edible at all stages of fruit growth. Despite of great potential, little or no information is available on its flower characteristic, which is a pre-requisite for understanding the reproductive biology of the species. Five genotypes of Eaeagnus latifolia L. collected from different locations of Meghalaya were used to study its flowering and fruiting traits. Result revealed that inflorescence is a raceme, appears in clusters from the leaf axils, flowers are light yellow coloured, hermaphrodite, actinomorphic and gives strong aroma. Ovary is inferior surrounded by hypanthium. Significant variations were observed among the genotypes for all the flower characteristics such as dimension of ovary, stigmas and pollen length in the polar region. Maximum bud intensity was recorded in REC-3 (16.0) on current season shoot. Number of flower buds was higher in the current season shoots as compared to previous season. Regardless of genotypes, number of flowers was higher in the middle portion of the shoot. Total number of flowers per shoot was maximum in REC-4 (127.0). Flowering duration per inflorescence varied from 6.0 days (REC-1 and REC-2) to 8.67 days in REC-4. Initial fruit set was recorded maximum in REC-1 (37.95%) and minimum in REC-2 (14.15%).

Foliar iron sulphate-organic acids sprays improve the performance of oriental plane tree in calcareous soil better than soil treatments

Oriental plane tree (Platanus orientalis) is among the much-used elements of urban decoration in Iran. Many thousands-of-years-old plane trees are still viable in different cities. In recent years, because of the changes in management practices of urban areas, like widespread use of asphalt for streets pavement and use of concrete in water canals together with the polluted water and air, the growing condition is worsened causing a widespread occurrence of chlorosis symptoms. In this study, we assessed the effect of foliar sprays (3000ppm or 6000ppm humic acid, 4 or 8mM of malic acid, citric acid or l-glutamine and a control blank treatment) in comparison to soil treatments (a localized placement method in which a mixture of sulfur, FeSO4 and decomposed manure is placed under the topsoil and a standard sequestrene Fe 138 application), for improving the performance of plane trees. All the sprays contained 0.7% FeSO4 as Iron source. The leaf area, leaf SPAD value, leaf thickness and trichome presence on leaves, the color of the newly emerged leaf and the current season shoot growth were recorded. The concentration of key leaf elements were also determined. Glutamine treated plants showed elevated acquisition of boron, manganese, zinc and copper. In all treatments, the leaf chlorophyll index (SPAD) significantly increased compared to the control treatment. Glutamine, citric acid, and sequestrene treatments were superior in improving the color of the young leaves. Treatments containing glutamine and citric acid had more trichomes on the leaf surface compared to the control and the leaf necrosis index was reduced by all applied treatments. Sequential Equations Modeling (SEM) is used to examine the path of noted responses to applied treatments.

Response of NPK fertigation on pheno-physiological status of Citrus sinensis Osbeck cv. Mosambi under high density planting

The field experiment was conducted during 2013-14 to study the effects of fertigation on the phenology and physiological status of Citrus sinensis cv. Mosambi. The experiment was laid out in randomized block design with seven fertigation level, viz. T1- 120% of RDF; T2- 100% of RDF; T3- 80% of RDF; T4- 60% of RDF; T5- 40% of RDF; T6- Full dose in basal with drip irrigation and T7- Full dose in basal without drip irrigation and each treatment were replicated three times. Results obtained showed that increase in plant height (36.75 cm), trunk girth (4.67 cm), canopy volume (1.83 m3), leaf area index (5.51) and growth of current season shoot (9.42 cm2) of the plant were more responsive to higher dose of fertigation i.e. T1 followed by T2. The treatment effect was not marked on reproductive growth as expressed in terms of bud emergence, full bloom, fruit set and duration of bud emergence to maturity. The tree physiological parameters viz. total chlorophyll (2.65 mg/g), net photosynthesis rate (6.83 μmol CO2 /m2/sec), stomatal conductance (0.18 mol/m2/sec) and leaf area (31.9 cm2) were also higher under treatment receiving higher dose of fertigation i.e. T1. Therefore, on the basis of results obtained, treatment 120% RDF found superior in maintaining pheno-physiological status of mosambi plant under high density planting.

