Stem-end Rot Research Articles

Induced resistance to control postharvest stem-end rot by methyl jasmonate in mango fruit

Induced resistance is an alternative disease control strategy for postharvest fruits and vegetables. Methyl jasmonate (MeJA) is a crucial phytohormone in the defense response to biotic and abiotic stresses. The effect and relevant mechanism of MeJA on the control of postharvest disease in mango fruit remain unclear. This study investigated the effect and possible mechanism of MeJA against stem-end rot caused by Lasiodiplodia theobromae in mango fruit. The results showed that MeJA significantly inhibited the lesion expansion on mango fruit inoculated with L. theobromae. 10 μM MeJA treatment effectively induced disease resistance against L. theobromae during postharvest storage. MeJA enhanced the activities of defense-related enzymes, including phenylalanine ammonia lyase (PAL), peroxidase (POD), β-1,3-glucanase (GLU), and chitinase (CHT), increased the accumulation of endogenous jasmonic acid (JA) and salicylic acid (SA) contents, up-regulated the expressions of the related genes on JA pathway (AOS, JAR1, MYC2, and COI1) and SA pathway (ICS, and PR1), stimulated the contents of total phenolics and flavonoids, and inhibited the accumulation of malondialdehyde (MDA). Furthermore, MeJA delayed the ripening and senescence of the fruit by inhibiting the peel yellowing, flesh softening and change in soluble solids content (SSC) of mango fruit. The results indicated that the enhanced resistance of MeJA-treated mango to stem-end rot was potentially due to the activation of defense responses induced by synergistic interaction between JA and SA pathways, as well as delayed postharvest ripening. The MeJA treatment is a promising strategy to control stem-end rot of mango fruit.

Development of Potting Media from Composted Organic Food Waste Supplemented with Trichoderma asperellum and Talaromyces tratensis for Control of Root and Stem-End Rot in Chinese Kale (Brassica oleracea)

Development of Potting Media from Composted Organic Food Waste Supplemented with Trichoderma asperellum and Talaromyces tratensis for Control of Root and Stem-End Rot in Chinese Kale (Brassica oleracea)

Cold storage conditions affect ‘Shepard’ avocado fruit ripening and quality

ABSTRACT There has been little research into long storage of ‘Shepard’ avocado. Simulated conditions for sea freight of Australian-grown fruit to key Asian markets were investigated. Thirteen storage treatments were applied to fruit of premium quality sourced from two commercial farms. Compared with the generally recommended 7°C, fruit stored at 5.5°C for up to 28 days were firmer at removal, slow to ripen, and had less severe flesh rots at the ripe stage. Compared with regular air storage (Air), controlled atmosphere (CA; 2% O2 and 5% CO2) decreased weight loss at removal, retarded ripening and, after 28 days of storage, reduced discrete patches on the skin of ripe fruit. However, CA storage also resulted in ripe fruit with more severe shrivel, stem end rot, and vascular browning. For 14 or 21 days at 5.5°C, Air resulted in the best overall quality of ‘Shepard’ fruit. CA was comparatively advantageous after a 28-day storage in improving external quality at ripe. There was considerable variation between both farms in storage effects on fruit ripening and quality. Given the high variability in fruit chilling responses apparently dependent on preharvest factors, further research is warranted to elucidate these results and better evaluate risks under commercial sea freight conditions.

First Report of Mango Stem-end Rot Caused by Pestalotiopsis kenyana in Yunnan Province, China.

