sdu faculty of forestry journal special edition 2009 - Orman Fakültesi

SDU Faculty of Forestry Journal
Serial: A, Number: Special Issue, Year: 2009, ISSN: 1302-7085, Page: 262
ATTEMPTS TO NATURALLY REGENERATE RED PINE CAN BE
THREATENED BY
DIPLODIA SHOOT BLIGHT DAMAGE TO UNDERSTORY SEEDLINGS
B. W. OBLINGER 1 , Denise R. SMITH 1 , Glen R. STANOSZ 1*
Department of Plant Pathology, University of Wisconsin-Madison, WI, 53706, USA
* grs@plantpath.wisc.edu
Changes in red pine (Pinus resinosa) management, due to aesthetic and
biodiversity concerns, include creation of harvest units with irregular edges, long
borders of mature trees, and retention of some overstory trees within a harvested
area. Also, in contrast to traditional even-aged management in which trees of one
age class are grown, clearcut at final harvest, and replaced by planted seedlings,
there is increasing interest in natural regeneration and developing multi-aged red
pine stands. However, crowns of red pines can be sources of abundant inoculum of
the shoot blight pathogen Diplodia pinea. To determine if Diplodia shoot blight
threatens young, naturally regenerated red pine in the understory, six replicate plots
were established in each of four mature plantations in central Wisconsin. The
frequency of standing, dead seedlings bearing shoot blight symptoms or signs of
the pathogen, and the incidence and severity of shoot blight damage to live
seedlings were recorded. Mean seedling mortality ranged from 13-30% and mean
incidence of blighted living seedlings ranged from 94-100% at all sites. The mean
frequency of live seedlings with their terminal leaders killed in the past was from
55-94%. Mean severity of damage to live seedlings, on a 0-3 scale, was ÿ2.16 at
all sites. Results of a PCR assay confirmed pathogen identity. These results
support previous research and concern that shoot blight pathogens threaten young
red pines in the understory.
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