Scion Wood Research Articles

Water soaking and benzyladenine treatment for higher grafting success in grapevine

The grafting of grapevines has become essential to overcome biotic and abiotic stresses. Also, stimulating the grafting union's rapid formation is the key to grafting success. This investigation was an attempt to study the effect of removing growth inhibitors through soaking of scion wood in water for 24 hours versus adding growth stimulation through fast dipping in 250 ppm benzyl adenine (BA) for 30 seconds before grafting, on the grafting success of Flame Seedless and Early Sweet scions (Vitis vinifera) grafted onto Freedom rootstock (Vitis champinii x 1613C) in addition to the control treatment. Water soaking was the best and followed by the treatment of 250 ppm BA, which significantly improved the grafting success of both cultivars. Grafting success was positively associated with increasing callus formation at the grafting zone, accompanied by the highest total indols content, the lowest total phenols content and peroxidase activity above and below the grafting zone. However, water soaking significantly increased total indols and decreased total phenols content of the ungrafted cuttings. This study suggests that applying water soaking to grape scion before grafting is an environmentally friendly, sustainable and alternative practice for synthetic growth regulators to improve grafted cuttings success.

Evaluation of criteria to assist the selection of good quality grafted grapevines prior to their commercialisation

The production of grafted grapevine plant material is a complex process with many steps running over at least one year, from grafting to final sorting in nurseries. To reach the market in France, grafted grapevines must meet three criteria by law: resistance to a manual graft union test (or thumb test), a minimum number of three roots and a woody, lignified stem which has grown from the bud of the scion wood of at least 2 cm long. This study aimed to evaluate the possibility of using visual criteria to select good quality grafted grapevines, without the need to do the thumb test because the thumb test is manual and therefore very subjective; the test depends on the strength applied by the person who realises it. This study was done on 22 scion/rootstock combinations with different degrees of grafting success, i.e., producing different proportions of marketable plants after one year in the nursery. The three legal criteria currently used to select marketable grafted grapevines in France as well as other external and measurable criteria such as the length of lignified stem and diameter, the number of thin and thick roots, and rootstock wood diameter were measured on the 22 scion/rootstock combinations. Variation in the values for these different criteria was observed and correlations between the criteria and the number of marketable plants were studied. This data was then analysed to determine which visible criteria contribute most to identifying marketable grafts. The percentage of marketable grafts was most strongly correlated with the thumb test and positively correlated with the length of the lignified stem. The variables with the highest predictive effect for identifying marketable plants (other than the thumb test) were the number of large roots and the length of the lignified stem. The possibility of using visible criteria to screen for good quality grafted plants is discussed, but no single, or combination of criteria, was sufficiently strongly correlated with the percentage of marketable plants to replace the thumb test.

Thermal treatment using microwave irradiation for the phytosanitation of Xylella fastidiosa in pecan graftwood.

Pecan bacterial leaf scorch caused by Xylella fastidiosa is an emerging disease for the U.S. and international pecan industries and can be transmitted from scion to rootstock via grafting. With the expanse of global transportation and trade networks, phytosanitation is critical for reducing the spread of economically significant pathogens, such as X. fastidiosa. We developed and evaluated thermal treatments using microwave irradiation and microwave absorbers [sterile deionized water (dH2O) and carbon nanotubes (CNTs)] as novel disinfectant methods for remediating X. fastidiosa in pecan scions. Partial submergence of scions in dH2O or CNT dispersions resulted in the transport of microwave absorbers in the xylem tissue via transpiration but did not compromise plant health. The microwave absorbers effectively transferred heat to the scion wood to reach an average temperature range of 55–65°C. Microwave radiation exposure for 6 sec (3 sec for two iterations) of CNT- or dH2O-treated scions reduced the frequency of X. fastidiosa-positive in pecan scions without negatively affecting plant viability when compared to the control group (dH2O-treated with no microwave). The efficacy of the new thermal treatments based on microwave irradiation was comparable to the conventional hot-water treatment (HWT) method, in which scions were submerged in 46°C water for 30 min. Microwave irradiation can be employed to treat X. fastidiosa-infected scions where the conventional HWT treatment is not feasible. This study is the first report to demonstrate novel thermal treatment methods based on the microwave irradiation and microwave absorbers of dH2O and CNT as an application for the phytosanitation of xylem-inhabiting bacteria in graftwood.

