WALNUT IMPROVEMENT PROGRAM 2006 Gale McGranahan, Chuck Leslie, Diego Bujazha, Nicolas Manterola, Soussan Hirbod, Abhaya Dandekar, Malli Aradhya, Bob Beede, Bill Olson, Kathy Kelley Anderson, Joe Grant, Monica Britton, Janet Caprile, and Bill Coates ABSTRACT The goal of the Walnut Improvement Program is to provide new cultivars of walnut to the California walnut industry while developing new knowledge and maintaining a breeding population. We also work with collaborators to develop new rootstocks and propagate them. This year we have over 17 thousand seedlings and selections in the program. Almost 10,000 are half sibs from selections at the Kearney selection block. Early harvest is a primary goal and several selections with Payne-time harvest dates are promising. These are 91-77-6, 91-90-41, 94-19-85, 94-20-28, 94-20-35 and 95-11- 14. We are seeking locations for field trials with them. Ten of our backcross selections for hypersensitivity to blackline are in field trials. Somatic embryos from a controlled cross between wingnut and walnut were initiated again this year. Plants initiated last year are being acclimatized and grown to verify parentage. Controlled crosses between Idaho and Chandler were made again this year to increase the population for developing a DNA map of traits of walnuts. OBJECTIVES The objectives of the Walnut Improvement Program are: to provide the California walnut industry with genetically superior walnut cultivars and rootstocks to develop knowledge that will increase the efficiency of walnut breeding to develop and maintain an array of traits available for breeding in the future The program consists of several projects with specific objectives: The classical cultivar breeding project uses traditional methods to develop and release new cultivars that combine precocity (high early yield) and early harvesting with kernel quality, in-shell traits, and disease resistance. The backcross breeding project is designed to introduce resistance to blackline disease from the Northern California black walnut into a commercially acceptable English walnut cultivar. Rootstock improvement objectives include development of selections with genetic resistance to Phytophthora, nematodes, and crown-gall and are done in conjunction with the clonal rootstocks improvement project. New technologies that increase the efficiency of breeding and the scope of genetic material available for walnut improvement continue to be evaluated and adapted to walnut breeding as opportunities arise. Germplasm collections are maintained and augmented when possible for future breeding use and are available for other researchers.
PROCEDURES Breeding program. The procedures for the breeding program have changed as the advanced generation selections have matured and become available as parents. In 2004 and 2005 we collected nuts from the selected parents at the Kearney Agricultural Center to produce half sib families. In 2005 the following were the selected female parents: 90-31-10, 91-76-24, 91-90-41, 93-26-6, 94-19-45, 94-20-35, 95-7-6, 95-11-14, and 95-22-26. In 2006 we made controlled crosses instead of collecting open-pollinated (OP) seed because the family size required for OP seedlings is prohibitive. In all cases, they are close planted and any that appear to be terminal bearers or have any of the signs of inbreeding (dwarfs, extra lates, etc.) are culled at about age 3. If no nuts have been produced by age 5 (under good growing conditions) they are also cut down. Full evaluations are only done on precocious and laterally fruitful individuals. This is similar to the methods we used for the supplemental pollination families (see previous reports). Surviving seedlings are evaluated for phenology (leafing, flowering and harvest dates), precocity, lateral fruitfulness, estimated yield, blight incidence, and crack-out characteristics (shell shape, texture, thickness and strength, kernel weight, percent kernel, and kernel color, fill, plumpness and ease of removal in halves). Data is evaluated at the annual crackout evaluation meeting that includes growers, processors, nurserymen, and farm advisors. Participants inspect kernel boxes and data sheets to identify possible selections. Data available includes current year field and crack-out data, performance data from past years, Diamond evaluations and computer-assisted selection. Team evaluations are followed by a general group discussion of each team s recommendations. Promising individuals are repropagated into three selection blocks (Chico, Kearney and Davis) and grower trials where evaluations continue. The off-campus selection blocks are under the control of the Bill Olson (Chico) and the Kearney field staff. Grower field trials are an essential component of releasing a new cultivar. We have increased the number of field trials in the last few years. (See Description of selections in this report). Backcross breeding for hypersensitivity to cherry leafroll virus. The backcross breeding project is designed to introduce resistance to blackline disease from the Northern California black walnut into a commercially acceptable English walnut cultivar. Crosses are conducted using the same methods as in conventional cultivar breeding but the selection process is different. The first backcross cull is based on shell thickness and percent kernel; those exhibiting the black walnut shell characteristics are discarded. Those that are promising are tested by PCR for hypersensitivity to the cherry leafroll virus as reported in Walnut Research Reports (1998) and modified recently (see WRR 2003). Marker selection has been improved but has a 10% chance of error. As potential parents and selections advance in the program, there is a need for more stringent testing for hypersensitivity. The screening method used is as described in previous papers: a selection is grafted on both black and English rootstock (two each); after the graft is established, bark from our CLRV-source trees is patched into the English rootstock or into the selection depending on the rootstock species. If the selection is hypersensitive it will survive on the black rootstock because the inoculum patch was rejected, and die (exhibiting a black line) on the inoculated English rootstock. Confirmed
