High density planting (HDP) of Jiaogan mandarine in the lowland area of Shantou (Guangdong China) and implications for greening control
Shantou is the place where the so-called JIAOGAN (TANKAN) MANDARINE (an easy peeling, late maturing, seedless tangor), originated. Historically, Shantou is also the center of the Citrus Greening Disease (CGD), the latter having been described from this area for the first time in 1919. Local farmers have tried to escape the devastating effects of CGD by adopting high densities planting HDP (from 1800 to 2000 trees/ha), in order to achieve early bearing and thus hasten the economic return on investment costs. As a consequence, orchard rotation was also accelerated, with return to rice cropping every 10 to 12 years. Although developed many years ago, this cropping system was somewhat intensified with the gradual spread of Greening. After more than half a century of experience the HDP practice was found to be poorly rewarding any time citrus material originated from contaminated nurseries. In addition, stringent control of Diaphrona citri was an absolute prerequisite for a successful short term profitability, even though registered disease free trees were planted. Nowadays disease free nurseries are operating in the region, but proper control of D. citri is far from being evenly achieved. Due to its relative isolation from other citrus regions of CHINA, based also upon very large scale plantations of a monovarietal scion/rootstock combination, the Shantou area is facing typical greening epidemics, with the exclusion of other virus diseases such as Tatter leaf, Exocortis, and even Tristeza. This paper describes in detail the cropping techniques developed in Shantou orchards and evaluates the risks and eventual merits of HDP in areas where citrus greening is endemic. However this technique is by no means an alternative answer to greening and may even seriously aggravate the problem in some cases. Emphasis must be laid on enforcing phytosanitary policies on targeted groups of farmers operating in a given area, and applying synchronized and integrated protection measures.
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| Format: | conference_item biblioteca |
| Language: | eng |
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FAO
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| Subjects: | F07 - Façons culturales, H20 - Maladies des plantes, |
| Online Access: | http://agritrop.cirad.fr/522162/ http://agritrop.cirad.fr/522162/1/ID522162.pdf |
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