Emerging Ornamental Plant Diseases and Their Management Trends in Northern Italy
1
Department of Civil, Chemical and Environmental Engineering, University of Genoa, Via Balbi, 5, 16126 Genova, Italy
2
Interdepartmental Centre for Innovation in the Agri-Environmental Field Agroinnova, University of Turin, Largo Paolo Braccini, 2, 10095 Grugliasco, Italy
*
Author to whom correspondence should be addressed.
Horticulturae 2025, 11(8), 955; https://doi.org/10.3390/horticulturae11080955
Submission received: 14 June 2025
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Revised: 4 August 2025
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Accepted: 11 August 2025
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Published: 13 August 2025
(This article belongs to the Special Issue Physiological and Molecular Biology of Ornamental Plants—2nd Edition)
Abstract
The ornamental plant sector is characterized by the production of a large variety of genera, species and cultivars that are much more numerous than those of other agricultural production sectors. Many countries throughout the world are involved in an intensive exchange of potted plants, cut flowers and propagation material. This intense trade exchange favors the introduction of the causal agents of new diseases on farms, in parks, along tree-lined avenues and in city gardens. Global warming can favor plant pathogens that thrive under high temperatures. Moreover, the interaction between the ongoing increase in temperature and in the CO2 concentration has caused a significant increase in the disease severity of many pathosystems. The numerous reports of new plant pathogens on ornamental plants in Italy in recent years fall into this context. In plant pathology research, living labs incorporate the complexities and variability of natural conditions, and they can thus be used to conduct experiments and test hypotheses. A private garden, located in the hamlet of Bariola (Piedmont, Biella province, northern Italy), has become an ideal living lab that is used to monitor the evolution of the phytosanitary situation of ornamental plants. The results obtained in this living lab are reported hereafter. Moreover, new trends in disease prevention and management, such as the adoption of appropriate prevention practices, water and fertilization management and use of environmentally friendly methods to reduce pesticide use as part of an integrated pest management approach, are also examined.
1. Introduction
The ornamental plant sector is characterized by the production of a large variety of genera, species and cultivars that are much more numerous than those of other agricultural production sectors. This is in part due to the growing demand for the novelty of increasingly competent and demanding buyers, as evidenced by the numerous floral events that are frequently held in a large variety of locations. Although these requests are often influenced by trends and fads, hybridizers, growers and nurserymen are obliged to constantly search for “novelties” for the market. The introduction of new species and cultivars mainly depends on the importation of plants and propagative material from abroad, which may be produced in geographically distant locations with very different climatic conditions. Some parasites, imported together with the new hosts, may find environmental conditions that are more favorable for their development in the new cultivation sites, or imported plants may encounter parasites that are already present in the new country to which they had not previously been exposed.
The ornamental plant industry is dynamic, and trends within this industry can change rapidly. The global demand for ornamental plants is generally increasing, and it is driven by the urbanization phenomenon and a growing interest in home and garden esthetics. The online sales of ornamental plants are increasing, and consumers are being provided with more and easier access to a wider variety of plants. In 2022, European Union countries, including Italy, imported 4.5 billion potted plants and 1.58 billion fresh cut flowers, all of which came from non-European countries, such as Kenya, Colombia and Ethiopia [1]. This facilitates the entry of new pathogens introduced with imported plants, and the rising volume of imports increases the risk of diseases.
Italian floriculture products have reached a value of more than EUR 1.2 billion, and Italy is in second place in Europe for their production after The Netherlands [2]. However, it is difficult to find public funding for research in the ornamental sector, although it is needed to improve its competitiveness. This research may involve, for example, the selection of widespread native species that grow spontaneously in Italian areas and have esthetic characteristics that could enrich the production of plants, flowers and cut fronds. Some examples of this kind of research are those studies that have been conducted on genera known for their rusticity, such as Euphorbia and Verbascum, which are suitable for low-maintenance gardens. The selection of genotypes of already cultivated species also helps to improve their production and/or to expand it, as in the case of hellebore, eucalyptus and viburnum. Research also provides a valid contribution through susceptibility trials, which have been carried out on several cultivars and hybrids of flowering plants against some of the most dangerous plant pathogens that can threaten such crops: Fusarium oxysporum f. sp. chrysanthemi on African daisy (Dimorphotheca sp.) and Gerbera jamesonii, Colletotrichum acutatum and Erysiphe azaleae on azalea [3] are some examples.