hypersensitive, thin-shelled individuals with the best commercial traits are then used as parents for the next generation of backcrosses to an English walnut parent. Rootstock improvement Rootstock breeding is aimed at producing selections with genetic resistance to Phytophthora, nematodes, crown-gall, and environmental stress while retaining or enhancing the vigor of hybrid rootstock. The limiting factor in developing improved rootstocks had been the absence of a commercially viable clonal propagation method but this has been overcome for many rootstock selections (see Clonal Propagation report). We attempted to initiate new somatic embryo cultures again this year from control-pollinated wingnut-walnut hybrids. This requires very early-season pollen. Gustine pollen was collected and used in mid-march to pollinate bagged flowers of three wingnut accessions (DPTE 1.09, DPTE10.01, DPTE 10.05) at the USDA Clonal Germplasm Repository in Winters. Seeds were collected in early May before shell hardening and were surface sterilized with 15% Clorox for 10 minutes. Zygotic embryos were excised and cultured in vitro on both DKW basal medium and DKW shoot medium. New technology for genetic improvement of walnut This part of the Walnut Improvement Program includes tissue culture, PCR, and isozyme analysis in support of genetic improvement as well as gene transfer and field-testing of transgenic plants. Current laboratory work includes micropropagation, use of DNA marker selection in backcrossing, and improvements in somatic embryogenesis. In 2005 vector pde00.0201, developed by Matt Escobar in the Dandekar lab, was used to insert crown gall resistance into additional rootstock genotypes expected to be more amenable to propagation than those previously employed. Somatic embryos of three genotypes (J1, J21 and RR4) which we had previously developed were used for this work. The vector, designed to silence the gall forming ipt and iaam genes of wild-type Agrobacterium, were inserted into these genotypes using the somatic embryo transformation procedure we previously developed and have reported. Transformants were selected on 200 mg/l kanamycin medium and germinated to generate microshoot lines for rooting and field trials. Forty independent lines plus controls have been identified as transformed by marker gene expression and are being propagated for a field trial on campus to test the proof of concept. In addition lines have been produced for crown gall screening by Dan Kluepfel. We continue to maintain somatic embryo and microshoot cultures of 12 genotypes exhibiting altered expression of shikimate dehydrogenase (SDH), an enzyme in the shikimate pathway that regulates gallic acid production. This gene is of interest for its effect on aflatoxin resistance. Rooting and acclimatization of these genotypes in the greenhouse is complete and they will be maintained in large pots in a lath house. Transgenic trees in field trials or in large pots are now at bearing age and transgenic trees with the following genes continue to be observed and evaluated: Bt - insect resistance (inoculation with codling moth) FAD - altered oil composition to avoid rancidity. PPO - altered phenolic composition to improve rooting and kernel traits.
NOTE: Transgenic walnuts are only grown on campus under USDA guidelines and catkins and nuts are removed. They are grown for proof of concept experiments. Germplasm resources Germplasm collections are maintained and augmented when possible for future breeding use and are available for other researchers. Current collections at Wolfskill and Davis include a diversity of California cultivars, leading cultivars and selections from around the world, material with unusual traits, and germplasm of interest for rootstock development. It differs in emphasis, content, distribution policy, and cultural practices from the USDA Germplasm Repository collection. Our major emphasis this year regarding germplasm was to determine the chilling requirements in Juglans regia germplasm. This was conducted under a Specific Cooperative Agreement between ARS and University of California, Davis. We used the methodology recommended by a recent workshop on standardizing methods for evaluating chilling requirements. Chilling was defined as hours under 45F. In early December, after the leaves had fallen and about 213 chill units had accumulated, 4 shoots, approximately one meter in length, were harvested from 12 genotypes of a diverse set of germplasm. After 200 hours of natural chilling another set was collected and so on until 1015 hours of chilling had accumulated. This was the maximum accumulated in 2005-2006. Items were chosen to represent terminal and lateral bearing habit, early, mid and late phenologies and reportedly low and high chill requirements. Shoots were placed at 22C under fluorescent lights (16h/8h) at 200-400μ mol m -2 s -1 in vessels of deionized tap water. Shoots were examined every several days and terminal bud break was recorded. The standard walnut descriptors were used to assess when bud break had occurred. The shoot bases were trimmed and water was changed every week. RESULTS AND DISCUSSION Cultivar breeding Three new walnut cultivars (varieties) were patented in 2006: Sexton, Gillet and Forde. These are characterized by high early yields, harvest dates before Chandler by 5-20 days, low blight scores and large light-colored kernels. They are described in more detail in a separate report (2004). It is interesting to note that as young grafted trees the harvest date is later than on more mature trees. This fits with the observation that the phenology of young trees advances to earlier in the season as a tree matures. Scionwood of these new varieties was distributed to 13 licensed nurseries and two randomized complete block field trials are underway with Joe Grant and Kathy Kelley. Currently we have 72 selections and our major focus is on getting earlier harvesting varieties. The most promising early selections are 91-077-6, 91-090-41, 94-019-85, 94-020-28, 94-020-35, and 95-011-14. Data on the selections are provided in Tables1-4. A description of each selection can be found at the end of this report. Seedlings under evaluation and selections are as follows:
Original Year Crosses Seedlings Selections Under Evaluation N N N N 1990 15 591 8 8 1991 18 493 9 9 1992 15 243 5 8 1993 14 116 2 3 1994 15 587 8 14 1995 15 758 19 32 1996 7 333 1 2 1997 13 611 12 28 1998 5 1759 7 102 1999 1 993 1 9 2000 12 2503-542 2001 16 210-114 2002 5 1200-1200 2003 11 4608-4608 2004 7 hs ** 6000-6000 2005 9 hs 3332-3332 2006 22 954-954 Totals 200 25291 72 10286 ** hs denotes half sib families Backcross breeding for hypersensitivity to cherry leafroll virus. Backcross breeding to develop an English walnut with a hypersensitive response to the cherry leafroll virus is proceeding ahead of schedule. We continue to test backcross seedlings for both nut quality and virus resistance and currently have approximately 670 seedlings under active evaluation. Attributes of the most commercially viable of the current backcross selections are listed in Table 5. Three backcross hypersensitive selections (92-16-1, 95-29-4 (tolerant, see below), 97-27-55) have been propagated by Dave Wilson Nursery and have been established in a field trial with Janet Caprile in Contra Costa County. Bill Coates also has these selections as well as 93-45-1, 95-27-19, 95-27-38, 95-27-55, 96-17-12, 96-27-8, 97-27-24, 98-17-44. They will be used to evaluate hypersensitivity after exposure to CLRV-infested pollen as well as commercial traits. One selection 95-29-4 in both trials has tested hypersensitive in the DNA test and tolerant in the bark test. In 2001 we started a new testing block for final confirmation of hypersensitivity by bark patch testing. Additional selections were added in 2002-2005 to a total of 81. Patches were checked for blackline formation this year and 18 tested hypersensitive, 49 were tolerant, and 14 were not yet ready to score. Only one selection that had tested hypersensitive by DNA appeared to be tolerant and one had inconclusive results. A total of 55 additional backcross trees that have been identified as hypersensitive by DNA testing are being added to the patch test block to confirm the DNA results.