Stem End Rot (SER) is a devastating post-harvest disease of mango fruits causing severe losses during storage. In 22 July 2023, 31 out of 50 intact mangoes (cv. Sensation) collected from five orchards in Huaping county (26°37'N 101°15') showed typical symptoms of SER after stored for 9 d in room temperature (24-28℃). Initially, small dark brown to black spots appeared around the fruit peduncle, which rapidly expanded through the pulp tissues. The symptomatic mangoes were surface disinfected by 3% NaClO for 30 s after soaking in 75% alcohol for 3 min, and cleaned by sterile water for 3 times. Tissues were cut from the edge of lesions, dried by sterile filter paper, transferred to PDA and cultured at 28 ℃ for 5 d (Tovar-Pedraza et al., 2020). The single-spore isolation method was used to obtain pure culture. Thirty eight isolates presented four distinct kind of morphology on PDA medium. Among them, 11 isolates with same morphology were significantly distinct from common pathogens of SER. The colonies were white and pale yellow on reverse side. Mycelia grew fast and reached the edge of 90 mm Petri dish after cultured for 5d. Pycnidia were black and scattered on the mycelial mats after 15-20 d. Conidia were fusoid, straight to slightly curved, four septa, and brown. Pigmented median cells doliiform, 14.97 - 18.62(16.11 ±0.89)×5.61- 7.28 (6.61±0.51) μm. Apical cell hyaline, subcylindrical; 1-3 tubular transparent apical appendages 12.27 - 16.68 (13.65±3.78)×1.14 - 1.99 (1.59±0.36) μm. Basal cell conical with a truncate base, hyaline, and 1-2 tubulose basal appendages with 2.85 - 7.97 (5.18±1.88)×0.99 - 1.85 (1.38±0.29) μm (n=50). These fungi were described as Pestalotiopsis kenyana. based on morphological characters (Maharachchikumbura et al., 2014) which were different from isolates characterized as other common SER pathogens (Botryosphaeria, Neofusicoccum). Based on morphology, HPSX-4 was selected for further identification. ITS region, tef1-α, β-tub of HPSX-4 were amplified and sequenced (Xun et al., 2023). The sequences were deposited in GenBank (ITS:OR889126, tef1-α:OR913431, β-tub: OR913432). The ITS, tef1-α, β-tub sequence of HPSX-4 showed 100% (525/525)，99.59% (241/242), and 100% (742/742) identity to the P. kenyana CBS442.67 sequences (ITS: NR147549，tef1-α: KM199502, β-tub: KM199395), respectively. HPSX-4 clustered with P. kenyana CBS 442.67 (type strain) based on maximum likelihood method by MEGA 7.0.21(Minh et al., 2013). Pathogenicity test was performed on 12 healthy mangoes (cv. Golek) by placing mycelial plugs around the peduncle and the middle of the fruit by pin-prick method according to Feng et al.(2023). Sterile PDA were used as control (three mangoes). Every inoculated fruit was incubated at 28°C, 95% ± 3% humidity with three replicates for each treatment. The experiment was repeated three times. Typical symptoms of SER were observed. There were no symptoms in the control group. The strain was reisolated and identified as P. kenyana with the method mentioned above which fulfilled Koch's postulates. This is the first report of P. kenyana causing SER disease on Mangifera indica L.. This study expands our understanding of the pathogen range of mango SER which conducive to prevent and control the SER caused by P. kenyana.

Volatile profiling of papaya fruit as an early detection tool for stem-end rot disease caused by Lasiodiplodia theobromae

Volatile profiling of papaya fruit as an early detection tool for stem-end rot disease caused by <i>Lasiodiplodia theobromae</i>

Lasiodiplodia iraniensis and Diaporthe spp. Are Associated with Twig Dieback and Fruit Stem-End Rot of Sweet Orange, Citrus sinensis, in Florida

Florida ranks among the most important citrus growing regions in the USA. The present study investigates the occurrence, diversity, and pathogenicity of fungal species associated with symptomatic sweet orange (Citrus sinensis) cv. Valencia plants and fruit. The survey was conducted on twigs and fruit collected in Southwest Florida during 2022. Based on morphological and molecular characteristics, the identified isolates belonged to the species Lasiodiplodia iraniensis, Diaporthe pseudomangiferae, and Diaporthe ueckerae. The pathogenicity of representative isolates was evaluated on citrus fruit and plants. Lasiodiplodia iraniensis was the most virulent on fruit and plants, followed by Diaporthe pseudomangiferae. Diaporthe ueckerae had the lowest virulence on fruit, and it was not pathogenic to plants. In vitro tests were performed to assess the effect of temperature on mycelial radial growth. The optimum temperature of growth ranged from 26.0 to 28.4 °C for all the evaluated species, and L. iraniensis showed the fastest mycelial growth. This study represents the first report of L. iraniensis as a causal agent of tree dieback and fruit stem-end rot on C. sinensis worldwide. Moreover, D. pseudomangiferae and D. ueckerae are reported here for the first time in association with citrus diseases worldwide.

Identity, Pathogenicity, and Genetic Diversity of Lasiodiplodia Species Associated with Stem-End Rot of Avocado in China.