New plant pathogens, the causal agents of emerging diseases, can also appear on ornamental herbaceous, shrubby and arboreal species grown in public and private greenery, of which Italy is particularly rich. Indeed, there are numerous historic gardens, tree-lined avenues and city gardens, that is, from large parks to the greenery of a neighborhood, for which the recent pandemic caused by COVID-19 increased the need for citizens to feel healthy. The management of this large green heritage is further complicated in Italy and in many other European countries by the stringent limitations on the use of pesticides, which are prohibited or minimized in sensitive areas, such as public parks, sports grounds, hospitals and schools.
This article focuses on the emerging fungal and bacterial pathogens detected in northern Italy over the past twenty years, whose appearance is often linked to ongoing climate changes. Furthermore, it highlights the importance of so-called “living labs” as early warning systems for monitoring the evolving phytosanitary landscape and for testing appropriate sustainable control strategies. The activities carried out in one such lab are summarized.
2. Factors That Affect the Emergence of New Diseases
The ornamental plant market is extremely lively, and many countries throughout the world are involved in an intensive exchange of potted plants, cut flowers and propagation material. The production of ornamental plants requires large investments, in part due to the costs of labor and the heating of greenhouses and tunnels, especially in countries with cold climates. Unrooted cuttings are often produced in third-world countries, where the production costs are significantly lower and the weather conditions are more favorable. The propagative material is transferred from these countries to the traditional hubs for ornamental production (such as The Netherlands and Denmark, in Europe), and it eventually reaches consumers all over the world. However, this movement of plant material has facilitated the spread of a variety of plant pathogens, including Phytophthora spp. such as P. ramorum and the fearsome formae speciales of Fusarium oxysporum [4,5]. Moreover, this intense trade exchange favors the introduction of the causal agents of new diseases and/or brings newly imported hosts into contact with plant pathogens already present in a territory. A highly significant aspect derives from theories developed regarding invasive alien plants [6]. Similarly, there is a risk that certain ornamental species, when introduced into new production contexts, may become naturalized and invasive, facing limited control from local natural enemies—including fungal pathogens. Examples include butterfly bush (Buddleja davidii) [7] and Japanese spirea (Spiraea japonica) [8].
Some pathogens find temperatures in the new cultivation sites that are more favorable for their propagation, and this in turn can lead to more severe attacks. Among the various environmental factors, temperature plays a significant role in the onset of disease. Global warming, on the one hand, can favor plant pathogens that thrive in high temperatures, as well as the survival of pathogens in the winter periods; on the other hand, it can weaken plants, especially the mesophilic species, thereby making them more susceptible to infection. Temperature variations can alter the development cycles of both plants and pathogens and can favor the development of some diseases at certain times of the year in which they normally would not appear. The climate changes recorded in recent years have caused more frequent and intense extreme weather events (prolonged heat waves, intense droughts, late frosts, torrential rains) than in the past, and these events can cause stress (thermal, water and light imbalances) that weakens the plants and makes them more vulnerable to diseases. Rises in temperatures can also determine an increase in the number of generations per year of dangerous insects, such as bark beetles. The occurrence of intense storms can promote, even indirectly, the proliferation of insects that are normally present [9]. An example of this is the “Vaia storm”: the numerous trunks that fell onto the ground represented a very abundant source of nourishment for the bark beetle (Ips typographus), whose proliferation compromises thousands of spruce trees.
The increase in the concentration of atmospheric carbon dioxide (CO2), as a result of the increase in human activities, has led to an increase in atmospheric temperatures. The impact of climate change on plant health can be studied through three different but complementary approaches: monitoring the evolution of the phytopathological situation in specific geographic areas; using models to hypothesize future scenarios; using special research climate cells (phytotrons) that are able to modify the main environmental parameters, including the temperature and the CO2 concentration [10]. For example, experimental tests carried out in a controlled atmosphere have shown that the interaction between the increase in temperature and in the CO2 concentration has caused a significant increase in the severity of many pathosystems, such as Pelargonium–Puccinia pelargonii [11]. A variation in just one of the studied climatic parameters can cause more variable effects. The same studies underlined that the host–parasite–environmental parameter interaction is very complex and variable, and it can also have consequences on the adopted control methods [12,13].
