A twig blight of understorey European beech (Fagus sylvatica) caused by soilborne Phytophthora spp.

Abstract

During and after prolonged periods of rainfall in late spring, blighted young twigs of European beech (Fagus sylvatica) were frequently observed in several beech stands in south-western and southern Germany. Long and short shoots of young understorey trees or lower branches up to 1.5 m above the soil level were affected. Symptoms also occurred regularly on twigs in heights up to 2 m and more above the ground. Necroses usually expanded within the current yearÕs tissue and often also reached into the previous yearÕs wood. Ponding rain water in the stands or along forest roads or open soil seemed to promote the disease. Of a total of 54 symptomatic twigs collected in four stands, 37 revealed Phytophthora isolates, of which 33 were P. plurivora and four were P. cambivora. Both species caused extensive lesions on beech twigs in laboratory pathogenicity tests. Patterns of the disease indicated that these pathogens, generally considered soilborne species, in most cases are transmitted from the soil to above-ground parts of the trees via rain splash. In larger heights, however, other vectors such as snails might be responsible for transmission. Although Phytophthora spp. are well known as causal agents of seedling blight as well as root and cambium rot and aerial bleeding cankers of mature beech, to our knowledge this is the first report of a twig blight in beech associated with soilborne Phytophthora spp. In particular in periods of high precipitation, this disease might pose an additional threat to Central European beech forests, especially endangering the success of artificial and natural regeneration of beech in affected stands.

Genotypic Diversity of Phytophthora cinnamomi and P. plurivora in Maryland’s Nurseries and Mid-Atlantic Forests

“…Despite being widely prevalent on numerous woody plants in nursery and forest ecosystems both in Europe and North America, disease caused by P. plurivora has not been observed on the scale of the forest dieback caused by P. cinnamomi. One major difference is that P. plurivora appears to have even greater ecological plasticity than P. cinnamomi; it is present in cooler northern and warmer southern locations and colonizes diverse ecological niches (e.g., soil and aquatic environments) (Balci and Halmschlager 2003a,b;Balci et al 2007;Jung and Burgess 2009;Jung et al 2016;Nechwatal et al 2011). This raises questions about whether or not genetic diversity is required for a pathogen to cause major losses or, rather, if it is more significant in adaptation to different environments and substrates.…”

“…The reason behind this pathological difference is likely related to its ecological adaptations. Unlike P. cinnamomi, P. plurivora is adapted to aquatic environments (e.g., fresh stream water or irrigation water), and can spread to aboveground plant parts through rain splash or overhead irrigation (Brazee et al 2016;Huai et al 2013;Jung et al 2016Jung et al , 2017Nechwatal et al 2011). Ecologically, P. plurivora appears to be not restricted by cold winter temperatures whereas P. cinnamomi is limited in its pathology and spread (Bergot et al 2004;McConnell and Balci 2014).…”

Occurrence of Phytophthora multivora and Phytophthora plurivora in the Czech Republic

“…This species is also the cause of a twig blight of understory beech trees (Nechwatal et al 2011) and diseases of rhododendron and other ornamentals ). Outside Europe, P. plurivora was predominantly recovered from highly managed plantations and nurseries in North America ).…”

Winter peridermal conductance of apple trees: lammas shoots and spring shoots compared

“…After defoliation due to herbivory or late spring frosts the ability for multiple flushing is of great advantage (Jones 1959; Cline and Harrington 2007). In contrast, lammas shoots have been found to be more susceptible to pathogens and frost damage in several species (Jones 1959; Kozlowski 1964; Nechwatal et al 2011). Our study demonstrates that lammas shoots can also have negative impacts on tree water relation as lammas shoots of apple trees show a high peridermal conductance due to an imperfect development of tissues.…”