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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #276314
Title: Use of standard area diagrams to improve assessment of scab on fruit of pecan: A nutraceutical tree nut

Author
item YADAV, NALINI V.S. - Fort Valley State University
item Bock, Clive
item DE VOS, STEPHANIE - University Of Florida
item Wood, Bruce

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/27/2011
Publication Date: 5/27/2011
Citation: Yadav, Nalini, V.S., Bock, C.H., De Vos, Stephanis M., Wood, B.W. 2011. Use of standard area diagrams to improve assessment of scab on fruit of pecan: A nutraceutical tree nut. Abstract presented at the American Council for Medicinally Active Plants, 2nd Annual Conference of ACMAP, July 17-20, 2011, A&M University, Huntsville, ALabama.

Interpretive Summary: The native American pecan contains the highest antioxidant levels of all tree nuts. Some of these antioxidants are currently being studied for treatment of cardiovascular diseases, obesity, diabetes, and nervous system disorders. The southeastern US supplies approximately 30% of the world’s pecans but yield is limited by pecan scab (Fusicladium effusum). In order to reduce economic loss and improve nutmeat composition control measures are needed. Accurate and precise disease assessments are required for comparison of scab control measures. The objective of the study was to develop a method to improve visual assessments of pecan scab. A series of standard area diagrams of disease were developed and when used rater precision and accuracy improved, ensuring better quality data is obtained. Improvement in rater estimates of fruit scab severity improves the ability to judge disease management options for enhancing profitability of commercial enterprises as well as increasing the nutraceutical value of pecan nutmeats.

Technical Abstract: Pecan (Carya illinoinensis) contains the highest antioxidant levels of all tree nuts, particularly tocopherol and other phytochemicals, which are currently being studied for treatment of cardiovascular diseases, obesity, diabetes, and nervous system disorders. The southeastern US supplies approximately 30% of the world’s pecans. Pecan scab (Fusicladium effusum) causes significant economic losses and reduces nutmeat composition. Accurate and precise disease assessments are required for comparison of scab control measures. Current methods of assessment rely on visual estimates of disease severity, which are often inaccurate and imprecise, and exhibit poor repeatability. This study produces a method improving visual assessments for pecan scab. Twenty-six raters estimated scab severity on 2 sets of 40 images of pecan fruit valves, either with or without the aid of a standard area diagram (SAD) set. Rater precision improved using the SADs (r2=0.44-0.94 and r2=0.84-0.95, without and with SADs, respectively). Agreement (measured with Lin’s Concordance Correlation Coefficient ['c]) improved using the SAD set ('c=0.28-0.95 and 'c=0.68-0.96 without and with SADs, respectively). Improvement in rater estimates of fruit scab severity improves the ability to judge disease management options for enhancing profitability of commercial enterprises as well as increasing the nutraceutical value of pecan nutmeats.