A survey of cherry leaf roll virus in intensively managed grafted english (Persian) walnut trees in Italy

Blackline disease, caused by Cherry leaf roll virus (CLRV), is considered a serious threat limiting English walnut (Juglans regia) production in Italy and the EU if walnut species other than J. regia e.g. \u2018Paradox\u2019 hybrid (J. regia 7 J. hindsii), French hybrid (J. regia 7 J. major or J. regia 7 J. nigra) or northern California black walnut (J. hindsii) are used as the rootstock. The virus transmissibility by pollen as well as latent infections can result in the spread of CLRVcontaminated propagative material, which is a major means of the virus dispersal by human activities. In 2014 and 2015 to ascertain the presence and the distribution of blackline symptoms in commercial orchards and to provide a description of the symptomatology, visual inspections and double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) analyses were carried out on 1,684 walnut trees in four different intensively managed grafted English walnut orchards in northeast Italy (Veneto Region). Trees with clear blackline symptoms at the scion-rootstock junction, often associated with general decline of the plant, were found only in one commercial orchard in northeast Italy on trees older than ten years of cvs. \u2018Tulare\u2019 and \u2018Chandler\u2019, grafted onto \u2018Paradox\u2019 rootstock. To our knowledge this is the first report of CLRV (blackline) decline and death in a commercial walnut orchard in Italy

\u3ci\u3eAcrobasis\u3c/i\u3e Shoot Moth (Lepidoptera: Pyralidae) Infestation-Tree Height Link in a Young Black Walnut Plantation

Acrobasis shoot moth infestations were evaluated in a young black walnut progeny test for 4 years, from ages 3 to 6. Infestation levels were greatest on the largest trees in the fourth and fifth year after plantation establishment, and were declining by the sixth year. Acrobasis infestation appears to be a problem primarily on young trees less than 2.5 m in height. There was no evidence for genetic resistance to Acrobasis infestation in black walnut

Detection of Cherry Leaf Roll Virus in intensively managed grafted English (Persian) walnut trees in Italy

Blackline disease, caused by Cherry leaf roll virus (CLRV), is considered a serious threat limiting English walnut (Juglans regia L.) production in Italy and the EU if walnut species other than J. regia are used as rootstock. In spring 2014, canopy decline or death of several walnut trees associated with presence of a necrotic strip at the rootstock-scion junction was observed on plants grafted onto \u2018Paradox' (J. hindsii 7 J. regia) in a commercial orchard located in the Veneto region (north-eastern Italy). To ascertain the presence of CLRV in this orchard and in other walnut intensively managed orchards located in the same region, a monitoring was carried out in 2014- 2015

Oviposition and Development of Emerald Ash Borer \u3ci\u3e(Agrilus Planipennis)\u3c/i\u3e (Coleoptera: Buprestidae) on Hosts and Potential Hosts in No-Choice Bioassays

Emerald ash borer (Agrilus planipennis Fairmaire) (Coleoptera: Bupres- tidae) is an invasive phloem-feeding pest native to Asia. It was first identified in North America in 2002 and has killed millions of ash (Fraxinus spp.) trees in southeast Michigan and Essex County, Ontario. Since then, additional populations have been discovered across Michigan and in areas of Ohio, Indiana, Illinois, Maryland, Pennsylvania and West Virginia. In Asia, A. planipennis reportedly colonizes other genera, including species of Juglans, Pterocarya and Ulmus. In North America, attacks on non-ash species have not been observed but there is concern about host switching as ash mortality progresses. From 2003 to 2005, we evaluated A. planipennis oviposition and larval development on 4 North American ash species: green ash (F. pennsylvanica Marshall), white ash (F. americana L.), black ash (F. nigra Marshall), blue ash (F. quadrangulata Michaux), and 6 potential alternate hosts including privet (Ligustrum and Forestiera spp.), Japanese tree lilac (Syringa reticulate (Blumb) Hara), American elm (Ulmus americana L.), black walnut (Juglans nigra L.), hickory (Carya ovata (Miller) K. Koch) and hackberry (Celtis occidentalis L.). In no- choice tests using cut branches in cages, female A. planipennis oviposited on all species tested. Larvae on green ash, white ash, black ash, blue ash and privet developed to the second instar before branches desiccated. Larvae attempted to feed on some black walnut, Japanese tree lilac, American elm and hackberry branches but died as first instars. There were no feeding attempts on hickory branches. We also conducted no-choice tests by placing adult A. planipennis in cages that encircled the lower 1 m of the trunk of live green ash, white ash, black walnut and Japanese tree lilac nursery trees. High densities of larvae developed on green ash and white ash nursery trees but there was no evidence of any larval survival, feeding, or development on the Japanese tree lilac or black walnut nursery trees

