Modelling the impacts of the foliar pathogen, Phaeocryptopus gaeumannii, on Douglas-fir physiology: net canopy carbon assimilation, needle abscission and growth

Manter, Daniel K.; Bond, Barbara J.; Kavanagh, Kathleen L.; Stone, Jeffrey K.; Filip, Gregory M.

doi:10.1016/s0304-3800(03)00026-7

Cited by 40 publications

(37 citation statements)

References 22 publications

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“…Occlusion of the stomata by pseudothecia of P. gaeumannii impedes gas exchange and regulation of transpiration, causing impaired photosynthetic activity, and is considered the primary mechanism of pathogenicity (Manter et al 2000(Manter et al , 2003. Estimates of the effect of P. gaeumannii on CO 2 assimilation indicate that occlusion of ∼25% of stomata results in overall negative needle carbon budgets, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…Estimates of the effect of P. gaeumannii on CO 2 assimilation indicate that occlusion of ∼25% of stomata results in overall negative needle carbon budgets, i.e. respiration exceeds assimilation, on an annual basis (Manter et al 2003). Because the physiological effects of the disease (impaired CO 2 uptake and photosynthesis) are quantitatively related to the abundance of the pathogen (proportion of stomata occluded by ascocarps), ascocarp abundance is an appropriate and easily measured quantitative response variable for assessing effects of environmental factors on disease.…”

Section: Discussionmentioning

confidence: 99%

“…Although a maximum of 100% pseudothecial density (every stomate on a needle occluded) is theoretically possible, needles are usually shed well before 100% of stomata are occluded. Foliage abscission occurs when needles switch from being carbon sources to carbon sinks (Cannell and Morgan 1990), usually before more than half the needle stomata are occluded, because of the effect on stomatal conductance and CO 2 fixation reducing needle carbon budgets (Manter et al 2003). The greatest proportion of occluded stomata observed on attached needles where disease is most severe is seldom above 50% (Hansen et al 2000).…”

Section: Discussionmentioning

confidence: 99%

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Distribution of Swiss needle cast in New Zealand in relation to winter temperature

Stone

Hood²,

Watt³

et al. 2007

Austral. Plant Pathol.

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Abstract. Phaeocryptopus gaeumannii, the causal agent of Swiss needle cast disease, is widely distributed throughout New Zealand, where the disease may cause significant growth losses in Douglas-fir (Pseudotsuga menziesii) plantations. In western Oregon, where the pathogen is native, pathogen abundance and disease severity are correlated with mean daily winter temperatures and spring moisture, enabling the development of climate-based disease prediction models. The distribution of P. gaeumannii and severity of Swiss needle cast was surveyed in 16 Douglas-fir plantations throughout New Zealand in 2005. Retention of foliage was assessed in the field and samples of 1-and 2-year-old needles were collected for assessment of P. gaeumannii abundance. Foliage retention and abundance of P. gaeumannii varied across sites. Less colonisation by P. gaeumannii and greater needle retention was found in the South Island. Abundance of P. gaeumannii was found to be positively correlated with August minimum temperature and June average temperature, and showed a similar relationship to winter temperature as observed in western Oregon. These data will be used to derive a disease prediction model for Swiss needle cast in New Zealand that can be used to guide further research and provide short-and long-term disease risk predictions and cost/benefit analyses.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Distribution of Swiss needle cast in New Zealand in relation to winter temperature

Stone

Hood²,

Watt³

et al. 2007

Austral. Plant Pathol.

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“…The disease has reduced tree vigor and caused premature needle abscission [40], significantly altering several crown structural attributes [65] and leading to average volume growth losses as high as 52% in severely affected plantations [38]. Growth losses presumably result from both reduced LAI [65] and disruption of gas exchange in surviving needles [39]. Better understanding of the disease's influence on LAI may improve predictions of growth losses.…”

Section: Introductionmentioning

confidence: 99%

Response of Douglas-fir leaf area index and litterfall dynamics to Swiss needle cast in north coastal Oregon, USA

Weiskittel

Maguire

2007

Ann. For. Sci.

