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Arboriculture & Urban Forestry Online
Volume 15, Issue 5 — May 1989

Physiological Responses of Deciduous Tree Root Collar Drenched with Flurprimidol    (View PDF)

J.P. Sterrett, T.J. Tworkoski, and P.T. Kujawski

Abstract: Root collars of 11 -yr-old pin oak (Quercus palustris), red maple (Acer rubrum), white ash (Fraxinus americana), and black walnut (Juglans nigra) were drenched in June, August, or October 1985 with 2 or 4 g a.i. (W.P.) flurprimidol {a-(1 -methylethyl)-a-[4-(trifluoromethoxy)-phenyl]-5- pyrimidine-methanol} to determine physiological responses. No treatment response occurred the year of treatment but significant terminal and lateral growth inhibition, 43 to 92%, respectively, occurred during the first growing season (1986) following treatment. In general, less growth inhibition resulted from October treatments. However, by the end of the second growing season following application (1987), all treatment combinations inhibited terminal and lateral growth. Leaf area of pin oak and red maple only was reduced (22 to 65%) in 1986 but by 1987 leaf area was reduced 17 to 65% on all species from all treatments. Except for white ash, leaf dry weight was reduced (28 to 64%) by 1987. In general, flurprimidol caused a slight decrease in photosynthetic activity and an increase in chlorophyll concentration but transpiration rates were unchanged. These results indicate that flurprimidol reduces growth without significantly altering energy assimilation or water movement in individual leaves.


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