Bautista-Baños Postharvest Decay

Control Strategies
1. Auflage 2014
ISBN: 978-0-12-411568-2
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, 394 Seiten

Written by a diverse group of research professionals, Postharvest Decay: Control Strategies is aimed at a wide audience, including researchers involved in the study of postharvest handling of agricultural commodities, and undergraduate and graduate students researching postharvest topics. Growers, managers, and operators working at packinghouses and storage, retail, and wholesale facilities can also benefit from this book. The information in this book covers a wide range of topics related to selected fungi, such as taxonomy, infection processes, economic importance, causes of infection, the influence of pre-harvest agronomic practices and the environment, the effect of handling operations, and the strategic controls for each host-pathogen, including traditional and non-traditional alternatives. - Includes eleven postharvest fungi causing serious rots in numerous fruits and vegetables - Offers selected microorganisms including pathogens of commercially important tropical, subtropical and temperate crops worldwide, such as tomatoes, pears, apples, peaches, citrus, banana, papaya, and mango, among others - Presents content developed by recognized and experienced high-level scientists, working in the postharvest pathology area worldwide - Provides basic information about each fungus, pre- and postharvest factors that contribute to infection and control measurements, including the use of chemicals and non-traditional methods

Autoren/Hrsg.

Bautista-Baños, Silvia

Leseproben

Chapter 2

Penicillium digitatum, Penicillium italicum (Green Mold, Blue Mold)

LluísPalou     Laboratori de Patologia, Centre de Tecnologia Postcollita (CTP), Institut Valencià d’Investigacions Agràries (IVIA), Montcada, València, Spain

Abstract

Green and blue molds, caused by the pathogens Penicillium digitatum and Penicillium italicum, respectively, are the most economically important postharvest diseases of citrus fruit in all production areas with low summer rainfall. Both fungi are strict wound pathogens that affect all citrus species and cultivars and can infect the fruit in the field, the packing house, and during distribution and marketing. Taxonomy and morphology of the pathogens and factors that can influence fruit infection and disease development are described in this chapter. Penicillium digitatum is the first phytopathogenic Penicillium species whose complete genome has been entirely sequenced. Implications of basic and applied research on host–pathogen interactions and disease control strategies are discussed. Conventional control with postharvest chemical fungicides like imazalil and alternative non-polluting physical, low-toxicity chemical and biological control methods are reviewed. Emphasis is given to advances developed over the last few years. Satisfactory disease control relies on an integrated disease management (IDM) approach in which all preharvest, harvest and postharvest factors are considered.

Keywords

Penicillium digitatumP. italicumcitrus postharvest decaygreen moldblue moldfungicidesalternative controlintegrated disease management

Contents

Overall Importance of Fungi?46

Importance in Citrus Fruits?46

Other Hosts?49

Taxonomy, Morphology and Genomics?50

Penicillium digitatum?50

Penicillium italicum?52

Biology of Penicillium digitatum and P. italicum Infection Process?53

Disease Triangle?53

Symptomatology?54

Factors Determining Host–Pathogen Interaction?54

Postharvest Factors Influencing Penicillium digitatum and P. italicum Infection?59

