Patent Grant
PP32461
Latin name: Corylus avellana cultivar.
Variety denomination: ‘Hunterdon’.
The present Invention relates to a new and distinct cultivar of Corylus plant, botanically known as Corylus avellana, and the designation ‘Hunterdon’, or as ‘Hunterdon’ Hazelnut (H3FR04P42 Rutgers 6), and hereinafter referred to by the name ‘Hunterdon’.
The new Corylus resulted from a controlled cross of the female parent ‘Sacajawea’ (unpatented, Mehlenbacher et al., 2008) with pollen of OSU 616.055 (unpatented) made in 2004. Hybrid seeds resulting from the cross were harvested in August 2004. They were provided a period of moist chilling, subsequently germinated, and the seedlings were grown in the greenhouse during the summer of 2005. From this cross, a total of 106 seedling trees were planted in a research field in East Brunswick, N.J., in October 2005. ‘Hunterdon’ was discovered and selected as a single plant within that progeny of the stated cross-pollination. It was originally assigned the designation H3FR04P42, which indicates the field, row, and tree location of the original seedling.
The female parent ‘Sacajawea’ was developed at Corvallis, Oreg. and is characterized by excellent kernel quality and tolerance to eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. The male parent OSU 616.055 is an unreleased seedling that also exhibits tolerance to EFB.
‘Hunterdon’ was asexually reproduced by rooted suckers and whip grafting in 2010 through 2015 in East Brunswick and New Brunswick, N.J. The unique features of this Corylus are stable and reproduced true-to-type in successive generations of asexual reproduction.
The following traits have been observed and are determined to be the unique characteristics of ‘Hunterdon’. These characteristics in combination distinguish ‘Hunterdon’ as a distinct cultivar:
Vigorous and upright-spreading plant habit.
Yellowish-green to green color of developing and fully expanded leaves during the spring and summer.
High level of tolerance (quantitative resistance/horizontal resistance) to eastern filbert blight (EFB) caused by the fungus Anisogramma anomala (Peck) E. Müller. The source of this resistance differs from the single dominant allele conferred from ‘Gasaway’ (unpatented, Mehlenbacher et al., 1991), which protects Corylus avellana ‘McDonald’ (U.S. Plant Pat. No. 28,200 P3, Mehlenbacher et al., 2016), ‘Wepster’ (U.S. Plant Pat. No. 27,141 P3, Mehlenbacher et al., 2014), ‘Dorris’ (U.S. Plant Pat. No. 25,022 P3, Mehlenbacher et al., 2013), ‘Jefferson’ (unpatented, Mehlenbacher et al., 2011a), ‘Yamhill’ (unpatented, Mehlenbacher et al., 2009), and several other Corylus avellana cultivars and pollenizers known to the Inventors.
Expression of incompatibility alleles S1 and S3 in the styles.
Kernels that blanch very well and have an excellent flavor after roasting.
Comparisons in several replicated plantings in East Brunswick, N.J., show that plants of ‘Hunterdon’ differed from plants of the Corylus avellana cultivar ‘Barcelona’ (unpatented), ‘Tonda di Giffoni’ (unpatented), ‘Yamhill’, ‘Jefferson’, and other cultivars and selections of Corylus avellana known to the Inventors, primarily in their response to EFB present in New Jersey, a region where the pathogen is native and highly genetically diverse (Muehlbauer et al., 2019). They also differed in S-alleles, nut size, kernel percentage (ratio of kernel weight to nut weight), frequency of defects (blank nuts, moldy kernels, twin kernels, etc.), time of pollen shed, and length of the husk or involucre. ‘Hunterdon’ is immediately distinguished from its parents by its incompatibility allele (S-allele) combination. ‘Hunterdon’ expresses S-alleles S1 and S3 in its stigmas whereas ‘Sacajawea’ expresses S1 and S22 and OSU 616.055 expresses S3 and S12. ‘Hunterdon’ also differs in its response to the disease eastern filbert blight (EFB) caused by Anisogramma anomala. Both ‘Sacajawea’ and OSU 616.055 express a similar moderate level of tolerance to EFB. For example, previous studies showed ‘Sacajawea’ exposed to EFB resulted in an average proportion of diseased wood of 21.0% (total length of EFB-diseased stems per tree divided by total length of shoot growth) (see [0142] Capik, J. M. and T. J. Molnar. 2012. Assessment of host (Corylus sp.) resistance to eastern filbert blight in New Jersey. J. Amer. Soc. Hort. Sci. 137:157-172). ‘Hunterdon’ has been shown to be highly tolerant expressing an average of only 2.2% diseased wood. ‘Monmouth’ has been shown to be highly tolerant expressing an average of only 1.8% diseased wood.