3. New or Re-Emerging Diseases, with Special Focus on the Mediterranean Area
The increase in temperature caused by climate change will continue to determine certain consequences in northern European countries, especially in the wintertime, and will lead to the expansion of areas that are climatically suitable for a large variety of crops. However, in southern European countries, the consequences will instead mainly concern the summer period, and they will lead to increased water shortages and to extreme events, such as heatwaves, storms and droughts [14]. Climatic data recorded in Italy in the last few decades have outlined a dangerous trend. The significant increase in summer temperatures, the reduction in rainfall, especially in flat and hilly areas, the early mild spring temperatures, which induce plants to develop leaves and flowers earlier, and the increased damage caused by late frosts are all causing particularly negative consequences on agricultural crops [15]. Ornamental plants grown on farms, and in nurseries, gardens and parks, can suffer from similar consequences.
4. Italy as a Hot Spot for the Appearance of New Diseases
The numerous reports on the presence of new plant pathogens on ornamental plants in recent years fall into this context [3]. Among these, special attention has been paid to pathogens that are favored by high temperatures, such as Fusarium oxysporum (Table 1), whose optimal temperature, which is between 25 and 30 °C, depends on its specific form.
The most favorable conditions for the causal agents of powdery mildew (Table 2) are warm and humid weather and temperatures ranging from 18 to 25 °C.
Among the emerging foliar plant pathogens, Alternaria spp. has been detected in recent years on numerous ornamental species [16], many of which are listed in Table 3.
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Figure 1.
Trend of the average temperatures registered in the summer months (1 June–31 August) and in the autumn months (1 September–30 November), in the last 40 years by the weather station of Oropa (Biella province, northern Italy). The temperature rise is related to the numerous powdery mildews detected in the Bariola garden listed in Table 2.
Figure 1.
Trend of the average temperatures registered in the summer months (1 June–31 August) and in the autumn months (1 September–30 November), in the last 40 years by the weather station of Oropa (Biella province, northern Italy). The temperature rise is related to the numerous powdery mildews detected in the Bariola garden listed in Table 2.
Figure 2.
Trend of the average temperatures registered in the summer months (1 June–31 August) and in the autumn months (1 September–30 November), in the last 40 years by the weather station of Tollegno (Biella province, northern Italy). The temperature rise is related to the numerous powdery mildews detected in the Bariola garden listed in Table 2.
Figure 2.
Trend of the average temperatures registered in the summer months (1 June–31 August) and in the autumn months (1 September–30 November), in the last 40 years by the weather station of Tollegno (Biella province, northern Italy). The temperature rise is related to the numerous powdery mildews detected in the Bariola garden listed in Table 2.
The appearance of insect pests and plant pathogens on new tree hosts can lead to a reduction in growth, decay and even the death of the trees, which in turn affects the esthetics of the landscape and the human health of the citizens and/or can have negative economic impacts on forest plants grown in the parks and gardens of urban areas [17]. A significant example is that of Geosmithia morbida (with the walnut twig vector Pityophthorus juglandis), the causal agent of the thousand cankers disease, which can spread on Juglans nigra, on Juglans spp. and also on Pterocarya fraxinifolia, with the latter host being grown in several urban and historical parks [18]. Temperature increases and water stress phenomena also favor the spread of plant pathogens that are already present in Italian areas, such as Anthostoma decipiens, which causes the decline and death of hornbeam (Carpinus betulus). This pathogen has been constantly detected on hornbeam together with Endothiella sp., and it has been proved that both of these fungi are potential pathogens for other forest species diffused in gardens and parks [19].
Some endophytic fungi that are usually considered “non-pathogenic” can cause diseases on plants subjected to certain stress conditions, such as the occurrence of prolonged periods of drought. An example is that of Tubakia dryina, which, in conditions of excessive heat and drought, becomes parasitic and causes leaf spots, early leaf drop and crown decline on some ornamental broadleaf trees, such as oaks (Quercus spp.), horse chestnut (Aesculus spp.) and beech (Fagus sylvatica) [20,21].
5. The Bariola Garden
In plant pathology research, a living lab is a real-world environment (e.g., a farm, orchard or natural ecosystem) that is used to conduct experiments and test hypotheses. Unlike controlled laboratory settings, living labs incorporate the complexities and variability of natural conditions, thereby offering more realistic data and insights into disease dynamics and management strategies. This approach bridges the gap between laboratory findings and practical applications, and it allows researchers to evaluate the effectiveness of interventions under realistic field conditions.
