‘Le Crete 1’ and ‘Le Crete 2’: two newly patented Seiridium cardinale canker-resistantcultivars of Cupressus sempervirens

By R. Danti1,2, V. Di Lonardo1, A. Pecchioli1 and G. Della Rocca1

1Istituto per la Protezione delle Piante, C.N.R. Area della Ricerca, Via Madonna del Piano 10, 50019, Sesto Fiorentino, Italy.2E-mail: r.danti@ipp.cnr.it (for correspondence)

Summary

In the Mediterranean area, common cypress (Cupressus sempervirens) has traditionally been used as a multipurpose tree, for its symbolicand ornamental role, for its valuable timber, as well as for windbreaks and soil protection. The epidemic spread of the Seiridium cardinalecanker has limited the use of this tree since the 1970s, inducing researchers to develop a breeding programme of cypress aimed at select-ing canker-resistant lines for different uses and to support a flourishing trade of cypress plants. ‘Le Crete 1’ and ‘Le Crete 2’ described hereare two new canker-resistant C. sempervirens varieties patented in 2010, selected through a 13-year assessment of their response to artifi-cial inoculations and growth traits. Both are characterized by a rapid growth and by a columnar and fastigiated habit that confers them anotable ornamental effect. Preliminary observations showed also that both tend to produce yearly few microsporophylls and little pollen.‘Le Crete 2’ was also selected for the high growth rate it maintained on heavy, clayey soils.

1 Introduction

Native to the mountainous semi-arid regions of the South–East Mediterranean basin and of the Middle East, Italian or com-mon cypress (Cupressus sempervirens L.) has been traditionally used as a multipurpose tree in ornamental plantations,windbreaks, protective woods, as well as for buildings, ships, cosmetics and phytotherapics (Andreoli and Xenopoulos1990) and has become, in the course of the centuries, an essential and irreplaceable element of the Mediterranean land-scape.Since the half of the last century, use and cultivation of cypress has been strongly conditioned by the bark canker, a

deadly pandemic caused by the mitosporic fungus Seiridium cardinale (Wag.) Sutton and Gibson, which spread worldwidefrom California where it was firstly reported as early as 1928 (Wagener 1928; Della Rocca et al. 2011). In few decades, thedisease caused tree mortality and heavy economic losses on most Cupressaceae, in plantations and nurseries in all conti-nents. The damages recorded were particularly severe in the Mediterranean area, where in the 1980s epidemics affected70% and 90% of trees in central Italy and Greece, respectively (Panconesi 1990; Graniti 1998). Despite the control ofcypress canker has been pursued since the seventies, the impact of the disease is currently still alarming in some districtsof central Italy where a prevalence as high as 40% and new infections increasing yearly with an incidence of 10% havebeen reported in the recent years (Roversi 2010).First studies evidenced a wide variability of the response to S. cardinale infection among the various species of Cupressus

(Raddi 1979; Andreoli and Ponchet 1991), whereas a fair variability was detected within some native and naturalizedC. sempervirens populations, with 88% susceptible, around 10% tolerant and less than 2% resistant plants (Raddi 1979;Raddi et al. 1990). Reaction of cypress to S. cardinale canker is a quantitative (polygenic) trait, based on the developmentof a neoperiderm, which gradually ranges from susceptibility (death of trees or stem tops) to resistance, represented bythe complete healing of the canker (Ponchet and Andreoli 1990; Spanos et al. 1999; Danti et al. 2006). Thus, phenotype isaffected by both genotype and environment, and candidates are usually evaluated in different sites to identify the cloneswith the highest level of resistance for each environment and eventually to select for fairly stable resistant clones (Santiniet al. 1997).Only slight variations in virulence have always been detected among the Mediterranean isolates of S. cardinale, and none

of them has showed to overcome the reaction of previously selected resistant clones (Raddi and Panconesi 1984; Ponchetet al. 1990; Della Rocca 2008). Also, genetic analysis carried out with the use of molecular markers has shown a substan-tial uniformity of the Mediterranean population of the fungus (Pedron et al. 2007; Della Rocca et al. 2011).Cypress selection at IPP-CNR has always been addressed towards genotypes having useful traits for users and commu-

