Seasonal evolution of Myzus persicae (Sulz.) (Homoptera, Aphidoidea) with relation to citrus fruit trees

Author(s):  
A. Melia
HortScience ◽  
2012 ◽  
Vol 47 (1) ◽  
pp. 11-17 ◽  
Author(s):  
François Mademba-Sy ◽  
Zacharie Lemerre-Desprez ◽  
Stéphane Lebegin

Citrus fruit trees grown under tropical climatic conditions have a high level of vigor and, consequently, late fruit-bearing and low productivity. The use of Flying Dragon trifoliate orange [Poncirus trifoliata var. monstrosa (T.Itô) Swing.] (FD) rootstock could overcome these negative effects by inducing small trees with early production. Trials including eight commercial cultivars began in Dec. 1992 on an irrigated plot on the main island of New Caledonia (South Pacific). Growth of the trees was observed over a 13-year period through twice-yearly measurements of tree height, canopy between and in the rows, and trunk diameter. Fruit production was recorded beginning 2 years after planting. According to the climatic and pedological conditions of the experimental site, trees grafted on FD could, depending on cultivar, be planted in densities from 519 to 1111 trees/ha. Over the 13 years, yields were 0.5 to 2.8 times greater than those of the same cultivar on the standard rootstock. ‘Tahiti’ lime cumulative planting and maintenance costs were only 1.5 times higher for a density five times as great, and the level of productivity per hectare (gross margin/ha) was 3.3 times that of traditional orchards. Grafting citrus cultivars on FD, which is seldom used in the Mediterranean zone as a result of its excessive dwarfing effect in relation with the climatic conditions, could prove, on the other hand, promising in tropical areas.


2020 ◽  
Vol 86 (9) ◽  
pp. 557-569
Author(s):  
Ali Ozgun Ok ◽  
Asli Ozdarici-Ok

In this study, we present an original unified strategy for the precise extraction of individual citrus fruit trees from single digital surface model (DSM) input data. A probabilistic method combining the circular shape information with the knowledge of the local maxima in the DSM has been used for the detection of the candidate trees. An active contour is applied within each detected region to extract the borders of the objects. Thereafter, all extracted objects are seamlessly divided into clusters considering a new feature data set formed by (1) the properties of trees, (2) planting parameters, and (3) neighborhood relations. This original clustering stage has led to two new contributions: (1) particular objects or clustered structures having distinctive characters and relationships other than the citrus objects can be identified and eliminated, and (2) the information revealed by clustering can be used to recover missing citrus objects within and/or nearby each cluster. The main finding of this research is that a successful clustering can provide valuable input for identifying incorrect and missing information in terms of citrus tree extraction. The proposed strategy is validated in eight test sites selected from the northern part of Mersin province of Turkey. The results achieved are also compared with the state-of-the-art methods developed for tree extraction, and the success of the proposed unified strategy is clearly highlighted.


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