Distribution of 15N applied to the soil in the ‘Bing’/‘Gisela®6’ sweet cherry (Prunus avium L.) combination

Labeled nitrogen (N) was applied as ammonium nitrate (15NH415NO3; 10% atom) to 6-year-old sweet cherry (Prunus avium L.) trees of the combination ‘Bing’/‘Gisela®6’ (‘GI®6’) at three different developmental stages, which constituted the treatments (TR), in equal amounts of N (120kgha−1). TR included: TR1=accelerated shoot growth (30days after full bloom, DAFB, Year 1), TR2=early post-harvest (105 DAFB, Year 2) and TR3=late post-harvest (165 DAFB, Year 2). The fertilizer was applied to the soil surface in the root zone. The N content in the trees was determined after the destructive harvest of seven replicates per TR 40days after N application. Trees were divided into different organs (i.e., buds, fruits, current-season shoots, wood from the trunk and branches, fruiting spurs, non-fruiting spurs and roots (fine and thick)). The total 15N recovered (mg) from whole trees was higher 30 and 105 DAFB than the amount recovered 165 DAFB. Wood from the trunk and branches had the highest NDFF% values, which varied from 0.35% (165 DAFB) to 3.82% (30 DAFB). The nitrogen derived from fertilizer (NDFF%) values for fruits, current-season shoots and fine roots were also high. The highest N use efficiency (NUE%) was observed 30 DAFB (5.5%), and the lowest occurred 165 DAFB (2.1%). The phenological stage at the time of application to the soil influenced N uptake by the tree as well as the N distribution among its organs. The results demonstrate that the source-sink relationship at a particular phenological stage has an effect on the uptake, distribution and accumulation of N applied to the soil in the semi-vigorous combination ‘Bing’/‘GI®6’. Therefore, N supply to commercial sweet cherry orchards using ‘GI®6’ as rootstock should consider nutritional strategies that follow the phenology and the source-sink relationships predominant at a particular stage during the growing season. N applications after fruit harvest to increase storage reserves should consider the reduction in NUE% of whole trees towards fall. As example, N applications early after harvest should be focused in supporting flower bud development, while N applications late after harvest should promote N storage in woody structures and root.

Rendimiento de la pera europea ‘Shahmiveh’ injertada sobre diferentes portainjertos

Scion-rootstock selection plays an important role in determining orchard performance. Pyrus communis and Cydonia oblonga are the most widely cultivated rootstocks for European pear cultivars. The lack of rootstocks adapted to different edaphoclimatic conditions and scion cultivars is widely acknowledged in pear culture. Hence, this study was designed to investigate the growth characteristics and performance of the ‘Shahmiveh’ pear grafted onto six rootstocks including Quince A, B, C, BA29, ‘Konjoni’, and generative seedling. The experiment was conducted during two consecutive years, 20132014, at the Agricultural Research Center of Kabutarabad, Isfahan, Iran. The experimental design was based on a randomized complete block design including three replications of six trees each. The assessed variables were trunk diameter, current season shoot length, tree height, leaf dimensions, the number of flowers and abscised flowers, and also the number and percentage of fruit set. Cumulative data from a 7- to 8-year-old pear orchard showed that rootstock selection markedly influenced trunk diameters, current season shoot growth, leaf length, and fruit set of the endemic ‘Shahmiveh’ pear. The largest trunk diameters were obtained from the ‘Konjuni’ rootstock, whereas the highest current season shoot length was observed on the generative seedling. PQBA29 exhibited the largest leaf length, number of fruits per current season shoot, and percentage of fruit set, whereas Q. A rootstock had the second highest cropping efficiency. This experiment demonstrates the significantly higher performance and compatibility of PQBA29 as a rootstock for endemic ‘Shahmiveh’ pear in the arid condition of Iran.

Phenologic and growth responses to early and late season water deficits in Cabernet franc

Phenologic and ontogenic responses to seasonal water deficits were investigated in the wine grape variety, Cabernet franc, in a California hillside vineyard. Water deficits were imposed by withholding irrigation water before or after the onset of veraison. In continually irrigated vines, midday leaf water potential (Ψ) declined from - 0.4 MPa to approximately -1.1 MPa between budbreak and veraison despite weekly irrigation at a rate which was 2 x the normal production practice for that commercial vineyard. Hence, water deficits may be a common component of grape production in hillside vineyards of California. When water was withheld until veraison, midday Ψ declined more rapidly and reached - 1.4 MPa at the time water was resupplied. For these vines, water status slowly recovered to the level of the continually irrigated vines. The water status of late deficit vines, (water withheld after veraison), decreased rapidly after veraison, reaching a minimum of - 1.6 MPa at harvest. These differences in vine water status had no effect on the major phenological indicators, i. e„ the timing (on basis of time or accumulation of degree days) of bloom, veraison, and harvest. However, early season deficits shortened the period of shoot elongation and node production, decreased the maximum rate of shoot elongation and node production, and accelerated periderm development on current season shoots. Possible ecological implications of accelerated periderm development are discussed. Shoot length and the number of nodes/shoot was reduced approximately 25 % by the early season water deficits. Radial shoot growth was also inhibited by early deficits but much less than axial shoot growth. Shoot growth had essentially ceased in all vines before late season deficits developed. The characteristic double-sigmoid growth pattern of berries was observed regardless of seasonal water deficits. Most fruit growth occurred during the first growth phase in all treatments. The rate of fruit growth was inhibited by early and late season water deficits. Yield was decreased more by early deficits than by late deficits.

