PECAN BREEDING AND CULTIVAR EVALUATION

PECAN BREEDING AND CULTIVAR EVALUATION

Sponsoring Institution

National Institute of Food and Agriculture

Project Status

TERMINATED

Funding Source

HATCH

Reporting Frequency

Annual

Accession No.

0222468

Grant No.

(N/A)

Project No.

GEO00272

Proposal No.

(N/A)

Multistate No.

(N/A)

Program Code

(N/A)

Project Start Date

Jul 1, 2010

Project End Date

Jun 29, 2015

Grant Year

(N/A)

Project Director
Conner, P. J.

Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016

Performing Department
Horticulture

Non Technical Summary
Pecans are attacked by a wide range of disease and insect pests causing substantial losses to the crop. In the humid growing conditions of the southeastern United States, the most economically damaging of these is pecan scab, caused by the fungus Fusicladosporium effusum. Scab infection results in reduction in both yield and quality of pecan, and if uncontrolled can result in total crop loss. Various levels of resistance to scab are available in pecan germplasm. However, few cultivars contain sufficient resistance so that fungicide applications are not necessary, and these usually lack many of the nut quality traits desirable for commercial plantings. In addition, many important cultivars such as Stuart and Desirable are becoming increasing susceptible to the scab pathogen, due at least partly to the presence of multiple races of the fungus. As a result, commercial pecan plantings require 8-11 applications of fungicides in order to remain profitable . Pecan scab has developed resistance to at least one common fungicide, Benlate. Recent tests have also shown a reduced sensitivity to sterol demethylation inhibiting (DMI) triazole fungicides since 1995, and these are an important class of pecan fungicides. In addition, concern over negative environmental health effects of pesticides has resulted in pressure to increase regulation of other valuable chemical control agents. Pecan prices have risen only 4% since 1980, while production costs have increased over 154%. The development of high-quality scab-resistant cultivars could result in savings of $115 / acre / year in fungicide and labor costs in addition to increased yields. Development of varieties with combinations of disease and insect resistance would result in further savings. Resistant varieties could also reduce risks of epidemics when weather conditions are favorable for disease growth and unfavorable for pesticide application. The development of resistant cultivars will play a vital role in maintaining the profitability of pecan culture in the Southeast.

Animal Health Component

(N/A)

Research Effort Categories

Basic

40%

Applied

50%

Developmental

10%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
201	1211	1081	30%
202	1211	1081	40%
212	1211	1081	20%
204	1211	1081	10%

Knowledge Area
202 - Plant Genetic Resources; 204 - Plant Product Quality and Utility (Preharvest); 212 - Pathogens and Nematodes Affecting Plants; 201 - Plant Genome, Genetics, and Genetic Mechanisms;

Subject Of Investigation
1211 - Pecan;

Field Of Science
1081 - Breeding;

Keywords

Goals / Objectives
The primary objective of this project is to develop new cultivars adapted to the humid southeastern growing region. These cultivars will need to combine the high quality attributes necessary for commercial acceptance with increased resistance to diseases. Secondary objectives are to 1) evaluate existing pecan germplasm for potential use as new cultivars or as parents in the breeding program, 2) to better define the genetic basis of key horticultural traits in order to improve the efficiency of the breeding program, and 3) to better understand the relationship between the fungus Fusicladosporium effusum (pecan scab) and pecan in order to breeder for durable resistance to pecan scab.