nity. A number of cypress clones and multiclonal varieties have been selected so far with the aim to enlarge as much aspossible the genetic variability of the canker-resistant lines, and six C. sempervirens clones were patented between 1986and 2004 (Raddi and Panconesi 1994; Danti et al. 2006). Among these ‘Bolgheri’, ‘Italico’ and ‘Mediterraneo’ have been soldsuccessfully as ornamental, whereas ‘Agrimed n. 1’ as windbreak and hedge tree. In the last few decades, Italian cypresshas been widely planted for its peculiar ornamental effect not only in the Mediterranean countries but also in most temper-ate regions of the world (Danti et al. 2006; Panconesi and Della Rocca 2007). The trade of cypress plants has reached aremarkable volume with more than 5 million cypress plants produced every year in the European nurseries (2.5 millionsin Italy alone) (Pichot et al. 1999).

Received: 4.6.2012; accepted: 17.11.2012; editor: S. Woodward

For. Path. 43 (2013) 204–210 doi: 10.1111/efp.12016© 2012 Blackwell Verlag GmbH

http://wileyonlinelibrary.com/

‘Le Crete 1’ and ‘Le Crete 2’ canker-resistant cultivars described here were patented in 2010 for some vegetative andgrowth traits, which make them suited to the current demand of users, both public and private.

2 Materials and methods

2.1 Origins

‘Le Crete 1’ was derived by grafting (on C. sempervirens seedling rootstocks) from an adult C. sempervirens var. stricta ortettree, selected for its fastigiated, columnar and dense crown, as well as for its vigour and healthy appearance within acentury-old, ornamental grove, located in the municipality of Chiusi in the Province of Siena. This tree is registered in theIPP-CNR Book of Mother Trees as number 2551.‘Le Crete 2’ was derived by rooted cuttings from an adult C. sempervirens var. stricta ortet tree, selected for its fastigiated

habit, its excellent growth and development on clay as well as for its healthy appearance, within a row lining a countryroad located in the municipality of Pienza, in the Province of Siena. This tree is registered in the Il Campino nursery ofSiena Province Book of Mother Trees as PMM-[01].

2.2 Propagation

‘Le Crete 1’ was propagated through scions collected in December–January and grafted on C. sempervirens seed rootstocksgrown in small pots containing a mixture of 3 peat/ 1 compost/ 1 perlite (v/v/v) (Moraldi et al. 2004). Grafts were keptin greenhouse until the end of spring, and then, they were transplanted into larger pots (4–5 dm3) and kept for two yearsin a shading tunnel before further transplanting.‘Le Crete 2’ was propagated by rooted cuttings to preserve its tolerance to clay (Stankowa and Panetsos 1997; Giannini

et al. 1999). Cuttings collected in November from the lowest part of the crown have a higher rhizogenic potential. Cuttingsof 10–20 cm long with a woody proximal part, after removal of their basal leaves (half of the length), were dipped for4–5 cm in a 0.5% indole butyric acid (IBA) solution or naftil acetic acid (NAA) (root-promoting substances) for few sec-onds. Then the cuttings were placed for one-third (or half) of the length in a bottom-heated bench (22–24°C) containingsterile perlite, in a mist greenhouse with a 20% reduced light intensity and with a humidity of near 90%, where theyremained for about 4 months until a complete root development was reached. Rooted cuttings were then transplanted into100 cc pots containing a mixture of 3 peat/ 1 sand/ 1 perlite (v/v/v) and hardened in a mist greenhouse at 22°C for4 weeks. Then they were transferred to larger pots (1.5 dm3) containing a mixture of 2 soil/ 2 peat/ 1 sand (v/v/v) andmaintained for 1 year in a shading tunnel.