Stem-end rot (SER) causes brown necrotic lesions in the pulp near the base of the fruit pedicel and is one of the most devastating postharvest diseases of avocados in all avocado-growing regions of the world. China's avocado industry is growing very rapidly, and the planting area is expanding, but little is known about the pathogens and genetic diversity of avocado SER. To determine the causal agents of SER, avocado fruits were sampled from the main avocado-producing areas in China during 2020 and 2021. Fungal isolates were obtained from SER symptomatic avocado fruits and identified by morphology combined with phylogenetic analysis of internal transcribed spacer (ITS), translation elongation factor 1-α (EF1-α), and β-tubulin (TUB2) gene sequences. All 101 isolates belonged to Lasiodiplodia spp.; four Lasiodiplodia species were identified, namely, L. pseudotheobromae (59.41%), L. theobromae (24.75%), L. mahajangana (7.92%), and L. euphorbiaceicola (1.98%); and six others are classified as Lasiodiplodia sp. (5.94%). There were only slight morphological differences in colonies and conidia of these four species of Lasiodiplodia. The pathogenicity tests showed symptoms of SER, and 92.08% of the isolates exhibited a high level of virulence on avocado (disease index >70), related to the disease severity on avocado fruits. All tested isolates grew well under the temperature ranging from 23 to 33°C. There was a significant difference in mycelial growth between the four species of Lasiodiplodia after treatment with high or low temperatures. The growth of L. pseudotheobromae was the fastest at 13 to 18°C but was the lowest at 38°C (P < 0.05). The red pigment could be produced by all tested isolates after culturing for 7 days at 38°C. The mycelial growth rate was the fastest on PDA medium, and the slowest on the OMA medium but promoted spore formation (P < 0.05). In addition, the genetic diversity of pathogenic Lasiodiplodia species associated with SER collected from avocado, mango, guava, and soursop fruits was determined. A total of 74 isolates were clustered into four main ISSR groups by the unweighted pair-group method with arithmetic mean analysis, and the classification of this group was related to the host. Extensive diversity was detected in the Lasiodiplodia populations. The diverse geographical origins and host species significantly influenced the population differentiation, and most of the genetic variation occurred within populations (P < 0.001). This is the first study to identify the major pathogens of avocado SER in China, survey their occurrence and pathogenicity, and include a comparative analysis of genetic diversity with Lasiodiplodia spp. causing SER on other fruit hosts. Collectively, the Lasiodiplodia species complex affecting avocado showed high pathogenicity and diversity, while L. pseudotheobromae was the most frequently isolated species in China. The results of this study provide insights into the aspects of the epidemic of SER disease caused by Lasiodiplodia species, which will help in developing strategies for the management and control of SER in avocado.

Mitigating postharvest quantitative and qualitative losses in mango fruits through the application of biocontrol agents: An in-vivo and in-vitro assessment

Mango is a commercial fruit crop of India that suffers huge postharvest losses every year. The application of biocontrol agents (BCAs) bears a vast potential for managing the same, which is yet to be exploited to its fullest extent. Hence, studies were conducted for BCAs application of Debaryomyces hansenii, Bacillus subtilis and Pseudomonas fluorescens strains on mango fruit under in-vitro, in-vivo conditions to know the efficacy of these BCAs on the postharvest pathogen, shelf life and quality retention of mango fruit. The ‘poisoned food technique’ was attempted for in-vitro studies. For the in-vivo studies, fruit of the commercial cultivar ‘Amrapali’ were un-inoculated and pre-inoculated with major postharvest pathogens (anthracnose: Colletotrichum gloeosporioides and stem-end rot: Botryodiplodia theobromae) were treated with BCA, followed by ambient storage at (24 ± 4 °C, 75 ± 5 % RH). From the results, it has been observed that under in vitro studies, BCA Debaryomyces hansenii (Strain: KP006) and Bacillus subtilis (Strain: BJ0011) at the treatment level 108 CFU mL−1 while, the Pseudomonas fluorescens at 109 CFU mL−1 (Strain: BE0001) were significantly effective for pathogen inhibition. However, under the in vivo studies, the BCA Debaryomyces hansenii (Strain: KP006) at 108 CFU mL−1 treatment level was found to significantly reduce the pathogen's decay incidence while positively influencing the shelf life and biochemical (quality) attributes. This treatment increased the storage life of mango fruit by more than three days over control fruit. Therefore, BCA Debaryomyces hansenii (Strain: KP006) at 108 CFU mL−1 can be used to control the postharvest pathological loss of mango fruit without affecting its internal quality.