Rootstock improvement A number of potential rootstock selections have been identified in the past and are maintained and micropropagated in the laboratory for confirmation testing and field trials (See Hackett et al. report). This material includes tolerant backcross selections (vigorous, CLRV tolerant), several Phytophthora survivors from growers orchards, PDS selections for crown gall, nematode, and Phytophthora resistance. Wingnut x walnut hybrid seed cultured in vitro at an early stage, while the shells were still soft, did not develop well again this year. Embryos were initiated on both basal medium and shoot medium, both of which work for walnut, but the embryos are much smaller than walnut and apparently require supplementary hormones for initial development if initiated at this early stage. The wingnut DPTE10.05 x (Gustine or UC86.011) embryo line (WNBxGRZ1) produced last year was germinated and microshoots were rooted and acclimated in the greenhouse. The plants are phenotypically hybrid and will be observed further in the greenhouse. An additional somatic embryo derived shoot line (DPTE 10.05 B) is phenotypically wingnut and is being propagated for use as a control in Phytophthora testing. New technology for genetic improvement of walnut Three new paradox genotypes (J1, J21, and RR4 ) thought to be easier to culture and propagate than existing lines were used to develop 40 new independent lines containing the construct for crown gall silencing. We used the same vector employed in the earlier lines to transform somatic embryos. Following selection of successful inserts on kanamycin medium and development of multiplying non-chimeric lines, embryos of each line were germinated. A total of 21 J1, 7 J21 and 12 RR4 shoot lines were developed and multiplied, along with controls, for rooting. Preliminary testing of in vitro material indicated that the gene is effective. Thirty three of these lines were tested for crown gall resistance by infecting 20 or more 1 cm length stem pieces of each transgenic line and several control lines using a wild-type Agrobacterium strain (20W5A). An additional 20 or more segments of each line were infected with a disarmed Agrobacterium strain (EHA101). Shoot pieces of controls exposed to the active Agrobacterium strain were extensively galled while shoot segments of twenty three of the transgenic lines showed no galling at all when exposed. Four transgenic lines exposed to 20W5A did show galling, indicating the inserted DNA was not effectively expressed. Another 6 showed ambiguous results, with either a few weak galls or some background callus, and will require further testing. Transgenic and control lines exposed to the disarmed Agrobacterium control showed no galling that could be distinguished from background callus. All lines and controls were then propagated, rooted, and established as plants in the greenhouse for further testing. The non-expressing transgenic lines were included for use as controls and to confirm that laboratory results are indicative of field results. Rooting and acclimatization of shoots of all of these lines was accomplished this year and the first set of plants has been tested by Kluepfel. A second set is being prepared for Janine Hasey for greenhouse screening, another for an on-campus field trial and a fourth set is being grafted to
determine whether there is transmission of the genes or gene products across the graft union. Rooting and acclimatization in the greenhouse of genotypes exhibiting altered expression of shikimate dehydrogenase (SDH), an enzyme in the shikimate pathway that regulates gallic acid production, is in progress so they can be used to study gallic acid production in nuts and its role in insect and disease resistance. To date, 57 plants from 14 of these genotypes have been fully acclimated in the greenhouse and several flowered this year. They have been chilled and will be maintained in large pots in a lath house for further analysis of gene expression and observation of phenotype and gene efficacy. Mature Chandler trees expressing the BT gene have shown good efficacy in tests conducted by the USDA and their field plot is in the process of being removed. The trees in the UC collection continue to be hedged to prevent flowering and are being held on campus to be available for future work if desired. Transgenic lines expressing or silencing the polyphenol oxidase gene, thought to play a role in rootability and kernel traits, FAD genes modifying oil composition, genes regulating gallic acid production for aflatoxin reduction, and genes regulating adventitious shoot and somatic embryo production are being maintained for use in further studies. A cross of Chandler x Idaho was made during the last three years to generate a population for developing markers for marker-assisted breeding. The parents were chosen to develop a seedling population that segregates for as many important traits as possible (kernel color, phenology, lateral bearing, shell appearance, protogyny/protandry, insect resistance, blight). An additional cross may be needed this year to further increase the population size to 200. Trees from the first year of crossing were planted in the field in 2004 and will be evaluated for horticultural traits as they mature over the next several years. Additional trees from this year s cross have been germinated and will be planted in the spring. DNA from these trees will eventually be used to develop map of the traits in the walnut genome and to develop markers for more efficient selection in breeding. Germplasm resources/chilling We continue to maintain a collection of in vitro germplasm for use by the Walnut Improvement Program, other cooperating researchers, and commercial labs and nurseries. We also maintain in vitro nematode population for use in nematode resistance research by the Dandekar lab and others. We introduced several new items into in vitro culture this year in support of other programs. These included UZ229, a PDS selection identified by McKenry with possible nematode resistance and Hartley for use in Brevaria research by Kleupfel s lab. Maintaining an in vitro germplasm collection is labor intensive and repetitive. In order to reduce costs and time committed to this activity we began to develop methods for cold storage of walnut shoots and somatic embryos. Part of this work is in cooperation with the USDA-ARS cryopreservation facility at FT. Collins, CO. We sent in vitro shoot cultures and somatic embryos for them to use in improving our existing liquid nitrogen storage protocol and they will attempt to develop methods for cryopreservation of both in vitro and field-grown shoots.
