‘Zuni’ is a new pecan (Carya illinoinensis) cultivar released and patented by the U.S. Department of Agriculture–Agricultural Research Service (USDA-ARS). ‘Zuni’ was released because of its large nuts in medium-size clusters; well-filled, cream-color kernels; medium precocity; and high resistance to scab disease (causal agent: Venturia effusa) in a test orchard in Brownwood, TX. However, ‘Zuni’ has only been monitored in orchards with limited scab pressure in central Texas and has not been observed under all environmental conditions and cultural practices. Therefore, some of its characteristics may differ outside of central Texas or with different management practices. ‘Zuni’ is one of the first three pecan cultivars patented by the USDA-ARS (U.S. Patent Application Serial No. 17/668127) (Grauke et al. 2022; Wang et al. 2022a). Parties interested in licensing ‘Zuni’ should contact license@usda.gov with any questions. Graftwood will only be distributed to licensees.
The USDA-ARS Pecan Breeding and Genetics Program conducts a national pecan breeding program and releases superior control-crossed pecan cultivars for all pecan-growing regions (Grauke 2019; Grauke et al. 2016; Thompson and Grauke 1991; Thompson and Hunter 1985). Crosses are made in both Brownwood and College Station, TX. Seedling trees are established on their own roots in basic breeding program orchards for initial evaluation of growth, disease, flowering, and nut yields (> 7 years). Then, controlled-cross seedlings that show potential are identified and grafted into a new National Pecan Advanced Clone Testing System (NPACTS) orchard for further evaluation. In general, an NPACTS orchard includes six blocks of trees containing five to six grafted clones of ∼30 breeding selections and three to five standard cultivars arranged in a completely randomized block design. After several years, the superior clones are given Native American tribal names and are released to nurseries and growers. ‘Zuni’ is one of first three patented USDA cultivars (Grauke et al. 2021; Wang et al. 2022b). The Zuni people are one of 19 Native American Pueblo tribes and are native to the Zuni River valley in the northwestern corner of the state of New Mexico. ‘Zuni’ is expected to perform well across all growing regions, but may perform best in the central and western growing regions.
Description
Origin
‘Zuni’, tested as 1996-01-0295, is a progeny of a cross between the ‘Pawnee’ (female parent) and ‘Waco’ (male parent) pecan cultivars in College Station, TX (Fig. 1). The USDA-ARS Pecan Breeding Program released ‘Pawnee’ in 1984 (Thompson and Hunter 1985) because of its early maturation (in the latter half of September). ‘Pawnee’ is protandrous with early- to midseason pollen shed and mid- to late-season pistillate receptivity. ‘Pawnee’ has elliptical nuts with an obtuse apex, a rounded base, and golden kernels. ‘Waco’ was released cooperatively by the USDA-ARS and the Texas Agricultural Experiment Station in 2005 (Thompson et al. 2005). ‘Waco’ is protandrous with early- to midseason pollen shed and midseason pistillate receptivity (similar to ‘Caddo’ and ‘Cheyenne’). ‘Waco’ has medium precocity, similar to ‘Pawnee’. Both ‘Pawnee’ and ‘Waco’ are susceptible to pecan scab disease. ‘Zuni’ was grown initially in College Station, TX, from 1997 to 2006 and was selected in 2007 for further testing because of its high nut quality and early nut maturity. ‘Zuni’ has been evaluated most extensively in orchards of the USDA-ARS NPACTS in Brownwood, TX, in a test with a completely randomized block design with six replicates of 49 breeding selections and three standard cultivars (Kanza, Pawnee, and Wichita) (Sparks 1992; Thompson and Hunter 1985; Thompson et al. 1996).
Parentage of ‘Zuni’. The upper branch depicts the known ancestry of the female parent. The lower branch depicts the known ancestry of the male parent. The breeder or contributor is listed in parentheses along with the date of origin.
