Phytophthora pluvialis Studies on Douglas-fir Require Swiss Needle Cast Suppression

Phytophthora pluvialis is associated with early defoliation and shoot dieback in Douglas-fir in Oregon and New Zealand. In 2013, P. pluvialis was described from mixed tanoak-Douglas-fir forests in the Pacific Northwest and concurrently recognized as the main causal agent of red needle cast (RNC) in New Zealand radiata pine plantations. Little is known about its infection cycle and impact on host physiology. P. pluvialis studies in Douglas-fir are challenging due to the ubiquitous presence of the endophyte Phaeocryptopus gaeumannii, which produces similar symptoms and premature defoliation with persistent needle wetness, known as Swiss needle cast (SNC). Nonetheless, our study showed P. pluvialis infection in the presence of SNC. Exclusive expression of P. pluvialis is difficult to achieve as both diseases are promoted by high humidity. Here we established a ‘dry leaf’ strategy to suppress SNC when inoculating Douglas-fir needles for RNC studies. Sheltering plants along with drip irrigation to avoid needle wetness during the P. gaeumannii sporulation period suppressed its development in the new season flush. The diminished endophyte inoculum enabled bias-reduced studies of P. pluvialis impacts on Douglas-fir without the confounding effects of stomatal blockage and premature defoliation caused by P. gaeumannii.

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Contrasting the Pathogen Loads in Co-Existing Populations of Phytophthora pluvialis and Nothophaeocryptopus gaeumannii in Douglas Fir Plantations in New Zealand and the Pacific Northwest United States

Phytopathology ◽

10.1094/phyto-12-18-0479-r ◽

2019 ◽

Vol 109 (11) ◽

pp. 1908-1921 ◽

Cited By ~ 3

Author(s):

Mireia Gómez-Gallego ◽

Jared M. LeBoldus ◽

Martin Karl-Friedrich Bader ◽

Everett Hansen ◽

Lloyd Donaldson ◽

...

Keyword(s):

United States ◽

New Zealand ◽

Pacific Northwest ◽

Spatial Scales ◽

Douglas Fir ◽

The Pacific ◽

Foliar Pathogen ◽

Swiss Needle Cast ◽

Phytophthora Pluvialis ◽

Foliar Pathogens

The emergence of Phytophthora pluvialis as a foliar pathogen of Douglas fir in New Zealand and the Pacific Northwest United States has raised questions about its interaction with the widespread Swiss needle cast (SNC) disease. During Spring 2017, we repeatedly sampled 30 trees along an environmental gradient in each region and 292 additional trees in a longitudinal transect to assess the P. pluvialis epidemic and the association between P. pluvialis and Nothophaeocryptopus gaeumannii, which are causal agents of SNC. Both pathogens were consistently more abundant in the host’s exotic environment in New Zealand. In both areas, the two pathogens co-exist in different spatial scales for regions and needles. The relative abundance of both pathogens was negatively correlated in the Pacific Northwest, where both presumably have co-existed for longer. Our findings confirmed the interaction of P. pluvialis and N. gaeumannii as foliar pathogens of Douglas fir and suggest a within-site spatial variation in the Pacific Northwest.

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Modeling crown structural responses to competing vegetation control, thinning, fertilization, and Swiss needle cast in coastal Douglas-fir of the Pacific Northwest, USA

Forest Ecology and Management ◽

10.1016/j.foreco.2007.04.002 ◽

2007 ◽

Vol 245 (1-3) ◽

pp. 96-109 ◽

Cited By ~ 34

Author(s):

Aaron R. Weiskittel ◽

Douglas A. Maguire ◽

Robert A. Monserud

Keyword(s):

Pacific Northwest ◽

Douglas Fir ◽

Needle Cast ◽

Vegetation Control ◽

Competing Vegetation ◽

The Pacific ◽

Swiss Needle Cast ◽

Structural Responses

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Management of red needle cast caused by Phytophthora pluvialis a new disease of radiata pine in New Zealand

New Zealand Plant Protection ◽

10.30843/nzpp.2014.67.5721 ◽

2014 ◽

Vol 67 ◽

pp. 48-53 ◽

Cited By ~ 4

Author(s):

R.J. Ganley ◽

N.M. Williams ◽

C.A. Rolando ◽

I.A. Hood ◽

H.S. Dungey ◽

...