Development of Neonectria ditissima infections initiated at grafting of apple trees

Infections of Neonectria ditissima, the cause of European fruit tree canker, may be initiated during propagation. In a survey of 19 commercial apple orchards in southern Norway in the year of planting or the following year, the graft-union area of 15,270 trees was examined. The disease was found in 53% of the orchards, at a low incidence (<10%) with two exceptions (13 and 42%). Scion wood from mother trees with no, a few or several cankers were used to propagate trees that were surveyed for up to 38 months. In total 20 out of 1116 (1.8%) trees developed canker. The higher the number of cankers was on the mother trees, the higher was the number of trees developing canker after grafting. Infections developed on both cultivars (Discovery, Summerred) and all three rootstocks (Antonovka, B9, M9), but more so on grafted than T-budded trees, and more in 2015 than in 2014. When the scion wood was inoculated at the time of T-budding or grafting, disease development went faster and to a higher incidence on T-budded (94%) than on grafted trees (50%). Dipping the scion wood end in a spore suspension prior to grafting resulted in more infections than when a suspension droplet was placed on the bud and bark surface of the scion wood after grafting. The present investigation documents that scion wood may harbour inoculum of N. ditissima. Furthermore, infections may be initiated at time of propagation, and management practices of both scion wood production and nurseries should encounter that fact.

Heat treatments of dormant scion wood killed the European canker pathogen &lt;i&gt;in planta&lt;/i&gt;, while chemical treatments did not

Neonectria ditissima, the causal agent of European canker, can be present in symptomless scion wood. Sanitation treatments could minimise this risk to nursery trees. In this trial, six heat treatments and five chemical treatments were tested for their effectiveness in removing this pathogen from dormant ‘Royal Gala’ wood. In July 2018, 120 symptomless inoculated shoots (three inoculations/shoot) were harvested and stored at 1oC for 3 months. Bundles of five inoculated shoots (45 cm) were placed in the centre of 24 bundles, each consisting of 25 wood pieces. Heat-treated bundles were submerged in water (45oC for 45 min or 50oC for 15 min), or wrapped in moist cloth, vacuum sealed inside plastic then submerged for 3–6 h at the same temperatures. Chemical-treated bundles were submerged for 16 h at room temperature. Treatments were compared with untreated wood. After surface sterilising, isolation of N. ditissima from inoculated wounds was attempted on apple-sap amended water agar. All wounds from the untreated wood and from the chemical-treated wood yielded the pathogen. However, N. ditissima was not isolated from wounds that had been heat treated. Therefore, heat treatments that do not affect scion wood viability may prove an effective tool to remove European canker from nursery material.

Effect of heat or chemical disinfection on the viability of ‘Fuji’ apple graft wood

Bundles of dormant wood were submerged in water (45˚C for 45 min or 50˚C for 15 min), or were wrapped in moist cloth, placed inside zip-locked bags and submerged for 3—6 h or treated with one of three GRAS chemicals or untreated (two bundles per treatment). Scion wood was grafted onto ‘M9’ rootstocks then planted in a randomised order, with growth assessed after 16 weeks. Two of the GRAS treatments and submersion at 45˚C for either 45 min or 3 h in a bag did not significantly affect viability compared with the untreated control (83—95% viable). Submersion at 50˚C for 15 min reduced viability significantly (70%). Scions did not survive exposure to 50˚C for 3—5 h in bags (P&lt;0.001). No significant differences in mean scion shoot length were observed between the untreated wood (107 cm) and that submerged in 45˚C water for 45 min, 3 h in a bag, or GRAS-treated. Wood treated at 45˚C for 5—6 h in a bag or at 50˚C for 15 min had significantly shorter shoots (54—75 cm, P&lt;0.001). Dormant ‘Fuji’ wood remained viable after treatments known to eliminate pathogens from wood.

Studies on factors influencing the vegetative propagation in walnut (Juglans regia L. )

The experiment was carried out to examine the effect ofdifferent status of physiologically resting scion wood,environment and grafting time for maximum graft success in walnut. Three status of physiologically resting scion wood (apical, sub- apical and basal), were subjected to grafting on four different grafting time (15th February, 1st March, 15th March and 1st April)placed under three environmental conditions(open field,poly trench and polyhouse).Sub-apical portion of resting scion wood resulted in highest sprouting, graft success and plant growth, whereas grafting on 15th March manifested highest graft success. Poly house environmental conditions recorded maximum grafting success and plant growth. Sub apical status of scion wood with 15th March grafting under poly house conditions recorded highest sprouting, graft success and plant growth of walnut and found ideal for clonal propagation of walnut.

