Pruning Tools Research Articles

Insight into the new infection pathway resulting from above-ground pathogen infection of grapevine crown gall.

Grapevine crown gall (GCG), a soil-borne plant disease caused by tumorigenic Allorhizobium vitis (TAV) (=tumorigenic Rhizobium vitis) strains, poses a significant threat to grapevines worldwide. Recently, outbreaks of GCG have been reported in several vineyards, necessitating investigation into potential alternative infection pathways beyond soil transmission. The spatiotemporal distribution of GCG in vineyards from 2020 to 2022 was analyzed using the binary power law (BPL) model, with variations in quadrat shapes. Both total and newly observed diseased plants exhibited an aggregated distribution, indicating that new infections clustered around existing diseased plants, with secondary infections appearing as independent cluster points. This study provides evidence that infected pruning tools can transmit the pathogen to healthy grapevines and that TAV inoculation through spraying contributes more to GCG incidence than planting in infected soil alone. This represents the first documented case of secondary above-ground TAV infection contributing to GCG in commercial vineyards.

Disinfection Methods of Pruning Scissor for Preventing Transmission of Fire Blight

Pathogens of fire blight can survive for a long time on pruning tools, etc., and fire blight can be spread through agricultural implements. In particular, in Korea, pruning is frequently performed to remove flowers, immature fruits, and succulent shoots, and this farm work is known to be a major factor of the spread of fire blight. Therefore, in this study, in order to completely sterilize pathogens on pruning shears, we verified the disinfection effect of disinfectants distributed domestically and used them to identify an effective disinfection method. When disinfecting by immersion after inoculating Erwinia amylovora TS3128 on the scissor blade, 70% ethanol and 1% and 0.2% sodium hypochlorite sterilized immediately 10 sec after immersion, while 30% chlorine dioxide showed little disinfection effect. When disinfecting by spraying, 70% ethanol sterilized bacteria 1 sec after spraying, but 1% and 0.2% sodium hypochlorite disinfected bacteria after 10 and 60 sec, respectively. After cutting the naturally disease occurring branches five and 100 times, the bacteria were not hardly sterilized in immersion treatment in 70% ethanol for 30 sec but perfectly disinfected over 60 sec. Considering these results, pruning shears should be disinfected by frequently immersing them in 70% ethanol for at least 60 sec during pruning work in the field.

Ergonomic Evaluation of Pruning in Simulated Greenhouse conditions

Greenhouse is a space-efficient structure for farming. The workers stretch their bodies to perform operations away from the body and at different heights. The present study aimed to assess the physiological and postural discomfort because of the varied working heights and horizontal distances and also attempts to suggest suitable interventions to overcome them. The current study investigated the physiological and subjective measures of exertion while working at different heights (elbow height, shoulder height and above shoulder height) and horizontal distances (30, 45, 60, and 75 cm) with two different pruning tools under simulated laboratory conditions. All the physiological parameters and responses against different conditions were recorded from six male participants and analyzed as per experimental requirements. The outcome of the present study demonstrated that physiological cost and subjective measure of exertion varied significantly with the variation in heights and horizontal distances. Heart rate, oxygen consumption, energy expenditure, and perceived exertion were significantly higher “above the shoulder height” than elbow and shoulder height. Similarly, all the measured physiological parameters and Rating of Perceived Exertion (RPE) exhibited a gradual increase with increasing the distance from the worker’s body. The study also revealed a differential effect of tools used while performing the pruning work. Further, the multiple regression analysis helped to predict Relative Cardiac Cost from RPE and other evaluated physiological parameters. Overall, findings from the current study concluded that conventional pruning activities need workspace optimization and ergonomic intervention to select pruning tools and achieve the desired productivity with minimum Musculoskeletal Disorders (MSDs).

Molecular characterization of divergent isolates of Citrus bent leaf viroid (CBLVd) from citrus cultivars of Punjab, Pakistan.