For example:
Eastern filbert blight response in New Jersey: In a multi-year trial in East Brunswick, N.J., the proportion of EFB-diseased wood across the canopy for ‘Hunterdon’ was 2.2% compared to 20.4% for ‘Yamhill’, 31.2% for ‘Jefferson’, 48.6% for ‘Gasaway’, and 67.0% for ‘Barcelona’.
Pollen shed: ‘Hunterdon’ sheds pollen in East Brunswick, N.J., with ‘Yamhill’ and ‘Santiam’ (unpatented, Mehlenbacher et al., 2007), after ‘Ratoli’ (unpatented, minor cultivar from Tarragona, Spain), and prior to ‘Jefferson’ and ‘Gasaway’. ‘Hunterdon’ descriptor=5.
Husk Length: ‘Hunterdon’ is 1.5 times nut length, like ‘Barcelona’, while ‘Wepster’ is 2.0 times the nut length.
‘Hunterdon’ produces kernels that are well-suited for the blanched kernel market for use in confections and baked goods. ‘Hunterdon’ combines very high levels of tolerance to eastern filbert blight (evaluated against Anisogramma anomala strains present in New Jersey, US) with globular nuts and kernels and excellent kernel blanching after roasting. The tree is vigorous with an upright branching habit that produces a desirable orchard tree when pruned to a single stem.
Field observations in East Brunswick, N.J., and results from greenhouse-based inoculations performed in New Brunswick, N.J., indicate that ‘Hunterdon’ expresses a high level of tolerance to eastern filbert blight (EFB) caused by the fungus Anisogramma anomala. While the cultivar is not immune to EFB, it rarely produces stem cankers and those that develop are typically small in size and lack fully formed reproductive stromata which show limited sporulation, equating to very little to no stem dieback and a greatly reduced canopy inoculum load even when infections are present. The high level of tolerance (horizontal resistance) is conferred by both of its unrelated, EFB-tolerant parent trees, which is unlike the cultivars currently grown in Oregon and Washington protected by the single dominant ‘Gasaway’ resistance allele. EFB is now present throughout the Willamette Valley of Oregon where 99% of the US hazelnut crop is grown and is endemic to the eastern US and southern Canada, where it has been historically impossible to grow Corylus avellana commercially. ‘Hunterdon’ was selected in central New Jersey and is adapted to the climate present in this region. Pruning to remove cankers and fungicide applications are currently used to manage the disease in orchards of ‘Barcelona’ and other susceptible cultivars in the Pacific Northwestern US. ‘Hunterdon’ is suitable for planting in areas with high EFB disease pressure. It has shown excellent tolerance in the eastern US where the EFB fungus is native and genetically diverse (Muehlbauer et al., 2019).
The figures include color photographic illustrations that illustrate the overall appearance of the new cultivar, showing the colors as true as it is reasonably possible to obtain in colored reproductions of this type. Foliage colors in the photographs may differ slightly from the color values cited in the detailed botanical description which accurately describe the colors of the new Corylus.
The cultivar ‘Hunterdon’ has not been observed under all possible environmental conditions. The phenotype may vary somewhat with variations in environment such as temperature and light intensity, without, however, any variance in genotype.
The figures of the present application and the following observations and measurements describe plants grown in East Brunswick, N.J., under commercial practice outdoors in the field during the spring and summer. Plants used for the photographs and description were the original tree (15 years old) and those propagated by tie-off layerage and growing on their own roots (six and seven years old).
Color references herein are made to The Royal Horticultural Society Colour Chart, 1966 Edition, except where general terms of ordinary dictionary significance are used. International Union for the Protection of New Varieties of Plants (“UPOV”) descriptors are described in the Mar. 28, 1979, UPOV Hazelnut guidelines.
Disease resistance: ‘Hunterdon’ differs from existing Corylus avellana cultivars based on its source and type of resistance to eastern filbert blight (EFB) caused by Anisogramma anomala.
Commercial cultivars previously widely grown in Oregon including ‘Barcelona’ (unpatented), ‘Ennis’ (unpatented), ‘Daviana’ (unpatented), ‘Butler’ (unpatented), etc. are highly susceptible to EFB and cannot be grown in the eastern US without copious applications of chemical fungicides and heavy pruning to remove infected stems. Tree death can occur in the eastern US within 5 years of exposure to the systemic fungus.