2.3 Cultivation

For adaptation trials and for canker resistance testing, fifteen 3-year-old grafted ramets of ‘Le Crete 1’ were planted out inthe field in 1999 at 3 9 3 m spacing: 10 ramets at Antella, near Florence, and five ramets at Roselle in the Province ofGrosseto. Antella has a continental, temperate Mediterranean climate characterized by hot summers and cold winters;Roselle has a subcontinental Mediterranean climate with prolonged, torrid summers and relatively mild winters.Twenty-six 3-year-old ramets of ‘Le Crete 2’ were planted out in the field in 1998 at 3 9 3 m spacing at Il Campino,

near Siena, which has a temperate suboceanic Mediterranean climate, characterized by short dry summers and coldwinters. The main environmental data of the three sites are summarized in Table 1.

2.4 Bark canker resistance testing

A standard procedure was followed for both execution of artificial inoculations and evaluation of the progress of can-kers, as described by Danti et al. (2006). When in their fourth year of growth, ramets were artificially inoculated inApril with the S. cardinale isolate ATCC 38654, the standard isolate that has been used for selecting resistant cypressesup to date.Inoculations were made where stems had reached a diameter of about 1 cm by the removal of a 3-mm-diameter circular

plug of bark through a cork borer and the replacement with a plug of the same size taken from the margin of a colony ofthe fungus grown on potato dextrose agar (PDA) for 2 weeks at 25°C in the dark. The inoculation site was covered withcotton and wrapped with tape, both of which were removed after 1 week. The progress of the canker was examined andevaluated yearly, based on a symptoms reference scale (see the paragraph 2.5 statistical analysis).

Table 1. Main environmental data of the three experimental sites.

Site Lat Elev. (m)Annual

Rainfall (mm)Temp. July(mean °C)

Temp. January(mean °C) Soil

Antella 43° 43′ 170 910 24.2 5.8 Gravelly, clay loam, calcareous, well drainedRoselle 42° 48′ 5 661 23.3 7.3 Alluvial, sandy loam, well drainedIl Campino 43° 18′ 205 750 22.9 5.7 Clay (Pliocenic) heavy, calcareous, poor drained

Bark canker-resistant cypress cultivars 205

2.5 Statistical analysis

For ‘Le Crete 1’, growth increments were obtained from measurements made during the first 14 years of age on the 10ramets growing at Antella and the five growing at Roselle. For ‘Le Crete 2’, growth increments were obtained from mea-surements made during the first 15 years of age on the 26 ramets growing at Il Campino. Crown width was taken in the14th and 15th year of age for ‘Le Crete 1’ and ‘Le Crete 2’, respectively. ‘Le Crete 1’ was compared through two-way analy-sis of variance with the cultivars ‘Bolgheri’, ‘Mediterraneo’ and ‘Italico’ grown in the same two sites (Roselle and Antella)and used as benchmarks for growth.Seiridium cardinale canker development was estimated for 5 years following stem inoculation on 15 ramets of ‘Le Crete

1’ cypress growing at Antella and Roselle and on 13 ramets of ‘Le Crete 2’ growing at Il Campino. ‘Le Crete 1’ wascompared through two-way analysis of variance to ‘Bolgheri’, ‘Italico’ and ‘Mediterraneo’ cultivars known to be resistantand to PM 243 known to be susceptible, all growing at both Antella and Roselle. ‘Le Crete 2’ was compared through one-way analysis of variance to PM 30 CSR, a susceptible C. sempervirens cultivar growing at Il Campino. A score ranging from1 to 3 with 0.3 gradations was assigned to each inoculated ramet, where 1 represented complete healing of the necroticlesion, 2 represented small cankers without resin and forming scars and 3 represented actively growing cankers with resinexudation, stem deformation and eventually dieback due to the girdling of the stem. Symptoms were compared with thoseof resistant and susceptible clones included as controls.