Studies on factors influencing the vegetative propagation in walnut (Juglans regia L. )

The experiment was carried out to examine the effect ofdifferent status of physiologically resting scion wood,environment and grafting time for maximum graft success in walnut. Three status of physiologically resting scion wood (apical, sub- apical and basal), were subjected to grafting on four different grafting time (15th February, 1st March, 15th March and 1st April)placed under three environmental conditions(open field,poly trench and polyhouse).Sub-apical portion of resting scion wood resulted in highest sprouting, graft success and plant growth, whereas grafting on 15th March manifested highest graft success. Poly house environmental conditions recorded maximum grafting success and plant growth. Sub apical status of scion wood with 15th March grafting under poly house conditions recorded highest sprouting, graft success and plant growth of walnut and found ideal for clonal propagation of walnut.

The Effect of Whip Grafting Method on Grafting Success and Plant Development in Some Cultivars of Anatolian Walnut (Juglans Regia L.)

The objective of this study was to determine the effects of whip grafting methods on graft success and plant development (the length and diameter of graft shoot) in open rooted walnut plant production. In the study, scion woods of “Chandler, Maras-18, Sebin, Kaman-1, Kaman-2, Bilecik and Sen-2” walnut cultivars and one year old walnut rootstocks were used. The study was carried out in the open field and under shaded greenhouse conditions. Walnut seedlings were dug out in February and were taken burial in soil. Seedlings were grafted with whip grafting method in a room and planted in March. After planting, graft union was covered by soil within plastic bag and grafting wax was applied to upper side of scion wood. However, some graftings with Chandler clones were planted in the plastic greenhouse. Thus, it was also aimed to determine the effects of greenhouse condition on grafting success and plant development in walnut. Grafting success was changed between 59.6% and 98.8%. The highest graft success was obtained from Chandler cultivar produced both in the greenhouse and open field. There were no statistical differences between open field and greenhouse conditions in this cultivar. However, better scion shoot length and diameter were obtained in the greenhouse.

Comparative Success of Budding and Grafting Citrus sinensis: Effect of Scion’s Number of Buds on Bud Take, Growth and Sturdiness of Seedlings

A greenhouse study was conducted at the Lilongwe University of Agriculture and Natural Resources (LUANAR) in Malawi to determine the effectiveness of budding and grafting of Citrus sinensis. The study aimed at establishing the effect of number of buds on scion wood on bud take and growth of seedlings. A total of 6 treatments were arranged in randomized complete block design with 3 replicates. Treatments were 1-bud budding and grafting with scion having 1-5 buds. Budding and grafting were conducted in June, 2014 and monitored for a period of 120 days. Data were analyzed using GenStat statistical package, 15th edition and R 3.4.1. Results revealed that grafting treatments had significantly higher bud takes on average while budding had the least bud take. Within grafted seedlings, number of buds had no significant effect on bud take and height. Similarly, number of buds did not affect sturdiness quotients of seedlings, of which all were within the recommended range. However, number of buds significantly affected shoot girth, number of leaves and number of branches. A significant linear relationship and positive correlation was found between number of branches and number of leaves. The study recommended that grafting should be adopted as an alternative propagation technique for sweet orange and must use scion wood with 3-4 buds for ideal bud take, growth and sturdiness quotients.

Node position influences viability and contamination in hazelnut shoot explants

Initiation of shoot cultures is difficult in many woody plants due to internal microbial contaminants and general lack of juvenility in material from the source plants. Hazelnuts (Corylus avellana L.) are generally difficult to initiate into culture for these same reasons. This study was designed to determine the effects of collection and surface disinfestation techniques and nodal position on the viability and contamination of shoot explants. In addition, culturable bacteria were identified on samples from surface-disinfested explants. Explants were collected from scion wood grafted onto seedling rootstocks and grown in a greenhouse. Single-node explants, excluding the shoot tip, were collected and the node location documented. After surface disinfestation, explants were held in liquid contaminant detection medium for 1 wk and the effect of this treatment on explant viability was evaluated. Node position was important for obtaining viable contaminant-free explants. Bacterial and fungal contaminations both increased with the distance from the shoot tip. The use of contaminant detection medium as a part of the initiation procedure did not affect viability. Explant-derived bacteria were identified as belonging to Brevundimonas sp. and Pseudomonas sp. through 16S rRNA sequence and API® tests. The best procedure for collecting axenic, viable hazelnut explants was to collect from the first three apical nodes, excluding the shoot tip, of actively growing greenhouse plants, place them in individual tubes for washing and surface disinfestation, and use contaminant detection techniques to identify contaminant-free cultures at initiation.

