Occurrence and infection rate of the alternaria brown spot disease of the Minneola tangelo in the west part of Mazandaran province

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1 Scholarly Journal of Agricultural Science Vol. 3(5), pp , May, 2013 Available online at ISSN Scholarly-Journals Full Length Research Paper Occurrence and infection rate of the alternaria brown spot disease of the Minneola tangelo in the west part of Mazandaran province S. E. Mahdavian Natural Resources and Agricultural Research Center of Mazandaran, P. O. Box 138, Iran. Accepted 14 April, 2013 Twenty infected leaves, stems and fruits of the tangelo tangerine collected proceeded after symptoms and primary studies record. During this study, Alternaria alternata was recognized and the symptoms and elements of this disease corresponded with foreign resources. Results of this study show that the disease infected more than 80% of tangelo trees and disease symptoms consist of round small to high necrotic spots produced on leaves. Necrosis in vein in infected leaves was the sensible symptoms of the disease. Addition to leaves and stems was also infected and several days after infection, the disease developed on fruit and a little sunken brown spots appear. Young infected fruits immediately fell after leaves fall but older fruits remained on the tree. Infected fruits epidermis became cork and cutting it out was simple. Key words: Tangelo mandarin, brown spots disease, alternaria. INTRODUCTION Tangelo tangerine Minneola tangelo (Blanco Macf)) is a hybrid obtained from confluence two items, Citrus reticulate Blanco Citrus paradisi Macf. In 1903, Alternaria brown spot was first reported on tangerine type, Emperor Mandarin Ten., in Australia (Pegg, 1966). The name of this disease was taken from brown sores properties produced on mentioned fruits. In 1973 in Florida of America, this disease suddenly appeared on tangerine and became a problem for some types of tangerine such as Dancy tangerine and Minneola tangelo (Whteside, 1976). The element of disease in addition produced leaf spot and cause decay in tangerine in garden and also after harvest. In 1984 and 1985, Alternaria disease prevalence was observed in tangerine gardens in Iraqi. The disease symptoms consist of: leaf burn, skin eruption production on fruit, stems burn and falling of fruit and Alternaria citri recognized as the cause of the disease (Attrachi et al., 1984). In 1985, this disease was reported on Raf lemon in Tanzania (Swai, 1980). In 1987, A. citri recognized on Myera lemons Tanaka was described briefly (Gulua, 1980). In August, 1990 and March, 1991, A. citri was recognized on Citrus in Vietnam (Wittle, 1992). In 1993, Alternaria disease was presented as a new disease on Cedrate in China Zhejiang (Jiang, 1993). In 1988 to 1990, during a visit to several countries, the region Maharashtra in India showed that A. citri fungus sometimes created damage on tangerine up to 21% due to transportation by truck (Naqvi et al., 1994). In 1991, the etiology showed the amount of damage and the distribution extent of leaf spot considered on Raf lemon (Awuach, 1991). These diseases were a disturbance in many areas where citrus were growing and in addition to tangelo, they damaged Raf lemon, citrus varieties and lemon. Researchers considered and reported this disease in South Africa, Turkey, Istanbul, Spanish, Brazil and Argentina (Schutte et al., 1992; Vicent, 2000; Canihos et al., 1997; Goes et al., 2001; Peres et al., 2003). Alternaria alternate was shown to cause the disease on tangerine and hybrid and brown spots appeared on leaves, stems and fruits (Timmer et al., 2000a). Lavern et al. (2003) studied this disease in MATERIALS AND METHODS Sampling Different areas where tangerine was grown were visited