Project Methods
The ultimate goal of the breeding program is to develop pecan cultivars adapted for use in the Southeast. Potential new cultivars will be selected on the basis of large nut size, good cracking and shelling characteristics, early nut maturity, light colored kernels, and a cluster size small enough to ensure adequate filling. Resistance or tolerance to major insect and disease pests, especially pecan scab, will also be major goals. Controlled pollinations are made in the spring of each year by bagging inflorescences and injecting pollen into the bag at receptivity. After collection in the fall, nuts are stratified for six weeks and then planted in the greenhouse. In the spring seedlings are transplanted into pots and transferred to a seedling nursery where they are grown for two seasons. At the end of the second season, most progenies are screened for the presence of leaf scab, and the most susceptible seedlings discarded. Seedlings are then either dug and transferred to the seedling orchard and planted at a spacing of 10 ft. X 15 ft, or grafted onto discarded seedlings already in the seedling orchard. Seedlings will be left in the orchard for a period of approximately 10 years. Detailed records are kept for nut size and quality, tree vigor and form, phenology, and disease and insect resistance. As selections are deemed unworthy of further study they are cut off approximately 1 m from the ground. The resulting stumps sucker freely and can be grafted to a new selection the following year. Selections with cultivar potential are propagated onto rootstocks and grown in a replicated trial orchards along with check cultivars to determine tree productivity, as well as nut quality, phenology, insect and disease resistance.

Progress 07/01/10 to 06/29/15

Outputs
Target Audience:Pecan growers in the southeastern United States. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest?Grower field days at the UGA campus farm. Scholarly peer-reviewed journal articles. Popular articles in grower magazines. On the UGA Pecan Breeding website. One on one interactions with growers. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Two relatively new cultivars 'Zinner' and 'McMillan' were tested and recommended for use in Georgia. Over a dozen other cultivars were tested and found not suitable for use in Georgia. Several additional cultivars are being tested and results are pending. Information on all these cultivars is available to growers and researchers on the UGA Pecan Breeding website which is updated annually. Nineteen selections have been made from the UGA pecan breeding program which are now in trials at the UGA campus and in grower orchards. One of these is slated for release in 2016.

Publications

Type: Journal Articles Status: Published Year Published: 2014 Citation: Conner, P. 2014. Performance of nine pecan cultivars in southern Georgia. J. Amer. Pom. Soc. 68(3):118-123.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Pecan growers and research scientists in the United States. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? Dr. Conner has worked to actively involve the pecan industry in his breeding program. The results of his breeding program are reported to the Georgia Pecan Commodity Commission, and the commission has funded the pecan breeding program every year. Dr. Conner also meets annually with a panel of growers and nurserymen who tour his pecan trial plantings and evaluate his new pecan selections. This panel consists of experts within the state of Georgia as well as from California and Arizona. All pecan cultivars have strengths and limitations, and the methods used in their management will determine their profitability. For this reason, Dr. Conner strives to present growers with timely and fact-based information on the performance of new cultivars in Georgia. The results of his trials have been presented to growers in talks, during field days, and in popular articles. Cultivar performance data from all cultivar trials going back to the inception of the program in 1921 were made available on a website which is updated annually with yield and quality data for interested researchers and growers. What do you plan to do during the next reporting period to accomplish the goals? This program will proceed as in years past.

Impacts
What was accomplished under these goals? This year we made 13 crosses and collected 1,810 seed from these crosses. Several UGA selections from this program were used as sources of resistance to scab along with good nut quality. Earliness was again an important trait as we continue to produce progenies that will have selections maturing in mid-September. The biggest change this year from prior years is the large amount of rainfall received. This provided us an excellent opportunity to evaluate scab resistance. Observations indicated that scab is present on some selections that have never before scabbed. In the unsprayed seedlings, scab ranged from total nut loss to completely clean. Due to strong susceptibility to scab, three advanced selections were removed from yield trials. In the spring of 2013 we began grafting eight advanced selections into the yield trial at the UGA Ponder Farm. These selections were also given to Shiloh Nursery to graft and will be planted at Shiloh Farm in 2014 for yield trials in south Georgia. Selections 99-1-246 and 03-6-32 were grafted into a yield trial at NILO Plantation near Albany. The total number of advanced selections in yield trial now stands at 14 (Table 1). Several selections were grafted into scab trials at NILO, Attapulgus, and Tifton.

