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Annual growth rings and the impact of Benlate 50 DF fungicide on citrus trees in seasonally dry tropical plantations of northern Costa Rica
 

Summary: Annual growth rings and the impact of Benlate 50 DF fungicide on citrus
trees in seasonally dry tropical plantations of northern Costa Rica
Marc D. Abrams a,*, Winand K. Hock b
a
School of Forest Resources, Pennsylvania State University, University Park, PA 16802, USA
b
Department of Plant Pathology, Pennsylvania State University, University Park, PA 16802, USA
Received 1 September 2005; received in revised form 13 February 2006; accepted 14 February 2006
Abstract
Tree ring scientists have generally ignored the use of dendrochronological techniques to assess growth impacts of cultural treatments for the
major horticultural trees in plantations. In this study, we investigated differences in radial growth between orange (Citrus) trees, a non-native
subtropical species, growing in plantations in northern Costa Rica and southern Nicaragua that were either treated or untreated with the fungicide
Benlate 50 DF (benomyl), which has potential phytotoxic effects. This region of Central America experiences prolonged and severe drought from
January through April each year, during which an average of only 10% (about 260 mm) of the annual rainfall occurs. Basal cross-sections taken
from the citrus trees reveal distinct annual tree rings that closely match the ages of the trees. The rings are reasonable concentric and have good
circuit uniformity. An analysis of 111 tree cores indicates that Benlate 50 DF treated trees had significantly slower radial growth during their first 6
years (averaging 4.54 mm/year) than untreated trees (averaging 10.7611.84 mm/year). After year 6, the treated trees had a similar growth rate
(11.27 mm/year) to the untreated trees. Four cores taken from each of 10 citrus trees at cardinal directions around the stem reveal that the mean
growth rate from any one aspect did not differ significantly from the mean growth per tree. Further analysis of these cores indicates that taking one
or two random cores per tree produced a similar average growth calculation. The results of this study suggest that young citrus trees produce distinct

  

Source: Abrams, Marc David - School of Forest Resources, Pennsylvania State University

 

Collections: Environmental Sciences and Ecology