Symptoms and the Associated Fungi of Postharvest Diseases on Non-Chemical Bananas Imported from the Philippines

Transcription

1 Jpn. J. Trop. Agr. 44(2) : 87-93, 2000 Symptoms and the Associated Fungi of Postharvest Diseases on Non-Chemical Bananas Imported from the Philippines Dionisio G. ALUINDIA, Takao KOBAYASHI*, Yukio YAGUCHI*2 and Keiko T. NATSUAKI* Department of International Agricultural Development, Graduate School of Agriculture *Faculty of International Agriculture and Food Studies *2 Faculty of Regional Environment Science, Tokyo University of Agriculture Sakuragaoka, Setagaya-ku, Tokyo , Japan Abstract Recently, the preference of Japanese consumers for healthy agricultural products has led to the increase in importation of banana grown without chemicals (hereafter referred to as gnon-chemical bananas h) mainly from the Philippines. Due to postharvest diseases, however, the marketability of the non-chemical bananas is affected, causing significant losses to importers and farmers. Hence, disease symptoms and the associated fungi of the non-chemical bananas from the Philippines were investigated, identified, and quantified in Japan from December 1997 to July The objective of the study was to provide benchmark information for further research to improve the quality of non-chemical bananas from the Philippines. Disease symptoms included crown rot, anthracnose, freckle, finger stalk rot, finger rot and finger end rot with an incidence of 86, 83, 71, 56, 11 and 3%, respectively. Twenty-five fungal genera were associated with these disease symptoms. The dominant fungi were Fusarium 49%, followed by Colletotrichum and Penicillium (8%), Verticillium (7%), Cylindrocarpon (5%), Cladosporium and Glomerella (4%), Thielaviopsis, Pestalotiopsis, Lasiodiplodia, Phoma (3%), Phomopsis and Aspergillus (1%). The frequency of occurrence of other genera was less than 1%. Colletotrichum and Glomerella were also isolated from anthracnose while Phyllosticta was observed in freckle. Dominance and population of fungi of the nonchemical bananas were almost the same during the period from December 1997 to July Key words Disease symptoms, Fungi, Non-chemical bananas, Postharvest diseases Introduction Recently, the preference of Japanese consumers for healthy agricultural products has led to the increase in the importation of bananas grown without chemicals (hereafter referred to as gnon-chemical bananas h) mainly from the Philippines. Non-chemical bananas are grown by small farmers in the Philippines without the use of chemicals during production and postharvest activities. About 3,000 tons of non-chemical bananas were imported from the Philippines in 1997 and the demand for the products is rapidly increasing. However, Philippine non-chemical Received Apr. 22, 1999 Accepted Nov. 19, 1999 bananas are associated with problems. Unlike plantation-grown bananas with high quality fruits meeting standard requirements for export markets10), the quality of non-chemical bananas is low. Non-chemical bananas often reach consumers with impaired quality and short shelf life due to postharvest diseases, which affect acceptance by the consumers. Moreover, wastage due to postharvest diseases results in significant losses to importers who avoid to import larger quantity of the products. Considering that Japan is a major outlet for Philippine bananas with a 70% market share8) and the rapidly growing market for non-chemical. bananas, quality improvement of non-chemical banana is very important and would be beneficial to farmers, importers and

