Mango Anthracnose: Economic Impact and Current Options For Integrated Managaement.

ilamentous fungi of the genus Colletotrichum and its teleomorph Glomerella are considered major plant pathogens worldwide. They cause significant economic damage to crops in tropical, subtropical, and temperate regions. Cereals, legumes, ornamentals, vegetables, and fruit trees may be seriously affected by the pathogen (3). Although many cultivated fruit crops are infected by Colletotrichum species, the most significant economic losses are incurred when the fruiting stage is attacked. Colletotrichum species cause typical disease symptoms known as anthracnose, characterized by sunken necrotic tissue where orange conidial masses are produced. Anthracnose diseases appear in both developing and mature plant tissues (4). Two distinct types of diseases occur: those affecting developing fruit in the field (preharvest) and those damaging mature fruit during storage (postharvest). The ability to cause latent or quiescent infections has grouped Colletotrichum among the most important postharvest pathogens. Species of the pathogen appear predominantly on aboveground plant tissues; however, belowground organs, such as roots and tubers, may also be affected. In this article, we deal in particular with methods used to identify and characterize Colletotrichum species and genotypes from almond, avocado, and strawberry, as examples, using traditional and molecular tools. The three pathosystems chosen represent different disease patterns of fruitassociated Colletotrichum. Multiple Species on a Single Host Numerous cases have been reported in which several Colletotrichum species or biotypes are associated with a single host. For example, avocado and mango anthracnose, caused by both C. acutatum and C. gloeosporioides, affect fruit predominantly as postharvest diseases (25,40,41). Strawberry may be infected by three Colletotrichum species, C. fragariae, C. acutatum, and C. gloeosporioides, causing anthracnose of fruit and other plant parts (31). Almond and other deciduous fruits may be infected by C. acutatum or C. gloeosporioides (Table 1) (1,5,46,50). Citrus can be affected by four different Colletotrichum diseases (61): postbloom fruit drop and key lime anthracnose, both caused by C. acutatum, and shoot dieback and leaf spot, and postharvest fruit decay, both caused by C. gloeosporioides. Additional examples of hosts affected by multiple Colletotrichum species include coffee, cucurbits, pepper, and tomato. Single Species on Multiple Hosts It is common to find that a single botanical species of Colletotrichum infects multiple hosts. For example, C. gloeosporioides (Penz.) Penz. & Sacc. in Penz. (teleomorph: Glomerella cingulata (Stoneman) Spauld. & H. Schrenk), which is considered a cumulative species and forms the sexual stage in some instances, is found on a wide variety of fruits, including almond, avocado, apple, and strawberry (Table 2) (6,15,31,46). Likewise, C. acutatum J.H. Simmonds has been reported to infect a large number of fruit crops, including avocado, strawberry, almond, apple, and peach (1,5,16,25,27). Examples of other species with multiple host ranges include C. coccodes, C. capsici, and C. dematium (14,56).

Lifestyles of Colletotrichum acutatum.

Over the last 10 years plant pathologists have begun to realize that more knowledge about the genetic structure of populations of plant pathogens is needed to implement effective control strategies (48). Research on the genetic structure of fungal populations has mushroomed, and review papers that summarize these studies are numerous (7,27,33,34,38). Although the number of fungal studies has increased greatly, the most comprehensive work has focused on a small number of plant-pathogenic fungi. The majority of these fungi can be recognized easily by their fruiting bodies or disease symptoms on aboveground plant parts. It has proven more difficult to assess the genetic structure of fungal populations that exist mainly belowground, because the distribution of individuals cannot be visualized directly and appropriate sampling procedures are less obvious and more cumbersome. Nevertheless, substantial progress has been made in interpreting the population genetic structure of some soilborne fungi (1,17). The purpose of this paper is to provide an overview of the tools and techniques of fungal population genetics. I will try to emphasize approaches that may be applied to studies of soilborne fungi. Instead of providing detailed methods, I will cite recent references where appropriate. There are many opinions regarding which techniques and tools are best suited to studies of fungal populations. I will give a personal and biased viewpoint, which I believe will be most useful to those who are just entering the field.