Differential Black Walnut Growth on a Recommended Soil Map Unit: Investigation of Related Soil Chemical and Physical Properties

Black walnut (Juglans nigra L.) is one of the best known and most valuable trees in Kentucky. However, due to its high value, the species has been aggressively harvested from natural stands, creating a limited supply of quality black walnut trees. Many landowners recognize this as an investment opportunity and have placed small tracts of unused land into black walnut production

The walnut plantations (Juglans spp.) in Italy and Spain: main factors affecting growth

Walnut tree species (Juglans spp.) are commonly used for high-quality wood production in plantation forestry. In this paper, the most relevant walnut plantations in Italy and Spain have been reviewed and analysed under a geographic and technician management point of view. Between 2016 and 2019 a total of 96 plantations (15 - 25 years old) were visited distributed in the North-western part of the Mediterranean basin. A statistical analysis (linear model no interaction and PCA) was then performed to evaluate the relative importance of some environmental and management variables for walnut trees in analysed plantations. Results highlighted a variable situation with many different adopted planting schemes across the regions as well as a not standardised spatial layout and management type (thinning). Lower densities and smaller trees were adopted in Italy with about 200 trees ha-1 versus 330 trees ha-1 in Spain. In addition to the age of the plantation as one of the most influencing parameters also the plantation density and the average crown diameter were highly statistically significant. Overall, the interesting potentiality of walnut for timber production with active management in suitable areas was detected as the focal point for a successful timber production from walnut trees

Characterization and selection of thin-shelled walnut (Juglans regia L.) genotypes of Mustang, Nepal

Walnut (Juglans regia L.) of seedling origin creates large variability within this crop. A research study was carried out at Directorate of Agricultural Research, Lumle, Kaski and Marpha, Mustang to characterize and deciphers the variability of thin-shelled walnut for further selection, conservation and variety registration. Walnut orchard of Mustang district was surveyed in March, 2018 and 50 walnut trees were labeled according to its flowering and flushing time. 36 accessions of thin-shelled walnut were characterized on 17 different parameters regarding growth habit, bearing habit, fruit and kernel characteristics. Around 88.89% trees exhibited terminal fruiting habit and remaining showed lateral fruiting habit. Three type of tree shape was noticed as spreading round, semi-erect and erect. Huge variation in nut shape was observed having 50% trees were with circular nuts. Four types of shell strength was recorded; 11.11% accessions having papery shell, 27.78% having weak shell, 47.22% having intermediate shell and 13.88 having strong shell strength. Average nut yield of trees ranged from 15-75 kg with an average of 26.67 kg. Nut weighted from 5.96-18.99 g with an average of 11.14 g.  Kernel weight ranged from 2.8-8.92 g. More than 50% shelling was recorded in 13 accessions. The kernel quality of 14 accessions (out of 36) showed 5 rank (Excellent quality); and remaining 22 accessions showed 4 rank (Good quality). Based on this characterization, 13 accessions were selected and recommended for further multiplication and variety registration

Tree Profile Equations for Black Walnut (Juglans nigra L.) and Green Ash (Fraxinus Pennsylvanica) in Mississippi

Black walnut (Juglans nigra L.) is a valued, Mississippi tree species with very little published mensurational data. Tree profile equations are effective tree volume predictors but are typically developed from measurements on destructively sampled trees, an impractical method on valuable species. This study developed black walnut and green ash (Fraxinus pennsylvanica) profile equations from non-destructive measurements using a Barr & Stroud FP15 optical dendrometer. Accuracy of the dendrometer was validated by taking both optical dendrometer and felled, direct measurements on green ash trees. Two profile models were evaluated for measured tree data. Separate equations were created from optical dendrometer tree profile data for black walnut and green ash and felled tree profile data for green ash. The Barr & Stroud allowed tree profile equations to be developed from standing tree measurements with acceptable accuracy, thus providing useful tools towards the valuation and management of southeastern black walnut and green ash

Relationship of Black Walnut Wood Color to Soil Properties and Site

This investigation is the first to provide information for any species on the magnitude of quantitative wood color differences between individual trees and between groups of trees at specified locations. It is also the first to report on the effects of specific environmental factors on wood color. Larger differences were found between black walnut (Juglans nigra L.) trees in heartwood luminance (lightness) than in dominant wavelength (hue) or purity (percentage of principal hue). Indiana-grown walnut heartwood had higher luminance than Missouri-grown. The relationship of heartwood color to soil properties was greater than it was either to tree age or to diameter-growth rate (rings per inch)