In order to extend the time interval between transfers of cultures to fresh medium we began experiments to test methods of maintaining cultures in refrigeration. It appears that we can extend the transfer interval for shoot germplasm from the current 3 weeks to at least 3 months by cold storage under fluorescent lights for 2 months followed by 1 month at room temperature. A similar approach for somatic embryos is being tested. In addition it appears that somatic embryos can be successfully desiccated for germination by placing them in a refrigerator in empty Petri plates containing no medium. This can replace the standard method of drying over saturated salts and somatic embryos remain viable for at least several months when stored this way. Chilling hours required to break bud in a varied set of germplasm accessions was studied. The maximum time an excised shoot could survive at 22C was 31days. All shoots showed a trend that as more chilling hours accumulated in the field fewer days at 22C were required to break bud (Fig. 1). The maximum chilling accumulated in the field was 1015 which might be too low for some genotypes but at this accumulation it took about 15 days at 22C to break bud even for the slowest. Genotypes grouped into 3 categories depending on how much chilling was required to result in bud break after 15 days at 22C. These categories closely correspond to their phenology in the field, i.e. early leafing genotypes required less chilling while later leafing genotypes required more Genotype Chilling hours required to break bud after 15 days at 22C Early Ehrhardt 627 Payne 627 Placentia 627 Serr 827 Tulare 984 Hartley 984 Cascade 1015 Chandler 1015 Fernor 1015 Howard 1015 S. Franquette 1015 XXX Mayette 1015
Description of Selections 2006. (*indicates most promising, indent indicates probable discard) Sexton (90-031-10) (Chandler x 85-008) (selected 2000): Kernels of this very precocious offspring of a Chandler x Chinese cross average 8.6 g. Color has been very good most years and was good again this. Nuts have smooth, round, solid shells and yield 53% kernel. Shells and seals can be weak in younger trees but were very good this year. The tree leafs a few days after Payne and harvest has varied from 1 to 2 weeks before Chandler. Yield has been excellent with little blight observed most years. Tree tends to have neck buds and narrowly forked branches. Pruning will be needed to set tree structure and to prevent possible stunting from early over-cropping. It maybe suitable for hedgerows where limb structure is less critical, heavy early yield is an objective, and limited tree size is an advantage. Its pollen shed overlaps the female bloom very well and it can have some 2 nd flowering like Chico, resulting in some small and late harvesting nuts. Released 2004. (Trials: Deseret, Stuke, Lang, Conant, Sierra Gold, Scheuring, Grunder, Crane, Driver, Crane Jr., Modest JC, Swall, Taylor) Gillet (95-022-26) (76-80 x Chico) (selected 2002): This protogynous selection has good yield, 8.0 g kernels, and harvests mid-season, about two weeks earlier than Chandler. Nuts average 51% kernel and yield halves easily. Kernels have had excellent color, little shrivel and few veins or blanks. Seals and shell strength appear adequate but may not be sufficiently strong for in-shell use. Seals should be watched, particularly in young trees. They This is a large and vigorous tree that has had very little blight. Watch for a possibility of alternate bearing. Released 2004. (Trials: Conant, Scheuring, Grunder, Crane Jr., Modesto JC, Swall, Taylor) Forde (95-026-37) (Lara x Chico) (selected 2001): This selection has had great color and excellent yield. The seedling tree clearly harvests earlier than Chandler, probably with Tulare and Vina, but young grafted trees are only a few days earlier. Continue to watch the timing. It has large, plump 8.7 g kernels, protogynous bearing habit, and 53% kernel yield. This is a large vigorous tree with little blight. Its strength, seal, fill, plumpness, and yield on young trees are better than Chandler and kernels show an absence of shrivel or veins. Its protogynous flowering suggests its additional potential as a pollenizer for Chandler. Released 2004. (Trials: Conant, Driver, Scheuring, Grunder, Modesto JC, Crane Jr., Swall, Stolp, Taylor) 90-023-37 (Tulare x Chase D9) (selected 1999): This is a protandrous selection with excellent yield harvests two weeks before Chandler and gives 55% kernel. This is a mid-season producer with nuts that are round in shape, have relatively smooth shells, and average 7.3 g kernels but seals are consistently weak. The tree has an upright growth habit. Kernel color was good this year but has been questionable and veins have been an issue. This selection continues to show very strong yields in selection blocks. Probable discard 2006. (Trials: Deseret, Stuke, Conant, Deardorff, Crane) 90-027-21 (Tulare x Sinensis #5) (selected 1998): This protandrous, upright, vigorous tree leafs out and harvests close to Payne. The shells are strong, well sealed, and shaped like Vina. Yield is very good and this could be an early in-shell selection. Nuts yield 48% kernel and kernels average 7.0 g. Kernel color has been mostly light but not excellent. Blight has been severe on unsprayed trees in wet years but little blight has been observed in sprayed blocks even though it leafs early. Nuts tend to have a white interior lining on the shell, sometimes don t fill well at the blossom end, and have