Citrus viroid infection is emerging as a serious threat because of its efficient systemic movement within the host plant and its quick spread due to contaminated pruning tools. A survey was conducted to investigate the primary distribution and molecular characterization of Citrus bent leaf viroid (CBLVd) and its variants in different citrus cultivars. A total of 154 symptomatic citrus samples were collected and detected by RT‒PCR with newly designed specific primers with the incidence of 36.33%. During biological indexing study on Etrog citron, expressions of reduced leaf size, yellowing with a light green pattern, and bending were observed. Amplified products were sequenced and analyzed using a nucleotide BLAST search, which showed 98% homology with other CBLVd isolates. The results of the phylogenetic tree analysis showed the presence of two main groups (A and B), with the predominant variants of CBLVd, i.e., CVd-I-LSS (Citrus viroid Low Sequence Similarity) sequences, clustering in subgroup A1 along with newly detected CVd-I-LSS from Palestinian sweet lime (Citrus limettioides), which has been identified as a new host of CVd-I-LSS in Pakistan. Further analysis of the sequences in subgroup A1 showed that the variant of CVd-I-LSS infecting citrus cultivars had a close relationship with isolates reported from China, Japan, and Iran, which may have resulted from the exchange of planting material. This study also unveiled the variability in nucleotide sequences of CBLVd, which made it unable to be detected by old primers. The results of this study indicate that the widespread presence of divergent variants of CBLVd is a major concern for the citrus industry in Pakistan and other countries where virulent isolates of CBLVd are prevalent. These findings suggest the need for future research on effective management and quarantine measures to stop the spread of CBLVd.

Transmission of Blood Disease in Banana.

Banana Blood disease is a bacterial wilt caused by Ralstonia syzygii subsp. celebesensis and is an economically important disease in Indonesia and Malaysia. Transmission of this pathogen is hypothesized to occur through insects mechanically transferring bacteria from diseased to healthy banana inflorescences and other pathways involving pruning tools, water movement, and root-to-root contact. This study demonstrates that the ooze from the infected male bell and the sap from various symptomatic plant parts are infective, and the cut surfaces of a bunch peduncle, petiole, corm, pseudostem, and the rachis act as infection courts for R. syzygii subsp. celebesensis. In addition, evidence is provided that R.syzygii subsp. celebesensis is highly tool transmissible, that the bacterium can be transferred from the roots of a diseased plant to the roots of a healthy plant and transferred from the mother plant to the sucker. We provide evidence that local dispersal of Blood disease occurs predominantly through mechanical transmission by insects, birds, bats, or human activities from diseased to healthy banana plants and that long-distance dispersal occurs through the movement of contaminated planting material. Disease management strategies to prevent crop losses associated with this emerging disease are discussed based on our findings.

Simulating Polyculture Farming to Learn Automation Policies for Plant Diversity and Precision Irrigation

Polyculture farming, where multiple crop species are grown simultaneously, has potential to reduce pesticide and water usage while improving the utilization of soil nutrients. However, it is much harder to automate polyculture than monoculture. To facilitate research, we present AlphaGardenSim, a fast, first order, open-access polyculture farming simulator with single plant growth and irrigation models tuned using real world measurements. AlphaGardenSim can be used for policy learning as it simulates inter-plant dynamics, including light and water competition between plants in close proximity and approximates growth in a real greenhouse garden at 25, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$000\times $ </tex-math></inline-formula> the speed of natural growth. This paper extends earlier work with a new action space that includes planting, which dynamically finds new seed locations that increases resources utilization, and an adaptive sampling technique to reduce the number of actions taken at each timestep without affecting performance. We also evaluate other automation policies using a novel metric that combines plant diversity and canopy coverage. Code and supplementary material can be found at <uri xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">https://github.com/BerkeleyAutomation/AlphaGarden</uri> . <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —Monoculture farming is often characterized by heavy agrichemical inputs, such as chemical fertilizers and pesticides, and increased vulnerability to disease and pestilence. This paper is motivated by the lack of long-term sustainability of industrial agriculture, and its implications for human food security. Although polyculture is a sustainable alternative to monoculture farming, it requires more human labor and is more challenging to automate. In this paper we propose a fast, first order simulator that simulates the growth of plants in a polyculture setting. Simulation experiments suggest that the simulator can be used to learn a planting, watering and pruning plan a robot can follow to produce maximal yield from a diverse set of plants with limited irrigation, however it has not yet been tested on a physical garden. In future research we will develop a fully automated controller that will operate planting, irrigation and pruning tools in a physical garden over multiple plant growth cycles.