Phytophthora blight, caused by the oomycete pathogen, Phytophthora capsici, is a devastating disease on bell pepper and cucurbit crops in the United States and worldwide (29,40). P. capsici causes a root and crown rot, as well as an aerial blight of leaves, fruit, and stems, on bell pepper (Capsicum annuum), tomatoes, cucumber, watermelon, squash, and pumpkin (29,35, 40,57,73). The disease was first described on bell pepper in New Mexico in 1922 (40). In recent years, epidemics have been severe in areas of North Carolina, Florida, Georgia, Michigan, and New Jersey. Oospores are believed to provide the initial source of inoculum in the field, and the disease is polycyclic within seasons (1,7,59,60,67). In this article, we discuss the biology and epidemiology of Phytophthora blight on bell pepper and also describe management strategies that can be implemented based on existing knowledge of the ecology of this devastating pathogen. The objectives of ecologically based pest management (EBPM) are the safe, profitable, and durable management of pests that includes a total systems approach (25). EBPM relies primarily on biological input of knowledge concerning a pathogen life cycle, and secondarily, when necessary, on physical, chemical, and biological supplements for disease management. An understanding of the ecological processes that are suppressive to plant diseases is emphasized rather than secondary inputs (25). Fortunately, we have a considerable amount of information available on the biology and ecology of P. capsici, which can now be integrated to improve our ability to manage the disease using ecologically based approaches. Strategies recommended for management of Phytophthora blight involve integrated approaches that focus first on cultural practices that reduce high soil moisture conditions, but also include monitoring and reduction of propagules of P. capsici that persist in the soil, utilization of cultivars with resistance to the disease, and when necessary, judicious fungicide applications. Symptoms and Life Cycle P. capsici can infect virtually every part of the pepper plant. The pathogen causes a root and crown rot on pepper (Fig. 1) and also forms distinctive black lesions on the stem (Fig. 2). P. capsici can also infect the leaves and causes lesions that are circular, grayish brown, and water-soaked (Fig. 3). Leaf lesions and stem lesions are common when inoculum is splash dispersed from the soil to lower portions of the plant. The pathogen can also infect fruit and causes lesions that are typically covered with white sporangia, a sign of the pathogen (Fig. 4). P. capsici typically causes a fruit rot or stem rot on cucumbers and squash (Fig. 5). P. capsici reproduces by both sexual and asexual means (Fig. 6). The pathogen produces two mating types, known as the A1 and A2. These are actually compatibility types and do not correspond to dimorphic forms. Each mating type produces hormones that are responsible for gametangia differentiation in the opposite mating type. Both A1 and A2 mating types are common in fields in North Carolina and have also been identified within the same plant (59). P. capsici produces a male gametangium, called the antheridium, and a female gametangium, called the oogonium. The antheridium is amphigynous in this species. Meiosis occurs within the gametangia, and plasmogamy and karyogamy result