2 88 Jpn. J. Trop. Agr. 44 (2) 2000 consumers. Presently, diseases of banana fruits reported in Japan are soft rot, fruit rot, stem end rot, black rot, freckle and anthracnose1,6,7,11,17-19). The lack of chemicals during production and postharvest activities for non-chemical bananas makes them prone to postharvest diseases. While the importation of non-chemical bananas in Japan is relatively new and the record of postharvest diseases, associated fungi and the extent of losses are not available, studies on these aspects are deemed necessary. Furthermore, it is considered that the results from such studies would provide benchmark information for further research to improve the quality of non-chemical bananas from the Philippines. Materials and Methods Disease symptoms of non-chemical bananas from the Philippines were investigated, identified and quantified from December 1997 to July In the Philippines, the rainy season occurs from May to November while the dry season from December to April. Alter Trade Japan (ATJ), a Japanese company importing nonchemical bananas from the Philippines provided the samples. Banana fruits originated from the production areas of Nueva Viscaya and Cavite in the Luzon Island, Ilo-ilo, Bacolod and Tagbilaran in the Visayas Islands. From harvest, it took 10 days to reach Japan, thereafter, 3 days for quarantine, 4 days to remain in warehouses for ripening and 1 day for re-packing, and 1 day for delivery to the consumers. Hence, the period from harvest to delivery covered 19 days. Sample size per trial was 5 kg with 3 `5 hands depending on the finger size. One hand had 8 `13 fingers. Incidence of various disease symptoms was recorded when the samples reached the laboratory. Incidence of postharvest disease symptom was assessed by computing the percent level of infected crowns; fingers with anthracnose; fingers with freckles; infected fingerstalks; infected fingers aside from anthracnose and freckles; infected finger-ends over the total number of samples. For the percentage of crown rot for instance, the formula was:% Crown rot = No. of infected crowns/total no. of 100 crowns ~ Two methods were adopted to identify and quantify the fungi associated with the disease symptoms of non-chemical bananas, i. e. tissue and direct isolation methods. Tissue isolation method was applied at the early stage when the disease symptoms could be clearly distinguished from one another. Five replicates for each disease symptoms were randomly selected from the samples. Tissue piece measuring about 1 `2 cm2 was taken from each replicate of advanced lesions of a particular disease symptom. Tissues were labeled according to disease symptoms. Thereafter, tissues from the same disease symptom were placed in a meshed metal container and under running tap water for 5 minutes, blotted dry on sterilized filter paper and plated together on water agar (WA). Plates were incubated at 25 Ž until substantial fungal growth was noted. Three isolates from each tissue were taken and transferred to Potato Dextrose Agar (PDA) slants. Successive detection of fungi associated with each disease symptom, i, e., after 3, 5, 7, 9 and 10 days was performed by direct isolation method. As in the method described above, fungi were isolated from 5 randomly selected replicates for each disease symptom. Using a sterile needle, 4 isolates were taken from each replicate of a particular disease symptom. Selection of the isolates was based on the mycelial appearance, color and texture; spores and fruiting bodies, originating from fungi in a particular disease symptom. Isolates were grown on PDA plates at 25 Ž until substantial fungal growth enabled the transfer to PDA slants. Thereafter, fruits were bagged in clear polyethylene plastic bags and sprayed with sterile distilled water to induce further development of disease symptoms and fungal growth. Bagged fruits were stored at 25 Ž. Fungi were identified up to the genus level. Results Disease symptoms of non-chemical bananas consisted of crown rot, anthracnose, freckle, finger stalk rot, finger rot and finger end rot (Fig. 1). White, gray, dark or pink mycelia were formed on the surface of the cut crown. Infected tissues turned black and reached the finger stalks, which fell when handled. Finger-stalk rot occurred directly, in the absence of crown rot, when the stalks were injured through flexing of the fingers. Finger rot and finger end rot usually began at the end of the finger or at a

3 ALVINDLA et al.: Symptoms and the k. ociated Fungi on Non-Chemical Fig. 1. Symptoms associated with postharvest Bananas diseases of non-chemical bananas imported from the Philippines: 1a) crown rot, 1b) finger stalk rot, 1c) anthracnose; 2) finger rot; 3) finger end rot and 4) freckle. 89

