Orchard Of Cv Research Articles

Population genetic diversity and structure of the pecan scab pathogen, Venturia effusa, on cv. Desirable and native seedlings, and the impact of marker number

AbstractScab (Venturia effusa) is the major cause of economic loss in pecan in the south‐eastern USA. We explored population genetic diversity and structure among orchards of cv. Desirable and native seedlings, and within‐orchard variability among trees of all cultivars sampled. We compared the ability of 30, 15 and 7 previously developed microsatellites to characterize the population genetic diversity and structure of V. effusa. Analyses of molecular variance (AMOVA) provided little evidence of structure dependent on cultivar, but there was some evidence of structure between orchards of a cultivar based on distance. Individual orchard AMOVA showed that three of 11 orchards had between‐tree population structure. Among six populations from cv. Desirable, a Mantel test showed that geographic distance was related to the pairwise genetic divergence (R2 = 0.84). Among 11 orchards of various cultivars there was little difference in diversity using 30, 15 or 7 markers, or population structure based on AMOVA. Some minor differences in population structure were seen based on discriminant analysis of principal components, or dendrograms. Thus, depending on the objectives, future studies may use as few as 15 or 7 markers without losing ability to discern population genetic diversity or structure. More populations exhibited linkage disequilibrium when using 15 or 30 markers compared to when using seven markers. Knowledge of population genetics of V. effusa in relation to host genotype is needed to understand pathogen population interactions and gene flow, knowledge that will help underpin future breeding efforts to develop durable resistance in this long‐lived orchard tree.

Response of Oil Production and Quality to Hedgerow Design in Super-High-Density Olive cv. Arbequina Orchards

An analysis is presented of the response of olive oil production and quality parameters, viz. fatty acids (palmitic, oleic and linoleic acids), phenolic compounds and oxidative stability to hedgerow spacing and orientation in 1-m wide super-high-density orchards of cv. Arbequina. Data reveal strong linear relationships between concentrations of fatty acids and internal irradiance within hedgerows, positive for palmitic and linoleic but negative for oleic acid. The result is a significant vertical trend in oil composition within hedgerows, but small to negligible differences in oil harvested from them in totality. The explanation is found in the small ranges and strongly correlated responses of individual fatty acids that together comprise 98% of oil mass. Phenolic compounds respond more widely and to higher levels of irradiance than fatty acids and did show increases in NS hedgerows grown at wide row spacing. Oxidative stability shows a similar trend in phenolic compounds. A simulation study that extended the known responses to 2-m wide hedgerows showed that the linkage between fatty acid profiles was maintained with no resultant differences in the oil composition of the total simulated oil harvest. Based on the current understanding of internal irradiance within olive hedgerows, there seems to be little opportunity to manage oil quality by orchard structure.

Composition and removal of nutrients by the harvested fruit of avocado cv. Hass in Antioquia

En tres zonas productoras de Antioquia (El Retiro, El Peñol y Amagá), se seleccionaron tres huertos de aguacate cv Hass, con el fin de cuantificar la cantidad de nutrientes removidos por el fruto. Se usó un diseño completamente al azar con 12 repeticiones (árboles), para lo cual se colectaron 25 frutos/árbol, de donde se obtuvo el peso fresco y seco de la epidermis, la pulpa, la testa y la semilla. En cada estructura del fruto, se determinó la concentración de N, P, K, Ca, Mg, Fe, Cu, Mn, Zn y B y se calculó la remoción de cada uno de ellos. El tejido con mayor concentración de nutrientes fue la testa. El nutrimento con mayor concentración en los cuatro tejidos fue K seguido de N. La remoción total por el fruto fresco, en kg t-1, para K fue de 4; N 3,3; S 0,56; Mg 0,51; Ca 0,31; 0,48 P y en g t-1 para el Fe fue 0,45; B 0,2; Zn 0,11; Mn 0,01 y Cu 0,03.

Production and composition of oranges cv. Lane Late under maintenance potassium fertilization

This study aimed to assess the production and composition of oranges from cv. Lane Late trees submitted to maintenance potassium fertilization. The experiment was conducted in an orchard of cv. Lane Late at Rosário do Sul (RS). The orange trees were submitted to supplementation with 0, 50 or 100% of the recommended dose of K2 O in each crop season from 2008/2009 to 2011/2012. Fruit production, fruit diameter, peel thickness, juice volume and juice, leaf and soil K levels were assessed in the 2008/2009, 2010/2011 and 2011/2012 crop seasons. Fruit composition parameters were assessed in the 2010/2011 and 2011/2012 crop seasons. The application of increasing doses of potassium to cv. Lane Late orange trees for three crop seasons had no effect on fruit production. However, soil supplementation with potassium increased the total nutrient levels in the leaves and juice.