Publications

Type: Journal Articles Status: Published Year Published: 2013 Citation: Conner, P. 2013. Evaluation of response to pecan scab pathogen race using a detached leaf protocol. HortScience 48:63-67.
Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Conner, P. 2013. Roadblocks and hindrances to the development of molecular tools in pecan: a breeders perspective. 1st Int. Symp. On Pecans & Other Carya in Indigenous and Managed Systems. July 16-21. College Station, Tex.
Type: Other Status: Published Year Published: 2013 Citation: Conner, P. 2013. Pecan breeding overview Part 3. The Pecan Grower 24(3):22-25.
Type: Other Status: Published Year Published: 2013 Citation: Conner, P. 2013. UGA variety test update: McMillan shows promise for low-input plantings. The Pecan Grower 24(4):40-44.
Type: Other Status: Published Year Published: 2013 Citation: Conner, P. 2013. UGA variety test update: Zinner looks good for commercial plantings in Georgia. The Pecan Grower 25(1):16-20.
Type: Websites Status: Published Year Published: 2013 Citation: http://www.caes.uga.edu/commodities/fruits/pecanbreeding/index.html

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: This year we made 10 crosses and expect to have several hundred seed collected from these crosses. Several UGA selections from this program have been used as sources of resistance to scab along with good nut quality. Earliness was again an important trait as we continue to produce progenies that will have selections maturing in mid-September. Numerous seedlings from prior years' crosses fruited in 2011 so that selection for nut quality could be made. Samples from these trees were evaluated for nut size, percent kernel, shelling ability, and kernel quality. In addition, rainfall this summer was frequent and seedlings were also evaluated for nut scab. Based on these observations, several hundred seedling trees were removed from the seedling orchards and these rows are being replanted with new crosses. Most discarded seedlings were rejected due to small nut size, high level of nut scab, low percent kernel, or poor kernel quality. Seedlings which show promise were marked and will be further evaluated, and may be propagated for replicated yield trials. Seven new selections looked promising enough that they were grafted into the Ponder Yield Trial in the spring of 2011/2012 for further evaluation, increasing the number of UGA advanced selections to 19 (Table 1). A new scab screening block was installed at NILO plantation in Albany, Ga. where 109 seedlings were grafted to UGA selections. In addition, a yield trial was of 99-2-108 and 99-2-28 was installed at NILO plantation. A trial of 99-2-15, 99-2-28, 99-2-108, 99-9-3, and 03-6-32 was installed at Shiloh Farms in Wray City, Ga. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Seven new selections looked promising enough that they were grafted into the Ponder Yield Trial in the spring of 2011/2012 for further evaluation, increasing the number of UGA advanced selections to 19 (Table 1). A new scab screening block was installed at NILO plantation in Albany, Ga. where 109 seedlings were grafted to UGA selections. In addition, a yield trial was of 99-2-108 and 99-2-28 was installed at NILO plantation. A trial of 99-2-15, 99-2-28, 99-2-108, 99-9-3, and 03-6-32 was installed at Shiloh Farms in Wray City, Ga.