packing tissue with a rather woody center. Tree is upright and branchy with a dense canopy and is likely easy to train. Kernel weight and percent are concerns but this selection continues to produce excellent yields. This also continues to show less boron sensitivity than other selections and maybe most suitable for high boron sites. Possible discard. 2003 (Trials: Deseret, Stuke, Conant, Deardorff, Scheuring) 90-027-23 (Tulare x Sinensis #5) (selected 1998): This short-season sibling of the previous selection leafs out close to Chandler but harvests about two weeks earlier. It exhibits good shell strength and kernel color. Kernels average 7.7 g and nuts average 52% kernel. Nuts are Vina shaped and have a striped appearance. Very good yield again this year, particularly at Kearney where it continues to harvest early. Vigorous, thrifty tree. (Trials: Deseret, Stuke, Conant, Deardorff, Carriere) 90-031-12 (Chandler x 85-008) (selected 2001): This sibling of Sexton leafs and harvests about 10 days before Chandler and nuts have smooth solid shells with a good seal, adequate strength, and 58% kernel. Kernels average 8.4 g and yield easy halves. Color is good most years but has been poor at Chico. Very precocious and strongly lateral bearing with good yield and only moderate blight, this harvests earlier than Sexton and has a similar growth habit but has thinner shells and less consistent color. (Trials: Sierra Gold) 91-076-24 (Howard x Sinensis #5) (selected 2000): Selected for its very early harvest date, this protogynous, short-season selection leafs mid-season but harvests approximately with Payne. Yield has been excellent with little blight. Nuts have light colored but rough, and often irregularly shaped, shells and yield 54% kernel. Seals and shell strength are probably not sufficient for in-shell and in some cases nuts have shown open stem-ends or seals but it may be suitable for a cracking selection. Kernels average 7.5 g but color is probably not good enough. Kernel lobes have a wide gap at the stem end and veins are a consistent defect. Foliage yellows by August at Davis and shows severe boron damage at Scheuring s trial but remained green into fall at other locations. Probable discard 2004. (Trials: Sierra Gold, Scheuring, Conant) 91-077-6 (Howard x 85-008) (selected 2000): This protandrous tree harvests close to Payne time but leafs about a week later than Payne. Yield has been huge on this precocious selection. The large 8.9 g kernels have shown consistently excellent color with easy removal of halves. The large, round, smooth-shelled nuts average 56% kernel but shell strength and seal may prove insufficient and it continues to show problems with incomplete shells as it ages. Not for in-shell use, but could be an early cracking selection if shell strength is adequate. Outstanding yield again this year. (Trials: Conant, Sierra Gold, Scheuring, Bonturi, Deardorff) 91-077-40 (Howard x 85-008) (selected 2001): This selection is characterized by precocity, excellent yield, protogynous bearing habit, and large kernels averaging 8.2 g. Color continues to show a pattern of excellence at Davis but not at other locations. Nuts are well sealed with 52% kernel and suitable strength, but maybe not appearance, for in-shell use. Harvest is mid-season or later. Yields have been huge for five years. 91-088-7 (Cascade x 56-224) (selected 2000): This mid to late-season selection is
protogynous, yields 49% kernel, and has 8.9 g kernels. The light-colored oval shells have an attractive appearance with excellent strength, thickness, and seal for in-shell use but this tree was not precocious as a seedling and laterals break slowly. Yield has not been consistently strong, it harvests too close to Chandler, and color has not held up over time. Probable discard 2005. (Trials: Deseret) *91-090-41 (87-009 x Chandler) (selected 1999): This early harvesting selection is notable for its light color relative to other selections in locations with generally poor color. It has an attractive shell appearance and growth appears to be upright. The nuts have thin shells and average 59% kernel. Seals and strength are not adequate for in-shell use. Yields have consistently been very strong, and color of the 8.1 g kernels has been light to extra-light with easy recovery of halves. Harvest is two weeks or more before Chandler and blight has been low. Grower comments and Diamond data suggest consideration for release but shells and seals were weak again his year and remain a concern. (Trials: Deseret, Stuke, Conant, Sierra Gold, Deardorff,) 91-094-18 (Cisco x 56-224) (selected 1999): Chosen for its excellent kernel color and appearance, attractive nuts with light shell color, and 56% kernel yield, this selection exhibits Chandler-like leafing and flowering phenology. It yields well and harvests 10 days to two weeks before Chandler. Nuts average only 6.9 g and tend to be variable in size. Looks great at Kearney (Mr. Green Tree) and had a huge yield again this year at most locations. Possible discard 2003. (Trials: Deseret, Stuke, Conant, Deardorff, Crane) 91-096-3 (Cisco x Chandler) (selected 1998): This early harvesting, short season selection is most interesting for its absence of blight. Very little blight has been observed, even in bad blight years. This selection appears far less susceptible than adjacent trees with similar phenology and the tree s fuzzy hull surface may play a role in resistance. Yield is excellent and harvest date is close to Payne. Nuts average 52% kernel but nut size is a concern. Kernels average only 6.5 g but continue to show excellent color. (Trials: Deseret, Stuke, Conant, Noreen, Sierra Gold, Deardorff, Crane, Scheuring, Grunder, Carriere, Spanfelner) 92-068-2 (Chandler x Sinensis #5) (selected 2003): This is a very early harvesting, protogynous selection. Probably not strong enough for in-shell and shells are not well-filled. It harvests before Payne with 56% kernel. The 8.2 g blocky kernels are not plump and have a wide gap between the lobes. Color on grafted trees has never been as good as on the seedling. Probable discard 2004. 92-070-12 (Soleze x Chandler) (selected 1999): Attributes of this selection include excellent kernel color, easy removal of halves, excellent shell appearance, 7.4 g kernels, and 55% kernel yield. This harvests a week or more before Chandler and blight incidence has been low. Shells are very smooth textured and light colored but seals and shell strength are rather weak. Great nut appearance and very high value scores from Diamond crackout in multiple years and locations. Nut size is larger and more consistent than Chandler with less variability and fewer small nuts. Possible discard 2003. (Trials: Deseret, Stuke, Conant, Deardorff, Crane Jr.) 92-080-11 (Tulare x Sinensis #5) (selected 2000): This large, vigorous tree harvests close to Payne and has excellent yield with little blight. The large 9.2 g kernels have