Numerous herbaceous, shrubby and arboreal ornamental plants, both native and from all over the world, are currently being grown in a private garden located in the hamlet of Bariola, in the municipality of Campiglia Cervo (Piedmont, Biella province, northern Italy, 45.65236894890476, 8.006370027342234), at 850 m above sea level, on a surface of about 2.5 ha. This garden has been enriched each year with new species and cultivars, and, over the past 25 years, it has become an ideal living lab that is used to monitor the evolution of the phytosanitary situation of ornamental plants. The observations that have been carried out have made it possible to:
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- investigate the impact of climate change on the prevalence and severity of plant diseases;
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- compare the disease resistance of different varieties/cultivars under natural infection pressure conditions, considering such factors as the weather and soil conditions;
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- evaluate the efficacy of new disease control methods (a novel fungicide, biocontrol agent or cultural practice) in reducing disease incidence and severity in a real-world agricultural setting.
This has led to the achievement of more reliable data than those that can be obtained in controlled lab experiments.
Numerous causal agents of powdery mildew, which has never been detected in a geographical area affected by their presence until a few decades ago (Table 2), are among the plant pathogens that have been reported on this site. Their appearance, in a Piedmont location known for its rainy climates and cool summers, on hosts that have been grown in the Bariola garden for many years (for example, on Akebia quinata, Cornus florida, Lonicera caprifolium and Potentilla fruticosa), supports the hypothesis that climate changes can favor the spread of these plant pathogens [12]. It is interesting to note that the appearance of the numerous powdery mildews reported on this site (Table 2) occurred during a period in which there was a gradual increase in the average temperatures in the summer months (1 June–31 August) and in the autumn months (1 September–30 November), as recorded by the nearby weather stations of Oropa (45°37′36.39″ N 7°58′52.47″ E) and Tollegno (45°35′27″ N 8°02′51″ E) (see Figure 1 and Figure 2).
Some of the fungal pathogens reported on this site, such as Erysiphe pulchra on Cornus florida, were later also detected on floricultural farms, and they successively appeared on the “Daybreak”, “Rainbow” and “Rubra” cultivars grown in nurseries in the same area. Among the numerous plant pathogens reported for the first time on ornamental hosts at this site (Table 2, Table 3, Table 4 and Table 5), bacterial pathogens were also identified (Table 6), including Pseudomonas syringae pv. viburnii, the causal agent of bacterial blight in Viburnum sargentii. A subsequent survey also assessed the susceptibility of various Viburnum species and cultivars to the disease. Therefore, the Bariola garden can be considered one of the so-called “sentinel gardens and nurseries” that play a fundamental role in intercepting parasites (fungi, bacteria, insects, nematodes, etc.) that could appear on new hosts grown in such locations [22]. An example of these locations is the sentinel gardens created in China, which have allowed the presence of some dangerous parasites on important ornamental species to be reported in a timely manner [23,24,25]. In this context, the International Plant Sentinel Network (IPSN) brings together gardens, arboreta, the National Plant Protection Organisations (NPPOs), and plant pathologists who collaborate to form a network capable of timely detecting new and emerging plant pathogens. The IPSN was the first to detect, on a global scale, the presence of Hymenoscyphus fraxineus on hosts other than ash trees: Phillyrea latifolia, P. angustifolia and Chionanthus virginicus [26].
6. New Trends in Disease Prevention and Management
Sustainable production practices of ornamental plants, including reducing pesticide use, conserving water and using eco-friendly packaging, have been emphasized more and more in recent years. Such trends have led to a profound change in disease management practices, even for intensive production systems. The use of healthy plant material and the adoption of appropriate prevention practices (good ventilation, reduction in relative humidity) in production systems, coupled with the use of tolerant or resistant varieties, when available, reduces the need for using pesticides, to which the resort has become very limited during the last few decades. All this takes on significant importance for protected crops, where closed environments create more favorable conditions for fungal and bacterial infections.
The transition from the use of chemical products to an integrated pest and disease pest management approach has been determined for many reasons: the risk of developing resistance to fungicides, phytotoxicity damage, high costs, detrimental effects for both the workers and for the environment [27,28]. Furthermore, there is a growing request from consumers for ornamental plants with no chemical residues and that are grown while respecting pollinating insects.
