Phytophthora can appear on citrus trees through a variety of symptoms. Eventually, the bark dries, cracks and falls off. UC IPM Pest Management Guidelines: Citrus Proceedings of the International Society of Citriculture, 1981. Targon III; Alessandra A. Souza III. Plants were stem-inoculated by removing a 5-mm-diameter disc of the bark of the scion on each plant using a cork borer to expose the cambium and placing a mycelial plug obtained from 5-day-old colonies (Álvarez et al. Phytopathology 103:1204–1208, Article  COMMENTS: For use on all susceptible citrus. Shape of sporangia was obpyriform or ovoid with the following lengths and widths: 50.6 (36.5–64.4) × 31.1 (23.6–38.6) μm and with a L:W ratio of 1.6 (1.3–2.3) based on 100 measurements. Citrus Gummosis Information. Australasian Plant Disease Notes No symptoms were observed on control plants. When the affected bark tissues were removed, the diseased wood surface appeared dark brown with decreasing intensity to light brown. Trunk - infection of the trunk by Phytophthora results in dark water soaked areas in the area of active infection. Typical Phytophthora-like noncaducous, papillate sporangia were observed when incubated in sterile soil extract (Fig. Hot summer weather slows disease spread and helps drying and healing of the lesions. Apply as paint or spray on trunk and crown right after excision of diseased bark; treat excised area and lower trunk. 315–322. 1999). 1a). © 1996–2020 Statewide IPM Program, Agriculture and Natural Resources, University of California Regents of the University of California unless otherwise noted. Lesions eventually spread around the trunk, and leaves yellow and drop. APS Press, St. Paul MN, FAOSTAT (2012). parasitica) and P. citrophthora.They are root and trunk pathogens causes slow decline of the tree (Fig 1). Phytophthora Root Rot and Gummosis of Citrus Introduction: Phytopthora root rot and gummosis caused by Phytophthora nicotianae var. Control plants were treated with PDA plugs. Lesions spread around the circumference of the trunk, slowly girdling the tree. PubMed Google Scholar. 2011). Apply in 100 to 400 gal/acre; spray to wetness when conditions favor disease development. CAS  Apply in 100 to 250 gal/acre; spray to wetness when conditions favor disease development. In conclusion, the present study confirmed earlier reports indicating that Phytophthora is the causal agent of citrus gummosis in Ghana. No chlamydospores were observed. When establishing a new orchard, carefully check the lower trunk and rootstock of new trees for any symptoms of gummosis before you plant. 2007). Francis C. Brentu. Growing colonies were transferred to potato dextrose agar (PDA) and maintained at 24 °C in the dark for characterisation of colony morphology. Sequences were compared with those available in the Phytophthora database 2.0 (Park et al. The focus of this study is temperature: specifically, the … Leaf - yellow foliage and shoot die-back. Acceptable for use on organically grown produce. Ten isolates, including FHCRC-PHY1, were grown on PDA and used in the pathogenicity tests. Oorspronkelijk komt Phytophthora voor in de bodem, maar door opspattend water kan de ziekte ook de stam, de bladeren en de vruchten van een plant infecteren. Valencia-Late grafted on rough lemon grown in plastic pots (40 cm diameter × 60 cm deep) containing potting mix (sterilised soil and rice husk Boucher). Use higher rate if trunk lesions are present. When you detect gum lesions, check soil and drainage conditions. Phytophthora Diseases of Citrus 2 susceptible rootstocks are used. Horticulture Export Industry Initiative, Ministry of Food and Agriculture, Accra, Park B, Martin F, Geiser DM, Kim HS, Mansfield MA, Nikolaeva E, Park SY, Coffey MD, Russo J, Kim SH, Balci Y, Abad G, Burgess T, Grünwald NJ, Cheong K, Choi J, Lee YH, Kang S (2013) Phytophthora database 2.0: update and future direction. Restricted entry interval (REI) is the number of hours (unless otherwise noted) from treatment until the treated area can be safely entered without protective clothing. Google Scholar, Hearn CJ, Fenton R (1970) Benomyl sprays for control of twig dieback of ‘Robinson’ tangerine. Affected trees showed leaf chlorosis and twig die-back with reduced fruit production. Bull Minist Food Agric 1:1–40, Offei SK, Cornelius EW, Ofosu-Budu GK, Kpesese VK (2002) Reaction of citrus rootstocks to Lasiodiplodia theobromae (Pat.) In Ghana, the disease was originally associated with Phytophythora