mostly light color. The nuts yield 54% kernel and have a good seal. Shells are rather rough and shell strength and appearance are probably not suitable for in-shell but it could be an early cracking selection. This tree looks good in the field with good branching and dense foliage that covers the large nuts well. Probable discard 2004. (Trials: Deseret, Conant) 92-081-17 (Tulare x Manregian) (selected 2003): Selected for its early harvest date, kernel color, large plump 8.8 g kernels, and solid shell. Nuts yield 55% kernel. Blight was severe in 2003 but otherwise low and color has been very good most years. Large tree with dense canopy but shows boron sensitivity and harvest dates have varied. Yield has not been consistent and may not be strong enough. Probable discard 2006. (Trials: Scheuring) 93-026-6 (Chandler x Sinensis #5) (selected 2001): Good yield with harvest averaging about a week after Payne or two weeks before Chandler. This protogynous selection has large Hartley-shaped nuts with solid shells and seals that yield 50 % kernel. The 8.6 g kernels have had mostly light to extra light color. Stem end holes should be watched but were acceptable again this year. Although Hartley-shaped, the shells can be irregular and may not be consistent enough in appearance for inshell use. Veins and tip shrivel are consistent defects. (Trials: Driver, Deseret, Stuke, Crain, Conant, Noreen, Sierra Gold, Scheuring) *93-028-20 (Chandler x PI 159568) (selected 2001): Tulare timing with large, oval, very attractive nuts. This selection leafs like Chandler but harvests about two weeks earlier and has had very little blight. The smooth, attractive, solid shells have good seals and 54% kernel. The very plump, Sunland-shaped kernels average 8.6 g and color is excellent. Yield was very good this year but needs to be watched further and it has had shrivel problems two year at Kearney. (Trials: Conant, Sierra Gold, Spanfelner) 94-019-29 (Vina x 67-013) (selected 2001): This tree was selected for its great yield, harvest 2 weeks before Chandler, and shell traits suitable for in-shell use. Kernel color has been excellent. This tree has shown severe blight susceptibility when not sprayed but has been blight free in selection blocks. Tree is upright and vigorous. Nuts average 53% kernel and average kernel size is 8.0 g. (Trials: Noreen) 94-019-45 (Vina x 67-013) (selected 2001): A large, vigorous, branchy, and heavy cropping selection with moderate blight susceptibility and 8.0 g kernels. Leafing date is similar to Chandler but it mid-season and nut traits are suitable for in-shell use. Nuts yield 53% kernel. Color has been good but tip shrivel is a concern some years and harvest date may be spread out. (Trials: Conant) *94-019-85 (Vina x 67-013) (selected 2001): This selection could serve as an early Hartley with a harvest date similar to Payne, a Hartley-shaped nut, and good kernel color. The shell remains thin and a bit rough but has relatively good strength, resembling Serr in this regard. Yield has been good, nuts contain 60% kernel with easy halves, and kernels average 8.4 g. Consider for release as an early variety. Watch the yield consistency. Also the leaves don t abscise normally in some years. Continue to watch. (Trials: Bonturi) 94-020-5 (Vina x PI159568) (selected 2001): This was selected as a good yielding early in-shell
with excellent color. It averages 7.8 g kernels and has great shell strength. It harvests within a week of Payne and averages 50% kernel. The tree is large and vigorous. Watch for spreading or sweepy growth habit, consistency of yield, and stem end opening. (Trials: Stolp, Conant, Sierra Gold) 94-020-19 (Vina x PI159568) (selected 2002): This selection harvests about two weeks before Chandler and leafs a week after Payne. It was selected as a potential early in-shell for its kernel color, very solid shell and seal, attractive shell appearance, and 8.1 g kernel size, and 49% kernel. Yields have been good but not outstanding. Laterals have been slow to leaf and color has not been consistently good, particularly at Kearney. Probable discard 2006. (Trial: Sierra Gold) *94-020-28 (Vina x PI159568) (selected 2005): This protandrous selection has Payne-time harvest date with good yield. The nuts contain 54% kernel and have a smooth, attractive shell that yields easy halves. The very plump kernels average 8.3 g with mostly good color but has also had some bad years. A potential early in-shell. Trees in selection blocks are still young. Watch for blanks and degree of lateral bearing *94-020-35 (Vina x PI159568) (selected 2001): This early in-shell selection harvests within a week of Payne with moderate blight and good yield. Shells are very solid and have excellent strength for in-shell use but are pointed and have a rough inner surface, which along with excellent fill, may impede halves. Kernels have had mostly good color and average 8.0 g. Nuts are long and oval like Sunland and the thick shell accounts for nuts averaging only 48% kernel. Tree appears to have a spreading weepy or willowy growth habit. (Trials: Stolp, Moore, Conant, Sierra Gold) 94-020-72 (Vina x PI159568) (selected 2001): This large vigorous tree was selected for its excellent yield, near absence of blight, large plump 8.2 g kernels, and very solid, well filled shells with 50% kernel but color has not been adequate for several years. Harvest date is mid-season. Nuts yield halves easily and shells are suitable for inshell but harvest is not early enough. Probable discard 2006. 