3 Results and Discussion

3.1 Description of the cultivars

The description of ‘Le Crete 1’ clone is based on the average of traits shown by fifteen 14-year-old ramets grafted onC. sempervirens seedling rootstocks grown in two localities (Antella and Roselle). Crown width and growth rate in bothheight and diameter were evaluated on all ramets and compared with other patented cypress cultivars grown in the samesites.‘Le Crete 1’ has a fastigiate, columnar habit and a monocormic stem (Fig. 1). It grows rapidly and has an annual mean

increment in height similar to that of the reference cultivars in both the sites of growth (Table 2). Even if differencesamong the mean increments of each single cultivar were not significant between the two locations, site had a significanteffect (p < 0.01) on both height and diameter growth. Stem has a round section and is slightly ribbed in the first 30–40 cmfrom the ground. In the colder site, it tended to fork at 6–7 m height. The crown is flame-shaped, dense, concealing thestem completely from top to bottom (Fig. 1). Its maximum width is at one-third height (Table 2). The bark is smooth andgreyish-light brown [156/b Royal Horticultural Society (1966)] not furrowed, with sparse, grey–brown (RHS 199/b)patches. The main branches are numerous, thin, rather long, regularly arranged, growing close to the trunk and inserted in

Fig. 1. The ‘Le Crete 1’ cypress.

206 R. Danti, V. Di Lonardo, A. Pecchioli et al.

the trunk forming a 15–30°. The branches of a second order are rather short; they are bright green (RHS 137/c) in the dis-tal herbaceous part and grey–brown (RHS 199/b) in the proximal wooded part. The branchlets are 3–5 cm long, com-pletely covered by the leaves. The foliage is scentless; the appressed leaves are dull green in colour (RHS 137/b), notbright.Few micro- and macrosporophylls are visible during blooming, and they ripen simultaneously from February to March.

Some preliminary observations conducted in March 2011 at Antella on 10 twigs collected throughout the crown of threeplants showed that a mean of 9.4% of the branchlets bore a microsporophyll. This value was even lower than 14% mea-sured on plants of the same age of the clone ‘Bolgheri’ growing at the same site. Cones are produced in small quantitiesand are localized in the upper third of the crown. These are borne alone or in small groups of 2–3 units, elongated, andtheir mean dimensions are 27 9 24 mm when mature.‘Le Crete 2’ is described by observation of traits shown by twenty-six 15-year-old ramets derived from self-rooted cut-

tings and grown in the nursery Il Campino, near Siena (central Italy). ‘Le Crete 2’ has a fastigiated, columnar habit and amonopodial growth (Fig. 2). On clay, it showed a rapid growth rate both in length and diameter of the trunk (Table 2). Thestem is monocormic, rounded and regular in section. On about 20% of the ramets, trunk is forked at 6–7 m height in bothgrowing sites. The crown is slightly tapered, less dense for two-third from the ground (Fig. 2), with a mean width of97.3 cm (Table 2). The bark is smooth, grey-light brown (RHS 197/c) in colour with sparse brown–orange (RHS 174/a)patches. The main branches are numerous and not so long, bended upward, inserted rather unevenly in the trunk, forminga 40–60°, 1 cm in diameter and have a light grey-brown bark (RHS 199/d). The branches of second order are relativelyshort. They are bright green (RHS 137/d) in the distal herbaceous part and grey–brown (RHS 199/b) in the proximalwooded part. Branchlets are 2–5 cm long and completely covered by leaves. Foliage is scentless and leaves are appressedand dull green (RHS 137/b). Few microsporophylls and even fewer macrosporophylls are visible during blooming. Theyripen simultaneously from February to March and are sparsely borne throughout the crown. Preliminary observationsmade in March 2011 on 10 twigs collected throughout the crown of three plants showed that branchlets bearing a micro-sporophyll are as few as 6.3%. Cones are fairly oblong, with mean dimensions of 33 9 27 mm when mature and are bornealone or in groups of 2–3 units.