Recent spread and potential pathways for fire blight in South Korea

AbstractIn 2020, 744 orchards in South Korea were reported to be infected by fire blight (Erwinia amylovora (Burrill) Winslow et al.). The Animal and Plant Quarantine Agency, South Korea, immediately conducted a surveillance study involving 350 orchards to determine the source of the outbreaks, and the extent of its spread and pathway(s). A delimiting survey and sampling surveys were carried out to gather and analyse data during 2020. The attempts to trace the source of the diseased plants revealed a possible pathway. Infected apple trees could have been transported to previously pest‐free regions such as Gwangju and Yangju of Gyeonggido via the purchase of infected materials, e.g. from a domestic nursery. Once established, the disease could readily spread by natural means such as insects and wind into flowers, shoots and growing tips on adjacent trees. This is the likely pathway for entry of fire blight in the new region. Contaminated pruning tools may be another pathway for long‐distance dispersal of this pathogen within South Korea based on data collected through this survey.

Ergonomic evaluation of hand tools used in grape pruning activities in vineyards

Grape farming is a labour-intensive operation, with pruning as one of the tasks performed with hand tools. Most of the tropical countries use locally made and commercially available hand pruning tools for grape pruning. Different pruning tools were selected for ergonomic evaluation and refinement was completed based on the physiological responses of the subjects. The comparison between the commercially available Economy tool (M2), Maharashtra tool (L1) and Karnataka tool (L2) model pruner shows that the model Economy tool (M2) gives better performance. Economy tool (M2) model is highly preferred by the grape farmers due to its high performance and more comfort than Maharashtra tool (L1) and Karnataka tool (L2) pruner. This is due to standard material, shape of the pruner slightly bent for easy handling. In Maharashtra (L1) and Karnataka pruning tool (L2) due to direct pressure or “contact stress” refers to on-going contact between a part of the body and a hard edge or surface which in cause the discomfort and pain. Similarly, pressure points of any type can interfere with production. The physiological responses were measured and compared between the ergo refined pruning tool (EM3) and other selected pruning tools. The results for the Ergo refined pruning tool (EM3) registered are 95.2 beats min-1 (Heart rate), 0.566 l min-1 (Oxygen consumption), 11.81 KJ min-1 (Energy expenditure), 30.31 and 20.8 percent of AWL and LCP which is lower values when compared to other selected pruning tools. It was also observed that cutting frequency and area coverage for selected pruning tool varies from 11 to 24 cuts/ min and 750 to 1350 m2/ h. Ergo refined pruning tool (EM3) registered 24 cuts/ min and 1350 m2/ h when compared with other pruning tools. A full hand loop was fitted below the lower handle to improve grip and uniformly apply force throughout the pruning operation, resulting in increased area coverage and frequency of cut.

Productivity and workload analysis between manual and motor-manual pruning of Pinus patula at two different lifts

ABSTRACT Tree pruning is integral to sawtimber production in South Africa, the main purpose being the production of knot-free wood and access for fire protection. Although handheld pruning tools have been used for decades, motor-manual tools have recently been introduced. However, knowledge of possible ergonomic risks and possible productivity associated with either pruning method is limited in the literature. Hence the objective of this study was to assess human workload associated with, and possible productivity gains of, motor-manual pruning against manual operations in 2.0 m and 3.5 m pruning lifts in Pinus patula stands. The study was completed in two stands in the KwaZulu-Natal Midlands of South Africa. Information collected included time study and heart rate data. Time study results showed that motor-manual operations were more productive than manual operations in both the 2.0 m and 3.5 m pruning lifts. Pruning operations fall under the “medium to heavy” workload classification. These results show promise as the first steps in investigating the effect of manual and motor-manual operations on productivity and workload of pruning operations in South Africa. However, it is recommended for this study to be repeated with gender, terrain conditions, temperature, and musculoskeletal efforts as additional factors to workload and productivity.