FIRST PRESUMPTIVE DIAGNOSIS OF XYLELLA FASTIDIOSA CAUSING OLIVE SCORCH IN ARGENTINA

In December 2013, in Aimogasta (La Rioja province) and Cruz del Eje (Cordoba province) olive trees older than 50 years of age were observed in six orchards of cv. Arauco, which showed symptoms recalling those induced by Xylella fastidiosa. Some branches displayed desiccated leaves at the top and basal leaves with apical scorching. Additional symptoms were slow decay, dull green coloration, curling and necrosis of the leaves, partial defoliation and rapid death of shoots and branches. Petiole and midrib samples from symptomatic trees reacted positively when ELISA-tested (Agdia, USA) for X. fastidiosa. Furthermore, PCR assays using primers targeting the conserved hypothetical HL protein (Francis et al., 2006) and the RNA polymerase sigma-factor 70 (rpoD) (Minsavage et al., 1994) amplified the expected products of 220 and 733 bp. Amplicons from the rpoD gene of three isolates were sequenced (nucleotide similarity 100%) and the sequences submitted to GenBank (KM206739, KM206740 and KM206741). BLASTN analysis indicated 100% identity with the rpoD gene from strain 9a5C (AE003849) from citrus and 97% with isolate OL-G (HG532022) from olive (Loconsole et al., 2014). In a phylogenetic tree constructed with rpoD gene sequences, the Argentinean olive isolates grouped with subspecies pauca. Our data match those from Italy, indicating that X. fastidiosa subsp. pauca is also involved in olive infections in Argentina. Isolation (Cariddi et al., 2014), pure culture and pathogenicity tests have to confirm our presumptive diagnosis and additional research is needed to elucidate the epidemiology of the disease and its potential vectors in our country.

Orchard Management for Decreasing Date Palm Bunch Fading Disorder

The date palm bunch fading disorder/disease is one of the greatest challenges faced by date palm growers. In the present study, the effect of appropriate orchard management on some qualitative and quantitative features of date palm bunch was studied. For this purpose, two orchards of cv ‘Kabkab’ with a history of previous incidence were selected in two districts of Bushehr province; Tangestan and Dashtestan. The orchards were divided into two parts; one as control and another as treated plants. On the treated part, some management practices such as plowing, leaf pruning, proper nutrition, regular irrigation, pollination, regulation of leaf-bunch ratio, thinning in pollination stage, control of weeds, pests and diseases were conducted scientifically while the control part was maintained with conventional local practices. During the treatment phase, all bunches in the Khalal stage were covered with a white cloth bag. The results from both treatment plots showed that proper orchard management can improve fruit yield (Dashtestan 52.2 kg tree-1, Tangestan 88.1 kg tree-1) and reduce the severity of symptoms and therefore reduce date palm bunch fading disorder.

Yield determination in olive hedgerow orchards. II. Analysis of radiation and fruiting profiles

Profiles of fruit density, fruit size, and oil content were measured on 12 occasions in 7 olive orchards in Spain and 2 in Australia. Orchard structure varied widely. Height ranged from 2.0 to 5.5 m, row spacing from 3 to 6 m, and canopy width from 0.7 to 3 m. Most orchards were oriented north–south (N–S) but one in Spain was oriented close to east–west (E–W) (20° NE–SW). All orchards in Spain were cv. Arbequina, and in Australia they were cvv. Barnea and Picual. Analyses with a model of interception and transmission that estimated interception by individual sides of hedgerows revealed that fruit size and oil content were strongly related to intercepted radiation during the month before harvest across all orchards. Relationships were also evident between fruit density and interception but varied among orchards and years, indicating the importance of other environmental and probably physiological effects. In N–S orchards of cv. Arbequina, average fruit size and oil content increased linearly from 0.40 g (dry weight) to 0.72 g, and from 36 to 49% (of dry weight), as daily intercepted PAR increased from 6 to 25 mol/m2 (15–60% of horizontally incident radiation). The general principles of response extended to E–W orchards. There, it was shown that generally large fruit with high oil content on S sides was consistent with the plateau responses to radiation evident in the more extensive N–S data. On the N side, however, and accounting for transmission through the hedgerow, both fruit size and oil content were greater than in positions intercepting equivalent radiation in N–S orchards. Examples are provided of the utility of responses of fruit density, size, and oil content in establishing combinations of row height, row width, and row distance to improve or maintain productivity in some of the orchards included in the study.

Population Diversity within Isolates of Colletotrichum spp. Causing Glomerella Leaf Spot and Bitter Rot of Apples in Three Orchards in North Carolina.