3.2 Bark canker resistance

Disease evaluations of the tested clones are shown in Table 3. One year after inoculation, mean score of ‘Le Crete 1’ wasnot different compared with that of all the control clones. From the 3rd year on, symptoms on ‘Le Crete 1’ and the resistantcontrol ‘Bolgheri’, ‘Italico’ and ‘Mediterraneo’ were significantly different (p < 0.05) than that of the susceptible control(clone PM 243) in both sites. Healing of the necrotic lesion and complete restoration of the trunk occurred for ‘Le Crete 1’

Table 2. Mean annual growth increments of height and diameter (measured at 0.3 m from the ground) and mean crown width of somecypress clones growing in three sites. Le Crete 1 clone was compared with other three benchmark cypress clones growing at the same two

sites, Antella and Roselle.

CloneAntella Roselle Il Campino

Mean CV% Mean CV% Mean CV%

Height increments (cm)Le Crete 1 74.6 a 7.7 69.6 a 2.7 –Bolgheri 74.0 a 4.7 69.2 a 6.8 –Italico 72.3 a 3.1 67.5 a 5.3 –Mediterraneo 74.8 a 8.8 71.6 a 2.4 –Le Crete 2 – – 88.0 8.3Site effect (Antella-Roselle): F = 11.21; p < 0.01Diameter increment (mm)Le Crete 1 10.4 a 10.1 11.2 a 20.7 –Bolgheri 10.2 a 4.8 10.8 a 5.8 –Italico 10.4 a 8.9 11.4 a 5.1 –Mediterraneo 10.7 a 8.9 11.9 a 10.8 –Le Crete 2 10.6 7.9Site effect (Antella-Roselle) : F = 9.29; p < 0.01Crown width (cm)Le Crete 1 95.8 ab 3.3 97.2 ab 4.6 –Bolgheri 86.6 a 5.9 88.5 a 5.9 –Italico 110.5 b 9.5 114.5 b 8.0 –Mediterraneo 96.9 ab 3.7 99.2 ab 12.6 –Le Crete 2 97.3 8.6Clone effect (Antella-Roselle): F = 19.55; p < 0.01

Differences among means were evaluated by two-way analysis of variance. Means not sharing same letters are significantly different forHSD Tukey (Spjtvoll/Stoline) test (p < 0.01). CV, coefficient of variation.

Bark canker-resistant cypress cultivars 207

as well as for the resistant controls within 4–5 years after inoculation; instead, on the susceptible clone PM 243, cankerscontinued to develop on all stems. On clay, ‘Le Crete 2’ showed significantly different scores (p < 0.05) than the susceptibleclone PM 30 CSR from the 2nd year on following inoculation. Five years after inoculation, cankers were completely healedin all inoculated stems of ‘Le Crete 2’, whereas they continue to develop on the susceptible clone.Even if the host–pathogen–environment interaction is known to be significant for most cypress genotypes, generally only

a slight variation was observed in the response of a given clone when inoculations are conducted in different environments(Santini et al. 1997). ‘Le Crete 1’ has revealed a fairly stable resistance to cypress canker, as its response to S. cardinale

Fig. 2. The ‘Le Crete 2’ cypress (arrow).

Table 3. Mean score of Seiridium cardinale canker development estimated for five years following stem inoculation on some cypress clonesgrowing in three sites. At Antella and Roselle, ‘Le Crete 1’ was compared with ‘Bolgheri’, ‘Italico’ and ‘Mediterraneo’ cultivars known to beresistant and PM 243 known to be susceptible. At Il Campino, ‘Le Crete 2’ was compared with the susceptible PM 30 CSR C. sempervirenscultivar. Scores vary on a scale of 1 to 3 with 0.3 gradations, where one represents complete healing of the necrosis and three represents

severe infection with expanding necrosis, resin exudation and stem deformation.