Diversity of the fungal community on mango associated with stem end rot and anthracnose diseases based on amplicon targeted metagenomics

This study aimed to comprehend the diversity of the fungal community on Chokanan mango, a premium mango variety from Thailand which is widely cultivated in Indonesia, associated with stem end rot and anthracnose disease using high-throughput amplicon targeted metagenomics analysis by next-generation sequencing (NGS). Samples used in this study were freshly harvested healthy fruits at the age of 15-weeks (H15.ITS), healthy fruits after 2 weeks incubation (H17.ITS), 17-week old fruits (S17.ITS) with stem end rot symptoms, and 17-week old fruits (A17.ITS) with anthracnose symptoms. Results showed that the Basidiomycota phylum was dominant in the healthy fruits, while the Ascomycota phylum was found dominantly in sick fruits. Based on OTUs alignment of sequenced data, some species found to be dominantly associated with stem end rot disease in this study were Lasiodiplodia theobromae, Neofusicoccum cordaticola and N. mangiferae. Dominant species which were associated with mango anthracnose disease were Colletotrichum gloeosporioides, Botryosphaeria corticis, Volutella sp., and Pseudofusicoccum violacearum. These fungal genera were not found to be dominant in healthy fruits at the same age indicating that specific genera contributed to developing postharvest diseases on mango differently. The findings confirmed that the fungal community associated with stem end rot and anthracnose disease on mango was unique, and specific species contributed in particular disease development. Since mango is an important global commodity, these research findings will contribute significantly to global biosecurity.

Machine learning-based metabolomics analysis reveals the early biomarkers for Diplodia stem-end rot in grapefruit caused by Lasiodiplodia theobromae

Lasiodiplodia theobromae is a key postharvest pathogen causing Diplodia stem-end rot (SER) disease in grapefruit. While the disease remains quiescent before harvest, its symptoms become evident during the postharvest period. This dormant behavior poses a challenge in managing fruits after harvest. To effectively detect asymptomatic fruit and detect SER disease at an early stage, it's crucial to identify early-stage biomarkers that can serve as disease indicators. In this study, a machine learning-based metabolomics analysis was utilized to identify characteristic metabolites and to elucidate the underlying biosynthetic mechanisms. Six machine learning algorithms were used, and Gradient boosting (GBT) exhibited the highest accuracy identifying early biomarkers such as shikimate, succinic acid, quinic acid, coumaric acid, tyrosine, phenylalanine, and tryptophan. Moreover, dynamic time warping (DTW), was used to investigate the trend of metabolites across timepoints. Our result revealed that the metabolic analysis enabled differentiating infected from non-infected fruits within 1 day, even though symptoms appeared after 7 days of inoculation. Pathway enrichment analysis indicated that three pathways (biosynthesis of plant hormones, phenylpropanoid biosynthesis, and glutamate metabolism) were strongly involved in the defense mechanism. Metabolite mapping analysis showed the behavior of each compound against the pathogen. With these novel strategies, our findings suggest a prediction model for identifying asymptomatic grapefruit affected by Diplodia SER.

Postharvest diseases of mangoes in Fiji

ABSTRACT Despite considerable research globally on postharvest diseases of mango, virtually no work has been done to determine the occurrence of these diseases and their causal agents in Fiji. This study is the first major field and market survey of postharvest diseases of mango in Fiji. For the field survey, fruits from five local mango cultivars were harvested at each of five locations. Fruits from five imported cultivars were also harvested from one location in Nadi. For the market survey, vendors were selected at five municipal markets for fruit collection, along with ten roadside stalls. For field and market surveys, fruits were incubated at 23°C and assessed for postharvest disease (incidence and severity of body rots and stem end rots) when ripe. Isolations were made from disease lesions and fungal cultures were identified using multilocus sequence typing. High incidences of body and stem end rots were recorded across all surveys. In the field survey of local cultivars, ‘Salusalu’ fruits were found to have the lowest severity of body rot and stem end rot on average, while for imported cultivars, ‘Nam Doc Mai’ had the lowest average severity of these diseases. The market survey showed that ‘Salusalu’ had a lower incidence of anthracnose on the body of fruit compared to all other cultivars, although it did have a surprisingly high incidence of stem end rot at some localities. Fungal isolates from anthracnose lesions in the field and market surveys were identified as Colletotrichum asianum, C. simmondsii and C. fructicola. C. asianum was the predominant species associated with anthracnose symptoms, accounting for 97% of isolations. Lasiodiplodia theobromae and Neofusicoccum parvum were the predominant species found in association with mango stem end rot symptoms. Other species isolated from mango stem end rot in lesser numbers included L. brasiliensis, N. umdonicola and N. kwambonambiense. All of these fungi represent new reports for Fiji.

