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A Survey on Pests and Diseases of Italian Hop Crops

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A Survey on Pests and Diseases of Italian Hop Crops Review n. 32 – Italus Hortus 24 (2), 2017: 1-17 doi: 10.26353/j.itahort/2017.2.117 A survey on pests and diseases of Italian Hop crops Elisabetta Gargani 1* , Luca Ferretti 1* , Francesco Faggioli 1, Anita Haegi 1, Marta Luigi 1, Silvia Landi 1, Sauro Simoni 1, Claudia Benvenuti 1, Silvia Guidi 1, Stefania Simoncini 1, Giada D’Errico 4, Tiziana Amoriello 3, Roberto Ciccoritti 2, Pio Federico Roversi 1, Katya Carbone 2 1Centro di ricerca Difesa e Certificazione, Consiglio per la ricerca in agricoltura e l’analisi dell’econo - mia agraria (CREA) 2Centro di ricerca Olivicoltura, Frutticoltura e Agrumicoltura, Consiglio per la ricerca in agricoltura e l’analisi dell’economia agraria (CREA) 3Centro di ricerca Alimenti e Nutrizione, Consiglio per la ricerca in agricoltura e l’analisi dell’econo - mia agraria (CREA) 4Dipartimento Scienze Agrarie, Università di Napoli “Federico II” Ricezione: 24 novembre 2017; Accettazione: 9 gennaio 2018 Screening di organismi ed avversità cal point of view, as they are one of the essential fitosanitarie in luppoleti italiani ingredients of brewing industry. Besides, hop cones are considered also an interesting source of natural Riassunto. Nel presente studio si riportano le prime bioactive compounds (Abram et al ., 2015). Evidences indagini condotte in luppoleti italiani nel 2017, con of the beneficial effects of hop phytochemicals in descrizione delle principali avversità che possono various chronic diseases are highlighted in literature infestare la coltura. Considerato fino ad ora una colti - (Inui et al ., 2017). vazione minore, il luppolo sta assumendo negli ultimi The areas in which hop can grow are limited by anni un crescente interesse come coltura alternativa short day length and temperature requirements for in diverse regioni italiane. Molte sono le problematiche flowering and hence cone production. Production is fitosanitarie che potrebbero interessare le coltivazioni generally restricted in areas that go from 35° to 55° italiane e qui si riportano alcune importanti segnala - latitudes in both hemispheres (Carbone et al ., 2017). zioni. Ad oggi si registra una mancanza pressoché completa di prodotti fitosanitari registrati per la coltura, According to FAOSTAT, hop world production in rendendo necessario un intervento legislativo che per - 2014 was about 133,000 tons, being 13% more than metta di superare questo gap per poter applicare, the one of the previous year (FAOSTAT, 2017). quando necessario, una corretta strategia di difesa. Germany is the top worldwide producer of hop, with an estimated annual production of about 33,000 tons, Parole chiave: luppolo, artropodi, nematodi, pato - United States being the second producer with around geni, difesa. 30,000 tons per y ear (fig. 1) (FAOSTAT, 2017). According to the biggest world companies, global hop crops during the past five years were below Introduction demand and inventories had been used up, with global demand growing by around one percent a year due in Hop ( Humulus lupulus L.) is a dioecious peren - part to the rising popularity of craft beer. nial, climbing plant native of Europe, Asia, and North Over the last years, the number of craft breweries America (Small, 1978). It belongs to the family of in Italy has increased, from about 40 in 2005 to Cannabaceae and the genus Humulus contains three around 1111 at present. Besides, Italy imports almost species: Humulus japonicus, H. lupulus, and H. yun - all of the brewing raw materials, especially hops nanensis . Hop’s female strobiles (cones) represent the (Carbone et al ., 2017). In order to address the most interesting parts of the plant from a technologi - growing internal demand of Italian raw materials, several farmers have begun cultivating hops in diffe - * [email protected]; [email protected] rent Italian regions (fig. 2). 1 Gargani et al. Hops provide bitterness, fullness, and flavour to the beer, all because of their unique phytochemical content (i.e. α- and β- acids, polyphenols, terpenes, etc.) (Inui et al ., 2017). However, the quality of hop cones depends on several parameters, varying accor - ding to genotype, climate, soil characteristic, root pro - perties, and orchard management (Matsui et al ., 2016). Several Authors highlighted a reduction in hop quality due to infections, caused by viruses, viroids, and by different microorganisms (e.g. fungi, bacteria, etc.) (Pethybridge et al ., 2008; Cerenak et al ., 2009). Fig. 1 - Hop production shared by region: average 1994 – 2014 Krofta and Nesvadba (2003) reported a reduction up (FAOSTAT; 2017). Fig. 1 - Produzione di luppolo per area geografica: media 1994 - to 25% of hop’s alpha acid content due to powdery 2014 (FAOSTAT; 