All these reasons explain the increasing recourse to the biological control of ornamentals crops in greenhouses that has been observed in Europe and in North America [29]. As far as biocontrol agents are concerned, Lecomte et al. listed 26 biological control products used for the control of Fusarium wilt and stated that a great deal of research is needed to learn how to best integrate biocontrol measures with other control methods [30]. Some microorganisms that are effective against plant pathogens have been registered in Italy for ornamental plants: Ampelomyces quisqualis and Bacillus amyloliquefaciens (powdery mildew agents), Pythium oligandrum (Botrytis, Pythium, Rhizoctonia, Fusarium, Phytophthora, Sclerotinia and Verticillium genera), Trichoderma asperellum (Sclerotinia), Trichoderma asperellum TV1 (root rot causal agents), Coniothyrium minitans (Sclerotinia). Encouraging results have been obtained in experimental trials from microorganisms that have antagonistic activity, such as a Trichoderma strain isolated from compost, which was able to control both Phytophthora nicotianae on Skimmia japonica and P. cinnamomi on azalea [31,32].
The increasing demand for environmentally responsible pest management methods requires the search for “alternative” control methods. The fungicide activity carried out by some salts, such as sodium and potassium bicarbonates, is of interest for this purpose. Some phosphites (currently registered in Italy as fungicides) and phosphates perform like resistance inducers, especially the latter against powdery mildew agents. Interesting results have been obtained for some calcium-based products, which have been found to make the plant cell wall stronger [33,34].
Prevention plays an essential role in parks and gardens, where respect for the ecological needs of species cannot be ignored, and which, for new parks, should already start at the project phase. Respect for ecological needs is the essential premise for the growth of vigorous plants that are less susceptible to disease. The essential starting point to prevent plant diseases is the use of healthy plants and propagative material of certain origin. In addition, landscapers should be aware of the main phytopathological problems and, if possible, orient their choices toward resistant or, at least, tolerant cultivars. In this regard, the numerous experimental tests that have specifically been conducted to evaluate the sensitivity of plants against the most important parasites have provided precise indications on how to detect resistant or tolerant cultivars. For example, a monitoring campaign carried out in the Burcina park (Biella province, northern Italy) established that most of the approximately 50 tested rhododendron cultivars were resistant or tolerant to Pycnostysanus azaleae, the causal agent of rhododendron bud rot. Similarly, interesting results have emerged for downy mildew on Coleus (Solenostemon scutellarioides) cultivars [35].
However, the cultural practices that can be implemented to modify environmental factors in parks and gardens are somewhat limited. Respect for the correct planting distance and the exploitation of the direction of the prevailing winds both help to reduce the moisture on the leaves of shrubs and hedges that are prone to fungal and bacterial pathogens. Water management, using drip irrigation systems and fertilization management, helps prevent the development of diseases. Moreover, if any new phytopathological problems appear, it is essential to eliminate the sources of infection as soon as possible. In this context, there is a growing need to train landscape architects, green technicians and specialized gardeners, who will have to be constantly updated in order to be able to recognize new plant pathogens. These professional figures will have to be trained through training courses, seminars, meetings and specialized reviews. Collaboration with laboratories specialized in diagnostic services can provide a fundamental contribution to improving plant disease protection, through traditional and molecular diagnostic methods.
Finally, certain actions (meetings, debates, and posters) undertaken to educate people and empower them with scientific knowledge are also very useful. Such actions allow the public to contribute constructively to the work of green technicians. In this context, a significant and innovative example of collaboration between the managers of public green areas and citizens is that of the so-called “Citizen science”, whereby citizens can contribute, on a voluntary basis, to the collection of scientific data, using smartphones and dedicated apps, to monitor the health of public parks and report any emerging problems. Scientific observations involving nature lovers, made during “phytopathological walks” in home gardens and green areas near homes during the pandemic period, produced surprising results [36].
Thus, it is reasonable to expect that the ornamental sector will continue to be enriched, more than other sectors, with new plant pathogens. This should encourage collaboration between specialized technicians, research institutions, growers, plant lovers and users of greenery to help update a constantly evolving phytopathological framework, which could, in particular, be used to identify the most significant dangerous emergencies.