The more recently developed cultivars ‘Santiam’, ‘Yamhill’, ‘Jefferson’, ‘Dorris’, ‘Wepster’, and ‘McDonald’ and their associated pollenizers are protected from EFB by a single resistance gene conferred from Corylus avellana ‘Gasaway’. This gene provides a high level of resistance in Oregon and Washington where the diversity of the fungus is limited (Muehlbauer et al., 2019), but does not provide a similar level of protection from disease in the eastern US where the pathogen is endemic and genetically diverse (Capik and Molnar, 2012; Molnar et al., 2010a, 2010b; Muehlbauer et al., 2018). ‘Hunterdon’ hazelnut is highly tolerant to EFB but does not carry the single ‘Gasaway’ resistance allele. It was developed by crossing two unrelated Corylus avellana plants both exhibiting a high level of tolerance and then selecting offspring exhibiting enhanced levels of tolerance in the presence of high disease pressure in East Brunswick, N.J. While ‘Hunterdon’ plants are not immune to EFB, they have been shown to rarely get destructive stem cankers that lead to stem die-back and yield decline.
In a multi-year trial in East Brunswick, N.J., completed in winter 2018 and spanning more than 8 years of exposure to EFB, the average proportion of diseased wood (total length of EFB-diseased stems per tree divided by total length of shoot growth) for ‘Hunterdon’ was 2.2% compared to 20.4% for ‘Yamhill’ (unpatented, Mehlenbacher et al., 2009), 31.2% for ‘Jefferson’ (unpatented, Mehlenbacher et al., 2011a), and 48.6% for ‘Gasaway’ (unpatented). Previous studies in New Jersey showed the proportion of diseased wood of ‘Barcelona’ to be 67.0%, ‘Tonda di Giffoni’ 39%, and ‘Sacajawea’ 21% (Capik and Molnar, 2012).
Differences were also observed in the number of cankers and average canker length for ‘Hunterdon’ in comparison to ‘Yamhill’, ‘Jefferson’, and ‘Gasaway’ in the study completed in 2018. ‘Hunterdon’ exhibited an average of 5.7 cankers per tree with an average canker length of 14.8 cm. In contrast, ‘Gasaway’ exhibited an average of 93.0 cankers per tree with an average length of 130.8 cm, ‘Jefferson’ exhibited an average of 36.9 cankers per tree with an average length of 72.3 cm, and ‘Yamhill’ exhibited an average of 40.5 cankers per tree with an average length of 37.9 cm. As reported in Capik and Molnar (2012), and as a further point of comparison in regard to EFB response, ‘Barcelona’ exhibited an average of 20.4 cankers per tree with an average length of 61.9 cm, ‘Tonda di Giffoni’ exhibited an average of 39.0 cankers per tree with an average length of 24.5 cm, and ‘Sacajawea’ exhibited an average of 7.7 cankers per tree with an average length of 21.5 cm (Capik and Molnar, 2012). While ‘Sacajawea’, a cultivar known to be tolerant to EFB, exhibits relatively similar canker numbers per tree and just slightly greater average canker lengths to ‘Hunterdon’, its proportion of diseased wood is much higher at 21.0% compared to 2.2%.
Nut and kernel characteristics: ‘Hunterdon’ hazelnut is targeted for the blanched kernel market and specifically for nut production in the eastern United States in USDA Plant Hardiness Zones 6a to 7b where most existing cultivars of Corylus avellana cannot be grown due to the impacts of EFB.
The nut shape is globular and slightly compressed along its depth. Kernels are mostly globular although some are slightly oblong. The average single nut weight over the past 6 years for ‘Hunterdon’ is 2.74 g, average single kernel weight is 1.24 g, with an average kernel to nut ratio of 45.5% (
‘Hunterdon’ kernels are smaller than those of ‘Barcelona’, ‘Jefferson’, and ‘Sacajawea’, and also differ in kernel to nut ratio. For example, ‘Barcelona’ (as described in Mehlenbacher et al., 2008), had an average single nut weight of 3.85 grams, average single kernel weight of 1.66 grams, and an average kernel to nut ratio of 43.1%. ‘Sacajawea’ (as described in Mehlenbacher et al., 2008) had an average single nut weight of 2.79 grams, an average single kernel weight of 1.45 grams, and an average kernel to nut ratio of 52.1%. ‘Jefferson’ (as described in Mehlenbacher et al., 2011a) had an average single nut weight of 3.69 grams, an average single kernel weight of 1.66 grams, and an average kernel to nut ratio of 42.9%.
‘Hunterdon’ kernels are slightly larger than ‘Yamhill’ and ‘Wepster’ and similar to ‘McDonald’ but differ from the three in several aspects including ratio of kernel to nut and pellicle removal after roasting. For example, ‘Yamhill’ (as described in Mehlenbacher et al., 2009), had an average single nut weight of 2.34 grams, an average single kernel weight of 1.13 grams, and an average kernel to nut ratio of 49.3%. ‘Wepster’ (as described in Mehlenbacher et al., 2014) had an average single nut weight of 2.39 grams, an average single kernel weight of 1.11 grams, and an average kernel to nut ratio of 46.6%. ‘McDonald’ (as described in Mehlenbacher et al., 2016) had an average single nut weight of 2.39 grams, an average single kernel weight of 1.21 grams, with an average kernel to nut ratio of 50.7%.
