Skip to main content
ARS Home » Pacific West Area » Corvallis, Oregon » Horticultural Crops Research Unit » Research » Publications at this Location » Publication #242598
Title: Cold Tolerance of Container-Grown Green Ash Nursery Trees is Influenced by Nitrogen Fertilizer Type and Rate

Author
item Scagel, Carolyn
item REGAN, RICHARD - Oregon State University
item HUMMEL, RITA - Washington State University
item BI, GUIHONG - Mississippi State University

Submitted to: HortTechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/4/2009
Publication Date: 4/1/2010
Citation: Scagel, C.F., Regan, R., Hummel, R., Bi, G. 2010. Cold tolerance of container-grown green ash nursery trees is influenced by nitrogen fertilizer type and rate. HortTechnology. 20(2):292-303.

Interpretive Summary: Cold damage has been associated with bud and shoot damage of ash trees. Previous research has shown that providing nitrogen (N) as ammonium nitrate (CRF) in a controlled release fertilizer increases bud failure and shoot dieback symptoms of green ash trees compared to trees grown with N from urea formaldehyde (UF). A study was conducted to determine whether N application rate and fertilizer form is related to cold tolerance of buds and stems of nursery-grown green ash (Fraxinus pennsylvanica ‘Summit’) trees. Lower cold tolerance of buds and stems were associated with higher N concentrations and lower carbon to nitrogen ratios (C/N ratios); however, stems and buds of trees fertilized with UF were generally more cold tolerant than stems and buds on trees fertilized with CRF regardless of N application rate. The results suggest differences in bud failure may be related to higher cold tolerance of green ash trees grown with N from UF compared to trees grown with CRF. Results from both studies indicate higher bud failure and lower cold tolerance are associated with higher N concentrations, lower C/N ratios, and differences in N partitioning between trees fertilized with N as CRF and UF. Our results indicate green ash trees with a similar N status may be able to tolerate different levels of cold depending on the type of fertilizer used during production. This may have to do with differences in how trees metabolize the different N types, where and when the N is stored, and how it is remobilized in the spring, especially in relation to C metabolism.

Technical Abstract: A study was conducted to determine whether nitrogen (N) application rate and fertilizer form is related to cold tolerance of buds and stems of nursery-grown green ash (Fraxinus pennsylvanica ‘Summit’) trees. Trees were grown with different rates of N from either urea formaldehyde (UF) or a controlled release fertilizer containing NH4NO3 (CRF) during the 2006 growing season, and growth, N and carbon (C) composition, and cold tolerance were evaluated in October 2006, December 2006, and February 2007 by assessing the lowest surviving temperature (LST) of stem and bud tissues on current season (2006) stems. Both fertilizer type and rate influenced the bud and stem LSTs. The influence of fertilizer rate was most evident on mid-winter (December) stem LSTs and the influence of fertilizer type was observed in bud and stem LSTs during the de-acclimation period in February. Higher LSTs were associated with higher N concentrations and lower carbon to nitrogen ratios (C/N ratios); however, stems and buds of trees fertilized with UF were generally more cold tolerant (had lower LSTs) than stems and buds on trees fertilized with CRF. Fertilizer type resulted in several differences in N and C translocation and metabolism during the autumn and winter. Our results indicate trees with a similar N status can withstand different levels of cold depending not only on the rate of N but also on the type or form of fertilizer used during production. This may have to do with differences in how trees metabolize the different fertilizer forms, where and when the N is stored, and how it is remobilized in the spring, especially in relation to C metabolism.