2 Scholarly J. Agric. Sci. 168 Figure 1. Alternaria necrotic brown spot with yellow halo on tangelo tangerine leaf. Figure 2. Produced alternaria necrotic brown spot on stem. and 20 infected leaves, stems and fruits collected from Siyaveraz area in Tonekabon. Infected samples transferred to the laboratory and their specifications were recorded. Infected samples considered apparently showed spots color with the help of binocular. Separation, purification and identification PDA culture was used to first separate the fungus. Small parts of about 4 to 6 mm was provided to plantation samples between infected and healthy tissue and after superficial washing by tap water, it was disinfected by mercury chloride with 1: 1000 concentration for 0.5 to 3 min or with 0.5 pure Sodium hypochlorite for 1 to 2 min and placed on the culture after colony growth of fungus in recent Petri dish purification through single spore. Barnet (1960) recognition key was used to recognize the disease element fungus. Pathogenicity According to pathogenicity demonstration, suitable inoculums (10 spore/ ml) were provided from the fungus and this pathogenicity considered on two years seedlings in greenhouse condition. Determine the percent of infected orchards Different gardens of tangelo tangerine were tested and the percent of infection determined based on the symptoms on leaves, stems, fruits, leaves falling and stem dried as compared to health trees and the percent

3 Mahdavian 169 Figure 3. A little sunken alternaria necrotic brown spot on fruit. Figure 4. Fall of infected fruits, leaf and drying end seedlings. of the disease infection with calculation of the means of gardens infection percent was presented. RESULTS Disease symptoms Disease symptoms consist of round small to big necrotic with yellow halo on leaves. The obvious disease symptoms were leaves becoming yellow and necrotic in vein in leaves infected (Figure 1). In addition to leaves, stems were also infected (Figure 2) and several days after infection, disease developed on fruits and small brown spots appeared a little sunken (Figure 3). Disease developed with infection in progress caused infected fruits and leaves to fall and drying on seedlings (Figure 4). Causal organism Twenty (20) separated samples of this kind was considered with tangelo tangerine (10 samples, Siaveraz), Miyansara (5 samples), Ghalehgardan (2 samples) and Khorramabad (3 samples) were obtained. The property under study separates with A. alternate

4 Scholarly J. Agric. Sci. 170 Figure 5. Alternaria alternate asexual spores. Table 1. The statistics of sampling tangelo tangerine polluted gardens to brown spot disease in Tonekabon area. Rank Sampling place 1 Siyaveraz 2 Miyansara 3 Khorramabad Citrus trees number (Tamson Navel and tangelo) infected tangelo tangerine trees number Extinct disease trees Disease trees Ghalehgardan Total (Fr.: Fr.) Keissler fungus except Ufer conidia length (less than 80 mm) which was shown to be compatible with the report of Ellis (1971) and Simmons records (1967). This type before now was reported on bitter orange and sweet lemon and Citrus sp. (Ershad, 1995) and also on lime, tangerine, citrus, grapefruit and orange (Ruhibakhsh, 1998). A. alternate (Fr.) Keissler fungus is the element of tangerine tangelo alternaria brown spot disease and its characteristics on Potato Dextrose Agar (PDA) culture is intertwined with yellowish or transparent olive thin air mycelium. Conidia in more different sizes and forms and were chain-like in maturation duration. Multi-cell club form rectangular conidia have short straight and linear partition in dark olive brown color (Figure 5). Pathogenicity Pure plantation was provided by single spore plantation and sprayed on the active seedlings of the Tangelo tangerine by use of 10 spore ml and first disease symptoms appeared in form of small necrotic spots on active seedlings after 3 weeks. Strewed fungus separated from infected spots and was equal when compared.