Raw kernels of ‘Hunterdon’ have a light brown pellicle with a very small amount of attached fiber (average rating was 1.3 on a scale of 1 [no fiber] to 4 [much fiber] with average based on 4 years of evaluations). Pellicle removal after roasting at 150° C. for 15 min and rubbing is rated on a scale of 1 (complete pellicle removal) to 7 (no pellicle removal). ‘Hunterdon’ exhibits excellent pellicle removal, which can be highlighted as one of the traits that differentiates it from most existing cultivars. Nearly all the pellicle is removed after roasting with an average rating of 1.0 (averaged from 4 years of evaluations). ‘Hunterdon’ demonstrated better average pellicle removal than that reported in Oregon for ‘Barcelona’ (4.2 out of 7.0 as described in Mehlenbacher et al., 2008), ‘Jefferson’ (3.9 out of 7.0 as described in Mehlenbacher et al., 2011a), ‘Yamhill’ (4.1 out of 7.0 as described in Mehlenbacher et al., 2011a), ‘McDonald’ (3.8 out of 7.0 as described in Mehlenbacher et al., 2016), ‘Sacajawea’ (2.9 out of 7.0 as described in Mehlenbacher et al., 2011), and ‘Dorris’ (2.4 out of 7.0 as described in Mehlenbacher et al., 2013). It is similar to ‘Tonda Pacifica’ as described in Mehlenbacher et al. (2011), which is reported to have a score of 1.5 out of 7.
The average percentage of good kernels (kernels free of defects) were calculated for ‘Hunterdon’ and found to be 83.8%. There was an average of 3.8% moldy kernels, 3.0% blank nuts, 2.5% nuts with shriveled kernels, 1.0% poorly filled, and 5.8% defective kernels attributed to defects from sucking insect damage, primarily Brown Marmorated Stink Bug (Halyomorpha halys, Stål, 1855). The percentage of good kernels for ‘Hunterdon’ was considerably higher than that reported for ‘Barcelona’ in multiple reports from Oregon (60.9% good kernels reported in Mehlenbacher et al. [2008] and 69.4% in Mehlenbacher et al. [2013]). The average percentage of good kernels for ‘Hunterdon’ grown in New Jersey was around the range reported in Oregon for ‘Yamhill’, ‘Jefferson’, ‘Dorris’, and ‘McDonald’. There were few twin kernels observed for ‘Hunterdon’ (0.25%) and no occurrences of black tips.
Nut maturity date: The nuts of ‘Hunterdon’ are typically borne in clusters of 2-3 in husks about 50% longer than the nuts. The husks are flared at the tip (
Incompatibility and pollinizers: The trees set a moderate to high amount of catkins that shed pollen in early mid-season a few days prior to ‘Yamhill’. Pollen has been collected and used in several controlled pollinations, and both quantity and viability appear to be good. ‘Hunterdon’ has incompatibility alleles S1 and S3 as determined by fluorescence microscopy. Both alleles are expressed in the female flowers. S3 is expressed in the pollen because of dominance. By convention, alleles expressed in the pollen are underlined.
Time of pollen shed and female receptivity were recorded weekly from early December 2017 to late March 2019 (
Pests and diseases: Based on field trials under high disease pressure and greenhouse inoculation trials, both performed in New Jersey, ‘Hunterdon’ expresses a very high level of tolerance to EFB (quantitative resistance). Fungicide applications are not expected to be needed. Small cankers that may develop can be removed through pruning to reduce inoculum load in production orchards.
Susceptibility to bacterial blight caused by Xanthomonas campestris pv. corylina has not been quantified, but the original seedling tree and clonal trees in the replicated trials were not affected.
Susceptibility to big bud mite (primarily Phytoptus avellanae Nal.) has not been quantified, but the original tree and trees in the replicated trials were not affected.
Propagation: Layers of ‘Hunterdon’ are vigorous and root well, similar to standard cultivars of Corylus avellana.
References:
Capik, J. M. and T. J. Molnar. 2012. Assessment of host (Corylus sp.) resistance to eastern filbert blight in New Jersey. J. Amer. Soc. Hort. Sci. 137:157-172.
Capik, J. M. and T. J. Molnar. 2014. Flowering phenology of eastern filbert blight-resistant accessions in New Jersey. HortTechnology 24:196-208.
Mehlenbacher, S. A., M. M. Thompson, and H. R. Cameron. 1991a. Occurrence and inheritance of resistance to eastern filbert blight in ‘Gasaway’ hazelnut. HortScience 26:410-411.
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