Patch Budding Pecan: Girdling, Tipping, Age, and Size of Budwood and Rootstock for Budding; Girdling, 2,3,5-Triodobenzoic Acid and 6-Benzylaminopurine for Bud Forcing

Patch budding is a common propagation technique for pecan (Carya illinoinensis) commonly used in the central and western United States, but seldom used in the southeastern United States. Success rates vary, but 75% is normally an acceptable survival rate. Selected budwood and rootstock treatments were evaluated to improve budding success. Additional studies were conducted to evaluate bud forcing techniques that would leave the rootstock intact, allowing a second bud to be inserted if the first patch bud failed. Girdling exceptionally vigorous shoots at the base used for budwood improved success, but neither tip pruning shoots used for budwood or rootstock affected patch bud survival. Patch budding was more successful using budwood from 1-year-old branches than from current season shoots, a finding that greatly extends the window available for propagation using patch buds. The age of rootstock wood at the budding site did not affect patch bud survival. Girdling the rootstock immediately above the dormant patch bud was less effective than top removal for forcing the patch bud in the spring. Application of a lanolin paste of 0% to 5% 2,3,5-triodobenzoic acid (TIBA) or 0.02% 6-benzylaminopurine (BAP) to a girdle immediately above the patch bud was positively related to the percentage of patch buds forcing when tree tops were left intact. The combination of girdling, 5% TIBA, and 0.02% BAP resulted in 76% of the buds forcing compared with 73% forced using top removal. This approach damages trees less and enables a second chance for patch budding on a stronger tree.

First Report of Boxwood Blight Caused by Calonectria pseudonaviculata in Delaware, Maryland, New Jersey, and New York.

Boxwood (Buxus spp.) are commercially important evergreen ornamental plants with an annual market value of over $103 million in the United States. The recent U.S. incursion of boxwood blight disease caused by the fungus Calonectria pseudonaviculata (syn. Cylindrocladium pseudonaviculatum, Cy. buxicola) threatens the health and productivity of boxwood in both landscape plantings and nurseries. The first confirmed U.S. reports of the disease were made from Connecticut and North Carolina in November 2011 (2,4), followed by diagnoses in 10 additional states during 2012 and 2013. By August 2013, symptoms consistent with boxwood blight had been observed from B. sempervirens in Delaware, Maryland, New Jersey, and southeastern New York. Affected plants showed rapid onset of disease symptoms: dark brown to black spots or diffuse dark areas on leaves, followed by defoliation. Narrow, elongate black cankers also formed on current season shoots. Symptomatic stems and leaves were placed in petri dishes with moistened filter paper at 22°C for 3 days under continuous light. Conidiophores were excised, then placed on potato dextrose agar amended with streptomycin and neomycin (0.3 g/l). Resultant colonies showed dark brown pigmentation at the colony center surrounded by tan to reddish brown rings with white mycelia at the advancing edge. Conidia (n = 30 per isolate) were hyaline, cylindrical, rounded at both ends, with a single septum (45 to 76 × 4 to 6 μm; avg. 63 × 5 μm). Conidiophores (n = 20 per isolate) comprised a stipe, a hyaline septate stipe extension (length 119 to 192 μm; avg. 150 μm) and a terminal ellipsoidal vesicle (diameter 4 to 10 μm; avg. 7 μm). Based on morphological characteristics, the causal agent was identified as C. pseudonaviculata (1,4). Voucher specimens were deposited in the U.S. National Fungus Collections (BPI 892698 to 701). To verify morphological diagnosis, genomic DNA was extracted from fungal biomass grown in liquid cultures of yeast extract peptone dextrose media. A portion of the β-tubulin gene (TUB2) was PCR amplified and sequenced bi-directionally using primers Bta/Bt2b (3). BLASTn searches of NCBI GenBank databases using the TUB2 sequences (Accession Nos. KF785808 to 11) demonstrated 96 to 100% sequence identity with other C. pseudonaviculata isolates. To confirm pathogenicity, 5-month-old B. sempervirens and B. microphylla seedlings were spray-inoculated with a spore suspension of 1 × 104 conidia/ml. One isolate from each state was independently tested with four replicates each. Non-inoculated water-sprayed plants served as negative controls. Plants were maintained in growth chambers at 22°C under constant light. Blight symptoms developed 4 to 5 days post inoculation. C. pseudonaviculata was re-isolated from inoculated plants; no symptoms or signs were observed from control plants. To our knowledge, this is the first report of C. pseudonaviculata in the states of Delaware, Maryland, New Jersey, and New York. This report demonstrates that C. pseudonaviculata is now widespread across the United States eastern seaboard, and represents a substantial threat to boxwood plants in North American landscapes and nurseries.