Design and Analysis of Spatial Skyline Queries Indexing

Dwelling in the information age permits nearly everybody needs to recover countless information and choices to gather from to fulfill their necessities. In distinctive cases, the quantity of information accessible and the speed of change may cover the ideal and required explanation. Spatial-textual queries provide the most acclaimed nearest points concerning a conveyed site and a keyword set. Current practice regularly thought on the most capable technique to expertly get the top-k resultset reestablished a spatial-scholarly query. A capable Spatial Range Skyline Query (SRSQ) algorithm is proposed which initially performsa spatial keyword query (SKQ) that relies upon an IRtree that documents the information. Skyline centers picked are not simply established on their partitions to a lot of inquiries and more subject to their significance to a social occasion of query keywords. Additionally, besides proposed range skyline (RS) methods based on R-tree multi-dimensional space including secondary- memory pruning tools for operating field skyline queries is accomplished. The advanced scheme is dynamic and I/O optimum. Ultimately, methodology presents a modern assessment that demonstrates the proficiency.

Risk assessment and reduction options for Ceratocystis platani in the EU

Following a request from the European Commission, the EFSA Plant Health (PLH) Panel performed a risk assessment for Ceratocystis platani in the EU with the aim to assess the effectiveness of risk reduction options (RROs) on the basis of the mechanisms of spread identified in the pest categorisation (natural and human-assisted means, including waterways, root anastomosis, contaminated pruning tools, machinery, insects, contaminated insect frass and sawdust). C. platani is a destructive pathogen of Platanus trees, which is currently present in the EU (in France, Greece and Italy). Three scenarios were considered: the current situation (A0 scenario); the situation without RROs (A1); and the application of additional RROs (A2). The risk of new introductions into the EU of C. platani by means of the main pathways of entry (i.e. plants for planting, wood and machinery, e.g. construction machinery and pruning/cutting tools) is relatively limited, but about 250 times higher for the A1 scenario compared to the A2 scenario (median numbers of established populations). The risk of spread from already affected EU regions is higher, but varies depending on the scenario. Machinery is the most important mechanism of long-distance spread. Focusing the additional RROs in A2 scenario on this mechanism of spread – which is not currently regulated – would be an effective way to reduce the likelihood of further spread and thus impacts of C. platani to not yet affected EU regions. The emergency measures applied by the C. platani-affected EU Member States (France, Greece and Italy) could be harmonised and improved. An enhanced programme could be developed which includes surveillance, early detection of the disease foci, effective eradication measures and planting resistant Platanus clones in new plantations in affected areas. Surveillance could also be intensified in the EU MSs not yet known to be affected by the disease.

Detection, diagnosis of orchid virus and inactivation of cymbidium mosaic virus (CYMV) on plants

Floriculture is one of the disciplines of Horticulture which is dealing with growing of ornamental plants flowering plants and garden maintenance etc. orchids are one of the floriculture plant. It is a member of Orchidaceae family consisting of more than 25,000 species, which are distributed almost all over the world. Vanda Orchid plant is collected from different nurseries showing chlorotic and mosaic symptoms were observed and it was suspected to infect with virus. So the symptomatic plants were tested with Direct Antigen Coating- Enzyme Linked Immunosorbent Assay (DAC-ELISA) for Cymbidium Mosaic Virus (CYMV), Odontoglossum ring spot virus (ORSV), Poty virus and Tomato Spotted Wilt Virus (TSWV) and further confirmed by Transmission Electron Microscopy (TEM). With the two methods CYMV were detected positively from the samples and low positive results were observed for ORSV, Potex, Poty virus and Tomato Spotted Wilt Virus (TSWV). High incidence of Cymbidium Mosaic Virus (CYMV) was observed. Chemicals were evaluated for inactivation of CYMV on pruning tools for disease control. Skimmed milk was found to be effective, non caustic and inexpensive for inactivation of CYMV inoculated on local lesion indicator host plants. However, systemic host plants (Orchids) were used in evaluation.