Mango (Mangifera indica L.) is one of the world's most significant economic fruit crops, and China is the second-largest producer of mango (Kuhn et al., 2017). Postharvest mango anthracnose is caused by Colletotrichum species and reduce the self-life of mature fruit (Wu et al., 2020). Colletotrichum species also cause postharvest anthracnose and fruit rot disease of Apple, Banana and Avocado (Khodadadi et al., 2020; Vieira et al., 2017; Sharma et al., 2017). In July 2019, mango fruits cv. 'Jin-Hwang' were observed at different fruit markets (39°48'42.1"N 116°20'17.0"E) of the Fengtai district, Beijing, China, exhibiting typical symptoms of anthracnose including brown to black lesions in different size (≤ 2 cm) with identified border on the mango fruit surface. Later, the lesions were coalesced and extensively cover the surface area of the fruit. The lesions were also restricted to peel the fruit and pathogen invaded in the fruit pulp. About 30% of mango fruits were affected by anthracnose disease. The margins of lesions from infected mango fruits (n=56) were cut into 2 × 2 mm pieces, surface disinfected with NaClO (2% v/v) for 30 s, rinsed thrice with distilled water for 60s. These pieces were placed on PDA medium and incubated at 25°C for 7 days. Pure culture of fungal isolates was obtained by single spore isolation technique. Initially, the fungal colony was off white, and colony extended with time, turning light gray at the center. The morphological examination revealed that conidia were hyaline, oblong, and unicellular. The conidia were measured from 10 days old culture and dimensions varied from 13.3 to 15.8 µm in length and 4.6 to 6.1 µm in width. For molecular identification, a multi-locus sequence analysis; the Internal Transcribed Spacers (ITS) region, partial actin (ACT) gene, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) gene and chitin synthase (CHS-1) gene were amplified by using the primer sets ITS1/4 (White et al. 1990), ACT-512F/ACT-783R (Carbone and Kohn 1999), GDF1/GDR1 (Guerber et al. 2003) and CHS1-79F/CHS-1-354R (Carbone and Kohn 1999) respectively. The partial sequences of MTY21 were deposited to GenBank accessions (MT921666 (ITS), MT936119 (ACT), MT936120 (GAPDH) and MT936118 (CHS-1). All obtained sequences showed 100% similarity with reported sequences of Colletotrichum alienum ICMP.18691 with accessions numbers JX010217 (ITS), JX009580 (ACT), JX010018 (GAPDH) and JX009754 (CHS-1) which represented the isolate MTY21 identified as C. alienum by constructing Maximum Likelihood phylogenetic tree analysis using Mega X (Kumar et al., 2018). For the confirmation of Koch's postulates, the pathogenicity test was conducted on 36 fresh healthy mango fruits for each treatment. Fruits were punctured with the help of a sterilized needle to create 2mm2 wounds and inoculated with 10µL inoculum (107 spores/mL) of MTY21. Control mango fruits were inoculated with 10µL sterilized distilled water and incubated at 25 °C with 90% relative humidity. The lesions appeared at the point of inoculation and gradually spread on the fruit surface after 7 days post inoculation. The symptoms were similar to the symptoms on original fruit specimens. The re-isolated fungus was identified as C. alienum based on morphological and molecular analysis. Mango anthracnose disease caused by several Colletotrichum species has been reported previously on mango in China (Li et al., 2019). Liu et al. (2020) reported C. alienum as the causal organism of anthracnose disease on Aquilaria sinensis in China. C. alienum has been previously reported causing mango anthracnose disease in Mexico (Tovar-Pedraza et al., 2020) To our knowledge, this is the first report of C. alienum causing postharvest anthracnose of mango in China. The prevalence of C. alienum was 30% on mango fruit which reflects the importance of this pathogen as a potential problem of mango fruit in China.

Summary‘Kensington Pride’ mango (Mangifera indica L.) fruit stored with 2 – 3 cm-long peduncles had significantly smaller anthracnose lesion areas after being inoculated with Colletotrichum gloeosporioides at 107 spores ml–1 than fruit that had been desapped and stored according to normal commercial practice. In contrast, lesion development in ‘R2E2’ mango fruit was not influenced by the presence of the peduncle. ‘Kensington Pride’ fruit, with their peduncles attached, contained significantly higher levels of 5-n-heptadecenylresorcinol and 5-n-pentadecylresorcinol in their peel compared with desapped fruit. At harvest, ‘Kensington Pride’ fruit sap contained approx. 61% of the total 5-n-heptadecenylresorcinol and 47% of the total 5-n-pentadecylresorcinol present in the fruit. ‘R2E2’ fruit sap contained lower concentrations of alk(en)ylresorcinols but, in both mango varieties, retention of the peduncle did not influence fruit ripening. These results suggest that harvesting ‘Kensington Pride’ mango fruit with a long (2 – 3 cm) peduncle maintained alk(en)ylresorcinol concentrations in the peel and in resin duct sap, and contributed to improved fruit resistance against anthracnose disease. Lower concentrations of sap alk(en)ylresorcinols correlated with weaker resistance to anthracnose in ‘R2E2’ mango fruit.

This study investigated treatment of mango (Mangifera indica L.) fruit with 2 host defence-promoting compounds for suppression of anthracnose disease (Colletotrichum gloeosporioides). Cultivar ‘Kensington Pride’ fruit were treated at concentrations of up to 1000 mg/L with either potassium phosphonate or salicylic acid. Applications were by various combinations of pre- and postharvest dips and vacuum infiltration. Postharvest treatments at up to 2000 mg/L salicylic acid were evaluated in a second fruiting season. Fruit were either uninoculated or inoculated with the fungal pathogen. Colour, firmness and disease-severity were assessed during shelf life at 23°C. There were no significant (P>0.05) effects of potassium phosphonate or salicylic acid on anthracnose disease severity in the first season. Moreover, phosphonate or salicylic acid treatment did not significantly affect fruit colour or firmness changes. There were significant (P<0.05) reductions in anthracnose severity in the second season, especially at the highest concentration of 2000 mg/L salicylic acid. Mango fruit skin colour and firmness changes were also slowed down significantly (P<0.05). These effects of salicylic acid were attributed to inhibition of mango fruit skin ripening (senescence).