Site Cultivar

Disease rating (years after inoculation)

1 2 3 4 5

Antella Le Crete 1 3.0 a 2.4 ab 2.1 b 1.3 ab 1.0 aItalico 3.0 a 2.1 a 1.8 ab 1.3 ab 1.0 aMediterraneo 3.0 a 2.3 ab 1.7 ab 1.2 ab 1.0 aBolgheri 3.0 a 2.4 ab 2.0 ab 1.5 b 1.0 a243 3.0 a 2.8 b 2.8 c 2.7 c 2.7 b

Roselle Le Crete 1 3.0 a 2.5 ab 1.9 ab 1.3 ab 1.0 aItalico 3.0 a 2.7 b 1.6 ab 1.2 ab 1.0 aMediterraneo 3.0 a 2.5 ab 1.8 ab 1.0 a 1.0 aBolgheri 3.0 a 2.3 ab 1.5 a 1.2 ab 1.0 a243 3.0 a 2.9 b 2.7 c 2.7 c 2.6 b

Cultivar effect was significant in the 2nd, 3rd, 4th and 5th year (p < 0.05); site effect was significant in the 2nd and 3rd year(p < 0.05).Il Campino Le Crete 2 2.9 a 2.3 a 1.9 a 1.2 a 1.0 a

PM 30 CSR 3.0 a 3.0 b 2.8 b 2.8 b 2.8 b

Differences among means were evaluated by two-way and one-way analysis of variance in the trial conducted at Antella-Roselle and atIl Campino, respectively. Means not sharing same letters within each column are significantly different for HSD Tukey (Spjtvoll/Stoline)test (p < 0.05).

208 R. Danti, V. Di Lonardo, A. Pecchioli et al.

inoculations was not significantly different between the two sites during the 5 years of testing. Ramets of ‘Le Crete 2’ haveshown an even level of resistance to S. cardinale infections in the pedo-climatic conditions, in which they were tested. Eval-uation of reaction to artificial inoculations of ramets derived by self-rooted cuttings allowed to evidence the full potentialresponse to S. cardinale infections (in that environment) of the ‘Le Crete 2’ genotype, excluding the possible influence dueto variability of the seed rootstock both in vigour (Andreoli et al. 1996) and susceptibility (unpublished data) that wouldhave occurred in case of propagation by grafting.The variability of the aggressiveness of the fungus is periodically assessed to address selection towards cypress geno-

types that are resistant to eventual more aggressive variants of the pathogen. The aggressiveness of 21 S. cardinale isolatescollected in 2008-2009 from cankered cypresses throughout the Mediterranean area (from Portugal to Greece) has beenrecently evaluated through stem inoculations on three different C. sempervirens clones (unpublished data). None of thetested isolates resulted to cause significantly larger necrosis compared with the ATCC 38654 isolate 6 months after inocula-tion and confirmed substantially the validity of the resistant lines selected so far using the standard isolate. The relativelysteady prevalence of bark canker (around 22–23%) registered in the last few years in central Italy on common cypress(Roversi 2010) does not even suggest a recent increase in virulence of the pathogen.Both ‘Le Crete 1’ and ‘Le Crete 2’ have shown good tolerance to usual winter cold in the localities where they have been

grown. Symptoms due to infection by other pathogens, such as Pestalotiopsis funerea (Desm.) Steyaert, Diplodia cupressiPhillips & Alves, Phomopsis occulta (Sacc.) Traverso or to common pests, Cinara cupressi (Buckton), Trisetacus juniperinus(Nal.) and Phloeosinus aubei (Perris), have not been observed.

3.3 Advantages of using ‘Le Crete 1’ and ‘Le Crete 2’

‘Le Crete 1’ and ‘Le Crete 2’, besides their appreciable ornamental and growth value and their resistance to cypress canker,are characterized by some other traits that respond to the current demand of users. From preliminary observations, bothclones showed a low production of microsporophylls and look promising to meet the increasing cases of pollinosis (allergyto cypress pollen) among the populations of southern Europe (Papa et al. 2001). They represent a first step towards theselection of fully non-allergenic cypresses. ‘Le Crete 2’ is also characterized by a marked tolerance to clay on which it main-tained a high growth rate and can be even used as vigorous rootstock for cypresses with other useful traits. These twonew cypress clones join the four patented cultivars that are already on the market, widening the range of the available can-ker-resistant lines and supporting the flourishing market of cypress plants in the Mediterranean countries.‘Le Crete 1’ and ‘Le Crete 2’ were patented by the Italian National Research Council (CNR) with the support of the Pro-

vincial Administration of Siena (patent numbers RM2010NV000003 and RM2010NV000002, respectively). Their namesderive from the so-called Crete Senesi, the area where the ortets of these two clones come from, a famous scenery in theProvince of Siena representing well the heart and spirit of Tuscany.