An overview on major diseases, damage pattern, and management of Mango (Mangifera indica L.) fruit and tree

Mango is one of the most important tropical fruits grown throughout the world particularly in Asia with high economic and nutritional value. However, several diseases and pests cause significant damages to different parts of mango trees and mango fruits, resulting in severe economic losses to farmers and the agricultural sector. Some of the major mango diseases are anthracnose, powdery mildew, die back, and mango malformation. These diseases affect various parts of mango tree, including leaves, flowers, fruits, stems, and roots. The causative organisms of mango diseases include fungi, bacteria, and viruses. Of these, the majority is caused by fungi. Some of the common fungal diseases of mango include anthracnose, powdery mildew, stem-end rot, and sooty mould. Therefore, it is a pressing need to accurately identify the causative organisms for determination of the best management strategy for an effective control. To manage mango diseases, farmers and researchers use several approaches, including cultural practices, chemical control, biological control, and genetic resistance. In this article, the major mango diseases, damage patterns, and management strategies for sustainable mango production has been critically reviewed and presented.

Important Diseases of Papaya in Andhra Pradesh

Papaya (Carica papaya L.) stands as one of the most delectable fruits globally, flourishing primarily in tropical and sub-tropical climates. Despite its widespread cultivation, the potential yield and marketability of papaya are continually threatened by various diseases. The susceptibility of papaya to an array of fungal, viral, and bacterial infections, such as Phytophthora root rot, anthracnose, powdery mildew, stem end rot, black spot disease, papaya ring spot, and papaya leaf curl, has impeded commercial production on a global scale. Among these diseases, Papaya ring spot virus, Phytophthora foot rot and anthracnose, incited by Colletotrichum gloeosporioides Penz. emerging as the most important problems those directly affecting the economic yield. This article delves into a comprehensive exploration of the symptoms, epidemiology, and control measures associated with the predominant papaya diseases prevalent in India. Furthermore, it elucidates effective strategies and control measures that can be employed to mitigate the impact of these diseases, offering valuable insights to farmers, researchers, and stakeholders involved in papaya cultivation.

Avocado (Persea americana cv. ‘Hass’) Fruit Mineral Composition at Canopy Level towards Sustainable Quality

Sustaining avocado fruit quality is crucial to maintain customer satisfaction and confidence. Among fruit qualities, mineral nutrient composition is an important contributor to postharvest robustness. Towards better understanding and addressing variability within the plant canopy, ‘Hass’ fruit from across seven orchard blocks were individually characterised. From five representative trees in each block, five fruit were harvested (one from each of five positions: top (sun-exposed), bottom (shaded), middle (shaded), East (sun-exposed), and West (sun-exposed)). Fruit dry matter was significantly higher (p ≤ 0.001) in fruit from the top, East, and West sun-exposed positions. No significant (p &gt; 0.05) effect of position was discerned for fruit weight at harvest or for either stem end rot (SER) or body rot (BR) incidence at eating soft. Shaded fruit had significantly higher (p ≤ 0.05) [N], [K], [Mg], N:Ca, K:Ca, and K + Mg:Ca in their flesh. Significant negative linear correlations (p ≤ 0.001) were obtained between fruit DM and flesh [N] (r = −0.75), [K] (r = −0.67), and N:Ca (r = −0.57). SER and BR incidence were significantly positively correlated (p ≤ 0.01) with flesh and skin mineral ratios of N:Ca, K:Ca, Mg:Ca, and K + Mg:Ca. Skin and flesh [Ca] were significantly negatively correlated with SER (r = −0.51, p ≤ 0.01) and BR (r = −0.74, p ≤ 0.001) incidences. Soil cation (Ca, Mg, K) availability (%base saturation of cation exchange capacity (CEC)) was not (p &gt; 0.05) correlated with skin or flesh mineral concentrations or ratios. Considered collectively, results suggest that selective harvest of sun-exposed fruit with inherently lower mineral nutrient ratios yields relatively robust fruit. Such fruit lots should better tolerate the rigours of harvest and postharvest treatment and handling. In this context, they should better maintain quality upon passage through long, in terms of accumulated time-temperature increments, export supply chains. In contrast, shaded fruit could be directed into shorter domestic supply chains. As a harvest strategy, segregating fruit lots from harvest could underpin the quality offered to consumers at the end of ‘short’ and ‘long’ supply chains.