Effects of gamma irradiation times on some flowering characteristics and pest resistances in two almond (Prunus amygdalus L.) cultivars

This study was conducted to evaluate the effects of different gamma-radiation exposition times on some biological traits of two late-blooming almond cultivars of “A200” and “Sahand”. Current season shoots of “A200” and “Sahand” were exposed to 36 μC gamma-radiation for 0, 5, 10, 30 and 150 minutes. The experiment was carried out on 4-years old trees based on completely randomized design. Analysis of variance showed that buds break date, bearing type, leaf area, resistance to aphid and mite as well as Polystigma were significantly influenced by different gamma irradiation times (p < 0.05). There were significant differences between two cultivars for bearing type, leaf area, and resistance to pests (p < 0.05). 30 minute gamma irradiation was increased buds break date and in this treatment, mutated trees had very late bud break date and they were late flowering habit. Gamma irradiation treatments were changed bearing type. The highest leaf area was achieved on 150 minute gamma irradiation. Short and long time treatments had not efficiency on improving resistance to Polystigma. The highest resistance to aphid and mite were observed on 150 minute gamma irradiation. Two studied cultivars were relatively resistance to aphid (control), but mutated trees had tended to resistance to aphid. Mutated trees had medium to relatively resistance to mite. Therefore, gamma irradiation treatments can be improved high considerable resistance to mite.

Pruning effects on vegetative growth and fruit quality of 'Bing'/'Gisela®5' and 'Bing'/'Gisela®6' sweet cherry trees (Prunus avium)

Abstract M. Villasante, S. Godoy, J.P. Zoffoli, and M. Ayala. 2012. Pruning effects on growth and fruit quality of ‘Bing’/‘Gisela®5’ and ‘Bing’/‘Gisela®6’ sweet cherry trees ( Prunus avium ). Cien. Inv. Agr. 39(1): 117-126. Annual pruning is one of the most efficient ways to regulate crop load and renew fruiting wood in highly productive sweet cherry ( Prunus avium L.) combinations. Although Chilean growers did not previously prune cherry trees of more vigorous combinations, in recent years, the adoption of more dwarfing rootstocks and self-fertile cultivars has led to the inclusion of annual pruning as a practice in modern orchards. At first, this alteration in orchard management practices was not considered by growers, and thus, many of the initially established cherry orchards were not pruned as intensively as they should have been. As a consequence, many trees showed a reduction in fruit quality after 4 or 5 years of being planted, as they became overcropped and, consequently, registered reductions in their vegetative growth. There are only a few studies related to the effect of corrective pruning on dwarfing combinations that display an imbalance between reproductive and vegetative growth due to a reduction in the leaf area to fruit ratio of the tree. For this reason, the objective of this research was to study the effect of pruning in an orchard consisting of the dwarfing combinations ‘Bing’/‘Gisela®5’ (‘Bing’/‘GI®5’) and ‘Bing’/‘Gisela®6’ (‘Bing’/‘GI®6’), which shown a reduction in vigor, fruit quality and yield. Trees of both combinations were treated with a medium intensity pruning in late winter (early September). Several vegetative (shoot length, leaf area of spurs and shoots, trunk cross sectional area) and reproductive (total yield per tree, fruit growth and quality) parameters were evaluated after pruning. One of the most important effects of pruning for both combinations was an increase in the total current season shoot (CSS) growth, which was 112.5 and 125.6% for ‘Bing’/‘GI®5’ and ‘Bing’/‘GI®6’, respectively. Additionally, the average shoot length increased by 820.0 and 325.4% for ‘Bing’/‘GI®5’ and ‘Bing’/‘GI®6’, respectively. Furthermore, CSSs developed a higher leaf number in the pruned trees. There was no change in leaf number for reproductive spurs, but these had bigger leaves in the pruned trees, demonstrating increased total leaf area per spur. Additionally, pruning allowed crop load regulation and increased fruit size by 8.5 and 6.1% for ‘Bing’/‘GI®5’ and ‘Bing’/‘GI®6’, respectively. However, fruits from pruned trees showed a higher susceptibility to mechanical damage compared with unpruned trees of both combinations.