Volutella Leaf Blight and Stem Canker on Japanese Pachysandra in the Czech Republic

Vol. 43, No. 1: 10–12 Plant Protect. Sci.

Ivana Šafránková

Department of Crop Science, Breeding and Plant Medicine, Mendel University of Agriculture and Forestry in Brno, Brno, Czech Republic

Abstract

Šafránková I. (2007): Volutella leaf blight and stem canker on Japanese pachysandra in the Czech Repub- lic. Plant. Protect. Sci., 43: 10–12.

Woody ornamental cover plants of Japanese pachysandra (P. terminalis S. et Z.) are planted in parks and gardens in the Czech Republic. A serious disease of these plants is Volutella leaf blight and stem canker caused by the fungus Pseudonectria pachysandricola (anamorph Volutella pachysandricola). It was described by Dodge (1944) in the United States and appeared in Europe in the 1980s. Volutella pachysandricola was isolated from Japanese pachysandra (P. terminalis cvs. Green Carpet and Variegata) from leaf spots and stem and stolon cankers in Brno in 2000–2003. The tan or brown spots with brown margins, often with concentric zones, develop on infected leaves. Stem and stolon cankers appear as water-soaked diseased areas, the stem often turns brown, shrivels and girdles. The infection often begins in damaged or senescent plant parts and spreads into the healthy tissues. Pink-orange sporodochia with spores form on newly killed stems and leaves during humid spring and summer periods. Ascospores develop in red-orange perithecia on the same tissues.

Keywords: Pseudonectria; Pachysandra terminalis; Czech Republic

Pseudonectria pachysandricola Dodge, anam. Republic (Mareček 1999). In 2002, P. pachysan- Volutella pachysandricola Dodge, is a phytopatho- dricola (V. pachysandricola) was detected in the genic micromycete which attacks the leaves, stems Botanical Garden and Arboretum of the Mendel and stolons of Japanese pachysandra (Pachysandra University of Agriculture and Forestry in Brno in terminalis L.) and causes Volutella leaf blight and both teleomorphous and anamorphous stages. The stem cankers (Dodge 1944; Sinclair et al. 1987; anamorph stage was found on the leaves, stems and Hudler et al. 1990; Rossmann et al. 1993). The stolons of P. terminalis cv. Green Carpet and on fungus is widely spread in North America (Dodge the leaves and the stems of cv. Variegata; the teleo- 1944; Chilton 1954; Samuels 1977; Gould & morph stage P. pachysandricola was detected only Kackley-Dutt 1992; Rossman et al. 1993). In on the stems of P. terminalis cv. Green Carpet. Europe it was reported from Britain (Sinclair et al. 1987), Poland (Wojdyla et al. 2000) and Germany Symptoms 2001 (Nennmann 2004). The fungus has not been reported from the Czech Republic so far. On the leaves regular yellow-brown to brown Pachysandra terminalis is considered to be an spots appeared, frequently with concentric lighter absolutely hardy plant that does not suffer from any and darker zones and dark-brown edges (Figure 1). diseases or pests under the conditions of the Czech The spots gradually spread over the whole leaves.

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At first the water-soaked green-brown bark can- rounded ends, 14–20 × 2.8–4.0 μm, with two oil- kers appear on the stems, that later dry up and drops. turn brown. The parts above the infected sites In culture on PDA, t = 24°C, sparse aerial myce- then wilt and die. The cankers gradually girdle lium near margin, at the centre immersed, slimy, the whole twig and most of the leaves die off. On surface of colony salmon-coloured. Conidiophores the stolons the first cankers often appear at the developing from vegetative hyphae, single, un- site of rooting. branched, monophialidic, 9.1–17.5 μm long, 2.5–3.5 wide at base, 1.7 μm at apex. Conidia Description of the isolated pathogen are unicellular, hyaline, long and ellipsoid with rounded ends, 10–21 × 3–4.1 μm. teleomorph: Pseudonectria pachysandricola Dodge Morphological characters and growth rate are consistent with previous reports on teleomorph Perithecia on recently killed browning twigs soli- Pseudonectria pachysandricola Dodge and ana- tary to gregarious, superficial or slightly immersed morph Volutella pachysandricola (Dodge 1944). in a thin stroma. Red-orange perithecia ± globose to broadly pyriform, 220–240 × 170–190 μm, with Disease cycle sparse long setae and numerous short hairs. Setae straight, unbranched, to 120 μm long. Hairs 6–12 × Japanese pachysandra is most susceptible to 5–7.0 μm long, straight, tapering to a round apex, infection on older parts of the plant and on those luteous, thick walled (1.4 μm at apex, 2.0 μm at parts that have been damaged by exposure to bright base). Asci unitunicate, 46–58 × 7–8 μm, slightly sun, winter drying, insect feeding or other factors. clavate, with eight spores. Ascospores two-celled, The infection often begins in damaged or senes- ellipsoid, 8.7–13.0 × 3.0–3.5 μm, ends rounded, cent parts and spreads into healthy tissues. Brown hyaline, thinwalled. spots show on the leaves 5–9 d after infection; on stems, diseased areas appear water-soaked, they anamorph: Volutella pachysandricola Dodge often girdle the stem within 2 weeks of infection. The minute, cushion-shaped sporodochia appear Sporodochia are formed on newly killed stems within a few days (6–8) (Figures 2), they produce and leaves during humid spring and summer pe- a number of microscopic, one-celled, colorless co- riods. Sporodochia regularly scattered, solitary, nidia. The older sporodochia or stromata produce erumpent, pale, later pink-orange, with sparse one or several perithecia ascospores. Conidia and hyaline setae at margins. Conidiophores solitary, ascospores germinate in moist weather and reinfect unbranched, monophialidic 8.5–18.5 × 2.6–3.5 μm. pachysandra plants. The spores are disseminated Conidia unicellular, hyaline, long ellipsoid with from plant to plant by air and splashing water.