Fungi Associated with Post-harvest Losses of Multani Mango

The Multani mango, renowned for its exceptional taste and aromatic profile, is a cultivar thriving in the fertile soils of Multan, Pakistan, representing a cherished tropical delicacy. Despite its esteemed status in the region's mango-producing legacy, a formidable challenge arises from its limited shelf life. Fungal pathogens associated with the mango curtail its shelf life and detrimentally impact fruit yield and quality. This study aimed to isolate and identify fungal pathogens linked to Mango anthracnose, stem end rot, side rot, and fruit fly attack symptoms. Ten mango fruits exhibiting symptoms were systematically sampled from three distinct markets in Multan, totalling 30 fruits for each disease symptom category. Isolation and identification outcomes revealed that in mangoes displaying anthracnose symptoms, Colletotrichum gloeosporoides was present in 100% of fruit samples, followed by Aspergillus fumigatus (72.72%). For mango fruits with stem end rot, Botryodiplodia theobromae was identified in 90.90% of samples, followed by Colletotrichum gloeosporoides (70%). Fruits exhibiting symptoms of fruit fly attack and side rot contained Aspergillus flavus in 99.90% and 88.81% of samples, respectively. These findings underscore the pivotal role of fungal pathogens in the Multani mango's shelf-life predicament, necessitating strategic interventions in cultivation and post-harvest handling. The identification of specific pathogens provides valuable insights for targeted management practices aimed at preserving the quality and extending the shelf life of this esteemed mango cultivar.

Fusariumoxysporum f. sp. tuberosi causing wilt disease on potato plants in Iraq.

Fusarium species are causing postharvest stem-end rot and dry rot throughout the potato growing season. At the current study, the causative wilt agent was identified in potatoes which were grown in Nineveh province, northern of Iraq, in autumn season of 2020. The disease manifests through symptoms like partial yellowing between the veins on the leaves of potatoes or overall wilting of the plant. Fungal species isolated from the infected potato plants were subsequently grown on potato dextrose agar, resulting in developing aerial mycelia appeared as white along violet-dark pigmentation. The fungus was identified from the phenotypic diagnosis as Fusariumoxysporum, and the pathogen was confirmed by Koch's hypotheses as well as affirmed through molecular test identification, where methodology proved it. Molecular based pathogen identification was carried out through an application of conserved DNA ribosomal region of internal transcribed spacer (ITS). Moreover, the complete verified ITS sequences are homologous to theisolates of Fusariumoxysporum in GenBank database having 99% similarity. At Gen-Bank, isolated one in Iraq was given #: MH859948.1 being an Accession. The best to the available knowledge, such is Fusariumoxysporum f. sp. tuberosi 1st molecular Potato record in Iraq

Assessment of mycotic diseases attack on indigenous old mango plants grown in Vatala park, Tehsil Bernala District Bhimber, Azad Kashmir

The current research work was explored fungal attacks on different parts of mango (Mangifera indica L.) trees naturally grown in Tehsil Bernala, District Bhimber Azad Kashmir. Different symptoms were observed, like stem end rot, anthracnose dieback, and blossom blight, during field survey. The identification of mycotic diseases was confirmed by further direct microscopic examination of affected parts of mango trees. Then fungal diseases of mango trees were isolated by microculture and purification methods on different media. Some other parameters, like disease incidence and disease severity rates, were measured against each identified disease through a pathogenicity test under in vitro conditions. It was indicated that maximum disease incidence (DI) was 33.73% measured against dieback disease. The lowest incidence (30.98%) was measured against blossom blight disease. It was also found that disease severity (DS) was rated from 0 to 4 on a visual rating scale.