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
Parentage of ‘Zuni’. The upper branch depicts the known ancestry of the female parent. The lower branch depicts the known ancestry of the male parent. The breeder or contributor is listed in parentheses along with the date of origin.
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
Parentage of ‘Zuni’. The upper branch depicts the known ancestry of the female parent. The lower branch depicts the known ancestry of the male parent. The breeder or contributor is listed in parentheses along with the date of origin.
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
Tree form and foliage.
‘Zuni’ has a tall, upright tree form with an average height of 13.66 m at 15 years after grafting, with a narrow canopy (height-to-width ratio, 1.46) (Fig. 2A). The mature tree trunk has a scaly texture and light-olive-gray bark (Fig. 2B). Its dark forest-green leaves are comparable in color to ‘Pawnee’ and are arranged in an odd pinnately compound opposite orientation. Leaflet orientation is similar to most pecan trees, in which the opposite leaflet pairs are oriented about 45° from the rachis (Fig. 2C).
‘Zuni’ pecan tree, leaves, and flowers. (A) Canopy structure of a 9-year-old tree after grafting on an open-pollinated ‘Apache’ seedling rootstock in 2007 (Brownwood, TX, 29 Oct 2015). (B) Mature tree trunk with scaly texture and light-olive-gray bark (2.5Y 5/2) (MUNSELL Plant Tissue Color Book 2012 Revision, 2018) (7 Apr 2021). (C) Leaf architecture at 15 years after grafting (Brownwood, TX, 4 Jun 2021). (D) Yellowish green staminate catkin (2.5GY 6/10) (29 Apr 2021). (E) Moderate-red pistillate flower (5R 3/4) (13 May 2021).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
‘Zuni’ pecan tree, leaves, and flowers. (A) Canopy structure of a 9-year-old tree after grafting on an open-pollinated ‘Apache’ seedling rootstock in 2007 (Brownwood, TX, 29 Oct 2015). (B) Mature tree trunk with scaly texture and light-olive-gray bark (2.5Y 5/2) (MUNSELL Plant Tissue Color Book 2012 Revision, 2018) (7 Apr 2021). (C) Leaf architecture at 15 years after grafting (Brownwood, TX, 4 Jun 2021). (D) Yellowish green staminate catkin (2.5GY 6/10) (29 Apr 2021). (E) Moderate-red pistillate flower (5R 3/4) (13 May 2021).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
‘Zuni’ pecan tree, leaves, and flowers. (A) Canopy structure of a 9-year-old tree after grafting on an open-pollinated ‘Apache’ seedling rootstock in 2007 (Brownwood, TX, 29 Oct 2015). (B) Mature tree trunk with scaly texture and light-olive-gray bark (2.5Y 5/2) (MUNSELL Plant Tissue Color Book 2012 Revision, 2018) (7 Apr 2021). (C) Leaf architecture at 15 years after grafting (Brownwood, TX, 4 Jun 2021). (D) Yellowish green staminate catkin (2.5GY 6/10) (29 Apr 2021). (E) Moderate-red pistillate flower (5R 3/4) (13 May 2021).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
Flowering.
‘Zuni’ is monoecious, anemophilous, and has a protandrous or type I bloom pattern comparable to its seed parent, ‘Pawnee’ (Thompson and Hunter 1985). ‘Zuni’ has yellowish green staminate catkins (Fig. 2D) that have an early- to midseason pollen shed (Table 1). It should be a good pollinizer for and be well pollinized by ‘Wichita’ and ‘Lakota’. It usually bears one to four alternately positioned pistillate flowers per pedicel spike that have mid- to late-season pistillate receptivity (1–10 May 2021 in Brownwood, TX) (Table 1). ‘Zuni’ has pistillate flowers with reflexed, moderate-red stigmas (Fig. 2E), similar to its seed parent ‘Pawnee’, but contrasting to the green stigmas of its male parent ‘Waco’. Its pistillate stigmas have mid- to late-season receptivity (Table 1). On average, spring budbreak for ‘Zuni’ was in late March in Brownwood, TX, a few days after ‘Wichita’ and a few days before its seed parent ‘Pawnee’ (Table 1). No damage was observed from the prolonged freeze in early Feb 2021 in central Texas.