Assessment of pospiviroid transmission by myzus persicae, macrolophus pygmaeus and bombus terrestris

During the past decade, pospiviroid outbreaks in tomato and sweet pepper crops have been regularly reported worldwide. Although seed transmission was often suspected, transmission from asymptomatic ornamentals and weeds through pruning tools, or via insect vectors could not be excluded. To evaluate the risk of pospiviroid transmission via insects, three insect spp. commonly observed in these crops were used in multiple transmission experiments with Potato spindle tuber viroid (PSTVd), Tomato apical stunt viroid (TASVd), Pepper chat fruit viroid (PCFVd) and Tomato chlorotic dwarf viroid (TCDVd)-infected source plants, such as tomatoes, petunias and peppers. The insect species belong to three different functional groups: a phloem-feeding pest (Myzus persicae Sulzer), a pollinator (Bombus terrestris L.) that feeds on pollen and nectar, and a generalist predator (Macrolophus pygmaeus Rambur), that consumes several species of insect pests and feeds on plant saps and pollen. For each insect, four transmission experiments were conducted in which different receptor host plants were challenged. During the experiments, insects that were seen probing or feeding on were captured and tested for viroids using PCR. The percentage of each insect species that was pospiviroid positive was 100 % for M. persicae, 4 % B. terrestris, and 0 % for M. pygmaeus. Although these results indicate that M. persicae may be a vector, none of the receiving host plants in four separate experiments tested positive. However, transmission by B. terrestris is possible since one of 18 receiving tomato plants tested positive for TCDVd in one of four transmission experiments, resulting in an overall transmission rate of 2.6 %. Based on these results, we believe that the use of pollinating insects and biological control agents in greenhouses does not imply a major phytosanitary risk for viroid dispersal.

Detection of Grapevine Fungal Trunk Pathogens on Pruning Shears and Evaluation of Their Potential for Spread of Infection.

Four vineyards visibly affected by trunk diseases were surveyed at pruning time in 2012 and 2013 in Spain, to determine whether pruning tools are capable of spreading grapevine trunk diseases from vine to vine. In each vineyard, pruning shears were regularly rinsed with sterile water, collecting liquid samples for analysis. Molecular detection of grapevine fungal trunk pathogens (GFTPs) was performed by nested polymerase chain reaction using specific primers to detect Botryosphaeriaceae spp. Eutypa lata, Cadophora luteo-olivacea, Phaeoacremonium spp., and Phaeomoniella chlamydospora. All of these GFTPs, with the exception of E. lata, were detected in samples from the four vineyards, C. luteo-olivacea and Phaeoacremonium spp. being the most prevalent. Co-occurrence of two, three, or four different GFTPs from the same sample were found, the simultaneous detection of C. luteo-olivacea and Phaeoacremonium spp. being the most prevalent. In addition, fungal isolation from liquid samples in semiselective culture medium for C. luteo-olivacea, Phaeoacremonium spp., and P. chlamydospora was also performed but only C. luteo-olivacea was recovered from samples collected in three of four vineyards evaluated. Pruning shears artificially infested with suspensions of conidia or mycelial fragments of C. luteo-olivacea, Diplodia seriata, E. lata, Phaeoacremonium aleophilum, and Phaeomoniella chlamydospora were used to prune 1-year-old grapevine cuttings of '110 Richter' rootstock. Successful fungal reisolation from the cuttings 4 months after pruning confirmed that infested pruning shears were able to infect them through pruning wounds. These results improve knowledge about the epidemiology of GFTPs and demonstrate the potential of inoculum present on pruning shears to infect grapevines.

