2007 Annual Report
1a.Objectives (from AD-416)
To prevent alternate bearing, water stage fruit split, pre-harvest nut germination, and nutrient element problems limiting profitability; and to develop improved strategies for the control of pecan scab, and other diseases of foliage and fruit.
New funding ($89,280) will be used to expand current CRIS project objectives.
(1) Determine if the virulence of the scab fungus has changed in regards to the key cultivars being grown.
(2) Determine if cultural and spray practices are contributing to increased scab inoculum levels in the upper canopy of trees, and how these practices should be changed to reduce scab related losses.
(3) Assess scab susceptibility as if it interacts with rate of growth of host tissues and the secondary metabolites being produced by such tissues.
(4) Assess the impact of tree nutrition on the ability of pecan to tolerate or resist damage by scab organisms.
New funding $54,863 will be used to (1) develop improved strategies for control of pecan scab; (2) develop improved strategies for the control of alternate bearing.
1b.Approach (from AD-416)
Problems will be addressed via development of strategies that regulate bearing using flowering regulators, fruit thinning, hedge pruning, and nutrient management. Fruit drop, split, and germination problems will be addressed via improved nutrient management. Disease control efforts will address strategies to improve spray coverage, efficacy of pesticides, and factors that regulate resistance or susceptability.
Resources ($89,280) will support ongoing research already taking place. Efforts will address the role of host plant nutritional status in relation to host resistance to scab; will access the possibility of changes in the virulence of the scab organism; will address how cultural practices are contributing to disease severity; and will investigate the role of secondary metabolites on scab.
Resources ($54,863) will support ongoing research to improve nutrition management, crop land management, control of alternate bearing, minimize fruit drop, and reduce scab susceptability of trees. Efforts will address improving plant nutritional status as a means of reducing tissue sensitivity to pecan scab.
Considerable progress was made regarding the potential for improving the profitability of perennial crop enterprises via improving plant nickel nutrition. Research also provides evidence that pecan scab disease susceptibility is being substantially influenced by tree nutrient element status and that greater attention to tree nutrient health is likely to reduce losses to pecan scab disease. Substantial progress is also made regarding development of a chemical approach to fruit thinning of pecan. New information has resulted in identification of a potential novel approach to developing a superior method for solving the ZN deficiency problem exhibited in pecan orchards.
This report documents research conducted under two specific cooperative agreements, one between ARS and New Mexico State University and the other between ARS and the University of Arizona; and one non-funded cooperative agreement between ARS and Georgia Pecan Farms, LLC.
SCA 58-6606-5-246 with New Mexico State University: The project resulted in a survey of nematodes in New Mexico pecan orchards; a model of pecan tree growth for the management of pruning and irrigation; development of a simple irrigation scheduling calendar for Mesilla Valley pecan growers; a case-study of irrigation management of a New Mexico pecan orchard; an evaluation of two inexpensive energy balance techniques for measuring water use in flood-irrigated orchards in New Mexico; establishment of water associated crop co-efficients for open-canopy pecan orchards; a simple mode for pecan water use efficiency in New Mexico; establishment of nitrogen uptake characteristics during fruit development; and establishment of nutrient availability in soil amended with pecan wood chips. Activities of this SCA was monitored via two site visits, one meeting, and several phone calls and e-mails.
SCA 58-6606-6-175 with the University of Arizona: A multiple year study on development of practical orchard methods to correct tree zinc deficiency by soil application of Zn was continued. Zinc uptake from alkaline soils is a major problem. Several different Zn sources were applied via soil banding, with subsequent monitoring of tree canopy nutrition. A preliminary report was made to the Western Irrigated Pecan Growers Association regarding strategies to manage orchard Zn nutrition. The field study continues during FY2008. Activities of this SCA were monitored via one site visit, one meeting, and several phone calls and e-mails.