5 Mahdavian 171 Infection percent determination Different gardens visited in Tonekabon areas was variant based on disease symptoms on leaves, stems, fruits, and leaves falling and stems drying when compared to healthy trees from 10 to 95% and recognized that about 80% of gardens polluted this disease by mean computation (table 1). DISCUSSION Most of tangelo tangerine producers confronted with Alternaria disease in Tonekabon is as a result of A. alternata fungus. This disease caused high quantitative and qualitative damage on crops. This fungus produced two kinds of disease on citrus types. The Alternaria brown spot disease of tangerine and Raf lemon and fruit stem end rot or the rot on the tangerine ripe fruit which account in part of the disease occurred after harvest. The symptoms of this disease on infected fruits in garden may appear like light to dark brown spots in skin or near the end of the stem. Fruits which do not show the disease should be sliced to show their inter rot. This disease is called black rot or central rot. The main anxiety in this disease is tree sprout infestation which can decrease the amount of available inoculums that infect the fruit. Many infected leaves fall before end of winter and probably disease element stays on stems damaged; this is an important place for first inoculums. Disease intensity decreases when tree strengthens and gardening functions. High manure and irrigation and precision function decrease disease intensity due to increase of seedling vegetative growth. Trees which did not show precision are resisting the disease element in start of the growth season before blossom and seedlings usually appeared on these trees that are not more sensitive to the disease for 2 to 3 months. The disease element fungus produce special toxin called Altenuene. This toxin destroys host tissue before aggressor tissues and it is accompanied with necrosis reaction in less than 2 days. Ershad, D. (1995). Fungi of Iran. Agricultural Research, Education and Extension Organization.10: pp. Goes A. de, Montes de Ocu, A.G. and Reis, R.F. (2001). Ocurrencia de las mancha de Alternaria en mandarina Dancy en el estado de Rio de Janeiro. Fitopatologia Brasileira 26(Suppl.), 386. Gulua, MK. (1980). Represntaives of harmful mycoflora causing rot and drop of flowers and young fruit on Meyera lemons. Subtropicheskie, Kultury. 3: Hong, S. (1991). Fungi associated with strong disease of citrus fruits. crop protection. 33(3): Jiang, DH. (1993). Fingered citron Altemaria blight. A new disease in Zhejjang. Acta, Phytopathologica, Sinica. 23(4): 292. Timmer, L.W, Peever, T.L., Solel, Z.V.I. and Kazuya, A. (2003). Alternaria diseases of citrus Novel pathosystems. Phytopathol. Mediterr. 42:3-16. Naqvi, S., Dass, HC. (1994). Assessment of post- harvest losses in Nagpur mandarin, a pathological perspectine. Plant disease Res. 9(2): Peever T.L., Su, L., Carpenter-Boggs, G. and Timmer, L.W. (2003). Molecular systematics of citrus-associated Alternaria species. Mycologia 95, (in press). Pegg, K.G. (1966). Studies of a strain of Alternaria citri Prierce, the causal organism of brown spot of Emperor mandarin. queensl. J. Agric. Anim. Sei, 23(1): Peres, N.A.R., Agostini, J.P. and Timmer, L.W. (2003). Outbreaks of Alternaria brown spot of citrus in Brazil and Argentina. Plant Disease. 87(750). Roohibakhsh A and Ershad, D. (1997). An investigation on mycoflora of citrus necrotic leaf spots in Western Part of Mazandaran.Iranian Journal of Plant Pathology.33(3, 4): Simmons, E.G. (1967). Typification of Alternaria,Stemphylium, and Ulocladium.Mycologia 59: Swai, IS. (1988). Citrus diseases in Tanzania. Acta, Horti. 218: Timmer L.W., Solel Z., and Orozco-Santos, M. (2000a). Alternaria brown spot of mandarins. In: Compendium of Citrus Diseases (L.W. Timmer, S.M. Garnsey, J.H.Graham, ed.), APS Press, Inc., St. Paul, MN, USA, pp Whitesid, J.O. (1979). Alternaria brown spot of Dancy tangerines and its control. Proc. Fla. Nortic. Soc. 92: Whittle, A.m. (1992). Diseases and pests of citrus in Vietnam. FAO, Plant protection, Blletin. 40(3): Vicent A., Armengol, J., Sales, R. and Garcia-Jimenez, J. (2000). First report of Alternaria brown spot of citrus in Spain. Plant Disease. 84(1044). REFERENCES Attrachi, A., Ahmed, KA.,Thman, NA.,Taha, KH. (1984). Studies on citrus bilght caused by Alternaria citri; Mesopotamia, Journal of Agriculture, 20: Awuah, R.T. (1991). Etiology, suspect range and distribution of leaf spot of rough lemon in the Ashanti region of Ghana, FAO, Plant protection, Bulletin, 39(2-3): Barnett. H.L. (1960). Imperfect fungi. Department of plant pathology, Bacteriology and Entomology, West Vitginia University, Morgan town, West Virginia. p Canihos Y., Erkilic, A. and Timmer, L.W. (1997). First report of Alternaria brown spot of Minneola tangelo in Turkey. Plant Disease. 81: Ellis, M.B. (1971). Dematiaceous Hyphomycetes. Commonwealth Mycological Institute, Kew, Surrey, England. p.608.