This is a complex challenge. However, the results from scientific research can provide innovative, rapid and specific solutions to defend one of the most important Italian agricultural production sectors as well as the Italian tree heritage in parks, public gardens and the gardens of historic mansions, of which there are many throughout Italy. In this context, molecular diagnostic methods—which have become increasingly sophisticated and precise in recent years [37]—can make a decisive contribution. These methods are continually evolving to become faster, more accurate and more cost-effective. Additionally, experimental trials carried out in controlled environment facilities (phytotrons) can simulate critical situations and provide valuable insights into the effects of ongoing climate change. Finally, the development of mathematical models enables the prediction of phytopathological trends in specific geographic areas, including urban environments [38].
Author Contributions
Writing—original draft preparation, M.L.G. and D.B.; writing—review and editing, M.L.G., D.B., M.P., and A.G.; supervision, M.L.G. and A.G.; funding acquisition, M.P. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the Fondazione Compagnia di San Paolo as a part of the “Biodiversità e Salute delle Piante (BIO-SAL)” project, by the University of Torino within the project Ricerca Locale (ex 60%) “Malattie delle piante e salute circolare: caratterizzazione, epidemiologia, diagnostica e strategie di lotta a patogeni emergenti” and by the European Union Next-Generation EU (PIANO NAZIONALE DI RIPRESA E RESILIENZA (PNRR)-MISSIONE 4 COMPONENTE 2, INVESTIMENTO 1.4-D.D. 1032 17/06/2022, CN00000022), Spoke 6, Task 6.1.1. This manuscript only reflects the authors’ views and opinions, and neither the European Union nor the European Commission can be considered responsible for them.
Conflicts of Interest
The authors declare no conflicts of interest.
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Table 1.
First reports of Fusarium oxysporum on ornamental plants in northern Italy in the last 20 years. The formae speciales are listed.
Table 1.
First reports of Fusarium oxysporum on ornamental plants in northern Italy in the last 20 years. The formae speciales are listed.
| Host | Forma Specialis | Region | Year |
|---|---|---|---|
| Gerbera jamesonii | Chrysanthemi | Liguria | 2004 |
| Osteospermum spp. | Chrysanthemi | Liguria | 2004 |
| Lewisia cotyledon | Unidentified | Piedmont | 2005 |
| Cereus peruvianus monstruosus | Opuntiarum | Liguria | 2011 |
| Crassula ovata | Crassulae * | Liguria | 2011 |
| Papaver nudicaule | Papaveris * | Liguria | 2012 |
| Echeveria agavoides | Echeveriae * | Liguria | 2013 |
| Cereus marginatus var. cristata | Opuntiarum | Liguria | 2014 |
| Echeveria tolimanensis | Echeveriae * | Liguria | 2015 |
| Euphorbia mammillaris var. variegata | Opuntiarum | Liguria | 2015 |
| Astrophytum myriostigma | Opuntiarum | Liguria | 2016 |
| Cereus peruvianus florida | Opuntiarum | Liguria | 2016 |
| Lavandula × allardii | Lavandulae * | Liguria | 2016 |
| Mammillaria zeilmanniana | Opuntiarum | Liguria | 2016 |
| Rudbeckia fulgida | Chrysanthemi | Piedmont | 2017 |
| Sulcorebutia heliosa | Opuntiarum | Liguria | 2019 |
| Mammillaria painteri | Opuntiarum | Liguria | 2020 |
| Sulcorebutia rauschii | Opuntiarum | Liguria | 2020 |
* New forma specialis.
Table 2.
The powdery mildews reported on ornamental plants for the first time in northern Italy in the last 20 years. The pathogen proliferation observed in the Bariola garden aligns with the increase in the average temperatures registered by the weather station of Oropa and Tollegno (Figure 1 and Figure 2).
Table 2.