95-002-1 (Chico x Manregian) (selected 2001): This was chosen for its early harvest date, within a week of Payne, its suitability for in-shell use, and its yield. Round nuts with good shell appearance, yield, and 53% kernel. The large kernels average 8.7g. Kernel color continues to be marginal, veins detract from kernel appearance, and the interior shell configuration is not conducive to halves. Tree shows considerable blight and shells can have a white unattractive coating on the interior. Probable discard 2005. 95-002-13 (Chico x Manregian) (selected 2001): This selection harvests close to Payne, has thick shells, good strength and seal, round, light-colored shells, and good yield. Its large nuts with very plump 7.8 g kernels and 50% kernel yield are well suited to in-shell use but excessive fill makes removal of halves too difficult and color has not held up in selection blocks. Blight susceptibility is also a concern. Probable discard 2005. 95-003-28 (Chico x Vina) (selected 2001): This is an early in-shell selection that harvests with, or before, Payne, has good yield, and can have excellent kernel color but the color has been inconsistent. Nuts have shells that are solid and attractive with a very good seal but only 48% kernel. Kernels average only 6.8 g and are losing size
in the selection blocks. Blight, nut size, and color are a concern. Probable discard 2006. 95-007-13 (77-012 x Serr) (selected 2001): A Serr seedling that harvests close to Payne, has good yield and a solid, attractive shell, this early in-shell candidate had great color as a seedling and again this year but was poor last year at several locations. The amount of shrivel and strength of seals need to be watched further. Nuts yield 53% kernel and kernels average 8.2 g. New foliage has been noted to have a wilting appearance in late summer at some locations. Continue to evaluate it in selection blocks and grower trials. (Trials: Stuke, Conant, Scheuring) **95-011-14 (67-013 x Chico) (selected 2001): This protogynous selection harvests with, or before, Payne and is characterized by great yield, excellent shell color and appearance, and mostly Chandler-like extra light kernels averaging 7.6 g. It may have sufficient shell strength for in-shell use but strength and seals should be watched and nut size is not large. Nuts yield 57% kernel with very easy removal of halves. Kernel quality and harvest date are excellent. This selection has shown some summer heat damage to the foliage and some summer nut drop. Watch for susceptibility to blight and summer heat stressed black nuts. (Trials: Sierra Gold, Scheuring, Conant, Moore, Bonturi, Spanfelner) 95-011-15 (67-013 x Chico) (selected 2001): Another selection with very good yield and kernel color, this tree has a solid shell and seal suitable for in-shell use but doesn t have the shell appearance of its above sibling. The harvest date is about ten days before Chandler and nuts average 52% kernel. Kernels weigh about 7.5 g. Color has been mostly light to extra light. Blight is a serious concern when unsprayed. It can have a thick leathery packing tissue and sometimes poor fill. (Trial: Sierra Gold) 95-011-16 (67-013 x Chico) (selected 2003): This protandrous early in-shell selection harvests about a week after Payne and has large, light colored kernels that average 7.9 g. Nuts have very solid, attractive, oval shells that give 54% kernel. Watch for variable nut size and it may have a tendency towards dark keels and tip shrivel. 95-011-22 (67-013 x Chico) (selected 2001): A high yielding selection with mostly light to extra light kernels and a mid-season harvest date. Nuts have 54% kernel with shell and seal strength suitable for in-shell use. Nut size is a concern. Kernels average 7.1 g but have declined noticeably as trees have aged. (Trials: Conant) 95-013-6 (Vina x Howard) (selected 2003): This tree was selected for its harvest date near Payne time, light kernel color, easy halves, and very solid shell suitable for in-shell use. It is a large vigorous tree. It had large, long kernels as a young tree but kernel weights on the seedling tree in a declining area of the block have been under 7 g the last five years and nuts average only 49% kernel. Trees in the selection blocks are still young. Hulls are thick so the nuts look bigger on the tree than they really are. Watch in selection blocks. Probable discard 2004. 95-013-12 (Vina x Howard) (selected 2003): Selected as an early in-shell possibility, this tree produces good yield close to Payne harvest time. The large, attractive nuts have a rounded Vina or Hartley shape, very solid shell, and average
48% kernel. Large, light kernels average 8.2 g and yield halves easily. Consider as a lateral bearing, earlier harvesting Hartley replacement. The original tree has severe crown gall. Watch in selection blocks but those averaged only 46% kernel this year on young trees. 