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Grey mould, caused by Botrytis cinerea and other Botrytis spp., is a major cause of fruit rot in strawberries and other fruit crops worldwide. Repeated fungicide applications are essential in order to secure harvests. However, resistance to all currently registered single-site fungicides is widespread. The rising importance of strains with multiple resistance to most or all fungicides is of particular concern. These strains may be introduced into fields via contaminated nursery plants and/or by immigration from adjacent plots. On the basis of research conducted in northern German and Danish strawberry production, a concept to manage fungicide resistance under northern European conditions has been developed and put into regional strawberry production practice. This principally includes the testing of nursery plants for fungicide-resistant Botrytis strains prior to planting; the restricted and specific use of fungicides at flowering in the production fields, taking account of the resistance spectrum within the local Botrytis population; and crop sanitation measures such as the removal of rotting fruits at the beginning of harvest. Further options such as protected cultivation, reduced fertilisation and biological control are also discussed. The practical implementation of such a strategy in northern Germany and Denmark has been shown to reduce the occurrence of multi-resistant strains to a tolerable steady-state level.

Abstract Background European canker, caused by Neonectria ditissima, is a disease of worldwide importance in apple production, yet knowledge about it is limited, highly regional and sometimes contradictory. This is an obstacle to successful disease management. Key aspects for Northern Europe are reviewed, based on research results from Northern Germany and Norway and on international literature data. Main topics Trunk cankers developing on young trees within the first 1–3 seasons of explanting can often be traced back to latent infections initiated in the nurseries. The most important nursery infection is a lateral canker on the main trunk of ‘knip’ trees, which are the standard tree type in Northern Europe. In strongly affected batches, up to 25% of trees have to be uprooted after the first growing season due to such trunk cankers. The establishment and maintenance of healthy orchards requires clean nursery material, especially in the case of susceptible cultivars. In Northern Germany, infections within commercial orchards most often proceed through wounds caused by fruit picking or leaf fall in autumn, as shown by the appearance of cankers in the following spring and by the high efficacy of fungicide treatments at leaf fall. Ascospores, commonly thought to be relevant for long-distance spread of infections, are not released until the end of leaf fall even in wet autumn seasons in Northern Germany. Therefore, their role in the disease remains unclear. Strong nitrogen-induced vegetative growth favours apple canker. In field trials conducted under conditions of current commercial practices, autumnal sprays with copper hydroxide or copper oxide were consistently more efficacious than copper oxychloride or captan in preventing new infections. Conclusions Restricted fertilisation and other measures to curb excessive vegetative growth during the first few years of an orchard, repeated canker pruning and well-timed treatments with effective fungicides in autumn are essential for IPM of apple canker. Nonetheless, canker remains capable of severely impairing the commercial success of susceptible cultivars in regions with wet climates even if all available measures are taken. This opens up long-term perspectives for the breeding of more resistant cultivars.

Rabbit pellets collected from the field were colonized by Podospora pleiospora at the exclusion of other coprophilous fungi, suggesting antibiosis. In liquid culture, P. pleiospora produced sordarin (1); sordarin B (2), a new compound in which sordarose is replaced by rhamnose; hydroxysordarin (3); and sordaricin (4). The major compounds 1 and 2 exhibited minimum inhibitory concentrations of 0.52.5 g ml-1 against the yeasts Nematospora coryli and Sporobolomyces roseus, but showed little or no activity against bacteria or coprophilous filamentous fungi. In liquid culture, the production of 1 and 2 together amounted to 2.7 g ml-1, whereas in rabbit dung only 1 was produced at a similar concentration (2.3 g g-1 fresh weight). The biosynthesis of these substances was unaffected by the presence of inoculum of other fungi tested (Sporobolomyces roseus or Penicillium claviforme) in liquid culture or on dung. Sordarin-type natural products are therefore synthesized by P. pleiospora at sufficiently high concentrations to account for antibiosis against yeasts, but not against filamentous fungi. [ABSTRACT FROM AUTHOR]

Phoma medicaginis was isolated as the dominant endophyte from surface-sterilized shoots of Medicago sativa and M. lupulina growing outdoors. Plants were either symptomless or showed signs of infection in the shape of limited lesions which sometimes contained melanized pycnidial initials. Rapid colonization of host tissue and sporulation were observed within 9 d on dead plant material upon incubation in a moist chamber. Such colonized material, but not freshly harvested living tissue, contained brefeldin A (1.7 μg g−1 D.W.). This toxin was also produced in pure culture (20 mg l−1) and in artificially inoculated autoclaved M. sativa stems (3 mg g−1 D.W.=920 μg ml−1). The latter concentration of brefeldin A should be similar to that produced within a fruiting lesion of P. medicaginis and suppressed spore germination and growth of nine of 11 common phylloplane fungi tested. This metabolite may thus have a function in substrate defence after the switch from the endophytic to the saprotrophic period in the life-cycle of P. medicaginis following the death of infected host tissue. [ABSTRACT FROM AUTHOR]

Names of fungi1. Sclerotinia curreyana (Berkeley ex Currey) P. Karsten = Myriosclerotinia curreyana (Berkeley ex Currey) Buchwald; conidial state Myrioconium Sydow2. Sclerotinia Fuckeliana (de Bary) Fuckel = Botryotinia fuckeliana (de Bary) Whetzel; conidial state Botrytis cinerea Persoon ex Fries3. Sclerotinia fructigena (Persoon) Schröter = Monilia fructigena Honey ex Whetzel; conidial state Monilia fructigena (Persoon) EatonIntroduction: Features of interest Members of the Sclerotiniaceae are plant pathogens characterized by stalked apothecia with inoperculate asci. Apothecia arise from stromata, e.g. sclerotia which are formed on or in the tissue of the host plant. The apothecial state and the type of stroma are typical and taxonomically relevant features of the Sclerotiniaceae, and the family has been supported and delimited by DNA sequence data (Carbone & Kohn, 1993; Holst-Jensen et al., 1997a,b). [ABSTRACT FROM AUTHOR]

Sunflower oil poured onto compost in November induced massive growth of Mortierella species. Mortierella hyaline was isolated into culture at 4 or 18 °C on weak media but not at 23-25 °C or on 2% malt agar. It grew well on olive oil agar, with its hyphae aggregating inside oil drops. The nature of nutrients utilized in normal soils and composts by Mortierella is not known but lipid levels there would appear to be low. Many Mortierella species are able to convert diverse carbon sources into lipids and are thus known as oleaginous fungi. Their biotechnological applications are briefly discussed. [ABSTRACT FROM AUTHOR]

The life-cycle of many plant-pathogenic fungi, especially those infecting aerial plant organs, contains several specific developmental stages. If these are sufficiently distinct in their physiology from vegetative hyphal growth, they present potential targets for non-fungitoxic plant protectants. The present review identifies such targets especially in the pre-penetration stages of the infection cycle of Magnaporthe grisea and other fungi infecting from air-borne spores. Examples of non-toxic natural products with activity against spore germination, attachment, appressorium formation, appressorium maturation and penetration of the host surface are given. In contrast, no substances selectively active against in planta growth or sporulation appear to be known. The selective activity of numerous secondary metabolites against specific infection stages without accompanying toxicity against vegetatively growing hyphae indicates a direction for the development of future natural product-derived fungicides which are more easily degraded in the environment and possess fewer non-target effects. Such substances are produced by many saprotrophic and endophytic fungi in pure culture. The paucity of data on the production of biologically active substances in natural situations limits the interpretation of their ecophysiological significance for the producer. [ABSTRACT FROM AUTHOR]