Performance of high density planting of mango (Mangifera indica L.) under mid-western plain zone of Uttar Pradesh

An experiment was conducted at Zonal Research Centre -Nagina (Bijnor)-246 762(U.P.) during 2000 to evaluate the performance of high density planting of mango ( Mangifera indica L.). The mango variety Dashehari scion wood of 20-22cm grafted on seedling rootstock in July 1999 were planted at Horticulture Section in August, 2000 at two spacing viz., 10m × 10m (100 plants/ha-normal density) and 3.0m × 3.0 (1111plants/ha-high density). Five grafts were planted in normal density and 160 grafts were planted in high density employing about 0.1940 ha area. Grafts in normal density were planted at marked points prepared by pit digging (1×1×1m) and then by filling the pits with dug soil mixed with 100 g N, 75 g P 2 O 5 and 75 g K 2 O fertilizer mixture, whereas grafts in high density were planted directly with the use of fertilizers containing 100 kg N, 75 kg P 2 O 5 and 75kg K 2 O/ha. Normal package of pracices was applied in both the system of plantings. The plant height (5.30m) was recorded under normal planting whereas it was found little different in high density of mango at 11 th year of their planting. The stem girth under normal system was noted as 55.7cm whereas,it was slightly reduced to 50.7cm under high density of planting. The expansion of East-West and North- South direction both were recorded same as 3.10m and 3.03m in normal planting and high density planting, respectively. The fruit yield 22.30q/ha was noted under normal density of planting whereas, it was 242.20q/ha at 5 th year of planting under high density planting system. The fruit yield ranged from 22.30to 109.80 q/ha from 5 th year to 11 th year, respectively under normal system of planting whereas it ranged from 242.2 to 1093.22q/ha under HDP system of planting. The observations showed that the fruit yield ratio of normal system of planting to HDP were 1:10.86, 1:9.92, 1:9.90,1:8.67, 1:9.80, 1:9.27 and 1:9.95 from 5 th year to 11 th year of age, respectively. So, it is a very informative and need of the hour to plant HDP system of mango just to get 9 to 10 times more yield for increasing mango productivity and to reach the king of fruit to the common people.

Development of improved techniques for grafting of pecan

This project was carried out at the Safiabad Agricultural Research Center of Dezful during 2011–12. Three graft methods are investigated in this project: cleft graft with hot cable system five times from late October till mid-February, cleft graft with polyethylene bag, and side-stub five times from early November till early March. For each grafting method, scion wood of ‘GraTex’, ‘Wichita’, ‘Choctaw’, ‘10J’ and ‘GraKing’ pecan cultivars were grafted onto two-year old seedling rootstocks 1–1.5cm in diameter. The best graft time was from late January till late February using the cleft graft with hot cable system graft method and from mid-February till late March using the cleft graft with polyethylene bag grafting method. Also, the highest percentage of graft success was achieved using ‘Wichita’ scion (92%), while ‘10J’ had the lowest percentage. The side-stub grafting method was unsuccessful compared to the other two methods and percentages of graft success for different cultivars using this method were below 20%.

Hot water disinfection treatment to eliminate &lt;i&gt;Neonectria ditissima&lt;/i&gt; latent infections in apple scion wood

The European canker pathogen Neonectria ditissima can be transmitted by apple scion wood into newly developing trees following grafting or budding resulting in disease development and progression An in vitro hot water treatment showed that both conidia and mycelium of N ditissima can be killed when placed into water at 50C for 8805; 5 min However diseased scion wood required 8805; 15 min disinfection at the same temperature to eliminate all internal pathogens including N ditissima At this temperature and time duration no mycelium growth was observed after 2 weeks incubation of cut pieces of the disinfected tissues on apple sap amended water agar Although the treatment was 100 effective at eliminating some identified and nonspecific pathogens visual assessment of both the scion and rootstock viability and vigour six months after the hot water treatment showed that 98 of the rootstocks and scions failed to grow and develop