3.4 Availability

‘Le Crete 1’ and ‘Le Crete 2’ will be available from commercial sources under licence from the CNR and Provincial Adminis-tration of Siena. Enquiries can be addressed to: Il Campino for the attention of Luciano Paggetti, Provincia di Siena, ViaMassetana, 106, 53100, (SI), Italy. Phone: +39 0577 241634. Fax: +39 0577 241635. e-mail: paggetti@provincia.siena.it.

References

Andreoli, C.; Ponchet, J., 1991: Potential use of exotic cypress species resistant to canker disease. In: Il Cipresso. Proposte Di ValorizzazioneAmbientale E Produttiva Nei Paesi Mediterranei Della Comunit�a Economica Europea. Ed. by Panconesi, A.; CNR, Regione Toscana, CEE,Firenze, pp. 150–157.

Andreoli, C.; Xenopoulos, S., 1990: Use of cypress. In: Agrimed Research Programme. PROGRESS in Eec Research on Cypress Diseases. Ed.by Ponchet, J.; Rep. EUR 12493 EN, Luxembourg, pp. 14–25.

Andreoli, C.; Ponchet, J.; Mari, E., 1996: Effects du porte-greffe sur la r�eaction du cypr�es �a la maladie du chancre cortical �a Seiridium cardi-nale. Agronomie 16, 563–571.

Danti, R.; Raddi, P.; Panconesi, A.; Di Lonardo, V.; Della Rocca, G., 2006: “Italico” and “Mediterraneo”: two Seiridium cardinale Canker-Resistant Cypress Cultivars of Cupressus sempervirens. HortScience 41, 1357–1359.

Della Rocca, G., 2008: Seiridium Cardinale, Agente Di Cancro Corticale Del Cipresso: Analisi Della Popolazione Europea Tramite TecnicheMorfologiche, Molecolari E Test Di Patogenicit�a. Doctoral Thesis. Universit�a degli Studi di Firenze, Italy, 109 pp.

Della Rocca, G.; Eyre, C.; Danti, R.; Garbelotto, M., 2011: Sequence and SSR analyses of the fungal pathogen Seiridium cardinale indicateCalifornia is the source of the Cypress canker epidemic for the Mediterranean region. Phytopathology. 101, 1408–1417.

Giannini, R.; Capuana, M.; Giovannelli, A., 1999: Raising plant material. In: Cypress. A Practical Handbook. Ed. by Tessier du Cros, E.; StudioLeonardo, Firenze, pp. 45–53.

Graniti, A., 1998: Cypress Canker: a pandemic in progress. Annu. Rev. Phytopathol. 36, 91–114.Moraldi, M.; Danti, R.; Di Lonardo, V., 2004: Produzione di piante di cipresso per innesto. In: Produzione Commerciale Di Piante Di Cipresso.

Manuale Tecnico. Ed. by Raddi, P.; Edizioni Centro Promozionale Pubblicit�a, Firenze, ISBN 88-88228-07-1, pp. 16–20Panconesi, A., 1990: Pathological disorders in the Mediterraneran basin,. In: Agrimed Research Programme. Progress in Eec Research on

Cypress Diseases. Ed. by Ponchet, J.; Rep. EUR 12493 EN, Luxembourg, pp. 54–81.Panconesi, A.; Della Rocca, G., 2007: Dal mito di Ciparisso al XX secolo. Un percorso attraverso le arti, la letteratura e le usanze civili e

religiose. In: Il Cipresso, Dalla Leggenda Al Futuro. Ed. by Panconesi, A. Edizioni Centro Promozionale Pubblicit�a, Firenze, ISBN978-88-88228-20-4, pp. 11–68.