Harvest and Transportation?59

Degreening?60

Control?61

Postharvest Treatments with Conventional Fungicides?61

Imazalil (IMZ)?62

Thiabendazole (TBZ)?63

Sodium Ortho-Phenylphenate (SOPP)?65

Reduced Risk Fungicides?65

Other Fungicides?67

Integrated Disease Management (IDM) Strategies?68

Preharvest Operations?68

Early Detection of Infection?69

Fruit and Packing House Sanitation?70

Control Methods Alternative to Conventional Fungicides?73

Physical Treatments?73

Low-Toxicity Chemical Treatments?76

Biological Control Treatments?85

Combination of Treatments?86

Concluding Remarks?88

Acknowledgments?89

References?90

Overall Importance of Fungi

Importance in Citrus Fruits

Citrus spp. (Rutaceae) are the most widely produced fruits for human consumption and they are grown in over one hundred countries. The total production of citrus fruits has been increasing over the last decades and exceeded 115 million tons in 2011. Oranges (Citrus sinensis L.), with a world production of 71 million tons in 2011; mandarins or tangerines (Citrus reticulata Blanco), including clementines (Citrus clementina hort. ex Tanaka), satsumas (Citrus unshiu Marcow.), and a variety of hybrid mandarins (26 million tons); lemons [Citrus limon (L.) Burm. f.] and limes [Citrus aurantiifolia (Christm.) Swingle] (13 million tons); and grapefruits (Citrus paradisi Macfad.) (6 million tons), are the largest cultivated citrus species and cultivars. In 2011, the most important producing countries were China, Brazil, the USA, India, Mexico, Spain, Egypt, Italy, Turkey, Argentina, Iran, Pakistan, Indonesia, South Africa, and Morocco, with 22.9, 22.7, 10.4, 8.2, 6.7, 6.6, 3.6, 3.2, 3.1, 2.5, 2.3, 2.2, 2.1, 1.9, and 1.7 million tons of total citrus, respectively. In terms of international trade, citrus are the highest value fruit crop and Spain is the leading country, with 3.6 million tons of exports of fresh produce in 2011 (FAO, 2012).

Postharvest handling in citrus packing houses is intended to commercialize fruit of maximum quality, increase their postharvest life, and reduce produce losses. Among postharvest losses, those of pathological origin are typically of considerable economical importance. Green and blue molds, caused by Penicillium digitatum (Pers.: Fr.) Sacc. and P. italicum Wehmer, respectively, are the most economically important postharvest diseases of citrus in all production areas that, like Spain or California, are characterized by a Mediterranean-type climate with low summer rainfall (Eckert and Eaks, 1989). Both pathogens have been isolated not only from common commercial citrus species and cultivars, but also from other citrus-related genera such as Fortunella, Poncirus, or Citrofortunella (Farr and Rossman, 2013). The symptoms of both diseases in the orange cv. Valencia are shown in Figure 2.1A. The geographical distribution of both species includes all citrus-producing areas in the world and they have been also described in citrus fruits imported to many countries (Frisvad and Samson, 2004). Both P. digitatum and P. italicum are strict wound pathogens that only infect the fruit through peel injuries produced in the field, the packing house, or during the fruit commercialization chain. A third Penicillium species that has been described as pathogenic in citrus fruits, but with much less economical importance, is P. ulaiense (Hsieh et al., 1987; MycoBank #126489). It was found in California in 1987 causing a citrus postharvest disease that was characterized by Holmes et al. (1994) and named ‘whisker mold’. Later, it was also comprehensively described by Frisvad and Samson (2004). The fungus resembles P. italicum, especially in colony color, but it grows more slowly and shows paler reverse colors on all media. It can be found in packing houses in mixed infections with P. digitatum in stored citrus fruits and it is typically more resistant to postharvest fungicides such as imazalil (IMZ) or thiabendazole (TBZ) than P. italicum. It is considerably less aggressive than P. digitatum and P. italicum, which decay citrus fruit about three to five times faster. Conidia are also less efficient in causing infection than those of P. digitatum and P. italicum. In contrast to these species, P. ulaiense has never been collected in citrus groves in California (Holmes et al., 1994).

Actual losses due to penicillium decay are variable and depend upon climate and orchard factors, citrus cultivar, the extent of physical injury to the fruit during harvest and subsequent handling, the effectiveness of antifungal treatments, and the postharvest environment (Smilanick et al., 2006a). In Spain, a study by Tuset (1988) estimated that fruit rots caused by Penicillium spp. accounted for 55–80% of total postharvest decay observed in oranges and mandarins during the entire commercialization season, and for 30–55% of decay observed in storage rooms in citrus packing houses. It was found in inspections in New York of citrus from California and Florida that green and blue molds were present in 30% of the inspected shipments (Ceponis et al., 1986). Early work by Pelser (1977) showed that penicillium molds accounted for about 75% of total decay present in South African ‘Valencia’ oranges shipped to London; they accounted for more than 50% on lemons and grapefruits. Green mold typically causes larger losses during commercialization because it is predominant at ambient temperatures, but blue mold becomes more important when citrus fruit are cold-stored for long periods because P. italicum grows faster than P. digitatum below 10°C (Plaza et al., 2003a).

In general, the incidence of postharvest decay is higher in production areas with abundant rainfall, such as Brazil, Florida or southeastern Asia. Wound pathogens such as Penicillium spp. are very important in all areas because they reproduce very rapidly and their spores are ubiquitous in the atmosphere and on fruit surfaces and are readily disseminated by air currents. Therefore, the source of fungal inoculum in citrus orchards and packing houses is practically continuous during the season and the fruit can become contaminated and infected in the grove, the packing house, and during distribution and marketing. In packing house facilities and storage rooms, the inoculum may build up to high levels if appropriate sanitation measures are not adopted. In addition, citrus fruit in...