4 90 Jpn. J. Trop. Agr. 44 (2) 2000 wound site. Finger rot was characterized by the presence of soft, watery, black and wrinkled fingers encrusted with white, gray and dark mycelia or pycnidia. Numerous small dark circular spots that enlarged, coalesced and became sunken characterized anthracnose. When the infection was severe, the whole fruit was covered with dark blemishes on the surface with bright salmon colored pustules. In freckle, minute black pycnidia projected through the crown, finger stalks and fingers resulting in roughness when touched. In non-chemical bananas from the Philippines during the period December 1997 to July 1998, crown rot, anthracnose, freckle, finger stalk rot, finger rot and finger end rot were recorded at the rates of 86, 83, 71, 57, 11, and 3%, respectively (Table 1). Incidence of anthracnose and freckle was higher in bananas harvested during the dry season (December to April) than during the rainy season (May to July). Frequency of isolation, frequency of occurrence and percent of dominance of fungi associated with the disease symptoms of non-chemical bananas are presented in Table 2. Twenty-five fungal genera were identified associated with the disease symptoms of non-chemical bananas with the following frequency of occurrence: Fusarium was dominant with 49%, followed by Colletotrichum and Penicillium (8%), Verticillium (7%), Cylindrocarpon (5%), Cladosporium and Glomerella (4%), Thielaviopsis, Pestalotiopsis, Lasiodiplodia and Phoma (3%), Phomopsis and Aspergillus (1%). Other genera occurred at a frequency less than 1%. Moreover, Colletotrichum and Glomerella were particularly associated with anthracnose. Through microscopic examination, Phyllosticta was found to be the fungus associated with freckle. Isolation of Phyllosticta in artificial culture media, however, was not successful. Prevalence of Fusarium was recorded in crown rot, finger stalk rot, finger rot and finger end rot. Colletotrichum and Glomerella dominated anthracnose lesions while Phyllosticta was the only fungus observed in freckle. Eleven fungal genera were isolated from the disease symptoms of non-chemical bananas when the samples reached the laboratory, including Fusarium, Colletotrichum, Penicillium, Verticillium, Cylindrocarpon, Cladosporium, Glomerella, Thielaviopsis, Pestalotiopsis and Phoma. Three days later, Aspergillus was detected, Lasiodiplodia 5 days later while Phomopsis was isolated after one week. Fungal population of the disease symptoms of non-chemical bananas isolated from the rainy to dry seasons in the Philippines, and from the winter to summer seasons in Japan are listed in Table 3. Almost the same fungal populations were recorded in the disease symptoms of nonchemical bananas regardless of the season. Table 1. Incidence (%) of disease symptoms of non-chemical bananas. CR: Crown rot, Anth: Anthracnose, FSR: Finger stalk rot, FR: Finger rot; FER: Finger end rot.

5 ALVINDIA et al.: Symptoms and the Associated Fungi on Non-Chemical Bananas 91 Table 2. Frequency of isolation, occurrence and % of dominance of fungi associated with disease symptoms of non-chemical bananas. CR: Crown rot, Anth: Anthracnose, Frec: Freckle, FSR: Finger-stalk rot, FR: Finger rot, FER: Finger-end rot. *; Frequency of occurrence = No. of isolates/total number of isolates 100 ~ **; % Dominance = No. of a particular genus isolated from a particular disease symptom/total no. of isolates 100 from a particular disease symptom ~ ND***; Under the light microscope, Phyllosticta was the only genus associated with freckle. Isolation in agar media was not successful. ****; Occurrence in banana fruits is new in Japan1,6,7,12,17-19) Discussion Disease symptoms on non-chemical bananas from the Philippines were crown rot, anthracnose, freckle, finger stalk rot, finger rot and finger end rot. Disease symptoms observed in non-chemical bananas were similar with those symptoms described by QUIMIO13), SNOWDON16), and WARDLAW21). The high incidence of disease symptoms such as crown rot, anthracnose, freckle and finger stalk rot can be considered to be as serious problem in non-chemical bananas. Among them, crown rot, anthracnose and freckle appeared to be persistent, occurring with a high incidence in almost every sample analyzed. Time of sampling did not appear to affect the incidence of crown rot, finger stalk rot, finger rot and finger end rot while a lower incidence of anthracnose and freckle was observed from May to July The following 19 fungal genera were newly isolated from bananas in Japan1,6,7,12,17-19), i. e. Fusarium, Phyllosticta, Verticillium, Cylindrocarpon, Cladosporium, Pestalotiopsis, Phoma, Phomopsis,