Figure 1. Brown spots on leaves of Pachysandra termi- Figure 2. Sporodochia of Volutella pachysandricola on nalis caused by infection with Pseudonectria pachy- the stem of Pachysandra terminalis sandricola

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The microclimate of the dense plants is very References favourable for the development of the fungus. The frequency of precipitation and/or irrigation Chilton J.E. (1954): Volutella species on alfalfa. Myco- of the stand considerably affected the intensity of logia, 46: 800–809. the fungal attack. The occurrence of the fungus was Dodge B.O. (1944): A new Pseudonectria on Pachysandra. prominent in the second half of 2003. Due to the Mycologia, 36: 532–537. irrigation of the stand, the effect of precipitation on Gould A.B., Kackley-Dutt K. (1992): Common spring- the occurrence of the disease could not be evaluated time diseases of woody ornamentals in the landscape. in detail. In the first half of the year, spots on the Rutgers Cooperative Research & Extension. leaves and stem cankers appeared only sporadically. Hudler G.W., Neal B.G., Banik M.T. (1990): Effect With increasing temperatures the visual symptoms, of growing conditions on wound repair and disease particularly on the leaves, receded. An increased resistance in Pachysandra terminalis. Phytopathology, intensity of occurrence was not detected until the 80: 272–277. second half of the year, but did not reach the inten- Mareček F. (1999): Zahradnický slovník naučný. N–Q. sity of the previous year. Owing to the shedding of ÚZPI, Praha. infected leaves it is very difficult to estimate the Nennmann H. (2004): Blattflecken und Stecklingsfäule damage, a degradation of the aesthetic quality of an Pachysandra. Available at http://www.lk-wl.de/rlplpf/ the undergrowth is more likely. sch/garden_zierpfl/pachysan.htm (date 20. 9. 2004) Infected plants were collected and infection Rossman A.Y., Samuels G.J., Lowen R. (1993): Leu- determined: Brno-Černá Pole (6765), 19. IX. 2002, conectria clusiae gen. nov. and its anamorph Gliocepha- brown blotches on the leaves and dark brown to lotrichium bulbilium with notes on Pseudonectria. black necrotic cankered stems with sporodochia Mycologia, 85: 685–704. on P. terminalis Green Carpet; 16. X. 2002, 15. XI. Samuels G.J. (1977): Nectria consors and its Volutella 2002, sporodochia on leaves and stem blight; 10. VI. conidial state. Mycologia, 69: 255–262. 2003, sporodochia on blighted stem; 17. V. 2003, Sinclair W.A., Lyon H.H., Johnson W.T. (1987): Dis- perithecia on stems of P. terminalis Green Car- eases of Trees and Shrubs. Cornell University Press, pet; 10. IX. 2003, rare leaf and stem blight on Ithaca and London. P. terminalis Variegata; 12. X. 2003, 15. XI. 2003, Wojdyla A., Orlikowski L., Labanowski G., Doika numerous sporodochia on leaves and stems of G. (2000): Ochrona ozdobnych krzewów liściastych. P. terminalis Green Carpet, rare on P. terminalis Plantpress, Kraków. Variegata. Received for publication November 6, 2006 Accepted after corrections December 19, 2006

Corresponding author: Ing. Ivana Šafránková, Ph.D., Mendelova zemědělská a lesnická univerzita v Brně, Ústav pěstování, šlechtění rostlin a rostlinolékařství, Zemědělská 1, 613 00 Brno, Česká republika tel.: + 420 545 133 048, e-mail: [email protected]