The powdery mildews reported on ornamental plants for the first time in northern Italy in the last 20 years. The pathogen proliferation observed in the Bariola garden aligns with the increase in the average temperatures registered by the weather station of Oropa and Tollegno (Figure 1 and Figure 2).
| Host | Pathogen | Region | Detected in the Bariola Garden | Year |
|---|---|---|---|---|
| Akebia quinata | Oidium sp. | Piedmont | Yes | 2004 |
| Aquilegia flabellata | Erysiphe aquilegiae | Piedmont | Yes | 2004 |
| Lonicera caprifolium | Oidium subgenus Pseudoidium | Piedmont | Yes | 2004 |
| Photinia × fraserii | Podosphaera leucotricha | Piedmont | 2005 | |
| Potentilla fruticosa | Podosphaera aphanis var. aphanis | Piedmont | Yes | 2005 |
| Veronica spicata | Golovinomyces orontii | Piedmont | Yes | 2006 |
| Coreopsis lanceolata | Podosphaera fusca | Piedmont | Yes | 2007 |
| Lamium galeobdolon | Golovinomyces orontii | Piedmont | Yes | 2007 |
| Petunia × hybrida | Golovinomyces orontii | Piedmont | Yes | 2007 |
| Argyranthemum frutescens | Golovinomyces cichoracearum | Liguria | 2008 | |
| Calendula officinalis | Podosphaera xanthii | Piedmont | Yes | 2008 |
| Hedera helix | Erysiphe heraclei | Liguria | 2008 | |
| Rudbeckia fulgida | Golovinomyces cichoracearum | Piedmont | 2008 | |
| Cleome hassleriana | Erysiphe cruciferarum | Piedmont | 2009 | |
| Cornus florida | Erysiphe pulchra | Piedmont | Yes | 2009 |
| Gerbera jamesonii | Golovinomyces cichoracearum | Piedmont | 2010 | |
| Phlox drummondii | Podosphaera sp. | Piedmont | Yes | 2011 |
| Verbascum blattaria | Golovinomyces cichoracearum | Piedmont | 2011 | |
| Aster novi-belgii | Golovinomyces cichoracearum | Piedmont | Yes | 2012 |
| Campanula rapunculoides | Golovinomyces orontii | Piedmont | Yes | 2012 |
| Euphorbia aggregata | Podosphaera sp. | Liguria | 2012 | |
| Euphorbia inermis | Podosphaera sp. | Liguria | 2012 | |
| Euphorbia perdorfiana | Podosphaera sp. | Liguria | 2012 | |
| Euphorbia susannae | Podosphaera sp. | Liguria | 2012 | |
| Oenothera biennis | Erysiphe sp. | Piedmont | Yes | 2012 |
| Phlox paniculata | Golovinomycesmagnicellulatus | Piedmont | Yes | 2016 |
| Thymus × citriodorus “Aureus” | Golovinomyces biocellatus | Liguria | 2016 | |
| Verbascum nigrum “Album” | Golovinomyces cichoracearum | Piedmont | Yes | 2016 |
| Campanula glomerata | Golovinomyces orontii | Piedmont | 2018 | |
| Echinacea purpurea | Golovinomyces cichoracearum | Piedmont | Yes | 2018 |
| Abelmoschus manihot | Golovinomyces orontii | Piedmont | 2019 | |
| Lavandula stoechas “Blueberry Ruffles” | Golovinomyces neosalviae | Liguria | 2020 | |
| Salvia nemorosa | Golovinomyces biocellatus | Piedmont | Yes | 2021 |
| Dianthus caryophyllus | Erysiphe buhrii | Liguria | 2022 | |
| Phlox maculata | Golovinomyces magnicellulatus | Piedmont | Yes | 2022 |
Table 3.
Leaf plant fungal pathogens reported on several ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
Table 3.
