LIBRO-CONGRESO-CITRUS

S15
S15P28
Optimization of copper application schedules for foliar citrus disease management based on fruit
growth, historical rainfall patterns and copper residue decay
Zortea T. 1 , Fraisse C.W. 1 , and Dewdney M.M. 2
1 University of Florida (UF), Agricultural & Biological Engineering, USA; and 2 Citrus Research and Education Center, University of Florida
(CREC UF), Plant Pathology, USA. mmdewdney@ufl.edu
Copper applications are essential for foliar citrus disease management in Florida. For effective disease control,
copper residues need to be maintained above 0.1 µg/cm2. Simulations show the standard timing of copper
applications every 21 days is insufficient in wet years. To minimize copper coverage gaps for grove operations
that plan a season’s applications in advance, optimized copper application schedules were developed for early,
average and late peak bloom. Fifty-five years of historical weather data from the National Weather Service
Cooperative Observer Program in five counties (Highlands, Hendry, Indian River, Lake and Polk) were used.
The copper residue decay for each year was calculated from equations for fruit growth, copper deposition
and residue reduction in the citrus copper application scheduler, a web-based tool to predict residue decay
(http://agroclimate.org/tools/cudecay/). To test schedules, intervals (days) between applications were varied
±2 days in a simulation and the best result was rerun until the results converged. Schedules were evaluated
based on the sum of unprotected days over the 55 years and a percent reduction of days without coverage
was calculated. For all locations combined there was a 51% reduction from 857 to 420 unprotected days for
the average bloom and a 19% and 13% reduction for early and late blooms, respectively, with the optimized
schedules. The greatest improvement occurred in Highlands County with a 57% reduction of unprotected
days.
S15P29
Phytosanitary situation of Chilean citrus industry
Besoain X., Castro M., Camps R., and López E.
Pontificia Universidad Católica de Valparaíso (PUCV), Facultad de Agronomía, Chile. xbesoain@ucv.cl
Chilean citrus industry has experienced a strong growth towards fresh-fruit exports. This situation is partly
caused by the Japanese market starting to import lemons and the American market mandarins and sweet
oranges. These markets have been accesed due to Chile’s competitive advantage since it has no pests and
diseases of world impact such as Fruit Fly (Ceratitis capitata), Citrus Scab (Elsinoë fawcettii), Black Spot
(Guignardia citricarpa), Citrus Canker (Xanthomonas citri subsp. citri), and Huanglongbing (Candidatus
Liberibacter spp.). The main diseases affecting citrus fruit in Chilean farms are: Gummosis caused by
Phytophthora citrophthora and P. hibernalis, Dry Root Rot caused by Fusarium solani, leaf and fruit spots
caused by Alternaria species. In the post-harvest period, the diseases are: Gray Mold caused by Botrytis cinerea
(also in pre-harvest), Green Mold and Blue Mold by Penicillium species, Sour Rot by Geotrichum candidum
and Black Pit by Pseudomonas syringae pv. syringae. Regarding nematodes, Tylenchulus semipenetrans has
caused considerable damages. Some of the virus diseases include Cachexia (CCaVd) affecting both lemon
trees and mandarins and Tristeza, only stem pitting syndrome caused by severe isolates of Citrus tristeza virus
(CTV) affecting grapefruit varieties located in the Pica oasis (Tarapaca Region). The main pests are the Chilean
False Red Mite (Brevipalpus chilensis), Citrus Red Spider Mite (Panonychus citri), the Pseudococcidae with
predominant species, Olive Black Scale (Saissetia oleae), Soft Scale (Coccus hesperidum) and Wooly Whitefly
(Aleurothrixus floccosus).
S15P30
Storage technology for conservation of seeds of citrus rootstocks
Nascimento L.M., Moreira J., Brito M.C.R., Brito P.C.N., and Sanches J.M.
Centro de Citricultura Sylvio Moreira, Brazil. lenice@centrodecitricultura.br
This study evaluated Xtend packaging and several fungicide treatments to improve the conservation of seeds
of ‘Swingle’ citrumelo and lemon ‘Cravo’. Seeds of ‘Swingle’ citrumelo were harvested, washed, and divided
270 - VALENCIA CONFERENCE CENTER, 18th-23rd NOVEMBER 2012