95-018-23 (Tulare x Chandler) (selected 2003): Excellent yield of mostly extra light kernels and harvests about a week after Payne. A short season selection that leafs after Chandler and has low blight. Shells are thin and have inadequate strength for in-shell use. Nuts yield 51% kernel and easy halves but fill is poor and kernels average only 6.9 g. Watch in selection blocks but young trees tere averaged only 7.1 g this year. (Trials: Scheuring, Carriere) 95-026-16 (Lara x Chico) (selected 2003): Selected for its early in-shell traits, this protogynous tree harvests with Payne, has very good kernel color, excellent yield, and very little blight. Nuts yield 51% kernel and have solid shells and seals. Nuts average only 6.9 g and nut size is the major concern with this selection. Watch in the selection blocks where nuts on young, less crowded trees averaged 8.2g this year. 95-026-17 (Lara x Chico) (selected 2003): This protogynous, short-season, and relatively late leafing selection leafs out after Chandler but harvests more than two weeks earlier. Yield is good and the tree has had little blight. Nuts average 51% kernel with solid shells but kernels average 7.2 g and nut size is a concern. Watch in the selection blocks where nuts averaged 7.9g this year. 95-026-21 (Lara x Chico) (selected 2001): A protogynous selection with excellent yield and little blight that harvests within a week of Payne. Nuts average 53% kernel but kernel weights have declined to only 6.6 g. Kernel color has been very good and kernels come out in halves easily. Seal and strength are good and shells have light color. Watch in selection blocks. This year grafted trees showed high yield but small nuts. (Trials: Conant) 95-026-22 (Lara x Chico) (selected 2001): This protandrous tree harvests mid-season with a very strong shell and seal and good nut size. Kernels average 8.8 g and nuts yield 48% kernel. Kernels have generally been large, shiny, and light. Blight incidence has remained very low. The rough textured shells are very solid and can have inner roughness as well. If nuts are too well filled, kernels can be a bit difficult to remove in halves. This tree continues to have good nut size and yield even on a crowded seedling tree. (Trials: Conant, Scheuring, Sierra Gold, Carriere, Taylor, Stuke) 95-026-24 (Lara x Chico) (selected 2003): A protogynous mid-season selection with little blight, this tree has excellent yield and generally light to extra light Chandler-like kernels but color was not good in the selection blocks this year. Shell strength is better than Chandler and harvest is earlier. Kernel size averages 7.5 g and 51% kernel. Continue to watch in selection blocks. (Trial: Scheuring) 96-013-13 (Howard x Chico) (selected 2003): This protogynous tree was selected for its excellent yield, light kernel color, good shell appearance, and mid-season harvest. It has had better yield than Tulare trees around it the last four years, an equivalent harvest date, and better color. The light
colored, smooth, attractive shells have been solid and adequate for in-shell use but were too thin this year. Nuts produce 53% kernel but kernels average only 6.6 g and size has declined to less than 6 g the last two years. Watch vigor and nut size in selection blocks on rootstocks. 97-003-11 (Tulare x Mixed Chinese Phase II) (selected 2004): Selected for its mid-season harvest, strong yield, Chandler leafing date, and large, plump, light colored kernels averaging 9.3 g. The large well-filled nuts yield 57% kernel. Shells are rough and seals should be watched. 97-003-23 (Tulare x Mixed Chinese Phase II) (selected 2005): This is has a mid-season harvest. Nuts have a very attractive smooth and light colored shell and give 54% kernel. Kernels have excellent color and easy removal but average only 6.4 g on the seedling tree. Look at this on rootstock. 97-003-40 (Tulare x Mixed Chinese Phase II) (selected 2005): This is a protogynous mid-season selection with good yield. Nuts have a very solid strong shell and seal resulting in only 48% kernel. Color of the 7.4 g kernels has been good. 97-003-46 (Tulare x Mixed Chinese Phase II) (selected 2005): This selection harvest very early, approximately with Payne and has large plump 8.6 g kernels with good color and easy removal. Shell strength and seal are probably not good enough or in-shell use. Nuts average 58% kernel. 97-003-65 (Tulare x Mixed Chinese Phase II) (selected 2005): This selection has excellent color and large 8.2 g kernels with solid shells and 52% kernel but the harvest time may be too close to Chandler and yield needs to be watched further. 97-003-79 (Tulare x Mixed Chinese Phase II) (selected 2005): This is a mid-season selection with exceptionally large 10 g kernels. Removal of halves is very easy, color is light but maybe not excellent, and the shells are solid, yielding 55% kernel. (Trial: Sierra Gold) 97-003-91 (Tulare x Mixed Chinese Phase II) (selected 2005): This selection has excellent yield in a grower trial and rather Hartley-shaped nuts. Color has been excellent and kernels average 7.3 g but harvest date now appears to be too close to Chandler. 97-003-96 (Tulare x Mixed Chinese Phase II) (selected 2005): This selection harvests about ten days after Payne. Nuts have a solid shell and seal with 51% kernel. The kernel color has been very good and kernels average 7.8 g. Pay attention to veins and watch this on rootstock. (Trial: Sierra Gold)
Table 1. Cultivar and Selection Evaluations at Davis (Spring 2006) Seedling or Leafing Pollen Shedding Pistillate Bloom Grafted Date DAP a 1st Peak Last Abund. b 1st Peak Last % Lateral Yield b Cultivars Payne G 4/4 0 4/18 4/22 5/3 7 4/21 4/24 4/27 100 8 Hartley G 4/19 15 4/24 4/29 5/9 6 5/1 5/4 5/7 0 6 S. Franquette G 5/2 28 5/6 5/14 5/20 4 5/15 5/18 5/23 0 5 Vina G 4/14 10 4/20 4/26 5/3 7 4/24 4/29 5/3 100 7 Serr G 4/7 3 4/19 4/24 5/2 8 4/24 4/27 4/30 60 6 Chandler G 4/24 20 4/26 4/30 5/10 7 5/2 5/6 5/11 100 7 Howard G 4/22 18 4/26 4/30 5/8 6 5/1 5/4 5/9 100 7 Tulare G 4/19 15 4/25 4/29 5/3 6 4/27 4/30 5/3 100 8 Sexton G 4/14 10 4/20 4/24 5/1 5 4/22 4/25 4/29 100 7 R. Livermore G 4/21 17 4/23 4/28 5/5 6 4/30 5/3 5/6 100 6 Gillet S 4/9 5 4/24 4/29 5/4 6 4/17 4/21 4/27 100 7 Gillet G 4/9 5 4/17 4/20 4/23 100 7 Forde S 4/17 13 4/28 5/2 5/10 5 4/19 4/24 4/28 100 7 Forde G 4/17 13 4/27 5/1 5/5 3 4/19 4/24 4/28 100 7 Selections 59-124 G 4/2-2 4/19 4/22 5/1 7 4/21 4/24 4/28 90 7 76-080 G 4/18 14 4/21 4/26 5/4 7 5/1 5/4 5/10 100 7 77-012 G 4/24 20 5/3 5/7 5/12 3 4/25 4/30 5/4 100 7 90-023-11 G 4/17 13 4/22 4/27 5/5 7 4/24 4/29 5/3 100 7 90-023-37 G 4/18 14 4/23 4/28 5/9 7 4/26 4/30 5/4 100 7 90-027-21 G 4/5 1 4/15 4/20 4/26 7 4/21 4/24 4/28 100 8 90-027-23 G 4/22 18 4/25 5/2 5/11 7 5/2 5/5 5/10 100 7 a Days after Payne leafing date at Davis b 1=low, 9=high