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-Sources of variation in leaf area index (LAI; m 2 of projected leaf area per m 2 of ground area) and its seasonal dynamics are not well known in managed Douglas-fir stands, despite the importance of leaf area in forecasting forest growth, particularly in stands impacted by insects or disease. The influence of Swiss needle cast (SNC) on coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb] Franco) LAI and litterfall dynamics was quantified by destructively sampling 122 stems from 36 different permanent plots throughout north coastal Oregon, USA, and by monitoring litterfall for 3 years in 15 of these plots. LAI, total annual litterfall, and the seasonal distribution of foliage and fine woody litterfall were all influenced by stand structural attributes, physiographic features, and SNC severity. Mean LAI in this study was 5.44 ± 2.16. The relatively low LAIs were attributed primarily to the effects of SNC on foliage retention, and secondarily to its direct measurement by hierarchical foliage sampling in contrast to indirect measurement by light interception or tree allometry. For a given stand structure and SNC severity, LAI was 36% greater in the fall after current year foliage was fully developed and older aged classes had not yet senesced. Annual litterfall expressed as a proportion of LAI at the start of the growing season varied from 0.13 to 0.53 and declined with increasing initial LAI. SNC also shifted more of the annual foliage litterfall to earlier in the spring. Fine woody litterfall experienced a different seasonal shift as the peak occurred later in the year on sites with high SNC, but this only occurred on northerly aspects. Defoliation from the endemic SNC pathogen can drastically reduce LAI and change both total and seasonal foliage litterfall patterns.Swiss needle cast / Douglas-fir / defoliation / leaf area index / foliage loss dynamics Résumé -Réponse de l'index foliaire (LAI) et de la dynamique de chute de litière du Douglas à la rouille suisse dans la zone côtière du Nord Oregon. Les sources de variation de l'index foliaire (LAI, m 2 de surface projetée des feuilles par m 2 de surface de sol) et sa dynamique saisonnière ne sont pas bien connues dans les peuplements aménagés de Douglas, malgré l'importance de la surface foliaire dans les prévisions de la croissance des forêts, particulièrement dans les peuplements touchés par des insectes ou les maladies. L'influence de la rouille suisse (SNC) sur l'index foliaire et la dynamique de chute de litière de Pseudotsuga menziesii var. menziesii [Mirb.] Franco ont été quantifiées grâce à un échantillonnage destructif de 122 tiges dans 36 placeaux permanents dans la zone côtière du Nord Oregon (USA) et le suivi pendant 3 ans des chutes de litière dans 15 de ces placeaux. L'index foliaire, la chute annuelle totale de litière, et la distribution du feuillage et la litière ligneuse fine ont tous été influencés par les attributs structuraux, les caractéristiques physiographiques et la gravité de SNC. Dans cette étude la moyenne de l'ind...

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“…In 1996, aerial surveys in coastal Oregon detected 196,000 ha with moderate to severe disease levels (Hansen et al 2000). The fungal pathogen of SNC, Phaeocryptopus gaeumannii (Rhode) Petrak, occludes stomata causing a reduction in maximum stomatal conductance (g smax ) (Manter et al 2000;Manter et al 2003) and chronic premature needle abscission (Hansen et al 2000). The disease cycle begins in the spring when newly emerging needles are infected by airborne spores.…”

Section: Introductionmentioning

confidence: 99%

Stomatal regulation in Douglas fir following a fungal-mediated chronic reduction in leaf area

Manter

Kavanagh

2003

Trees - Structure and Function

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Pathogens can cause chronic premature needle abscission in coniferous species. To assess the potential impacts on tree productivity, stomatal regulation was investigated in Douglas fir with chronic stomatal occlusion and defoliation from varying levels of the Swiss needle cast (SNC) fungus, Phaeocryptopus gaeumannii. Levels of SNC disease and subsequent defoliation were manipulated by choosing six sites with varying levels of disease and by foliar applications of fungicides on six trees per site. Diurnal measurements of leaf water potential (Y leaf ), stomatal conductance (g s ) and vapor pressure deficit (D) were made on six fungicide treated and six control trees per site. In addition, leaf specific hydraulic conductance was calculated on a single branch (K L_B ) from three trees per treatment per site. Stomatal conductance at D=1 kPa (g sref ) was negatively correlated with fungal colonization (number of fruiting bodies present in needle stomata) and positively correlated with K L_B . Despite reduced needle retention in diseased trees, K L declined due to a reduction in sapwood area and permeability (i.e., increasing presence of latewood in functional sapwood). In general, stomatal sensitivity to D for all foliage was consistent with stomatal regulation based on a simple hydraulic model [g s =K L (Y soil Y leaf )/ D], which assumes strict stomatal regulation of Y leaf . However, when fungal presence reduced maximum g s below the potential maximum supported by hydraulic architecture, stomatal sensitivity was lower than expected based on the theoretical relationship: dg s /dlnD=0.6·g sref .The results indicate that losses in productivity associated with physical blockage of stomata and defoliation are compounded by additional losses in K L and a reduction in g s in remaining functional stomata.

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Modelling the impacts of the foliar pathogen, Phaeocryptopus gaeumannii, on Douglas-fir physiology: net canopy carbon assimilation, needle abscission and growth

Cited by 40 publications

References 22 publications

Distribution of Swiss needle cast in New Zealand in relation to winter temperature

Distribution of Swiss needle cast in New Zealand in relation to winter temperature

Response of Douglas-fir leaf area index and litterfall dynamics to Swiss needle cast in north coastal Oregon, USA

Stomatal regulation in Douglas fir following a fungal-mediated chronic reduction in leaf area

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