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Primiano IV, Barbosa Junior JT, Bassanezi RB. Comparison of insecticide sprays in alternate rows and in all rows on Asian citrus psyllid control and Huanglongbing progress in sweet orange orchards. Plant Dis 2024. [PMID: 38654535 DOI: 10.1094/pdis-03-24-0646-re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/26/2024]
Abstract
One strategy to reduce Huanglongbing (HLB) is controlling its insect vector, the Asian citrus psyllid (ACP) Diaphorina citri, by preventive insecticide sprays. The recommendation is to spray insecticide in all rows (conventional spray - CONV), but some growers empirically spray in alternate rows (ALT) to increase the spray frequency without increasing the operating cost. Therefore, this work compared the effect of ALT with CONV on the ACP population and HLB incidence. The spray deposition (amount of metallic copper per leaf area), coverage (percentage of water-sensitive paper area covered by spray), and efficacy (ACP mortality) of each treatment were also evaluated on both sides of the trees. Two field trials were performed: Trial #1 compared ALT every 7 days (ALT7) with CONV every 14 days (CONV14), and trial #2 compared different spray frequencies of ALT with CONV every 7 days (CONV7). In trial #1, no differences were observed in the ACP population or HLB progress between ALT7 and CONV14 after 5 years. In trial #2, ALT7 presented the highest percentage of ACP and cumulative HLB incidence than CONV7 and ALT every 3 to 4 days, after 2 years. Hence, when the frequency of ALT was half the frequency of CONV, similar results were observed. Spray deposition, coverage, and efficacy were similar between tree sides in CONV, but they were uneven in ALT, resulting in higher values on the tree side that directly received the spray. Insecticide spray should be performed with the frequency enough to keep new shoot protected during their growth.
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Affiliation(s)
- Isabela V Primiano
- Fundo de Defesa da Citricultura, 316572, Department of Research and Development, Av. Dr. Adhemar Pereira de Barros, 201, Vila Melhado, Araraquara, São Paulo, Brazil, 14807-000;
| | - Jonas Tadeu Barbosa Junior
- Fundo de Defesa da Citricultura, 316572, Department of Research and Development, Araraquara, São Paulo, Brazil;
| | - Renato Beozzo Bassanezi
- FUNDECITRUS, Epidemiology, Av. Dr. Adhemar Pereira de Barros 201, Araraquara, Sao Paulo, Brazil, 14807-040;
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Behlau F, Belasque J, Leite RP, Filho AB, Gottwald TR, Graham JH, Scandelai LHM, Primiano IV, Bassanezi RB, Ayres AJ. Relative Contribution of Windbreak, Copper Sprays, and Leafminer Control for Citrus Canker Management and Prevention of Crop Loss in Sweet Orange Trees. Plant Dis 2021; 105:2097-2105. [PMID: 33373290 DOI: 10.1094/pdis-10-20-2153-re] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The management of citrus canker, caused by Xanthomonas citri subsp. citri, has been widely studied in endemic areas because of the importance of the disease in several citrus-producing countries. A set of control measures is well established, but no study has investigated the efficiency of each measure individually and their combination for disease suppression. This study comprised a 3-year field study to assess the relative contribution of three measures for the control of citrus canker and reduction of crop losses. Windbreak (Wb), copper sprays (Cu), and leafminer control (Lc) were assessed in eight different combinations in a split-split plot design. The orchard was composed of 'Valencia' sweet orange trees grafted onto 'Rangpur' lime. Casuarina cunninghamiana trees were used as Wb. Cu and Lc sprays were performed every 21 days throughout the year. Individually, Cu showed the highest contribution for canker control, followed by Wb. Lc had no effect on reducing citrus canker. Wb+Cu showed the highest efficiency for control of the disease. This combination reduced the incidence of diseased trees by approximately 60%, and the incidence of diseased leaves and fruit by ≥90% and increased the yield in 2.0- to 2.6-fold in comparison with the unmanaged plots. Cu sprays were important for reducing disease incidence and crop losses, whereas Wb had an additional contribution in minimizing the incidence of cankered, non-marketable fruit. The results indicated that the adoption of these measures of control may depend on the characteristics of the orchard and destination of the production.