The antifungal activity of five invasive alien plant leaf extracts against Colletotrichum gloeosporioides was studied in vitro and in vivo. The in vitro antifungal activity was based on the inhibitory effects of the extracts on C. gloeosporioides radial growth and conidia formation, while the in vivo activity was based on the development of anthracnose disease on detached mango fruits. For the in vivo test, two plant extracts that showed higher inhibitory effect in vitro were selected and their minimum inhibitory concentrations were determined and tested against the disease on detached mango fruits applying the extracts at three times of application. The study revealed that the inhibitory effect of the extracts depends on the type of plant species used, method of extraction and time of application of the extracts. Prosopis juliflora and Lantana camara extracts were the most effective plant extracts that significantly reduced radial growth and conidia formation, and reduced disease development on mango fruits. Thus, P. juliflora and L. camara extracts can serve as an alternative means of post-harvest mango anthracnose disease management.

BackgroundMango anthracnose, caused by Colletotrichum gloeosporioides, is one of the most important diseases of mango crop. It mainly attacks leaves, flowers, young fruits and twigs and also appears as a post-harvest disease of ripened fruits. Application of bio-control agents has huge potential in plant disease management. The goal of the present research was to establish the potential of individual and combined bio-control agents for the management of mango anthracnose under in vitro and under field conditions.ResultsThe antagonistic reaction of six fungi, six bacteria and nine yeasts against C. gloeosporioides on potato dextrose agar medium and malt extract agar medium was observed among which Trichoderma harzianum was found to be the most efficient with 89.26% mycelial growth inhibition. Evaluation of bio-control agents against anthracnose disease development on mango fruit revealed that dip treatment of mango fruits in spore suspension (1.2 × 104 cfu/ml) of T. harzianum for 5 min was the most effective and provided disease control to the tune of 81.67%. Combined application of effective bio-control agents as a post-harvest fruit dip treatment was also evaluated against the mango anthracnose on mango fruits, where the treatment of T. harzianum + Pichia anomala was very effective with 93.39% disease control. Under field conditions, three consecutive sprays of T. harzianum, starting with the initiation of disease on leaves, followed by other two sprays at an interval of 15 days during 2015 and 2016 were found the best for the management of mango anthracnose disease both on leaves and on fruits at two locations.ConclusionsThe combined and individual applications of bio-control agents, viz.T. harzianum, Bacillus subtilis and P. anomala, through foliar spray or by fruit dip had the potential to control mango anthracnose. The bio-formulations of these bio-control agents had the potential to replace chemical fungicides and also protect the natural environment, thus playing a significant role in integrated disease management.

Influence of chitosan coating combined with spermidine on anthracnose disease and qualities of ‘Nam Dok Mai’ mango after harvest

Pseudomonas syringae Diseases of Fruit Trees: Progress Toward Understanding and Control.

Fumonisins in Maize: Can We Reduce Their Occurrence?

Abstract. Widiastuti A, Suryanti, Giovanni AC, Santika IA, Paramita NR. 2023. Fungal community associated with mixed infection of anthracnose and stem end rot diseases in Chokanan Mango. Biodiversitas 24: 2163-2170. Anthracnose and stem end rot are the top two prevalent diseases causing losses in mango fruit worldwide. Both diseases often appear together in ripened fruits. The aim of this research was to evaluate the fungal community associated with mixed infection of anthracnose and stem end rot diseases in Chokanan mango based on metagenomics analysis through amplicon targeted next generation sequencing. The results showed that approximately 152,000 sequences were observed. The average total tags from the observed OTUs number were 146,485, of which 126,230 were taxon tags. The ten most common occurring fungal genera were Colletotrichum, Penicillium, Diaporhte, Purpureocillium, Aspergillus, Cunninghamella, Neofusicoccum, Mortierella, Rhizopus, and Kazachstania. Of these, genus Colletotrichum showed 77% dominance of based on Krona display value. Based on the number of OTUs, seven species, such as Colletotrichum gloeosporioides (Penz.) Penz. & Sacc., Penicillium simplicissimum (Oudem.) Thom, Neofusicoccum cordaticola Pavlic, Slippers & M.J.Wingf., Diaporthe arengae R.R.Gomes, Glienke & Crous, Purpureocillium lilacinum (Thom) Luangsa-ard, Houbraken, Hywel-Jones & Samson, Alternaria alternata (Fr.) Keissl., and Fusarium oxysporum Schltdl., showed dominance in mixed infection. These findings reveal the major status of post-harvest pathogens in mango fruits that should be controlled. This is the first report on N. cordaticola and D. arengae associated with mixed infection of anthracnose and stem and rot disease on post-harvest mango in Indonesia.