The population diversity within isolates of Glomerella cingulata and Colletotrichum spp. associated with Glomerella leaf spot and bitter rot of apples was studied in an orchard of cv. Granny Smith located in Wilkes County, NC, and one orchard each of cultivars Granny Smith and Gala located in Lincoln County, NC. Morphological characters and vegetative compatibility groups (VCGs) were used to determine diversity within the species. The relative frequencies of the morphological types found within each species in each orchard were also determined. G. cingulata was the predominant species associated with bitter rot in the three orchards and Glomerella leaf spot in the Gala orchard. In the three orchards, different morphological types were observed within isolates of G. cingulata and Colletotrichum acutatum, but not within isolates of Colletotrichum gloeosporioides. Isolates of C. gloeosporioides were not found in the orchard of cv. Granny Smith in Lincoln County. In the other two orchards, C. gloeosporioides represented the lowest proportion of the population. Three VCGs were found among isolates of G. cingulata (VCG-1, 2, and 6), two among isolates of C. gloeosporioides (VCG-9 and 10), and two among isolates of C. acutatum (VCG-15 and 16). VCGs 2, 6, 9, 10, 15, and 16 were found in the Granny Smith orchard in Wilkes County, VCGs 1, 2, and 6 in the Gala orchard in Lincoln County, and VCGs 2 and 6 in the Granny Smith orchard in Lincoln County. Differences in frequencies among the different morphological types found within the three orchards remained relatively similar throughout the season and from year to year, suggesting that the relative frequencies of G. cingulata, C. gloeosporioides, and C. acutatum remain stable in an orchard once the fungi are established.

Controle químico do oídio do mamoeiro

Realizaram-se três experimentos, em Linhares-ES, de controle do oídio (Ovulariopsis sp.) do mamoeiro (Carica papaya). A severidade da doença foi estimada usando escala de notas de 0 a 4. Em casa de vegetação, utilizaram-se mudas de 'Improved Sunrise Solo Line 72/12', em delineamento inteiramente casualizado com seis tratamentos e cinco repetições. Foram feitas três pulverizações de triflumizole (150, 225 e 300 mg.l-1 i.a.), enxofre (1560 mg.l-1 i.a.) e tiofanato metílico (700 mg.l-1 i.a) e quatro avaliações da severidade da doença a intervalos semanais. Em campo, realizaram-se dois experimentos com o 'Baixinho de Santa Amália', tendo delineamento em blocos casualizados e quatro repetições. Foram feitas cinco pulverizações, a intervalos bissemanais e cinco avaliações da severidade da doença, sendo uma previamente e as demais aos 21, 35, 49 e 63 dias após a primeira pulverização. Em casa de vegetação, todos os produtos reduziram a área abaixo da curva de progresso da doença (AACPD). Triflumizole foi mais eficiente, não tendo diferenças entre suas doses. No primeiro experimento de campo, enxofre (1560 mg.l-1 i.a.) e bicarbonato de sódio (2000 mg.l-1) foram os produtos mais eficientes na redução da AACPD, seguidos por triflumizole, que não apresentou diferenças entre as doses aplicadas (150, 225 e 300 mg.l-1 i.a.). Tiofanato metílico (700 mg.l-1 i.a.) não diferiu da testemunha. No segundo experimento, azoxystrobin (20 a 100 mg.l-1 i.a.) aplicado a cada 14 ou 28 dias, com ou sem adjuvante-molhante, e enxofre (1560 mg.l-1 i.a.) não reduziram a AACPD. Este trabalho mostrou a possibilidade de utilização de enxofre e de bicarbonato de sódio no controle do oídio do mamoeiro.

Studies on the epidemiology of peach rosette and decline disease in Victoria

The spread of peach rosette and decline dlsease (PRD) was studied in two clingstone peach orchards, located 24 km apart in the Goulburn Valley of Victoria. Over 11 years the incidence of diseased trees in an orchard of cv. Golden Queen increased from 0.9 to 91.5%, while in an orchard of cv. Pullar's Cling the proportion of diseased trees rose from 1.5 to 29.6% over 5 years. The apparent infection rates were identical in both orchards over the first 5 years of the two epidemics.In both orchards, a significantly higher proportion of healthy trees growing adjacent to previously diseased trees became infected in subsequent seasons. This pattern of spread of the disease is discussed in relation to pollen transmission of the viruses and the foraging habits of bees. The spread of PRD was reduced by 29.4% over 2 years by the grubbing of all visibly diseased trees before flowering in a planting of cv. Golden Queen. Removing the flowers from diseased trees at the 'pink bud' stage also reduced the rate of spread of the disease by 13.8% in 1 year. Removing newly diseased limbs at the crotch of the tree within 4 weeks of flowering, however, did not prevent the spread of the disease into the rest of the tree.