Non-Funded Cooperative Agreement, "Preventing Early-Season Fruit Drop," (CRIS 6606-21220-009-05N), between ARS (Byron, Georgia) and Georgia Pecan Farms, LLC: A multiple year study was initiated to test the effect of improving tree potassium nutrition on June-drop and fruit-set. Treatments were established and results monitored. For the first time in six years the orchard did not exhibit June-drop, even in the check; thus, this year's study is inconclusive. Activities of this project were monitored via several on-site visits. Additional details of research can be found in the report of parent project 6606-21220-009-00D, Pecan Cultivation and Disease Management.
Use of phytomined nickel as a micronutrient fertilizer for plants:
Organically certifiable micronutrient fertilizers are needed for niche markets producing certified organic crop products; additionally, there is need for an agricultural usage of phytomined nutrients from soils containing excessive metals. An organic nickel fertilizer derived from Alyssum, a nickel hyperaccumulator, biomass is shown to correct nickel deficiency in pecan trees. This demonstrates that metal enriched biomass from phytomining operations can function as natural fertilizers to correct micronutrient deficiencies of agricultural crop enterprises. This accomplishment impacts the Sustainable Cropping Systems Problem of Component I: Integrated Production Systems, of NP-305.
The efficiency of nitrogen and carbon cycling in crops potentially depends on plant nickel nutritional status:
There is need from perennial crops to rapidly convert dormant season stored nitrogen and carbon reserves to forms needed for new structures during early spring; thus, ensuring optimal yields. It was found that this conversion efficiency is affected by plant nickel nutrition, with deficiency during early spring disruption, timely availability of nitrogen and carbon resources needed for rapid growth and optimal yields. This demonstrates that perennial crop species possessing relatively high nickel requirements can potentially exhibit nickel deficiencies during early spring, causing crops to perform below their physiological optimum. Attention to early season nickel nutrition can potentially increase crop production. This accomplishment impacts the Sustainable Cropping Systems Problem of Component I: Integrated Production Systems of, NP-305.
Improving tree nickel nutritional status reduces damage to fruit by pecan scab fungus:
There is great need to improve tree resistance against pecan scab disease so as to reduce production losses. Foliar nickel sprays were found to reduce scab damage to developing fruit and to increase kernel quality. This provides growers with a means of reducing economic losses in pecan to scab disease and indicates that plant nickel nutritional status might affect disease susceptibility of other crops. This accomplishment impacts the Integrated Pest Management Problem of Component I: Integrated Production Systems, of NP-305.
5.Significant Activities that Support Special Target Populations
|Number of new commercial licenses granted||1|
|Number of non-peer reviewed presentations and proceedings||6|
|Number of newspaper articles and other presentations for non-science audiences||1|
Wood, B.W., Chaney, R.L., Crawford, M. 2006. Correcting micronutrient deficiency using metal hyperaccumulators: alyssum biomass as a natural product for nickel deficiency correction. HortScience. 41(5):1231-1234.
Wood, B.W., Smith, M. 2006. Pecan tree biomass estimates. HortScience. 41(5):1286-1291.
Wood, B.W., Reilly, C.C., Nyczepir, A.P. 2006. Nickel deficiency in trees: symptoms and causes. Acta Horticulturae. 721:83-98.
Bai, C., Reilly, C.C., Wood, B.W. 2007. Identification and quantitation of asparagine and citrulline using high-performance liquid chromatography (HPLC). Analytical Chemistry. 2:31-36.
Bai, C., Reilly, C.C., Wood, B.W. 2007. Nickel deficiency affects nitrogenous forms and urease activity in spring xylem sap of pecan. Journal of the American Society for Horticultural Science. 132:302-303.
Wood, B.W., Reilly, C.C. 2007. Interaction of nickel and plant disease. In: Datnoff, L.E., Elmer, W.H., Huber, D.M., editors. Mineral Nutrition and Plant Disease. Minneapolis, MN: American Phytopathological Society Press. p. 217-247.