Two species of Mangifera are found in Sri Lanka, the cultivated Mangifera indica L. and the endemic M. zeylanica (Blume) Hook.f. Et-amba (S). Mangifera indica is a climacteric fruit, susceptible to ...infection by many fungal pathogens, causing postharvest diseases at ripe stage. Among them, Colletotrichum spp. and Lasiodiplodia theobromae that cause anthracnose and stem-end rot disease respectively, are considered the most destructive postharvest pathogens in ripe mangoes. Harvested fruit of M. zeylanica also showed a climacteric pattern of respiration and the pulp was sweet to taste, with acceptable TSS value for mango fruit. The present study investigated the resistance or susceptibility of the fruit of endemic M. zeylanica to these two pathogens. Artificial inoculation of fruits with C. gloeosporioides and L. theobromae separately, produced anthracnose as well as stem-end rot symptoms respectively, showing that M. zeylanica fruits are susceptible to the pathogens. However, considering the pattern and the extent of disease development, M. zeylanica fruits can be considered moderately resistant to both pathogens. Alternaria sp., Pestalotiopsis sp., Lasiodiplodia theobromae, Curvularia sp. and Neofusicoccum sp. were frequently isolated from the pedicel and the stem-end region of healthy fruits of M. zeylanica at harvesting maturity. However, Colletotrichum species could not be isolated from either the pedicel or the stem-end region of M. zeylanica. TLC-Cladosporium bioassay of peel extract of the unripe M. zeylanica fruit resulted in a large inhibition zone at Rf 0.00 which corresponded with antifungal gallotannins contributing to the constitutive defences of M. indica fruit against invading pathogens.
Stem-end rot (SER) is one of the most destructive postharvest diseases affecting some tropical and sub-tropical fruits. The disease is caused by several fungal pathogens, including Botryosphaeriaceae ...species. In mango, Dothiorella dominicana, D. mangiferae, Lasiodiplodia theobromae, Phomopsis mangiferae, Cytosphaera mangiferae, Pestalotiopsis sp. endophytically colonize the inflorescence in the orchard or field. Fungi may occur endophytically in the stem tissue of the trees prior to inflorescence emergence. During the endophytic stage, the fungi colonize the phloem and xylem at stem-end and, after fruit ripening, some fungi become necrotrophic and colonize the fruit pulp causing SER. The SER pathogens in other fruit species, including ripe avocado or papaya, are not known to undergo an endophytic phase. Stem-end rot is a disease that is difficult to control. Preharvest cultural practices and selection of resistant varieties are beneficial to reduce field infections. Studies have shown that numerous control options, involving cultural, chemical (fungicides, essential oils) and biological approaches, are available to manage SER through either direct inhibition of fungi or induction of host defenses. These may be used individually or integrated manner. The most common and effective practice for controlling the SER is pre- and postharvest application of synthetic fungicides. With the new tools that are currently available, and expected to emerge, there is a possibility of a better understanding the host–pathogen or host-microbiota interactions within the stem-end region, leading to newer technologies as alternatives to toxic synthetic fungicides for the management of SER in fruits.
The study investigated the possible role of the three classes of constitutive antifungal substances in mangoes in the differential cultivar resistance to anthracnose and stem-end rot (SER). Fruits of ...eleven mango cultivars were screened for anthracnose and SER development during ripening. Basal level of antifungal activity due to constitutive gallotannins, resorcinols and chitinase in the fruit peel/latex was determined in six of these cultivars. The results showed a clear variability in the resistance of fruits to anthracnose and SER among cultivars. The cultivars, ‘
Gira
’ and ‘
Karutha Colomban
’, were among the most resistant to anthracnose disease but were susceptible to SER. Gallotannin activity was high in unripe and ripe fruit peel of all except ‘
Willard
’, the cultivar most susceptible to anthracnose but resistant to SER. There was a significant negative correlation between the level of gallotannins in the fruit at ripe stage and anthracnose development among six cultivars tested. ‘
Gira
’ and ‘
Karutha Colomban
’ that are among the most resistant cultivars to anthracnose showed higher levels of total resorcinols in the latex and 5-(12-
cis
-heptadecenyl)resorcinol in the unripe fruit peel. Chitinase activity was highest in ‘
Rata
’ and ‘
Kohu
’ that are resistant to SER and lowest in cultivars ‘
Gira
’ and ‘
Karutha Colomban
’ that are susceptible to SER. The results suggest that mainly the gallotannins and also 5-(12-
cis
-heptadecenyl)resorcinol contribute to the cultivar resistance of mango fruit to anthracnose pathogen,
Colletotrichum gloeosporioides
, while chitinases appear to contribute more to the fruit resistance to the SER pathogen,
Botryodiplodia theobromae
.