Etiology and management of citrus Melanose disease in Pakistan: A review

Diaporthe species are important pathogens of many hosts, including economically important crops. They cause severe melanose disease, stem-end rot of fruits, and gummosis of perennial plants worldwide. Among the Diaporthe species, Diaporthe citri is responsible for causing melanose disease. Melanose disease harms fruit, leaves, twigs, branches, and in certain cases, the main stem of trees of any age. The melanose infection can affect practically all citrus cultivars. Citrus melanose disease is a persistent and incurable disease leading to a massive loss of output in the citrus industry. Due to the lack of resistant cultivars, the failure of chemical treatments, and the dangers to environmental health, large-scale research is being conducted to develop a long-term remedy. Recently, biological control agents (BCAs) have been used as an alternative to fungicides to manage citrus melanose disease. In this review, we highlighted some significant aspects of melanose disease (Diaporthe citri) in citrus, such as its history, morphology, disease cycle, pathogenicity symptoms, and impact on the economy of the citrus industry. The current literature assists the researchers in averting melanose disease in citrus, developing genetically resistant cultivars, and ecofriendly management against Diaporthe citri. Keywords: Diaporthe citri, Melanose, Symptoms, Transmission, Disease cycle, Control management

Application of Thymol Vapors to Control Postharvest Decay Caused by Penicillium digitatum and Lasiodiplodia theobromae in Grapefruit.

Two of the major postharvest diseases impacting grapefruit shelf life and marketability in the state of Florida (USA) are stem-end rot (SER) caused by Lasiodiplodia theobromae and green mold (GM) caused by Penicillium digitatum. Here, we investigated the in vitro and in vivo efficacy of vapors of thymol, a natural compound found in the essential oil of various plants and the primary constituent of thyme (Thymus vulgaris) oil, as a potential solution for the management of GM and SER. Thymol vapors at concentrations lower than 10 mg L-1 significantly inhibited the mycelial growth of both pathogens, causing severe ultrastructural damage to P. digitatum conidia. In in vivo trials, the incidence and lesion area of GM and SER on inoculated grapefruit were significantly reduced after a 5 d exposure to 50 mg L-1 thymol vapors. In addition, the in vitro and in vivo sporulation of P. digitatum was suppressed by thymol. When applied in its vapor phase, thymol had no negative effect on the fruit, neither introducing perceivable off-flavor nor causing additional weight loss. Our findings support the pursuit of further studies on the use of thymol, recognized as safe for human health and the environment, as a promising strategy for grapefruit postharvest disease management.

Using Trichoderma asperellum to Antagonize Lasiodiplodia theobromae Causing Stem-End Rot Disease on Pomelo (Citrus maxima).

Stem-end rot disease has been causing damage to the production of pomelos in Vietnam. The cur-rent study aimed to (i) isolate fungal pathogens causing pomelo stem-end rot disease (PSERD) and (ii) discover Trichoderma spp. that had an antagonistic ability against pathogens under in vitro conditions. Fungi causing PSERD were isolated from pomelo fruits with symptoms of stem-end rot disease and collected from pomelo farms in Ben Tre province, Vietnam. Moreover, 50 fungal strains of Trichoderma spp. also originated from soils of these pomelo farms in Ben Tre province and were dual-tested with the fungal pathogen on the PDA medium. The results demonstrated that 11 pathogenic fungi causing PSERD were isolated from the fruit and showed mycelial growth of roughly 5.33-8.77 cm diameter at 72 h after inoculation. The two fungi that exhibited the fast-est growth, namely, S-P06 and S-P07, were selected. ITS sequencing of the S-P06 and S-P07 fungi resulted in Lasiodiplodia theobromae. All the 50 Trichoderma spp. strains were allowed to antago-nize against the S-P06 and S-P07 strains under in vitro conditions. The greatest antagonistic effi-ciency was found in Trichoderma spp. T-SP19 at 85.4-86.2% and T-SP32 at 84.7-85.4%. The two antagonists were identified as Trichoderma asperellum T-SP19 and T-SP32. The selected strains of Trichoderma asperellum were potent as a biological control for fruit plants.