2017). mildew infection. Patzak et al . (2001) demonstrated by biochemical analysis a significant influence on the lupulin chemical composition of cone when Hop latent viroid (HLVd) infects the plant. Plant infestations and infections may cause impor - tant economic losses due to reductions in cone yield and quality. As far as pests and diseases are concer - ned, generally, cultural practices and chemical control measures can be applied, beginning early in the sea - son, in order to reduce damage levels. However, there are no registered pesticides for hops in Italy up to day. In this scenario, the present study intends to look into Italian arthropod community abundance and phe - nology, presence of phytoparasitic nematodes in the soil and occurrence of diseases, for a better understan - ding of Italian hop crops phytosanitary status, prere - quisite to approach sustainable control strategies. In fact, an understanding of the biology and life cycles of pests and their natural enemies and an understan - ding of the environmental conditions may provide valuable information for pest management. To reach this overall objective, the present study Fig. 2 - Distribution of Italian hop farms: the darker coloured was conducted at three different levels: i) a biblio - regions are those with a higher number of hop farms. graphic review on the main hop pests and infections Fig. 2 - Distribuzione delle coltivazioni italiane di luppolo a dicembre 2017: le regioni di colore più scuro sono quelle con un reported in the world areas; ii) the evaluation of a numero maggiore di coltivazioni. questionnaire submitted to farmers, and skilled hop growers to provide information on the incidence of Hop is currently included amongst the innovative different pests and infections that have affected crops agricultural sectors promoted by the Italian Ministry in the last two/three years; iii) a survey including of Agricultural, Food and Forestry Policies (Mipaaf) visual inspection, sampling, and laboratory analysis of (Carbone et al ., 2017). monitored Italian hop crops to evaluate the plant At this regard, at the end of 2016, a national health status. research project, named Luppolo.it, funded by Mipaaf and coordinated by Consiglio per la ricerca in agricol - Overview on Hop pests and diseases tura e l’analisi dell’economia agraria (CREA), started. Nowadays, the Italian hop-growing area is estima - Arthropods and Nematodes ted to be about 30 hectares and it will significantly Arthropod communities are a reflection of climate, increase in the next future; the average surface per landscape, crop management, and it is evident that farm is equal to 5140 m 2 (data from the survey con - there are differences in environment between histori - ducted within the project Luppolo.it). cal North European or American hop-growing regions 2 A survey on pests and diseases of Italian Hop crops and new Italian areas. Hop aphid [ Phorodon humuli horticultural crops, ornamentals and fruit trees (Helle (Schrank)] (Hemiptera: Aphididae) and two spotted and Sabelis, 1985). Furthermore, it can quickly adapt spider mite ( Tetranychus urticae Koch) (Acari: to different plant varieties, also those selected for Tetranychidae) have been reported as key arthropod resistance, as was shown for, e.g. tomato, broccoli pests in US and European hop-growing regions and cucumber (Fry, 1989). On hop, T. urticae , may (Biancardi and Wagner, 1989, Mahaffee et al ., 2009; be frequent whether broad-spectrum insecticides are Woods et al ., 2014) but pest arthropod communities sprayed or not (Lilley and Campbell, 1999). in hop crops include a large number of species Generally, TSSM, causes economic damage to hop (Carter, 1984; Mahaffee et al ., 2009; Calderwood et yield and quality following applications of pesticides al ., 2015; O’Neal et al ., 2015; Eppo, 2017) (tab. 1). aimed at reducing other arthropod pests: for example, Phorodon humuli , the first key pest, can determine spring application of neonicotinoids can successfully production losses and reduction of economic value of contain hop aphid populations, but, at the same time, the hop cones (Lorenzana et al ., 2013). Hop aphid natural enemies of hop aphid and two-spotted spider overwinters as eggs on ornamental and agricultural mite can increase, providing so opportunity for secon - species of the genus Prunus ; it has a holocyclic life dary pests, mainly TSSM, to reach uncontrollable cycle where adult, winged females ( alate ) give birth to outbreak levels (James 2003). Research studies evi - live nymphs, which develop into wingless males and denced Glycine max (soybean), Humulus lupulus females in addition to alate female reproductive adults (hop), Laburnum anagyroides (golden chain) and (Calderwood, 2015). In Spain, peak hop aphids’ date Nicotiana tabacum (tobacco) as highly accepted is typically
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