Keyword(s):

New Zealand ◽

Chemical Control ◽

Radiata Pine ◽

Management Options ◽

Needle Cast ◽

Pine Trees ◽

Breeding Programmes ◽

Forestry Industry ◽

Phytophthora Pluvialis ◽

Red Needle Cast

Ten years ago there were no known foliar diseases caused by Phytophthora on pine trees worldwide Since then two significant Phytophthora diseases have emerged on radiata pine one of which is only known in New Zealand Red needle cast is a disease caused by the pathogen Phytophthora pluvialis which is thought to have originated from northwestern USA This paper reviews the challenges the New Zealand forestry industry faces when dealing with this disease and evaluates the management options such as chemical control biological control and breeding programmes being investigated to minimise its effect on forest productivity The distribution of the pathogen in New Zealand and research that shows bark logs and wood are free of the pathogen therefore unlikely to pose biosecurity threats through trade in these products are also outlined

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Associations between Swiss Needle Cast Severity and Foliar Nutrients in Young-Growth Douglas-Fir in Coastal Western Oregon and Southwest Washington, USA

Forest Science ◽

10.1093/forsci/fxz022 ◽

2019 ◽

Vol 65 (5) ◽

pp. 537-542

Author(s):

Yung-Hsiang Lan ◽

David C Shaw ◽

Gabriela Ritóková ◽

Jeff A Hatten

Keyword(s):

Pacific Northwest ◽

Disease Incidence ◽

Douglas Fir ◽

Cooperative Research ◽

Foliar Nutrition ◽

Needle Cast ◽

The Pacific ◽

Foliage Nutrients ◽

Swiss Needle Cast ◽

Plot Network

Abstract Swiss needle cast (SNC) is a foliage disease of Douglas-fir (Pseudotsuga menziesii) caused by Nothophaeocryptopus gaeumannii, an ascomycete fungus (Mycosphaerellaceae) that causes tree growth reductions in the Pacific Northwest. The epidemiology of the fungus is generally well known, but the relations between disease expression and foliar nutrition are unclear. In this study, we used data from the Swiss Needle Cast Cooperative research and monitoring plot network in western Oregon and SW Washington to assess associations between SNC severity, carbon, and nine foliage nutrients (nitrogen, Na, K, P, Ca, Mg, Mn, Al, S). Foliage samples were collected from midcrown of selected Douglas-firs from each plot. SNC severity was determined on 2-year-old needles by multiplying disease incidence and fungal reproductive (pseudothecia) density. Disease severity and nutrient relations were determined using linear mixed models. SNC severity showed statistically significant positive trends with concentrations of carbon, nitrogen, Na, K, and S, no relation with concentrations of Ca, Mg, or Al, and slightly negative trends that were not significant for P and Mn. This is the first such analysis of associations between a conifer foliage disease and foliage nutrients across a landscape; subsequently, there is little published literature on how or why these nutrients may interact with disease.

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Predicting Swiss Needle Cast Disease Distribution and Severity in Young Douglas-Fir Plantations in Coastal Oregon

Phytopathology ◽

10.1094/phyto.2003.93.7.790 ◽

2003 ◽

Vol 93 (7) ◽

pp. 790-798 ◽

Cited By ~ 32

Author(s):

Pablo H. Rosso ◽

Everett M. Hansen

Keyword(s):

Prediction Model ◽

Disease Severity ◽

Pacific Northwest ◽

Regression Tree ◽

Douglas Fir ◽

Slope Aspect ◽

Disease Prediction ◽

Needle Cast ◽

Swiss Needle Cast ◽

The Relationship

Swiss needle cast (SNC), caused by the fungus Phaeocryptopus gaeumannii, is producing extensive defoliation and growth reduction in Douglas-fir forest plantations along the Pacific Northwest coast. An SNC disease prediction model for the coastal area of Oregon was built by establishing the relationship between the distribution of disease and the environment. A ground-based disease survey (220 plots) was used to study this relationship. Two types of regression approaches, multiple linear regression and regression tree, were used to study the relationship between disease severity and climate, topography, soil, and forest stand characteristics. Fog occurrence, precipitation, temperature, elevation, and slope aspect were the variables that contributed to explain most of the variability in disease severity, as indicated by both the multiple regression (r 2 = 0.57) and regression tree (RMD = 0.27) analyses. The resulting regression model was used to construct a disease prediction map. Findings agree with and formalize our previous understanding of the ecology of SNC: warmer and wetter conditions, provided that summer temperatures are relatively low, appear to increase disease severity. Both regression approaches have characteristics that can be useful in helping to improve our understanding of the ecology of SNC. The prediction model is able to produce a continuous prediction surface, suitable for hypothesis testing and assisting in disease management and research.

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Why is the productivity of Douglas-fir higher in New Zealand than in its native range in the Pacific Northwest, USA?

Forest Ecology and Management ◽

10.1016/j.foreco.2008.03.049 ◽

2008 ◽

Vol 255 (12) ◽

pp. 4040-4046 ◽

Cited By ~ 30

Author(s):

Richard Waring ◽

Alan Nordmeyer ◽

David Whitehead ◽

John Hunt ◽

Michael Newton ◽

...