Viroidler ve Türkiye'de Saptanan Viroid Hastalık Etmenleri

Viroids are circular, single-stranded RNAs that infect plants. Viroids belong to two families, Pospiviroidae and Avsunviroidae, whose members replicate in the nucleus and chloroplast of plant cells, respectively. The host range of viroids includes vegetable crops, ornamentals, and woody perennials, depending upon the viroid species. Viroids are easily transmitted mechanically through contaminated pruning tools. They can also be spread vegetatively by grafting, tuber propagation, infected seed, pollen, and insects. There are over 30 known viroid species that are taxonomically divided into two families. Viroids are also responsible for several cultivated plant diseases in Turkey. Viroids and viroid disease agents causing plant disease (Potato spindle tuber viroid, Chrysanthemum stunt viroid, Citrus exocortis viroid, Hop stunt viroid, Citrus cachexia viroid, Citrus viroid III–IV, Grapevine yellow speckle viroid 1–2, Avocado sunblotch viroid, Peach latent mosaic viroid) in Turkey were discussed in this review

Ergonomic aspects and productivity of different pruning tools for a first pruning lift of Eucalyptus grandis Hill ex Maiden

Ergonomic aspects and productivity of different pruning tools for a first pruning lift of Eucalyptus grandis Hill ex Maiden

WORK PRODUCTIVITY OF TEAMS WITH DIFFERENT PRUNING TOOLS IN OLIVE

Pruning is second only to harvesting in cost, as it generally accounts for about 20-30% of annual cultivation costs, besides it can be hazardous to pruner safety. Tests to facilitate pruning were performed in an olive grove in central Italy in 2007, consisted of 20-year-old trees of the ‘Frantoio’, ‘Leccino’ and ‘Maurino’ cultivars, trained to vase and having a planting distances of 5×5 m. The aim was to compare five pruning teams with different tools, in which pruners stand on the ground, to find the most effective as work productivity and the less tiring. Each pruning team was composed by two well trained pruners. The pruning’s kit includes chain saw, chain pruner, and lopper, pneumatic pruning shear with and without an extension pole. Those pruning tools have been used in different association by the five teams. In the pruning team in which one pruner used the chain saw and the lopper and the other the chain pruner and the pneumatic pruning shear with an extension pole the work capacity amounted to 23 trees per hour, whereas the tiredness was 5 (range 1-10). In this team the number of cuts/tree was 34 with a diameter of 26 mm, in average, and 70% of cuts was smaller than 30 mm. In the less tiredness pruning team, in which one pruner used the chain pruner and the other the pneumatic shear, the work productivity amounted to 16 trees per hour and the 77% of cuts was smaller than 30 mm. When larger and more numerous cuts were necessary to prune olive tree, the most suitable pruning team resulted that in which one worker used the chain saw and the chain pruner, while the other used the pneumatic pruning shear with an extension pole.

Testing and Performance Evaluation of Tractor Mounted Hydraulic Elevator for Mango Orchard