Performance of High Density Planting of Mango(Mangifera IndicaL.) Under Mid-Western Plain Zone of Uttar Pradesh

An experiment was conducted at Zonal Research Centre -Nagina (Bijnor)-246 762(U.P.) during 2000 to evaluate the performance of high density planting of mango ( Mangifera indica L.). The mango variety Dashehari scion wood of 20-22cm grafted on seedling rootstock in July 1999 were planted at Horticulture Section in August, 2000 at two spacing viz., 10m × 10m (100 plants/ha-normal density) and 3.0m × 3.0 (1111plants/ha-high density). Five grafts were planted in normal density and 160 grafts were planted in high density employing about 0.1940 ha area. Grafts in normal density were planted at marked points prepared by pit digging (1×1×1m) and then by filling the pits with dug soil mixed with 100 g N, 75 g P 2 O 5 and 75 g K 2 O fertilizer mixture, whereas grafts in high density were planted directly with the use of fertilizers containing 100 kg N, 75 kg P 2 O 5 and 75kg K 2 O/ha. Normal package of pracices was applied in both the system of plantings. The plant height (5.30m) was recorded under normal planting whereas it was found little different in high density of mango at 11 th year of their planting. The stem girth under normal system was noted as 55.7cm whereas,it was slightly reduced to 50.7cm under high density of planting. The expansion of East-West and North- South direction both were recorded same as 3.10m and 3.03m in normal planting and high density planting, respectively. The fruit yield 22.30q/ha was noted under normal density of planting whereas, it was 242.20q/ha at 5 th year of planting under high density planting system. The fruit yield ranged from 22.30to 109.80 q/ha from 5 th year to 11 th year, respectively under normal system of planting whereas it ranged from 242.2 to 1093.22q/ha under HDP system of planting. The observations showed that the fruit yield ratio of normal system of planting to HDP were 1:10.86, 1:9.92, 1:9.90,1:8.67, 1:9.80, 1:9.27 and 1:9.95 from 5 th year to 11 th year of age, respectively. So, it is a very informative and need of the hour to plant HDP system of mango just to get 9 to 10 times more yield for increasing mango productivity and to reach the king of fruit to the common people.

Susceptibility of grape varieties to esca disease

In the scion wood mother block belonging to Vivai Cooperativi Rauscedo (VCR) the surveys on esca disease have been performed for decades, and the symptomatic plants are uprooted every year. We hereby present and discuss the survey results relating to a group of vines planted in 1995–2006. The first symptoms of esca appeared in 10–12 year-old vines; only in more recent times the disease has appeared invines of 6–8 years. Esca affects more white grape varieties than black varieties. Within each type of grape,it was possible to identify a number of varieties with lower esca incidence than other varieties, which are affected with a very high incidence, in some cases more than 50% of plants eradicated in the oldest vineyards. The genetic component has proved to be crucial for the varietal susceptibility to expression of esca symptoms; this aspect should be taken into account in the prevention and prophylaxis actions aimed to the limitation of the risks associated with vine trunk decay.

Evaluation of Epicotyl Grafting on 25- to 55-day-old Pecan Seedlings

Scion wood of ‘Caddo’ and ‘Desirable’ pecan (Carya illinoinensis) was grafted onto the epicotyl of 1-month-old, open-pollinated ‘Shaoxing’ pecan seedlings for evaluation as a grafting technique to reduce the time to produce grafted trees. The results showed that seedlings grafted with “base scions” had higher survival than those grafted with “terminal scions” for both ‘Caddo’ and ‘Desirable’. Also, grafting with paraffinic tape could achieve greater success rate than that with medical tape. The most ideal time to perform this grafting was late April in Nanjing, China, when pecan seedlings were about 35 days old. This study demonstrated that the technique yielded successful epicotyl grafting of &gt;70%, and it could thus be applied in practice.