Keyword(s):

New Zealand ◽

Pacific Northwest ◽

Douglas Fir ◽

Native Range ◽

The Pacific

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The Genetic Structure of Populations of the Douglas-Fir Swiss Needle Cast Fungus Nothophaeocryptopus gaeumannii in New Zealand

Phytopathology ◽

10.1094/phyto-06-18-0195-r ◽

2019 ◽

Vol 109 (3) ◽

pp. 446-455 ◽

Cited By ~ 1

Author(s):

P. I. Bennett ◽

I. A. Hood ◽

J. K. Stone

Keyword(s):

Population Structure ◽

New Zealand ◽

Genetic Structure ◽

Random Mating ◽

Douglas Fir ◽

Needle Cast ◽

The North ◽

Genetic Structure Of Populations ◽

Swiss Needle Cast ◽

North And South

Swiss needle cast is a foliar disease of Douglas-fir (Pseudotsuga menziesii) that results in premature foliage loss and reduced growth. The causal fungus, Nothophaeocryptopus gaeumannii, was first detected in New Zealand in 1959 and spread throughout the North and South Islands over the following decades. The contemporary genetic structure of the N. gaeumannii population in New Zealand was assessed by analyzing 468 multilocus SSR genotypes (MLGs) from 2,085 N. gaeumannii isolates collected from 32 sites in the North and South Islands. Overall diversity was lower than that reported from native N. gaeumannii populations in the northwestern United States, which was expected given that N. gaeumannii is introduced in New Zealand. Linkage disequilibrium was significantly higher than expected under random mating, suggesting that population structure is clonal. Populations of N. gaeumannii in the North and South Islands were weakly differentiated, and the isolates collected from sites within the islands were moderately differentiated. This suggests that gene flow has occurred between the N. gaeumannii populations in the North and South Islands, and between the local N. gaeumannii populations within each island. Eighteen isolates of N. gaeumannii Lineage 2, which has previously been reported only from western Oregon, were recovered from two sites in the North Island and four sites in the South Island. The most likely explanation for the contemporary distribution of N. gaeumannii in New Zealand is that it was introduced on infected live seedlings through the forestry or ornamental nursery trade, as the fungus is neither seed borne nor saprobic, and the observed population structure is not consistent with a stochastic intercontinental dispersal event.

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Predicting the severity of Swiss needle cast on Douglas-fir under current and future climate in New Zealand

Forest Ecology and Management ◽

10.1016/j.foreco.2010.09.034 ◽

2010 ◽

Vol 260 (12) ◽

pp. 2232-2240 ◽

Cited By ~ 18

Author(s):

Michael S. Watt ◽

Jeffrey K. Stone ◽

Ian A. Hood ◽

David J. Palmer

Keyword(s):

New Zealand ◽

Douglas Fir ◽

Future Climate ◽

Needle Cast ◽

Swiss Needle Cast

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Susceptibility of Intermountain Douglas-Fir to Rhabdocline Needle Cast When Grown in the Pacific Northwest

Plant Health Progress ◽

10.1094/php-2001-1029-01-rs ◽

2001 ◽

Vol 2 (1) ◽

pp. 2 ◽

Cited By ~ 3

Author(s):

Gary A. Chastagner

Keyword(s):

Pacific Northwest ◽

Rio Grande ◽

Coastal Areas ◽

Douglas Fir ◽

National Forest ◽

Santa Fe ◽

High Susceptibility ◽

Needle Cast ◽

Christmas Trees ◽

The Pacific

Douglas-fir are traditionally grown as Christmas trees in the Pacific Northwest (PNW). Intermountain (IM) provenances of Douglas-fir are less likely to be injured after harvest by exposure to subfreezing temperatures than the coastal provenances. However, planting IM Douglas-fir in the coastal areas of the PNW is currently not recommended because of their high susceptibility to Rhabdocline needle cast. During a three-year period, needle cast severity was rated (0 to 100 scale) on trees in a replicated planting of IM Douglas-fir near Puyallup, WA. In 1997, needle cast ratings ranged from 0.8 to 70. Trees from the Cibola National Forest (NF) had significantly higher needle cast ratings (70.0) than trees from Carson NF (17.3), Coconino NF (15.7), Rio Grande NF (5.0), and Upper Clearwater, ID (0.8). Trees from the Apache NF (51.4), San Isabel NF (32.3), two collections representing the Lincoln NF (25.4-30.2), and the Santa Fe NF (21.3) had intermediate levels of needle cast. This study shows that certain sources of IM Douglas-fir can be grown in the PNW with minimal Rhabdocline needle cast problems. Applications of chlorothalonil also provided effective needle cast control on all but the most susceptible provenance. Accepted for publication 15 October 2001. Published 29 October 2001.

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