Budbreak, pollen shedding, and stigma receptivity of ‘Zuni’ and three standard pecan cultivars in the U.S. Department of Agriculture– Agricultural Research Service National Pecan Advanced Clone Testing System orchard in Brownwood, TX.
Scab disease resistance.
‘Zuni’ exhibited minimal susceptibility to scab disease, caused by the fungal pathogen V. effusa, within our unsprayed orchards in Brownwood, TX. Brownwood, TX, occurs in a geographic area that has greater scab disease pressure under specific weather conditions, which makes it suitable for assessing leaf and nut scab susceptibility. Both its seed parent, ‘Pawnee’, and pollen parent, ‘Waco’, have moderate-to-severe scab susceptibility (Thompson and Hunter, 1985; Thompson et al. 2005). Within our Brownwood orchard from the years 2010–12 and 2015, ‘Wichita’ showed severe leaf scab disease symptoms (Hunter-Roberts scale = 5) (Hunter and Roberts 1978), whereas most other cultivars, including ‘Pawnee’, ‘Kanza’, and ‘Zuni’, showed little to no leaf scab disease symptoms (Table 2). From 2015 to 2017, we observed the expected levels of nut scab disease for the known susceptible varieties (‘Pawnee’ and ‘Wichita’) in that orchard, whereas ‘Zuni’ continued to demonstrate scab resistance. The greatest nut scab disease severity, measured as a percentage of disease coverage per the total amount of nut tissue area, observed during that period for ‘Zuni’ was only 1.38% on the standard area diagram scale of 1% to 100% (Yadav et al. 2013), comparable to the scab-resistant cultivar Kanza at 1.42%. The worst nut scab disease severity observed on ‘Pawnee’ and ‘Wichita’ in that period was 30.89% and 91.51%, respectively (Table 2). This supports ‘Zuni’ having a greater resistance to nut scab disease than its maternal parent ‘Pawnee’ and another susceptible control cultivar. We observed low nut scab disease severity (1.5%) in ‘Zuni’ in the Brownwood orchard in 2015–17. This limited testing in an environment with lower to modest scab pressure indicates ‘Zuni’ may have good levels of scab resistance. However, given its pedigree and limited testing, growers in more scab-prone areas should be prepared to spray fungicides if it becomes necessary.
Comparison of average leaf and fruit scab susceptibility of ‘Zuni’ and three standard cultivars in the U.S. Department of Agriculture–Agricultural Research Service National Pecan Advanced Clone Testing System unsprayed orchard in Brownwood, TX.
Nuts.
‘Zuni’ has consistently produced large, high-quality nuts, even under limited irrigation, that mature early and are ready to harvest in early October in central Texas. In Brown County, TX, ‘Pawnee’ nuts mature in late September, and nuts from the pollen parent, ‘Waco’, mature in mid-October (Thompson et al. 2005). On average, from 2009 to 2018 (no data in 2013), ‘Zuni’ nuts matured around 3 Oct, 10 d later than ‘Pawnee’ (Table 3). ‘Zuni’ nuts are oval–elliptic in shape and are compressed laterally, as in ‘Pawnee’. The average nut weight is 9.5 g for ‘Zuni’, compared with 8.5 g for ‘Pawnee’ and 7.1 g for ‘Wichita’. The average number of nuts per kilogram is 107.4 for ‘Zuni’, compared with 120.5 for ‘Pawnee’ and 148.1 for ‘Wichita’ (Table 4). ‘Zuni’ has, on average, a wider nut than its seed parent, ‘Pawnee’ (22.76 vs. 21.43 mm). ‘Zuni’ kernels are consistently a light cream color with wide, shallow dorsal grooves that do not trap packing material (Fig. 3B). ‘Zuni’ averages 56.2% kernel compared with ‘Pawnee’, which has an average of 59.14% kernel with a golden color, and ‘Kanza’, which has 52.83% kernel with a golden color in the same NPACTS orchard in Brownwood, TX (Table 4).