Publications

No publications reported this period

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: This year we made 12 crosses (and collected 2,177 seed from those crosses. Two relatively new parents used were Amling and Leger-1, both of which are grower selections that appear to have some degree of resistance to the black pecan aphid (Melanocallis caryaefoliae). Several UGA selections from this program have been used as sources of resistance to scab along with good nut quality. Earliness was again an important trait as we continue to produce progenies that will have selections maturing in mid-September. Numerous seedlings from prior years crosses fruited in 2011so that selection for nut quality could be made. Samples from these trees were evaluated for nut size, percent kernel, shelling ability, and kernel quality. In addition, rainfall this summer was frequent and seedlings were also evaluated for nut scab. Based on these observations, 922 seedling trees were removed from the seedling orchards and these rows will be replanted with new crosses. Most discarded seedlings were rejected due to small nut size, high level of nut scab, low percent kernel, or poor kernel quality. Seedlings which show promise were marked and will be further evaluated, and may be propagated for replicated yield trials. Seven new selections looked promising enough that they were grafted into the Ponder Yield Trial in the spring of 2011 for further evaluation, increasing the number of UGA advanced selections to 14 (Table 2). Of the advanced selections, UGA 00-7-75 looked particularly promising as it was ready to shake on Sept. 30, has commercial size and kernel quality, and has not scabbed in our unsprayed seedling block. UGA 99-2-15 and UGA 00-9-32 also have good size, quality, and scab resistance. UGA 99-9-3 is a Pawnee x Elliott seedling that had 80% shuck split on Sept. 25 and only trace nut scab in the unsprayed block. All selections in the yield trials are being compared to commercial cultivars to evaluate their potential for release. We have an additional 2 selections that have been propagated for scab tests at various locations. Several new selections will be entered into advanced tests in 2012 depending upon the availability of understocks. We have begun testing selections in a 60 tree scab test at Attapulgus to provide another testing site. PARTICIPANTS: Partner organizations: University of Georgia Research Foundation - Financial Support Georgia Agricultural Commodity Commission for Pecan - Financial Support Shiloh Pecan Farms - Pecan Testing Site in kind support NILO Pecan Farms - Pecan Testing Site in kind support TARGET AUDIENCES: Our target audience is commercial pecan growers and homeowner growers in the state of Georgia and the Southeastern U.S. These groups are reached via talks at the Georgia and Florida Pecan Growers Association, and at the Georgia Farm Bureau Annual Meeting, and more broadly on our website. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The Ponder Variety Test was continued with data being taken on replicate trees of about two dozen cultivars and selections. This data is summarized on our website. Several new selections have been provided to growers and nurserymen and have been recommended for trial planting in Georgia including: Zinner, McMillan, and Amling. In the spring of 2011 I provided stock wood of Cherryle, Zinner, Amling, and McMillan to Shiloh Farms Nursery so that they can begin carrying these varieties. This spring I will provide wood of McMillan, Zinner, Kanza, and Mandan to Patten Tree Nursery to increase the availability of these cultivars. 20ll data from the pecan cultivar trials have been included on our public website at http://www.caes.uga.edu/commodities/fruits/pecanbreeding/ for growers to use in making decisions for planting new pecan orchards. In addition talks have been given at several state and regional grower meetings describing these findings.

Publications

No publications reported this period

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: This year we made 14 crosses and collected 976 seed from those crosses. Much of the focus of 2010 was in using very early cultivars and scab resistant cultivars in crosses. Early cultivars include: Byrd, Pawnee, 86-3-32, and Lucas. Cultivars with superior scab resistance include: Leger-1, Syrup Mill, Faircloth, 00-7-75, Excel, and Amling. A new shade house was built and the 2009 seedlings were grown in pots rather than being planted in the ground. These seedlings were inoculated with scab by spraying seedlings with a scab inoculum isolated from a wide array of seedlings from the Ponder Farm. This resulted in very good scab pressure with as much as 80% of some progenies being discarded for scab susceptibility. This will help in reducing the number of seedlings being planted in our limited field space. PARTICIPANTS: P.I. - Dr. Patrick Conner Education session at the Georgia Pecan Growers Annual Convention. Education session at the Pecan session of the Southeastern Fruit and Vegetable Conference in Savannah, Ga. TARGET AUDIENCES: Georgia peacan growers. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The Ponder Variety Test was continued with data being taken on replicate trees of about two dozen cultivars and selections. This data is summarized on our website. Several selections have been provided to growers and nurserymen and have been recommended for trial including: Zinner, McMillan, and Amling. A new pecan website was launched (www.caes.uga.edu/commodities/fruits/pecanbreeding/).

Publications

No publications reported this period