Leaf plant fungal pathogens reported on several ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
| Host | Pathogen | Year |
|---|---|---|
| Hydrangea macrophylla | Phoma exigua | 2006 |
| Clematis × jackmanii | Phoma sp. | 2007 |
| Hydrangea macrophylla | Alternaria alternata | 2007 |
| Hydrangea anomala | Alternaria compacta | 2008 |
| Cornus florida | Botrytis cinerea | 2009 |
| Platycodon grandiflorum | Botrytis cinerea | 2009 |
| Fuchsia × hybrida | Phoma multirostrata | 2010 |
| Rudbeckia fulgida | Phoma sp. | 2010 |
| Aquilegia flabellata | Phoma aquilegiicola | 2011 |
| Lupinus polyphyllus | Pleiochaeta setosa | 2012 |
| Saponaria officinalis | Alternaria nobilis | 2013 |
| Verbascum nigrum | Phoma novae-verbascicola | 2013 |
| Verbascum blattaria | Phoma novae-verbascicola | 2014 |
| Campanula glomerata | Alternaria sp. | 2015 |
| Campanula medium | Stagonosporopsis trachelii | 2015 |
| Rudbeckia fulgida | Alternaria sp. | 2015 |
| Salvia oxyphora | Botrytis cinerea | 2015 |
| Anemone japonica | Botrytis cinerea | 2016 |
| Campanula medium | Alternaria alternata | 2016 |
| Liquidambar styraciflua | Colletotrichum kahawae | 2016 |
| Salvia greggii | Boeremia exigua var. linicola | 2016 |
| Salvia leucantha | Colletotrichum fioriniae | 2016 |
| Campanula trachelium | Stagonosporopsis trachelii | 2017 |
| Ceratostigma willmottianum | Alternaria alternata | 2019 |
| Abelmoschus manihot | Alternaria alternata | 2020 |
| Coreopsis lanceolata | Colletotrichum fuscum | 2020 |
| Mahonia aquifolium | Colletotrichum fioriniae | 2020 |
| Phlox maculata | Alternaria alternata | 2020 |
| Aquilegia flabellata | Plectosphaerella cucumerina | 2021 |
| Campanula rapunculoides | Stagonosporopsis trachelii | 2022 |
| Hydrangea paniculata | Alternaria alternata | 2023 |
| Rhododendron arboreum | Botrytis cinerea | 2024 |
Table 4.
Soil-borne plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
Table 4.
Soil-borne plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
| Host | Pathogen | Year |
|---|---|---|
| Heuchera sanguinea | Rhizoctonia solani | 2007 |
| Lupinus polyphyllus | Verticillium dahliae | 2007 |
| Aquilegia flabellata | Rhizoctonia solani | 2009 |
| Digitalis purpurea | Rhizoctonia solani | 2009 |
| Rudbeckia hirta | Verticillium dahliae | 2012 |
| Phlox paniculata | Verticillium dahliae | 2014 |
| Campanula trachelium | Rhizoctonia solani | 2015 |
| Lychnis coronaria | Rhizoctonia solani | 2015 |
| Campanula carpatica | Rhizoctonia solani | 2018 |
| Echinacea purpurea | Rhizoctonia solani | 2019 |
| Coreopsis lanceolata | Phytopythium oedochilum | 2022 |
| Anemone japonica | Globisporangium sylvaticum | 2023 |
Table 5.
Obligate plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
Table 5.
Obligate plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
| Host | Pathogen | Year |
|---|---|---|
| Fuchsia × hybrida | Pucciniastrum circaeae | 2012 |
| Digitalis purpurea | Peronospora digitalidis | 2013 |
| Impatiens walleriana | Plasmopara obducens | 2013 |
| Oenothera biennis | Peronospora arthurii | 2018 |
Table 6.
Bacterial plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
Table 6.
Bacterial plant pathogens reported on ornamental plants for the first time in Italy in the Bariola living lab in the last 20 years.
| Host | Pathogen | Year |
|---|---|---|
| Phlox paniculata | Pseudomonas cichorii | 2005 |
| Viburnum sargentii | Pseudomonas syringae pv. viburnii | 2005 |
| Coreopsis lanceolata | Pseudomonas cichorii | 2009 |
| Verbena hybrida | Erwinia sp. | 2011 |
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Gullino, M.L.; Bertetti, D.; Pugliese, M.; Garibaldi, A. Emerging Ornamental Plant Diseases and Their Management Trends in Northern Italy. Horticulturae 2025, 11, 955. https://doi.org/10.3390/horticulturae11080955
AMA Style
Gullino ML, Bertetti D, Pugliese M, Garibaldi A. Emerging Ornamental Plant Diseases and Their Management Trends in Northern Italy. Horticulturae. 2025; 11(8):955. https://doi.org/10.3390/horticulturae11080955
Chicago/Turabian StyleGullino, Maria Lodovica, Domenico Bertetti, Massimo Pugliese, and Angelo Garibaldi. 2025. "Emerging Ornamental Plant Diseases and Their Management Trends in Northern Italy" Horticulturae 11, no. 8: 955. https://doi.org/10.3390/horticulturae11080955
APA StyleGullino, M. L., Bertetti, D., Pugliese, M., & Garibaldi, A. (2025). Emerging Ornamental Plant Diseases and Their Management Trends in Northern Italy. Horticulturae, 11(8), 955. https://doi.org/10.3390/horticulturae11080955
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