Problem statement: The harvesting and pruning of horticultural crops is quite difficult due to their tallness. There are small hand tools available for harvesting and pruning. But these tools of harvesting and pruning are restricted due tree height, unavailability of trained labours for climbing and cost of operation etc. The mechanized machines are available; these are heavy and costly and are not suitable for low land holding, Indian marginal famers. Harvesting and pruning of horticultural crops with the available hand tool is very difficult. The labor has to climb on the tree by carrying these hand tools, which requires skill too. To overcome the above problems a Tractor Mounted Hydraulic Elevator (TMHE) powered by tractor PTO, was tested for the mechanical harvesting and pruning of mango orchards using digital load cell, digital Vibration meter and digital Techometer for elevator stability study and pruner engine RPM measurements while in branch cutting respectively. The field performance of the above machine was carried out on plane mango plot, at Dr. Balasaheb Sawant Konkan Krishi Vidyapeeth, Dapoli, Dist: -Ratnagiri (Maharashtra, India). The machine was tested for the better stability at maximum reach position for harvesting and pruning of various mango varieties, like Alphanso, Totapuri etc. Approach: To reduce the harvesting /pruning cost, increase the harvesting/pruning efficiency and enhance the overall productivity of mango orchards. Also to use the traditional mechanized/ manual pruning tools with the developed tractor mounted hydraulic elevator. To develop and refine the power operated mechanism for marginal farmers. This stability study was carried out, by using strain gauge load cell (S-beam), having capacity of 2000 kg. The load cell guiding device was designed and fabricated for conducting the above experiments following standard material specifications of American society of testing material. The reaction on rear wheel of tractor was measured by using digital load cell, which converts the force acting on rear wheel of tractor into electrical signals and get it displayed on the control panel. The speed of pruner engine is measured for various mango trees branches at different heights, using digital tachometer. The vibrations of the pruning platform are measured for the respective pruner engine speed and height of Pruning Platform. The speed and vibration readings are taken for different branches of different diameter and height. The time required for pruning the branches is also measured. Results: The tractor mounted hydraulic elevator is most suitable for harvesting and pruning of mango orchards upto 12 m tree height without affecting the stability of machine with available tools. The field capacity of elevator was 0.08 h−1 for mango harvesting. The observed field capacity of the developed TMHE is 5,400 mango (1400 kg) day−1 for Alphanso mango, research is underway to develop hydraulic man-positioned, which would be easier to harvest, prune tree and spraying by hand or machine. Conclusion: The overturning of the elevator is not observed, up to 12 meter height of tree from ground including 150 kg load in the lifting platform for harvesting and pruning of mango orchards. The vibrations of the lifting platform noted are in safe limit.

Bacterial Canker of Sweet Cherry in Oregon-Infection of Horticultural and Natural Wounds, and Resistance of Cultivar and Rootstock Combinations.

This study was done to (i) compare seven types of natural or horticultural injuries and wounds for incidence, severity, and mortality of infection of sweet cherry (Prunus avium) by Pseudomonas syringae pv. syringae; (ii) determine the relative resistance to bacterial canker of 14 cultivar-rootstock combinations; (iii) determine if P. syringae pv. syringae is transmitted by contaminated pruning tools; and (iv) determine if summer and winter pruning cuts become resistant to infection. Infection occurred at all of the seven types of injury and wound sites on both cvs. Sunset Bing and Golden Heart. Infection of inoculated wounds made in spring and summer (heading cuts when trees were planted, scoring cuts, and summer pruning) resulted in the greatest canker incidence and severity. Inoculation of heading cuts resulted in the highest tree mortality (86%). 'Bing' and 'Sweetheart' were the most susceptible cultivars while 'Regina' and 'Rainier' appeared to be more resistant. Bing trees had the highest mortality of any cultivar with 70% dead at the end of the 3-year study. Canker severity of the three rootstocks varied considerably but mortality was greatest for trees on Gisela 6 (77%). Bacterial canker was not transmitted in summer or winter by cutting through active cankers, then immediately using the same pruning tool to make heading cuts on healthy trees. Heading cuts became resistant to infection after about 1 week in summer and 3 weeks in winter. Results are discussed as part of an integrated management program for bacterial canker of sweet cherry.

Pollen transmission of Peach latent mosaic viroid

Peach latent mosaic viroid (PLMVd), the causal agent of peach latent mosaic disease, is transmissible by grafting and pruning tools and, occasionally, by aphids. There is no information on other possible ways of transmission. The high incidence of field infections and the rate of natural spread (5-10% of newly infected plants per year), prompted us to investigate the role, if any, that pollen, seed and root contact could play in PLMVd dissemination. The viroid was detected by molecular assays in pollen, seeds and roots of infected trees. Five out of 18 plants, pollinated with pollen from infected trees, became positive for PLMVd. Seeds from PLMVd-infected trees were also viroid-positive, but their seedlings were apparently viroid-free. PLMVd was not detected in the roots of healthy seedlings grown for six years in a container together with infected seedlings, indicating that no transmission had occurred via roots. Thus PLMVd is pollen-transmitted but is not transmitted through seeds nor roots of infected peach plants.