HOT-WATER TREATMENT OF PECAN SCIONS AS A MEANS OF PHYTOSANITATION TO REDUCE THE POTENTIAL INTRODUCTION OF XYLELLA FASTIDIOSA, THE CAUSAL AGENT OF PECAN BACTERIAL LEAF SCORCH, INTO ORCHARDS AND NEW GEOGRAPHIC REGIONS

Pecan (Carya illinoinensis) bacterial leaf scorch is a chronic disease of pecan that reduces yield, causes defoliation, and retards growth. The causal agent of this disease, Xylella fastidiosa subsp. multiplex, is a xylem-inhabiting bacterium that can be transmitted in pecan by grafting with infected plant tissue or by insects in the families Cercopidae and Cicadellidae that feed exclusively in the xylem. No economically effective treatment for this disease exists once a tree becomes infected, and no immune pecan cultivars have been identified. Infection is persistent and disease and yield loss will occur annually. A simple, hot-water treatment in which pecan scions are submerged in water at 46°C for 30 min prior to grafting provides a means for reducing the potential introduction of X. fastidiosa into orchards through grafting without harming the viability of the scions. The recent increase in international germplasm exchange within the genus Carya, as a result of interest in pecan production outside of its native range (North America), increases the probability of pathogen and insect introductions into new geographic regions. Such introductions may result in significant changes in the health of the Carya species, as well as other non-native and native plant hosts, in these regions. Xylella fastidiosa is known to infect over 100 plant species and to cause disease in economically important crops, ornamentals, and landscape trees. The geographic distribution of X. fastidiosa, with the exception of Taiwan, is currently limited to the Americas. Application of the hot-water treatment to pecan scions may not only slow the spread of X. fastidiosa in areas where it already exists, but also reduces the introduction of this pathogen into regions where it is not established. This treatment should be adopted as a standard phytosanitation treatment in regions that import pecan scion wood.

Almond Leaf Scorch Disease Development on Almond Branches High-Grafted on Peach Rootstock

Development of almond leaf scorch (ALS) disease was monitored on young almond (Prunus dulcis 'NePlus' and 'Peerless') shoots produced from almond scion wood that was high-grafted on peach rootstocks (P. persica 'Queencrest/Nemaguard'), after the almond shoots were mechanically inoculated with Xylella fastidiosa. The objective of this study was to evaluate the potential movement of X. fastidiosa through almond-peach graft unions. ALS symptoms developed on both X. fastidiosa-inoculated and uninoculated almond shoots that were high-grafted on different peach limbs of the same tree in September following inoculations with X. fastidiosa made in June and July 2002, respectively, when the average distance in peach rootstock between the two almond-peach graft unions was 30.5 cm or shorter. No ALS symptoms were observed on uninoculated almond shoots late in the growing season of the second year. The incidence of ALS-affected leaves on shoots inoculated with X. fastidiosa decreased in the second year on the inoculated shoots of Peerless as determined by the number of inoculated shoots showing ALS symptoms in 2002 versus 2003. No visible ALS symptoms were observed in NePlus late in the growing season of the second year, suggesting that survival of X. fastidiosa in NePlus was less than in Peerless. These data demonstrate that movement of X. fastidiosa through two almond-peach graft unions was possible during the year of inoculation when the peach rootstock stem distance between the two almond-peach graft unions was minimal. However, X. fastidiosa may not survive the winter season or survived so poorly as not to be able to produce ALS symptoms in the second growing season on the uninoculated shoots that previously showed ALS symptoms in the fall of the year when an adjacent shoot was inoculated. The results suggest that high-grafting almond scion wood on multiple peach rootstock limbs may provide a means to limit movement of X. fastidiosa from one almond limb to another on the same tree.

Homonymy, synonymy and hybrid misassignments in butternut (Juglans cinerea) and Japanese walnut (Juglans ailantifolia) nut cultivars

Butternut (Juglans cinerea), a tree native to North America and Japanese walnut (J. ailantifolia), native to Japan, form the basis for a small but growing specialty nut crop industry in the eastern United States and Canada. Over the last century, Canadian and American nut tree growers, academic plant breeders and nursery owners have clonally propagated cultivars and freely exchanged scion wood, creating the possibility of misidentification. To detect homonymy, synonymy and hybrid misassignments, we used 12 highly polymorphic microsatellites to genotype most of the butternut and Japanese walnut cultivars grown in the United States and Canada. Bayesian clustering and identity analyses revealed high levels of homonymies (genetically different cultivars with the same name) and synonymies (genetically identical cultivars with different names). Over 41% of the butternut cultivars and 45% of the Japanese walnut cultivars tested had homonymies, and a majority of the cultivars in both species also had synonymies. Further, 43 entries (~15%) identified by the contributors as either J. cinerea or J. ailantifolia were interspecific hybrids. Given our results we recommend that any comparative studies on the cultivars of either species or their hybrids include reference genetic fingerprints as a part of the study.