Bark canker-resistant cypress cultivars 209

Papa, G.; Romano, A.; Quaratino, D.; Di Fonso, M.; Viola, M.; Artesani, M. C.; Sernia, S.; Di Gioacchino, M.; Venuti, A., 2001: Prevalence of sen-sitization to Cupressus sempervirens: a 4-year retrospective study. Sci. Total Environ. 270, 83–87.

Pedron, L.; Piva, G.; La Porta, N., 2007: The genetic structure of Cypress canker fungus in Italy using RAPD and minisatellite Markers. Acta.Silvatica. Lignaria. Hungarica., Special Edition, 159–168.

Pichot, C.; Xenopoulos, S.; Raddi, P.; Papageorgiou, A.; Fady, B.; Andr�eoli, C.; Panconesi, A., 1999: Choice of reproductive material. In:Cypress. A Practical Handbook. Ed. by Tessier du Cros, E.; Studio Leonardo, Firenze, pp. 35–44.

Ponchet, J.; Andreoli, C., 1990: Compartmentalization and reactions in the host. In: Agrimed Research Programme. Progress in Eec Researchon Cypress Diseases. Ed. by Ponchet, J.; Rep. EUR 12493 EN, Luxembourg. pp 96–111.

Ponchet, J.; Andreoli, C.; Xenopoulos, S.; Caetano, M. F.; Raddi, P.; Panconesi, A.; 1990: Pathogenic variability in Seiridium, In: AgrimedResearch Programme. Progress in EEC Research on Cypress Diseases. Ed. by Ponchet, J.; Rep. EUR 12493 EN, Luxembourg, pp. 112–126.

Raddi, P., 1979: Variabilit�a della resistenza al cancro nel cipresso comune (C. sempervirens) e di altre specie. In:. Il Cipresso: Malattie EDifesa. Ed. by Grasso, V.; Raddi, P.; CEE, Agrimed, Firenze, pp. 185–193.

Raddi, P.; Panconesi, A., 1984: Pathogenicity of some isolates of Seiridium (Coryneum) cardinale, agent of cypress canker disease. Eur. J. For-est Pathol. 14, 348–354.

Raddi, P.; Panconesi, A., 1994: Present and future of cypress canker disease research. In: Proc. Joint. Meet. IUFRO Working Parties. Shootand Foliage Disease in Forest Trees, Vallombrosa (Firenze), Italy. June, 6-11, 1994. Ed. by Capretti, P.; Heiniger, U.; Stephan, R.; Univer-sit�a degli Studi di Firenze, CNR, Firenze, Italy, pp. 112–117.

Raddi, P.; Panconesi, A.; Xenopoulos, S.; Ferrandes, P.; Andreoli, C., 1990: Genetic improvement for resistance to canker disease. In: AgrimedResearch Programme. Progress in EEC Research on Cypress Diseases. Ed. by Ponchet, J. Luxembourg: Rep. EUR 12493 EN, pp. 127–134.

Roversi, P. F., 2010: Avversit�a degli alberi e delle foreste. In: Rapporto Sullo Stato Delle Foreste Della Toscana 2009. Ed. by ARSIA - Regi-one Toscana; Compagnia delle Foreste, Arezzo, pp. 86–94.

Royal Horticultural Society, 1966: Colourchart. Ed. By Royal Hort. Soc., London.Santini, A.; Casini, N.; Di Lonardo, V.; Raddi, P., 1997: Canker resistance stability of some Cupressus sempervirens clones to Seiridium cardi-

nale. J. Genet. Breed. 51, 269–277.Spanos, K. A.; Pirrie, A.; Woodward, S.; Xenopoulos, S., 1999: Responses in the bark of Cupressus sempervirens clones artificially inoculated

with Seiridium cardinale under field conditions. Eur. J. Forest. Pathol. 29, 135–142.Stankowa, T.; Panetsos, K., 1997: Vegetative propagation of Cupressus sempervirens L. of Cretan origin by softwood stem cuttings. Silvae

Genet. 46, 137–144.Wagener, W. W., 1928: Coryneum canker of cypress. Science 67, 584.

210 R. Danti, V. Di Lonardo, A. Pecchioli et al.