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Title: Components of yield in pecan depend on tree height due to the distribution of scab in the canopy

item Bock, Clive
item Hotchkiss, Michael - Mike
item Wood, Bruce

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: 5/8/2015
Publication Date: 11/1/2015
Citation: Bock, C.H., Hotchkiss, M.W., Wood, B.W. 2015. Components of yield in pecan depend on tree height due to the distribution of scab in the canopy. Phytopathology. 105(Suppl. 4): S4.17.

Interpretive Summary: Abstract only.

Technical Abstract: Scab (caused by Fusicladium effusum) severity (SS) and sample height in a pecan canopy has been previously characterized. In 3 field experiment in GA, SS at different sample heights and consequent effect on components of yield were characterized in fungicide treated (FT) and control (C) trees. FT trees were sprayed using an airblast sprayer. In August 2010 on cv Desirable mean SS on fruit was 39.6% on C and 22.4% on FT trees. Due to dry conditions in 2011, SS was 1.1% on C and 0.12% on FT trees on cv Desirable, but was 10.4% and 4.0%, respectively on cv Wichita. ANOVA showed significant effects of height in August on SS on fruit, fruit weight, and in October on fruit weight, nut fresh and dry weight, depending on cv and season (P=<0.0001-0.4). Whereas SS decreased with height on C trees, it remained similar or increased with height on FT trees. However, yield components tended to increase with height on C, but remained similar or decrease with height on FT trees. SS on C trees decreased with height (R2=0.57-0.98), but there was little effect on FT trees (R2=0.01-26). On C trees components of yield (fruit, nut fresh and dry weight) most often increased with height (R2=0.08-0.94), while on FT trees components of yield most often decreased with height (R2=0.04-0.89). SS (all heights) in August was most often negatively related to fruit weight in August (R2=0.01-0.92) and nut dry weight (R2=0.29-0.86) in October in both C and FR trees.