6 92 Jpn. J. Trop. Agr. 44 (2) 2000 Table 3. Fungal populations in non-chemical bananas during trials conducted. Other genera are Acremonium, Aspergillus, Auereobasidium, Curvularia, Monilia, Mucor, Oidiodendron, Oedocephalum, Papularia, Phomopsis, Rhizopus, Spiromyces, and Trichoderma. Aspergillus, Auereobasidium, Acremonium, Monilia, Oidiodendron, Trichoderma, Curvularia, Mucor, Oedocephalum, Papularia and Spiromyces. The results of this study are in agreement with the findings previously reported in banana frults2-5,9,11,13-16,20,21) Crown rot, finger stalk rot, finger rot, finger end rot were associated with two or more fungi, suggesting the complexity of the disease symptoms. For example, from crown rot of non-chemical bananas alone, 16 fungal genera were isolated. Likewise, the isolation of Colletotrichum and Glomerella in anthracnose suggests the complexity of the disease symptoms. The association of various isolated fungi with particular disease symptoms could be determined through inoculation tests. Thus, identification and pathogenicity tests to characterize the economic importance of these fungi for non-chemical bananas will be conducted in the future. The occurrence of 25 fungal genera and the high incidence of disease symptoms illustrate the susceptibility of non-chemical bananas to quality deterioration. Furthermore, the high incidence of disease symptoms and occurrence of fungal populations regardless of the sampling period, suggest their persistence in non-chemical bananas almost all the year round. It remains to be determined whether the persistence in non-chemical bananas is related to production or postharvest processes. Acknowledgment We are grateful to Matsushima Horticultural Development Foundation (Japan) for the financial support and to Mr. Hideaki NAKJIMA, Alter Trade Japan (ATJ) for supplying nonchemical banana samples from the Philippines. Likewise, we thank Dr. Shozo KAWAI, Head of Laboratory of Tropical Plant Protection, Mr. Chiharu NAKASHIMA, Ms. Erika IMAIZVMI, Mr. Keiichi MOTOUADHI, and all the members of the Laboratory of Tropical Plant Protection, Tokyo University of Agriculture for their assistance during the study. References 1. AKAI, S. and H. KUNOH 1968 Survey of market disease in Kyoto Central Market. Proc. Kansai Plt. Prot. Soc. 10: GANAPATHI, N Factors in the postharvest losses due to diseases. Proc. Workshop on Postharvest Loss Assessment of Horticultural Produce, Manila, Phil. Feb : GREENE, G. L. and R. D. GOOS 1963 Fungi associated with crown rot of boxed bananas. Phytopathology 53: GRIFFEE, P. J.1976 Pathogenicity of some fungi isolated from diseased crowns of banana hands. Phytopathol. Zeits. 85:

7 ALVINDIA et al.: Symptoms and the Associated Fungi on Non-Chemical Bananas HASSAN, A. and E. R. PANTASTICO 1990 Banana: Fruit Development, Postharvest Physiology and Marketing in ASEAN. ASEAN Food Handling Bureau HEMMI, T List of market diseases. Proc. Kansai Plt. Prot. Soc. 19: HIRAI, T Diseases of the banana in transport from Formosa. Ann. Phytopathol. Soc. Jpn. VIII 2: (in Japanese with English summary) 8. KITAGAWA, H The market for tropical fruits in Japan. In: Postharvest Handling of Tropical Fruits. (Champ, B. R., E. Highley and G. I. Johnson eds.) ACIAR Proceedings No. 50: KNIGHT, C., D. F. CUTTS and J. COLHOUN 1977 The role of Fusarium semitectum in causing crown rot in bananas. Phytopathol. Zeits. 89: LIZADA, M. C Fruit handling systems in developing countries. In: Postharvest Handling of Tropical Fruits. (Champ, B.R., E. Highley and G.I. Johnson eds.). ACIAR Proceedings No. 50: LUKESIC, F. L., W. J. KAISER and M. M. MARTINEZ 1967 The incidence of crown rot of boxed bananas in relation to microbial populations of the crown tissue. Can. J. Bot. 45: MAYAMA, M Market disease of fresh fruits and vegetables at wholesale markets in the Tokushima area. Bull. Shikoku Univ. (B) 5: (in Japanese with English summary) 13. QUIMIO, A. J Postharvest diseases of bananas and their control in the Philippines. In Banana and Plantain Research and Development. PCARRD Book Series No ROTH G. and F. C. LOEST 1965 Collar rot of banana hands and its associated microorganisms. Tech. Comm. Dep. of Agr. Tech. Services of South Africa No. 44: SEPIAH, M. and N. A. M. NIK MOHD 1987 Effects of benomyl and prochloraz on postharvest disease of banana. ASEAN Food J. 3: SNOWDON, A. L A Color Atlas of Postharvest Diseases and Disorders of Fruits and Vegetables. Vol. I: General Introduction and Fruits. Univ. of Cambridge (Cambridge) TANAKA H. (ed.) 1990 Market disease guide book. Jpn. Pit. Prot. Assoc. Tokyo, 226 p. (in Japanese) 18. \1995 Diseases of tropical fruit trees. Assoc. Intern. Coop. Agric. & For. (AICAF) Tokyo, 143 p. 19. The Phytopathological Society of Japan (APS) (ed.) 1984 Common names of economic plant diseases in Japan. Vol. 3. Fruit trees. Jpn. Plt. Prot. Assoc., Tokyo, 190 (in Japanese) 20. WALLBRIDGE, A Fungi associated with crown rot disease of boxed bananas from the Windward Island during two-year survey. Trans. Brit. Mycol. Soc. 77: WARDLAW, C. W Banana Diseases Including Plantains and Abacas. Longmans (London), pp.878