LIBRO-CONGRESO-CITRUS

S12P15
Systemic insecticides are effective in preventing the transmission of “Candidatus Liberibacter
asiaticus” by Diaphorina citri?
Yamamoto P.T. 1 , de Miranda M.P 2 , and Felippe M.R. 2
1 Escola Superior de Agricultura Luiz de Queiroz (ESALQ), Entomologia e Acarologia, Brazil; and 2 Fundo de Defesa da Citricultura
(Fundecitrus), Científico, Brazil. pedro.yamamoto@usp.br
The purpose of this study was to evaluate the effectiveness of soil-applied systemic insecticides in the
control of Asian Citrus Psyllid (ACP) Diaphorina citri and thereby prevent the transmission of “Candidatus
Liberibacter” spp. in citrus bearing trees. The experiments were conducted in farms located in the region of
Araraquara, SP, Brazil. The first experiment was carried out in 7-year-old ‘Valencia’ sweet orange on ‘Swingle’
citrumelo, with application in Aug/2009. The second and third were conducted in 8-year-old ‘Pera’ sweet
orange on ‘Rangpur’ lime, in sandy and clay soil, with application in Nov/2009 and in Feb/2010. In the first
experiment, the insecticides were effective in controlling ACP. Thiamethoxam at doses of 0.31 and 0.62 g ai/m
of plant height and imidacloprid at a dose of 1.2 g ai/m were effective. Application with a volume of 1 liter/
plant and applied to the soil at the base of the trunk was more efficient compared with 0.5 L and application
in the projection of the canopy. For applications done in Nov/2009 and Feb/2010 systemic insecticides were
not effective in controlling ACP. The concentration of thiamethoxam (0.31 g/m) reached 1000 ppb in the first
experiment; however, when applied in the other two experiments, was less than 200 ppb. The answer to the
question is yes, because the systemic insecticides are efficient to control ACP. However, in some conditions
they are not absorbed and translocated into the citrus trees, showing low efficiency.
S12P16
Vector control and foliar nutrition for management of Huanglongbing in Florida citrus
Stansly P.A., Arevalo H.A., Qureshi J.A., Jones M., Hendricks K., Roberts P.D., and Roka F.M.
University of Florida (IFAS), SW Florida Research and Education Center, USA. pstansly@ufl.edu
Vector control and foliar nutrition are widely employed in Florida citrus to respectively slow the spread of
HLB and mitigate effects of the disease on citrus trees. A replicated field study was conducted in a 13-acre
commercial block of young ‘Valencia’ through four harvests employing a factorial design to evaluate individual
and compound effects of a popular nutrient/SARs program and threshold-based vector management. Asian
Citrus Psyllid populations were maintained at contrasting levels in insecticide-treated and untreated plots despite
proximity. Nevertheless, incidence of HLB, estimated by PCR at near 30% at the beginning of the study, rose to
over 90% early in the third year without significant contribution from vector control. However, yields were
significantly improved all four years by the combined effects of nutrition and vector control, with a significant
contribution from nutrition in the fourth year when production in the combined treatment approached the
pre-HLB regional average. Economic analysis showed that, while the insecticide nutritional treatment produced
the highest gain in production, it would not have been profitable at current juice prices. Fine tuning by reducing
costs of the nutrient package and/or the insecticide regime could have made the program profitable, as could
higher margins of a fresh fruit market. Further research is necessary to establish economic thresholds for both
insecticide and nutrient application under different market and environmental conditions.
S12P17
Foliar spray of nutrients and growth regulators on the management of citrus affected by HLB – Is
it possible?
Medina C.L. 1 , Bataglia O.C. 2 , Furlani P.R. 2 , Machado R.S. 2 , and Creste A. 3
1 Grupo de Consultores em Citros (GCONCI), Research, Brazil; 2 Conplant - Consultoria, Treinamento, Pesquisa e Desenvolvimento
Agrícola LTDA (Conplant), Research, Brazil; and 3 Fazenda São José (FSJ), Manager, Brazil. clmedina@conplant.com.br
The phloem of HLB affected plants are obstructed by callose that inhibit carbohydrates, minerals and water
flow to the newer developing tissues. This causes damages to plant development, debilitates the plants
and thus reduces the yield. The callose phloem obstruction may be related with the reaction defense
XII INTERNATIONAL CITRUS CONGRESS 2012 - 205
S12