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Affiliation(s)
- Franklin Behlau
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Araraquara, São Paulo 14807-040, Brazil
| | - José Belasque
- Departamento de Fitopatologia e Nematologia, Escola Superior de Agricultura "Luiz de Queiroz," Universidade de São Paulo, Piracicaba, São Paulo 13416-382, Brazil
| | - Rui P Leite
- Laboratório de Bacteriologia, Instituto de Desenvolvimento Rural do Paraná, Londrina, Paraná 86047-902, Brazil
| | - Armando Bergamin Filho
- Departamento de Fitopatologia e Nematologia, Escola Superior de Agricultura "Luiz de Queiroz," Universidade de São Paulo, Piracicaba, São Paulo 13416-382, Brazil
| | - Timothy R Gottwald
- United States Department of Agriculture, Agricultural Research Service, Fort Pierce, FL 34945, U.S.A
| | - James H Graham
- Citrus Research and Education Center, University of Florida, Lake Alfred, FL 33850, U.S.A
| | - Luis H M Scandelai
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Araraquara, São Paulo 14807-040, Brazil
| | - Isabela V Primiano
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Araraquara, São Paulo 14807-040, Brazil
| | - Renato B Bassanezi
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Araraquara, São Paulo 14807-040, Brazil
| | - Antonio J Ayres
- Departamento de Pesquisa e Desenvolvimento, Fundo de Defesa da Citricultura (Fundecitrus), Araraquara, São Paulo 14807-040, Brazil
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Bassanezi RB, Primiano IV, Moreira AS. Inoculum reduction and vector control on the temporal progress of citrus variegated chlorosis incidence. Pest Manag Sci 2021; 77:3333-3340. [PMID: 33763949 DOI: 10.1002/ps.6377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 02/22/2021] [Accepted: 03/25/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Citrus variegated chlorosis (CVC) is an important citrus disease caused by the sharpshooter-transmitted bacterium Xylella fastidiosa subsp. pauca. Information about the efficacy of its disease management is bounded to either inoculum reduction or vector control. This study aimed to assess the role of different frequencies of roguing of symptomatic trees combined with different chemical control programs for the sharpshooters on CVC temporal progress. The experimental area was set up in October 2005 and had a 3 × 3 factorial design. Symptomatic tree removal intervals were every 28, 56, and 112 days to May 2012. Vector control treatments were no control, program A (PA), and program B (PB). Contact insecticides were sprayed every 28 (PA) or 14 (PB) days. Trees within both programs were treated with systemic and foliar insecticides to October 2008. After this, systemic insecticides were discontinued and only foliar treatments were applied. The number of diseased trees and the sharpshooter population were assessed to April 2015. RESULTS Detection of the first symptomatic trees was similar for all treatments and occurred, on average, in month 50 after planting. Sharpshooter population and cumulative disease incidence were similar for all roguing intervals and between vector control programs, differing in plots with no control. We observed a reduction over 85% in disease incidence for both PA and PB compared with no control. CONCLUSION These results support systematic control of sharpshooters as an efficient strategy for reducing CVC progress. © 2021 Society of Chemical Industry.
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Affiliation(s)
- Renato B Bassanezi
- Research & Development Department, Fund for Citrus Protection - Fundecitrus, Araraquara, Brazil
| | - Isabela V Primiano
- Research & Development Department, Fund for Citrus Protection - Fundecitrus, Araraquara, Brazil
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Pereira WV, Primiano IV, Morales RGF, Peres NA, Amorim L, May De Mio LL. Reduced Sensitivity to Azoxystrobin of Monilinia fructicola Isolates From Brazilian Stone Fruits is Not Associated With Previously Described Mutations in the Cytochrome b Gene. Plant Dis 2017; 101:766-773. [PMID: 30678575 DOI: 10.1094/pdis-09-16-1247-re] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Quinone-outside inhibitor (QoI) fungicides are effective tools for preharvest control of brown rot of stone fruit. These fungicides have a very specific site of action so the risk of resistance selection is high. The sensitivity of Monilinia fructicola (G. Winter) Honey isolates to azoxystrobin (QoI) was investigated in 143 isolates collected between 2002 and 2011 from four Brazilian states in orchards with different frequencies of fungicide use (0 to 6 fungicides sprays/season). Sensitivity of the isolates to azoxystrobin was determined in vitro, by inhibition of mycelial growth and spore germination on fungicide-amended media or ex vivo by pathogen inoculation in untreated or treated fruit with azoxystrobin. Potential mutations in codons 143, 137, and 129 of the cytochrome b (Cyt b) gene and the occurrence of an intron immediately after codon 143 were analyzed in a subpopulation of the isolates. The M. fructicola population of São Paulo State was less sensitive to the fungicide than the population from the states of Paraná, Santa Catarina, and Rio Grande do Sul. The low sensitivity of the isolates was confirmed also by comparing to the sensitivity of the baseline isolates. Mutations in G143A, F129L, and G137R in Cyt b gene were not found. In addition, 58 isolates tested showed an intron after codon 143 in Cyt b gene. Our results indicate that other mechanisms of selection for low sensitivity to QoI fungicides should be investigated.
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Affiliation(s)
- Wagner V Pereira
- Departamento de Fitotecnia e Fitossanitarismo, Universidade Federal do Paraná, R. Funcionários, 1540, 80.035-050, Curitiba, PR, Brazil
| | - Isabela V Primiano
- Departamento de Fitopatologia e Nematologia, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, 13418-900, Piracicaba, SP, Brazil
| | - Rafael G F Morales
- Departamento de Fitotecnia e Fitossanitarismo, Universidade Federal do Paraná, R. Funcionários, 1540, 80.035-050, Curitiba, PR, Brazil
| | - Natalia A Peres
- University of Florida, Gulf Coast Research and Education Center, Wimauma 33598
| | - Lilian Amorim
- Departamento de Fitopatologia e Nematologia, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, 13418-900, Piracicaba, SP, Brazil
| | - Louise L May De Mio
- Departamento de Fitotecnia e Fitossanitarismo, Universidade Federal do Paraná, R. Funcionários, 1540, 80.035-050, Curitiba, PR, Brazil
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