Phytophthora fungi are present in almost all citrus orchards. Under moist conditions, the fungi produce large numbers of motile zoospores, which are splashed. The main symptom of citrus gummosis is oozing of gum from the affected parts on the trunk. Infected bark remains firm with small, longitudinal cracks through. Gummosis is the formation of patches of a gummy substance on the surface of certain plants, particularly fruit trees. This occurs when sap oozes from wounds or .
|Published (Last):||19 February 2007|
|PDF File Size:||11.83 Mb|
|ePub File Size:||9.18 Mb|
|Price:||Free* [*Free Regsitration Required]|
Visit for more related articles at Journal of Horticulture. Citrus production in Ethiopia is threatened by a number of biotic and abiotic factors.
Among these citrus gummosis is one of the most important biotic constraints in the country. This study was conducted with the objective to measure and estimate the incidence and distribution of citrus gummosis Phytophthora spp. Surveys were conducted in ten major citrus growing areas of Ethiopia. In each orchard, 30 trees were selected and totally trees were assessed for gummosis incidence. A tree was defined and recorded as cankered when it had any of the following symptoms: Results showed that growth and fruit production are greatly reduced on trees infected by gummozis disease.
Cracked lesions that exude sap are found on infected scions, which become gradually girdled and killed. Gummosis was more frequent on scions trunk and branch which had Ann Jose ankara escort.
Home Publications Conferences Register Contact.
Garden Guy Hawaii: Citrus Gummosis
Guidelines Upcoming Special Issues. Research Article Open Access. Assessing and Measuring of Citrus gummosis Phytophthora spp.
April 16, Accepted: July 17, Published: July 20, Citation: This is citus open-access article distributed under the terms of the Creative Gummosiis Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Abstract Citrus production in Ethiopia is threatened by a number of biotic and abiotic factors.
Introduction Citrus Citrus sinesis L. The origin of citrus citfus believed to be south eastern Asia including eastern Arabia to the Philippines and from the Himalayas south to Indonesia or Australia [ 2 ].
Citrus constitutes a major group of fruits comprising of mandarins, oranges, lemon, pummelo, grape fruits, tangelo, trifoliate orange, citron, and citranges [ 3 ]. Citrus is among the most important fruit crops in Ethiopia. Its cultivation started in Upper Awash valley and Melkassa areas in central Ethiopia [ 4 ].
It is being produced mainly in Dire Dawa areas, lower and middle Awash and Cittus areas in southeast region of Ethiopia. Ethiopia’s agro-climatic conditions are highly suitable for production citrux high quality citrus fruits. Five phenological regions were identified based on the blooming season and climate as potential production centers capable of supplying citrus throughout the year [ 5 ].
It occupied hectares of land in in the country, but the citurs has come down to 5, hectares oranges, mandarin and hectares limes and lemon with a production of 33, metric tons only [ 6 ]. The decline in production land through time was attributed to a number of gummoais limiting biotic and abiotic factors. Hence, there is a need to undertake coordinated and multi-phased research investigations on citrsu causes of citrus decline and find a sustainable, eco-friendly and easily commercialized technology that fits for our subsistence agriculture system.
Determining the actual importance of a possible citrus decline factors viz gummosis Phytophthora spp. Foot rot and gummosis occur when Phytophthora propagules are splashed onto the trunk near ground level, infect wounds or growth cracks and produce lesions which extend down to the bud union and cause a twig dieback and if severe, trees may eventually die [ 7 ].
Few studies have suggested a possible mechanism of gummosis occurrence on citrus tree and as a cause of for citrus decline elsewhere in the world much work was not done in Ethiopia thus far on gummosis. Consequently this study was conducted with the objective to measure and estimate the incidence and distribution of citrus gummosis Phytophthora spp.
Materials and Methods Description of the study area A survey was conducted between October and November to determine the incidence and distribution of gummosis Phytophthora spp. In all orchards, the root stock was sour orange and the scion was the sweet orange cultivar Valencia in all the surveyed orchards.
Disease survey was conducted cirus ten established citrus orchards in Upper awash, Errer-Gota, and Koka areas.
The average minimum and maximum annual temperature were Disease assessment In each orchard, 30 trees were selected and a gummosis incidence was assessed. Gummosis incidence was determined as gummsois proportion of plants showing gummosis symptoms, expressed as a percentage of the total number of plants assessed [ 8 ].
