Numerous Penicillium spp. have been associated with postharvest fruit spoilage. This study investigates pathogenicity and aggressiveness of selected Penicillium spp. previously isolated from South African and European Union fruit export chains. Penicillium expansum was the most-and P.crustosum the second most aggressive on all apple cultivars (Royal Gala, Granny Smith, Golden Delicious, Topred and Cripps Pink) and two pear cultivars (Packham"s Triumph and Forelle) tested.Penicillium digitatum was the most aggressive on Beurre Bosc, Beurre Hardy and Sempre (Rosemarie) pear cultivars and the third most aggressive on Granny Smith and Cripps Pink apple cultivars. To our knowledge this is the first report where P. digitatum has been described as aggressive on certain pome fruit cultivars. These cultivars are also the most commonly associated with decay on the export markets resulting in considerable end-market losses. Penicillium brevicompactum was detected pathogenic on pears, but was not further evaluated in the study.Penicillium solitum was observed more pathogenic (broader cultivar range and higher disease incidence) and aggressive (larger lesions) on pear cultivars than on apple cultivars. This study provides new information on host specificity and the importance of pathogenic Penicillium spp.isolated from various environments in the shipping and marketing channels. INTRODUCTIONThe South African pome fruit industry is economically important in terms of global trade. The industry produces over 1.1 million tons of fruit of which 46.6% are exported as fresh produce, earning close to $431.6 million in net export realization in 2012 (9). Postharvest losses have been reported as high as 50% in developing countries (5,21,26). Significant losses have been attributed to decay caused by Penicillium spp. (12,14,16,20,22,32).A report by Sanderson and Spotts (22) indicates that numerous Penicillium spp. naturally inhabit pome fruit environments (packinghouses and storage facilities) and are prominent on fruit bins. Of these species, P. expansum Link ex Gray, P. crustosum Thom, and P. solitum Westling have been described as the most important on apples (Malus domestica L. Borkh.) and pears (Pyrus communis L.) in causing decay (14,22,32). Other pathogenic species reported include P. aurantiogriseum Dierckx., P. brevicompactum Dierckx., P.commune Thom, P. griseofulvum Dierckx., P. verrucosum, Dierckx. and P. carneum Frisvad (2,12,16,18,23). However, these species have less often been associated with decay of pome fruit.Several other Penicillium spp. isolated from pome fruit environments (2,22) are best known as pathogens on other fruit crops. These include P. digitatum (Pers.:Fr.) Sacc. on citrus (8) and P. glabrum (Wehmer) Westling on pomegranates (3). Complex fruit trade networks result in a large variety of fruit from different countries being retained together in storage or holding facilities (34). In addition, citrus and pome fruit are sometimes re-packed in the same facility to remove decaying fruit. This practice can p...

Citrus fruit are exposed to numerous postharvest pathogens throughout the fresh produce supply chain. Well-known postharvest citrus fruit pathogens are Penicillium digitatum and P. italicum. Lesser-known pathogens include P. crustosum and P. expansum. This study examined pathogenicity and aggressiveness of Penicillium spp. present in fresh fruit supply chains on various Citrus spp. and cultivars. The impact of different inoculation methods and storage conditions on decay were also assessed. P. digitatum and P. italicum were the most aggressive Penicillium spp. on citrus but aggressiveness varied significantly over the evaluated citrus range. Decay and tissue-response lesions caused by P. crustosum were observed on ‘Nules Clementine’, ‘Nova’, ‘Owari Satsuma’, ‘Delta Valencia’, ‘Cambria Navel’, ‘Eureka’ seeded, and ‘Star Ruby’ for the first time. Likewise, these lesions caused by P. expansum were noted on Nules Clementine, Owari Satsuma, Delta Valencia, ‘Midknight Valencia’, and Eureka seeded for the first time. Tissue-response lesions affect fruit quality and some Penicillium spp. sporulated from the lesions, causing the inoculated species to complete their life cycle. New citrus–Penicillium spp. interactions were observed and the importance of monitoring inoculum loads of pathogens and nonhost pathogens were highlighted.

A total of 344 dogs belonging to people in resource-poor communities in North West Province, South Africa, was examined for ectoparasites, and all visible arthropods were collected from the left side of each dog. By doubling these numbers it was estimated that the dogs harboured 14 724 ixodid ticks, belonging to 6 species, 1028 fleas, belonging to 2 species, and 26 lice. Haemaphysalis leachi accounted for 420 and Rhipicephalus sanguineus for 14 226 of the ticks. Pure infestations of H. leachi were present on 14 dogs and of R. sanguineus on 172 dogs. Small numbers of Amblyomma hebraeum, R. appendiculatus, R. evertsi evertsi and R. simus were also collected. The predominance of R. sanguineus accounts for the high prevalence of canine ehrlichiosis (Ehrlichia canis) within the survey region, compared to canine babesiosis (Babesia canis), which is transmitted by H. leachi, and is a much rarer disease.

Single‐spored isolates of Pyrenophora associated with spot and net type net blotch of barley were compared using total DNA banding patterns, morphological and cultural characteristics, symptomatology and mating studies. Isolates of spot and net type net blotch were found to vary regarding conidium length and cultural growth rate. Mating studies among and between ascospore, spot and net type isolates proved unsuccessful under the conditions studied. Total DNA polymorphisms of the net spot and ascospore isolates digested with the restriction enzymes HpaII and HaeIII showed that the isolates have similar banding patterns. Random amplified polymorphic DNA (RAPD) showed that the banding patterns of the spot and net type isolates were again similar but were distinct from outgroups such as P. semeniperda and P. triticirepentis. The homology in DNA banding patterns of local isolates indicated that the difference in conidium length is insufficient to separate them as two species. It is concluded that spot and net type isolates occurring in South Africa belong to P. teres. Therefore spot type lesions are caused by P. teres f. sp. maculata and not by P. japonica as reported previously.

Stone fruit are highly perishable and susceptible to numerous postharvest pathogens. P. expansum is a well-known pathogen of stone fruit but little is known about other Penicillium spp. that could potentially cause decay. This study aims to determine pathogenicity profiles of P. expansum, P. crustosum, P. solitum and P. digitatum on selected nectarine and plum cultivars, and in part examine the disease cycle within new fruit-Penicillium interactions to observe the potential of the pathogens to cross-infect. Lesions caused by Penicillium spp.isolated from the pear and citrus handling chain environments were not different on nectarine.P. digitatum was the most aggressive species on most nectarines and plums evaluated. Decay was associated with older fruit (long stored). The highest aggression was observed on Nectargold, May Glo and African Rose. P. expansum and P. crustosum had the highest disease incidences and were the second and third most aggressive species respectively. P. solitum caused small lesions. Its role in the fresh produce market can be negligible.Scanning electron microscopy confirmed infection and provided new information on the growth and reproduction of P. expansum, P. crustosum and P. digitatum on infected nectarine, pear and lemon. Pear and lemon can serve as cross-infection sources for stone fruit in the fresh produce chain. To our knowledge this is the most complete description of disease Postharvest decay of nectarine and plum caused by Penicillium spp.2 caused by P. digitatum, P. crustosum and P. solitum on nectarine and plum. Rapid decay caused by P. digitatum highlighted the potential of the species to contribute to losses in the stone fruit industry. Future research should investigate the presence and impact of P. digitatum in the stone fruit supply chain. The role of fruit maturity in fruit-Penicillium interactions requires further investigation.