Hydraulic conductivity in roots of ponderosa pine infected with black-stain (Leptographium wageneri) or annosus (Heterobasidion annosum) root disease

Abstract

Roots from healthy and diseased mature ponderosa pine, Pinus ponderosa Laws., trees were excavated from a site near Burns, Oregon. The diseased trees were infected with black-stain root disease, Leptographium wageneri Kendrick, or annosus root disease, Heterobasidion annosum (Fr.) Bref., or both. Axial hydraulic conductivity of the roots was measured under a positive head pressure of 5 kPa, and the conducting area was stained with safranin dye to determine specific conductivity (k(s)). In diseased roots, only 8-12% of the cross-sectional xylem area conducted water. Resin-soaked xylem completely restricted water transport and accounted for 13-16% of the loss in conducting area. In roots with black-stain root disease, 17% of the loss in conducting area was associated with unstained xylem, possibly resulting from occlusions or embolisms. Based on the entire cross-sectional area of infected roots, the k(s) of roots infected with black-stain root disease was 4.6% of that for healthy roots, whereas the k(s) of roots infected with annosus root disease was 2.6% of that for healthy roots. Although these low values were partly the result of the presence of a large number of diseased roots (72%) with no conducting xylem, the k(s) of functional xylem of diseased roots was only 33% of that for healthy roots. The low k(s) values of functional xylem in diseased roots may be caused by fungus induced occlusions preceding cavitation and embolism of tracheids. The k(s) of disease-free roots from diseased trees was only 70% of that for healthy roots from healthy trees. The disease-free roots had the same mean tracheid diameter and tissue density as the healthy roots, suggesting that the lower k(s) in disease-free roots of diseased trees may also have been caused by partial xylary occlusions.

Stem increment and hydraulic architecture of a boreal conifer (Larix sibirica) under contrasting macroclimates

“…The evaluated literature included studies by Joseph et al (1998), Piñol and Sala (2000), Martínez-Vilalta and Piñol (2002), Mayr et al (2003), Oliveras et al (2003), Stout and Sala (2003), Domec et al (2004), Mainiero and Kazda (2006), Martínez-Vilalta et al (2009), andCharra-Vaskou et al (2012). The Tables S2 and S3 in the Supplementary Information contain these variables for 51 stands together with climatic data.…”

The holoparasitic endophyte Bdallophyton americanum affects root water conductivity of the tree Bursera simaruba

“…In general, root water conductivity is higher than in stems or leaves (Joseph et al 1998), so reduction in water flow as a result of parasitic activity should be easily detected. Our data show significant differences in root specific conductivity of B. simaruba between seasons and with infection by B. americanum in our studied area.…”

“…Previous reports showed that root parasites of different species modify water flux, often by rendering vessels or tracheids dysfunctional. The presence of black stain root disease (Leptographium wageneri: Ascomycetes) and annosus disease (Heterobasidion annosum: Basidiomycetes), reduce the hydraulic conductivity in roots of ponderosa pine (Pinus ponderosa: Pinaceae) (Joseph et al 1998). Water flux reduction is the result of most tracheids being non-conductive in diseased roots (Joseph et al 1998).…”

“…The presence of black stain root disease (Leptographium wageneri: Ascomycetes) and annosus disease (Heterobasidion annosum: Basidiomycetes), reduce the hydraulic conductivity in roots of ponderosa pine (Pinus ponderosa: Pinaceae) (Joseph et al 1998). Water flux reduction is the result of most tracheids being non-conductive in diseased roots (Joseph et al 1998). Baker et al (1994) also recorded hydraulic conductivity reduction (20-70%) in infected roots of Douglas fir (Pseudostuga menziesii: Pinaceae) with a complex of diseases including annosus and black-stain root disease.…”

Using chemical markers to detect root disease in stressed ponderosa pine stands with a low incidence of disease in eastern Oregon

“…Cobb (black-stain root disease) or H. annosum (annosum root disease), or both, the crown symptoms do not appear until the infection reaches moderate to severe levels with 61.2 and 85.5% of the total cross-sectional root area being non-functional at 30 cm distance from the root collar, respectively . Black-stain is a wilt disease that disrupts water transport in the host (Hessburg, 1984;Hessburg and Hansen, 1987;Joseph et al, 1998), and contributes to symptom development in the crown because of the relationship between water supply and tissue growth. For example, artificially limiting water supplies to healthy red pine, Pinus resinosa Ait, causes decreased bud size and reduced shoot elongation compared to those trees supplied with ample water (Clements, 1970).…”