Potassium phosphite (Phi) was evaluated for its in vitro activity against Penicillium expansum and for its potential long-term efficacy against postharvest blue mold infections on apple fruit. Phi amended to malt extract agar medium at 2 and 4mg/ml completely inhibited mycelial growth and conidial germination, respectively. Conidia of P. expansum suspended for 3min in a solution of 2mg/ml Phi at 20°C or heated to 50°C germinated at 53 and 0%, respectively. Disease incidence of P. expansum on Elstar apples wounded and inoculated with a thiabendazole-resistant isolate was reduced significantly (P=0.01) following a curative treatment with Phi at 2mg/ml. When applied on freshly harvested unwounded Elstar apples, Phi (2mg/ml) reduced blue mold incidence about three-fold compared to the control and was found to be as effective as thiabendazole against natural blue mold infections after six months of storage at 2°C. Our results suggest that potassium phosphite has a potential to be part of the general management program implemented for the control of postharvest blue mold infections on pome fruits.

BACKGROUND:Sclerotinia sclerotiorum (Lib.) de Bary is a major pathogen of witloof chicory. For lack of authorised field treatment, post-harvest sprays with dicarboximide fungicides have been standard practice since the 1970s to prevent root rot and chicory heart decay during the forcing phase. However, the registration of procymidone and vinclozolin has been withdrawn in Europe. The development of organic agriculture and the necessity to reduce fungicide applications in conventional agriculture prompted an assessment of the efficacy of new fungicides and the use of the mycoparasite Coniothyrium minitans (Campbell).RESULTS:A mixture of the fungicides fludioxonil and cyprodinil (Switch(®) ) applied on chicory roots achieved a very good control of S. sclerotiorum (up to 95%). The use of C. minitans limited root infection, both when applied in the field (50-65% efficacy) and before the forcing period (post-harvest treatment up to 80%).CONCLUSION:In organic agriculture, two treatments with C. minitans (in field and later at the forcing period) could improve protection against S. sclerotiorum. In conventional agriculture, after the field biological treatment, a post-harvest chemical treatment could be applied. The addition of other prophylactic methods could lead to a high level of performance in practice against decay caused by S. sclerotiorum.

The activity of eugenol oil was evaluated in vitro and in vivo against four apple pathogens namely Phlyctema vagabunda, Penicillium expansum, Botrytis cinerea and Monilinia fructigena. The minimum inhibitory concentration (MIC) of eugenol incorporated in malt extract agar medium was found to be 2 ring ml(-1). Mycelial growth of the four test pathogens was completely inhibited when treated with 150 mu l l(-1) of volatile eugenol whether at 4 or 20 degrees C. Conidia of P vagabunda, P. expansum, M. fructigena and B. cinerea suspended for 2 min in eugenol solution at 2 mg ml(-1) heated to 50 degrees C germinated at rates of 19, 37, 38 and 39%, respectively. Three different eugenol formulations (Tween 80, ethoxylate and lecithin) were tested for their in vivo efficacy against the tested pathogens on apples. Ethoxylate- and Tween 80-eugenol formulations applied at room temperature were ineffective in reducing disease incidence. When heated to 50 degrees C, both formulations induced phytotoxicity on apple surface and caused cuticle damages as revealed by scanning electronic microscopic observations. A mixture of eugenol at 2 mg ml(-1) and soy lecithin at 50 mg ml(-1) suppressed the phytotoxic symptoms produced by eugenol on apples and reduced the disease incidence of P. expansum. P. vagabunda, B. cinerea and M. fructigena to less than 7, 6, 4 and 2% respectively after 6 months of storage at 2 degrees C. The application of heated lecithin-formulated eugenol could become a successful alternative to the traditional fungicides used in postharvest disease management of apple fruit. (C) 2008 Elsevier B.V. All rights reserved.

Mefenoxam applied on chicory roots at 4.8g active ingredient 100l−1 achieved a very effective control of Phytophthora cryptogea, one of the main pathogens of witloof chicory. In seven trials, less than 10% of the roots treated with mefenoxam showed necrosis. The mefenoxam efficacy was better than that of propamocarb-HCl at 180g100l−1 (89–100% of infected roots) or mancozeb at 300g100l−1 (97–100% of infected roots). The efficacy of fosetyl-Al appeared to be irregular (2–98% of infected roots). Sensitivity to mefenoxam and azoxystrobin of some P.cryptogea strains was studied on amended media. Among the six strains tested, one was resistant to mefenoxam and two were moderately sensitive to azoxystrobin. The risk of occurrence of resistant strains in practice has to be considered; management of resistance to the two fungicides by application scheduling is proposed.

When transformation of Botrytis cinerea occurred in mononucleated protoplasts the hygromycin resistance phenotype was stable and integrated plasmid DNA although rearranged was transmitted through meiosis. We observed that transformants were often heterokaryotic and using serial conidial transfer, we showed failure of expression of the entire copies of integrated plasmids in some conidial isolates. A non-Mendelian segregation of the hygromycin resistance phenotype was observed in most crosses between these transformants and sensitive strains. However, a 1:1 segregation ratio of plasmid DNA hybridisation was observed. Mechanisms of gene silencing in B. cinerea, in both the asexual and the sexual cycle, are discussed.