The anthracnose caused by Colletotrichum gloeosporioides poses a significant threat to the global mango (Mangifera indica L.) fruit industry. Although histone deacetylases (HDACs) are well recognized to be involved in plant immunity, the role of HDAC-mediated nonhistone deacetylation in the fruit immune response remains elusive. In the present study, MiHDA3, an HDAC from the RPD3/HDA1 subfamily, was identified as a candidate for regulating mango resistance based on the greatest induction of MiHDA3 in response to infection of C. gloeosporioides among the 19 tested HDAC genes. Transient overexpression of MiHDA3 in mango fruit strengthened the disease resistance by enhancing the activities of defense-related enzymes (phenylalanine ammonia-lyase (PAL) and β-1,3-glucanase (GLU)) and upregulating the expression levels of MiPAL and MiGLU. These increases occurred concomitantly with increased accumulation of local H2O2, a critical signaling molecule. The opposite effects on resistance and H2O2 production were observed in MiHDA3-silenced mango fruit. Physiological assays revealed that exogenous H2O2 treatment suppressed anthracnose development in mango fruit after inoculation with C. gloeosporioides, whereas treatment with diphenylene iodonium, an inhibitor of endogenous H₂O₂ generation, exacerbated disease symptoms. Furthermore, the mango catalase 1 (MiCAT1), a redox homeostasis-related protein, was confirmed to negatively regulate the resistance of mango fruit to C. gloeosporioides by catalyzing the decomposition of H2O2. Mechanistic investigations revealed that MiHDA3-mediated deacetylation of MiCAT1 at lysine residues K227 and K233 reduced the enzymatic activity and protein stability of MiCAT1, contributing to enhanced resistance in mango fruit. Collectively, these findings highlight that the functional interplay between HDACs and catalases can modulate the immune response in post-harvest fruits, and reveal a novel mechanism by which HDACs enhance mango disease resistance through the deacetylation of nonhistone proteins and the regulation of their biochemical functions.

SummaryNear-ripe ‘Kensington Pride’ mango (Mangifera indica L.) fruit with green skin colour generally return lower wholesale and retail prices. Pre-harvest management, especially nitrogen (N) nutrition, appears to be a major causal factor. To obtain an understanding of the extent of the problem in the Burdekin district (dry tropics; the major production area in Australia), green mature ‘Kensington Pride’ mango fruit were harvested from ten orchards and ripened at 20 ± 0.5 ° C. Of these orchards, 70% produced fruit with more than 25% of the skin surface area green when ripe. The following year, the effect of N application on skin colour and other quality attributes was investigated on three orchards, one with a high green (HG) skin problem and two with a low green (LG) skin problem. N was applied at pre-flowering and at panicle emergence at the rate of 0, 75, 150, 300 g per tree (soil applied) or 50 g per tree as foliar N for the HG orchard, and 0, 150, 300, 450 g per tree (soil applied) or 50 g per tree (foliar) for the LG orchards. In all orchards the proportion of green colour on the ripe fruit was significantly (P<0.05) higher with soil applications of 150 g N or more per tree. Foliar sprays resulted in a higher proportion of green colour than the highest soil treatment in the HG orchard, but not in the LG orchards. Anthracnose disease severity was significantly (P<0.05) higher with 300 g of N per tree or foliar treatment in the HG orchard, compared with no additional N. Thus, N can reduce mango fruit quality by increasing green colour and anthracnose disease in ripe fruit.