Adhesion and removal of conidia of Botrytis cinerea and Penicillium expansum from grape and plum fruit surfaces

Adhesion and removal of dry and wet conidia of Botrytis cinerea and Penicillium expansum on dry and wet surfaces of grape and plum fruit were investigated Conidia of B. cinerea adhered more strongly when applied in a water suspension or to the wet surface of grape fruit than when dry conidia were applied to a dry surface. Inoculation method did not consistently affect recovery of conidia of P. expansum from grape or plum fruit surfaces. None of the four removal methods (shake, sonicate, swab, and spatula) were consistently more effective over the range of inoculation methods and fruit surfaces used in this study.Articl

The association of Tarsonemus mites (Acari: Heterostigmata) with different apple developmental stages and apple core rot diseases

Information on the role of mites in the genus Tarsonemus Canestrini and Fanzago, 1876 in the epidemiology of apple core rots (wet and dry) is limited. The aims of this study were to (1) assess the effect of different apple developmental stages (buds, blossoms, 4-cm diameter fruit, mature fruit and mummies) on the relative abundance of Tasonemus mites, (2) determine if there is a tendency of Tarsonemus mites to be associated with wet core rot (WCR) and dry core rot (DCR) apples, and (3) evaluate the suitability of three core-rot-associated fungal genera as food sources for the mites. Investigations into four orchards, two core-rot-susceptible (Red Delicious) and two-core-rot resistant (Granny Smith), revealed that Tarsonemus mites were the dominant mite genus in all the apple developmental stages in all orchards. The Tarsonemus mites had the highest incidence in mature fruits and mummies in all the orchards. In the cores of healthy and DCR Red Delicious fruits, Tarsonemus mites had a high occurrence of 56% and 84%, respectively. In these fruits, a significant association was found between DCR and the presence of mites in the core. In contrast, in Granny Smith fruits, mites were restricted to the calyx tubes, and only a calyx tube decay symptom was identified. The Tarsonemus mites were fungivorous and reproduced on cultures of a Cladosporium sp. Cultures of Alternaria sp. and Penicillium sp. were unsuitable for mite reproduction, even though the mites did ingest a red fluorescently labeled Alternaria sp. culture. The survival and reproduction of mites on fungal cultures were better at 30°C than at 25°C. © 2011 Copyright Taylor and Francis Group, LLC

Penicillium species associated with preharvest wet core rot in south africa and their pathogenicity on apple

Symptoms associated with the core region of apple fruits (Malus domestica) can be classified as moldy core (MC), wet core rot (WCR), and dry core rot (DCR). Infections leading to WCR are thought to occur primarily postharvest, although in South Africa preharvest symptoms also have been reported. The first aim of this study was to investigate the causative agent(s) of preharvest WCR by isolating fungi from eight internal positions in asymptomatic, MC, WCR, and DCR fruits. Secondly, the pathogenicity and virulence of all Penicillium isolates were investigated using three apple fruit inoculation methods: surface wounding, deep wounding, and nonwounding. Isolation of fungi from WCR fruits showed that Penicillium was the predominant fungal genus from most isolation positions including the lesion area. Penicillium ramulosum was the predominant species isolated from all fruits. However, in WCR fruits, the incidence (58%) of P. ramulosum was much higher than in MC (6%), DCR (7%), or asymptomatic (7%) fruits. Less frequently isolated Penicillium species included P. expansum and a few other species. Pathogenicity testing using the nonwounding method was best at discriminating highly virulent isolates. P. expansum was the most virulent species, followed by a putative new Penicillium species with closest sequence similarity to P. dendriticum. P. ramulosum isolates, although showing varying degrees of virulence, all had low virulence, causing only small lesions in wounded apple fruits. © 2010 The American Phytopathological Society.Articl