Use of biologically safe, essential oil-incorporated fruit coatings to reduce postharvest losses has become an attractive alternative to synthetic fungicides in recent years. Increase in shelf life ...due to reduced water loss and reduced evaporation of essential oils (EO) within the coating are key advantages of incorporating EOs to fruit coatings. The effect of beeswax as a fruit coating with and without essential oil on the postharvest quality and natural disease development of mango (cv. Willard) was evaluated by conducting a laboratory experiment. Pure Beeswax, dissolved either in vegetable oil (1:3 w/v) or petroleum ether (1:4 w/v), served as the coating material. Basil oil at 400 or 600 μL L-1 was incorporated to the different coating material. Fruits with no coating and no essential oil served as controls. Eight replicate fruits were used per treatment and three trials were performed. Treated fruits were arranged in a Completely Randomized Design and kept under ambient conditions. Daily observations were made on natural disease development and weight loss. The Total Soluble Solid content and titrable acidity were measured at eating ripe stage and sensory evaluation by a taste panel was also obtained. Data were analyzed using ANOVA with SPSS software version 20.0 package. Results indicated that basil oil in beeswax significantly reduced physiological weight loss, delayed fruit ripening and also delayed and reduced postharvest disease development.
Anthracnose caused by Colletotrichum sp. and stem-end rot (SER) caused predominantly by Lasiodiplodia sp. are common postharvest diseases affecting papaya in Sri Lanka and are currently managed by ...synthetic chemicals which are hazardous. Use of essential oils (EOs) is considered a non-hazardous alternative. This in vitro study investigated the antifungal potential of selected EOs against anthracnose and SER pathogens isolated from papaya var. ‘Red Lady’.A poisoned food bioassay was carried out to evaluate the antifungal effect of EOs (Cardamom, citronella, orange, mustard and lemon). Colony diameter was taken as a measure of growth. Bioassays consisted of EOs at 500, 750, 1000 μl l-1 with untreated control, three replicates and three separate trials. Cardamom (1000 μl l-1) and citronella (750 μll-1) significantly (P<0.05) inhbited Colletotrichum sp. and Lasiodiplodia sp. from papaya. According to GC-MS, higher percentages of antifungal geraniol, geranyl acetate are present in citronella while a-terpinyl acetate, 1, 8-cineole are present in cardamom oil.
Unripe mangoes contain a network of minute latex canals in its exocarp, outer mesocarp and the pedicel. Latex, when retrieved, separates into an upper oily layer containing antifungal resorcinols and ...a lower aqueous layer with chitinase activity. Latex disappears in coincidence with ripening and decline of fruit resistance to fungal pathogens. The present study investigated if retention of latex at harvest enhances fruit resistance and reduces anthracnose and the stem-end rot (SER) development during ripening. Latex was retained by harvesting fruit with a portion (approximately 1 cm) of pedicel while in the controls, latex was drained off by removing the pedicel. Anthracnose and SER development from natural infections or following artificial inoculation was assessed at ripe stage. The results showed a significant reduction in the incidence and severity of anthracnose in the cultivar ‘Willard’ susceptible to anthracnose when latex was retained at harvest. There was delayed SER development when latex was retained in the susceptible cultivar ‘Karutha Colomban’. A negative trend was observed between the pedicel length and anthracnose or SER level in cultivars susceptible to the two respective diseases. The fruit peel in which latex was retained had greater chitinase activity. The reduction of anthracnose and SER could be due to the greater resorcinols and chitinase activity respectively in latex-retained fruit. The results indicate a direct involvement of latex in fruit resistance and the possibility of its manipulation to protect ripe fruit from fungal rotting.
Purpose: Stem-end rot (SER) is a major disease of mango that causes serious postharvest losses. Application of fungicides is environmentally unsound and is being practiced currently in its control. ...This study was conducted to develop essential oil treatment systems as eco-friendly strategies to control SER of Karthakolomban mango and to determine the pathogenicity of several SER associated fungi.Research Method: Pathogenicity of four fungal isolates in SER was assessed by inoculating them on Karthakolomban mango fruits. Karthakolomban mango fruits were subjected to spray and fumigation treatments using four essential oils and their pathological, physicochemical and sensory properties were evaluated after a 8-day storage at 12 – 14 ºC.Findings: Lasiodiplodia theobromae, Pestalotiopsis sp., Phomopsis sp. and Xylaria feejeensis were the major SER pathogens of mango. X. feejeensis was identified as a SER pathogen for the first time in Sri Lanka. Spray and fumigation treatments conducted using basil, clove, cinnamon leaf and cinnamon bark oils effectively controlled SER of Karthakolomban mango stored at 12 – 14 ºC for 8 days. Mango sprayed with 1.6 µL/mL cinnamon bark oil has displayed no SER after induced ripening. None of the treatments caused drastic alterations in physicochemical and sensory properties of mango.Research Limitations: Storage period of mango was restricted to 8 days due to the initiation of natural ripening which was the major limitation to achieving a further enhanced shelf life.Originality/value: The treatment strategies developed by this research could be commercialized as bio-safe SER control strategies in reducing postharvest losses of mango in the local and international trade.
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