Disease severity index DSI was then calculated as: Isolation of Phytophthora spp. The disease samples were taken from the active lesion near to the crown and branch showing the symptom of the disease. A total of 30 samples, obtained from 10 surveyed orchards, were processed. The modified V-8 agar consisted of eight vegetable agar V-8 agar composed of 2 g CaCO 3mL V8 juice and 15 g agar in mL distilled water amended with 20 mg Pimaricin, mg Ampicilin, 75 mg Vancomycin, 50 mg Dichloran, citurs were dissolved in 10 ml distilled sterile water and added to 1 liter of V-8 agar [ 10 ].
Pure cultures of Phytophthora spp. Results and Discussion Distribution gummosis citrus gummosis phytophthora spp.
The survey results have shown that the disease was prevalent in all the surveyed orchards with different magnitude of infection. The gumming and cracking symptoms were observed on root stock, trunks and branches which produced a light yellow and brown gum across the sampling orchards.
Branches with this symptom resulted in die back of a tree that could not keep their fruits and leaves alive for the next season. Infections of tree parts Gummosis was more frequent on scions trunk and branch The disease mainly affected mature citrus trees; Diseased trees showed cankers and gum exudations mainly on above-union parts, especially on the major limbs, whereas rootstocks generally remained healthy.
The dominant status of P. The outbreak of this disease could be the variation in environmental factors and changes in citrus cultural practices. Inoculums raised from the soil and move to the trunk and branches possibly due to poor cultural practice conducted at the orchards during harvesting, irrigating and pruning.
Likewise, the particular and most importantly this pathogen were spread during harvesting when climbing to the tree. During irrigation, weeding, pruning etc.
In addition; probably some insects and animals have had contribute for the spread of the pathogen to the upper branch. The disease usually attacks the plant when soil comes into contact with the scion, or when a tree is planted in a basin which may be flooded during irrigation, allowing the fungus to reach the scion [ 13 – 15 ]. These relations clearly mean when altitude increases incidence on root stock, branch and trunk as well as tree decline also decreases.
Disease severity index The overall result of disease severity index showed that Erer and Hurso orchards were highly affected by the disease. The lower disease severities were recorded at Tibilla Similarly Jagtap et al.
In the soil analysis result all citrus orchards show clay texture except Melkassa which is loam relatively with low PH 7.
This clay nature of the soil favors the pathogen by keeping the soil moisture for the long period of time and breaking of spore dormancy to be infective. Leonard and Nathan [ 17 ] reports about the spore survival mechanism were that the fungus survives in the soil as a thick-walled spore capable of withstanding extremes in both moisture and temperature.
Clay nature of the citrus orchard and optimum temperature for the development of the spores of the pathogen as well as weak management of the orchards made the disease highly sever in the area. Morphological aspects of isolates were used in accordance with the descriptions made by Drenth and Sendall [ 18 ] Figure 3.
Isolates from the bark tested for growth on the selective medium at 23oc of temperature shows a white cottony colony after 72 hrs. But after seven days of incubation different types of spores were become visible on the culture under microscope including chlamydospores, sporangia and hyphal swellings. Isolations from the bark of citrus tree revealed the presence of the fungus Phytophthora spp, the cause of citrus gummosisaffecting root crown and the branch.
All thus features were also described by Farih, et al.
Fact Sheet: Phytophthora | Citrus Diseases
Conclusion and Recommendations Citrus gummosis Phytophthora spp. But it can be reversed with the integration of fungicides, dimethomorph the data is not observedby avoiding excessive overwatering, poor drainage and soil structure, proper bud union avoiding a bud union at soil surface or less than 15 cm above soil line those which enhances the disease gummosis. In general if the inoculums of the disease from soil were kept away through by any means to the rootstock and the trunk, the disease pressure will be minimized.
AgricultraTropica et Subtropica HaileMariam Phenological regions for citrus production in Ethiopia: Basis for production planning. X African Symposium on Horticultural Crops. Fao Production Data Base. Pakistan Journal of Botany Is gummosis becoming more of a problem?
CRC for tropical plant protection Brisbane Austrialia. Turk Journal of agricultural forestry Select your language of interest to view the total content in your interested language. Can’t read the image?
Agri and Aquaculture Journals Dr. Pharmaceutical Sciences Journals Ann Jose ankara escort. BoxDire Dawa, Ethiopia. Related article at PubmedScholar Google.