parasitica, but details of the aetiological methods used were not provided (Leather 1959; Clerk 1974). Four weeks after inoculation all plants inoculated with P. citrophthora showed symptoms of the disease, consisting of gum exudation and bark discoloration (Fig. When lesions girdled the trunk, trees eventually died, especially after an exceptional heavy crop load. Oomycete strains with coenocytic hyphae and petaloid colony pattern were consistently isolated from affected tissues in all 50 samples analysed (Fig. Do not exceed four applications of fosetyl-al per year. Preharvest interval (PHI) is the number of days from treatment to harvest. Phytophthora Root Rot and Gummosis of Citrus Introduction: Phytopthora root rot and gummosis caused by Phytophthora nicotianae var. Inoculation sites in the plants were previously disinfested with 70 % ethanol. Phytophthora fungi are present in almost all citrus orchards. 2011) in the Phytophthora-ID database 2.0 (Grunwald et al. Phytophthora citrophthora was confirmed as the causal agent of the disease. Correcting any soil or water problems is essential for a recovery. A guide to methods and applications. There are 2 main types of Phytophthora that effect citrus: Phytophthora gummosis: Damage symptoms include sap oozing from small cracks in the infected bark creating a bleeding appearance. Recheck frequently for a few months and repeat if necessary. Citrus Phytophthora Info. Fumigants such as metam sodium are a prime source of volatile organic compounds (VOCs), which are a major air quality issue. Part of Springer Nature. Google Scholar, Robideau GP, De Cock AW, Coffey MD, Voglmayr H, Brouwer H, Bala K, Chitty DW, Desaulniers N, Eggertson QA, Gachon CM, Hu CH, Kupper FC, Rintoul TL, Sarhan E, Verstappen EC, Zhang Y, Bonants PJ, Ristaino JB, Levesque CA (2011) DNA barcoding of oomycetes with cytochrome c oxidase subunit I and internal transcribed spacer. Management in Citrus Peggy A. Mauk County Director/Subtropical Horticulture Advisor Citrus Diseases PhytophthoraRoot Rot PhytophthoraGummosis Phytophthora Root Rot Phytophthora Gummosis New or ongoing concerns HendersonulaDieback Coniophorawood decay Phytophthora Root Rot Susceptible Rootstock Phytophthoraspp. COMMENTS: Use when disease occurs. Lesions may exude copious amount of gum and a brown necrotic area will be found under the bark lesions. Thoroughly wet the lesion. 1999). Isolates grew at 5 °C but not at 35 °C. PubMed  Do not exceed four applications of this product per year. Plant Dis 70:1038–1043, Leather RI (1959) Diseases of economic plants in Ghana other than cacao. 1c). Not all copper compounds are approved for use in organic production; be sure to check individual products. Cite this article. Allow the exposed area to dry out. Valencia Late) grafted onto rough lemon rootstock (C. jambhiri) and severely affected by gummosis were collected from the experimental orchards at five locations of the University of Ghana, Forest and Horticultural Crops Research Centre located at Kade (06° 08′ 54.76″ N, 0° 54′ 53.35″ W). The complex of citrus diseases caused by Phytophthora spp. Phytophthora citrophthora was confirmed as the causal agent of the disease. Ghana Publishing Corporation, Accra, Dade HA (1940) A revised list of Gold Coast fungi and plant diseases. If citrus weevils are present adults may feed on leaves causing notching. Citrus gum, which is water-soluble, disappears after heavy rains but is persistent on the trunk under dry conditions. Infected bark remains firm with small cracks through which abundant gum exudation occurs. Plant Dis 95:337–342, Article  Remove the dark, diseased bark and a buffer strip of healthy, light brown to greenish bark around the margins of the infection. Phytophthora fungi are present in almost all citrus orchards. Under moist conditions, the fungi produce large numbers of motile zoospores, which are splashed onto the tree trunks. The Phytophthora species causing gummosis develops rapidly under moist, cool conditions. COMMENTS: Use neutral, spray-dried, one package copper spray materials stirred into water to make consistency of house paint. All the citrus producing regions are facing threat due to a soil borne water loving pathogen Phytophthora species. Google Scholar, Álvarez LA, Vicent A, De la Roca E, Bascón J, Abad-Campos P, Armengol J, García-Jiménez J (2008) Branch cankers on citrus trees in Spain caused by Phytophthora citrophthora. 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