Isolates of Penicillium spp. were collected regularly from 2001 to 2003 from the surfaces of apple fruit pre‐ and postharvest, and from the atmosphere of orchards and storage rooms in France. Penicillium spp. were not detected from the atmosphere of conventional orchards, while their density did not exceed 50 spores m −3 in the atmosphere of organically managed orchards. Penicillium spp. were seldom detected on apple surfaces in the orchard. The density of Penicillium on apples increased from 10 to 50 spores cm −2 after 1 month in storage to 300–400 spores cm −2 after 6 months. The level of airborne Penicillium increased by up to 2 × 10 4 and 2·5 × 10 3 spores m −3 within nondisinfected and previously disinfected warehouses, respectively. Penicillium expansum (30–62%) and P. solitum (6–45%) were the most prevalent species on apple or in storage rooms. Other species of Penicillium isolated included P. commune , P. verrucosum , P. chrysogenum , P. rugulosum and P. digitatum . Apple fruit were also surveyed for wounds and the number of open lenticels using the sulphur dioxide test. The incidence of wounding at harvest varied from 12 to 36%, depending on cultivar and locality. When apples were inoculated at harvest by either aqueous or aerial inoculum of P. expansum , the decay incidence was constantly higher than the incidence of wounding. The number of open lenticels per cm 2 of apple surface varied from 0·5 on cv. Boskoop to 4·4 on cv. Golden Delicious. An average of 13 and 2·1% of lenticels, respectively, were infected when they were inoculated by P. expansum and P. verrucosum . Cultivars of apple fruit that showed a greater number of open lenticels, combined with a large diameter varying from 100 to 200 µ m, were more susceptible to P. expansum .

The fumigation of apple and pear fruit for 2h with 2ml/l of sulfur dioxide at room temperature enabled adequate detection of fresh and old micro-wounds varying from 0.1 to 5mm in diameter. A bleached spot surrounded by a brown halo formed around the wounds allowing their visualization. Otherwise, the same symptoms were observed when fruit were treated for 2h with 20ml sodium metabisulfite solution at 20g/l.

Conidia of Penicillium expansum, the causal agent of blue mold decay on apple and pear fruit was found to be highly hydrophobic when young, whereas aged spores were mainly hydrophilic. The retention (R) of freshly harvested conidia (15-day-old) were significantly greater (R>80%) than 40-day-old spores (R<15%) on hydrophobic gels and on polystyrene. Conidia of P. expansum adhered at high rates (>80%) on hydrophobic substrata that had a high advancing contact angle (θa>100°) including Teflon, polystyrene and apple cuticle. On glass, agar media and UV-treated polystyrene sheets, substrata which showed high wettabilities (θa<50°), the conidial attachment decreased sensibly (≤35%). On the other hand, conidia of P. expansum suspended in dH2O germinated at poor rates (<20%) on either hydrophobic or hydrophilic substrata, whereas germination was triggered significantly (>50%) by addition of yeast extract or glucose. Attachment of the airborne spores to apples seems to be mediated by the level of both humidity and airborne Penicillium within the warehouse. After 8 days of storage, the density of spores was about 3- to 4-fold higher on apple stored at a high humidity level (≥92%) compared with fruit stored at a low level of humidity (≤75%). When hydrated, spores of P. expansum attached amply to wounds (80%) and to a lesser degree to lenticels (70%) and apple cuticle (66%) after 4h of incubation. The SEM revealed any specific structures in dormant spores of P. expansum. However on apple tissue, conidia exhibited a flattened surface and were covered with echinus that may be involved in adhesion of ungerminated conidia.

The effects of physical characteristics and cell wall enzymatic activities of several strawberry cultivars were investigated for possible industrial use. The enzymes study showed that the softest varieties had the highest pectin methylesterase (PME) and polygalacturonase (PG) activities. Differences in alcohol-insoluble pectin, water-soluble pectin, and parietal residue compositions were observed between Darsanga ("firm fruit") and Senga sengana ("soft fruit"). Finally, the study of pectin composition of Darsanga and Senga sengana indicated that the softest fruit had the highest water-soluble pectin content. The measurement of fruit PME activity permitted a preliminary screening of fruit maturity characteristics.

Azoxystrobin at 0.25 g/m2 applied by spraying roots achieved very good control of Phytophthora cryptogea an important pathogen of witloof chicory. Its efficacy was better than propamocarb-HCl at 7.22 g/m2, with a reduction of 50–90% in the root infection rate at the end of the forcing period. In one trial, the efficacy of azoxystrobin was better than that obtained with fosetyl-Al at 12 g/m2 .

Mycotoxins are produced by secondary metabolism of various fungal species. Numerous studies were performed on the occurrence of the mycotoxins in raw commodities and foodstuffs. These studies were carried out on account of their high toxicity and the possible risk they can present for the health of the consumers. The purpose of this paper is to review the occurrence of mycotoxins in fruit juices and wine.