‘Zuni’ pecan nuts. (A) Nut clusters (20 Aug 2018). (B) Nut quality panel (19 Jan 2016).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
‘Zuni’ pecan nuts. (A) Nut clusters (20 Aug 2018). (B) Nut quality panel (19 Jan 2016).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
‘Zuni’ pecan nuts. (A) Nut clusters (20 Aug 2018). (B) Nut quality panel (19 Jan 2016).
Citation: HortScience 57, 11; 10.21273/HORTSCI16827-22
Average nut clusters and maturation of ‘Zuni’ and three standard cultivars in the U.S. Department of Agriculture–Agricultural Research Service National Pecan Advanced Clone Testing System orchard in Brownwood, TX, from 2009 to 2017.
Nut characteristics of ‘Zuni’ and three standard cultivars in the U.S. Department of Agriculture–Agricultural Research Service National Pecan Advanced Clone Testing System orchard in Brownwood, TX, from 2009 to 2018 (2–11 years after grafting to open-pollinated ‘Apache’ rootstocks).
Nut yield.
‘Zuni’ averages 2.32 nuts/cluster (Table 3), compared with 2.99 for ‘Kanza’, 3.28 for ‘Pawnee’, and 3.31 for ‘Wichita’ (Table 3), indicating ‘Zuni’ has a medium-size cluster. In the sixth leaf year after grafting, ‘Zuni’ bore 7.28 kg dry weight of nuts, compared with 3.75 kg for ‘Kanza’, 9.60 kg for ‘Pawnee’, and 10.60 kg for ‘Wichita’ (Table 5). Based on the yields from 2009–12 (2–6 leaf years after grafting), ‘Zuni’ showed a medium alternate bearing tendency (0.73), slightly greater than ‘Pawnee’ and ‘Kanza’ but less than ‘Wichita’ in the test orchard in Brownwood, TX. This alternate bearing tendency was also observed when the tree became older (data not shown because tree nuts were not harvested individually) based on the terminals with cluster, nuts per cluster, and nut samples (Table 3). However, alternate bearing in pecan has been shown to vary with differing management practices such as fungicide applications to control scab in eastern pecan orchards (Conner and Worley 2000) or tree hedge pruning in western pecan orchards where there is no scab pressure (Wood and Stahmann 2004). The greater alternate bearing tendency of ‘Wichita’ may be caused by its greater scab susceptibility and lack of scab management in the test orchard alongside limited irrigation.
Average dry nut yield (kg/tree) of ‘Zuni’ and three standard cultivars growing in the U.S. Department of Agriculture–Agricultural Research Service National Pecan Advanced Clone Testing System orchard in Brownwood, TX, from 2009 to 2012 (2–5 years after grafting open-pollinated ‘Apache’ rootstocks).
Availability
‘Zuni’ is patent pending. The USDA Pecan Breeding and Genetics Program staff cannot discuss licensing terms with prospective licensees but can discuss the trees. The USDA does not have trees for distribution. Graftwood is currently being grown and will be distributed to licensees in Jan 2023. Parties interested in licensing ‘Zuni’ can visit https://www.ars.usda.gov/ott/licenses-section-folder/licensing-process/ for more information on the licensing process or contact license@usda.gov with any questions. It is requested that appropriate recognition be made if this germplasm contributes to developing a new variety.
References
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Grauke, L.J 2019 Family trees: Generations and propagations Pecan South Mag. 52 6 25
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Grauke, L.J., Thompson, T.T. & Madden, G.D. 2022 Pecan tree named ‘Zuni’ U.S. Patent Application Serial No. 17/668127. U.S. Patent and Trademark Office
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