Soluble and insoluble copper formulations and metallic copper rate for control of citrus canker on sweet orange trees

The management of citrus canker, caused by Xanthomonas citri subsp. citri, has been widely studied in endemic areas due to 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 ~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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Spray Volume and Rate Based on the Tree Row Volume for a Sustainable Use of Copper in the Control of Citrus Canker

Plant Disease ◽

10.1094/pdis-12-19-2673-re ◽

2021 ◽

Vol 105 (1) ◽

pp. 183-192

Author(s):

Franklin Behlau ◽

Fabrício E. Lanza ◽

Marcelo da Silva Scapin ◽

Luis Henrique Mariano Scandelai ◽

Geraldo José Silva Junior

Keyword(s):

Sweet Orange ◽

Metallic Copper ◽

Sustainable Use ◽

Citrus Canker ◽

Tree Canopy ◽

Minimum Threshold ◽

Diseased Fruit ◽

Citrus Orchards ◽

Spray Volume

Copper is the most efficient pesticide for the control of citrus canker (Xanthomonas citri subsp. citri). To mitigate the environmental impacts and costs, the copper sprays in citrus orchards are being optimized based on the tree row volume (TRV). A previous investigation allowed for significant reductions of the spray volume and copper rates. Nevertheless, the results also indicated the need for additional studies. The aim of this work was to assess whether both the spray volume and the metallic copper rate based on the TRV may be further reduced. A field trial was carried out during two seasons in a 3-year-old commercial orchard of Pera sweet orange located in the municipality of Paranavaí, Paraná, Brazil. The volumes of 20 and 40 ml of spray mixture per m3 of the tree canopy were assessed in combination with the metallic copper rates of 10.5, 21.0, 36.8, or 52.5 mg/m3. Disease was measured as the temporal progress of canker incidence on leaves, cumulative dropped fruit with canker, and incidence of diseased fruit at harvest. The quality of sprays was assessed by measuring the copper deposition and leaf coverage. The treatment with the highest citrus canker control for the lowest use of water and copper was the combination of 40 ml and 36.8 mg/m3. Regression analyses indicated that the minimum threshold deposition of copper was ∼1.5 µg Cu2+/cm2 leaf area. In addition, the lowest spray volume and copper rate necessary to achieve this deposition are 35 ml/m3 and 30 mg/m3. The use of 20 ml/m3 did not efficiently control the disease due to the deficient coverage of treated surfaces. This study demonstrated that it is possible to use even lower amounts of copper and water without interfering with the efficiency of control of citrus canker.

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First record of a Hop stunt viroid variant on Nagpur mandarin and Mosambi sweet orange trees on rough lemon and Rangpur lime rootstocks

Plant Pathology ◽

10.1111/j.1365-3059.2005.01194.x ◽

2005 ◽

Vol 54 (4) ◽

pp. 571-571 ◽

Cited By ~ 3

Author(s):

P. Ramachandran ◽

J. Agarwal ◽

A. Roy ◽

D. K. Ghosh ◽

D. R. Das ◽

...

Keyword(s):

Sweet Orange ◽

First Record ◽

Rangpur Lime ◽

Stunt Viroid ◽

Rough Lemon ◽

Hop Stunt Viroid ◽

Orange Trees

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Characteristics of Citrus Canker Lesions Associated with Premature Drop of Sweet Orange Fruit

Phytopathology ◽

10.1094/phyto-04-18-0114-r ◽

2019 ◽

Vol 109 (1) ◽

pp. 44-51 ◽

Cited By ~ 4

Author(s):

Fabrício E. Lanza ◽

Weber Marti ◽

Geraldo J. Silva ◽

Franklin Behlau

Keyword(s):

Sweet Orange ◽

Linear Regression Analysis ◽

Negative Relationship ◽

Citrus Fruit ◽

Citrus Canker ◽

Multiple Linear Regression Analysis ◽

Detachment Force ◽

Fruit Drop ◽

Orange Fruit ◽

The Relationship

During the development of a citrus fruit, many cycles of infection by Xanthomonas citri subsp. citri may occur leading to the development of a range of characteristics of citrus canker lesions scattered across the fruit surface. This study aimed to determine whether the size of the lesions, their distance from the peduncle, and the number and time of appearance of the lesions on fruit of sweet orange were associated with premature fruit drop. A multiple linear regression analysis revealed a negative relationship between the fruit detachment force and the lesion diameter, the proximity of the nearest lesion to the peduncle and the number of lesions. A survival analysis demonstrated that these characteristics significantly influenced the probability and the time that a cankered fruit remained attached to the tree. More than 90% of dropped fruit had large lesions (>5 mm) but not all fruit with large lesions dropped before harvest. Approximately 50% of the harvested fruit had lesions >5 mm. On the harvested fruit remaining on the tree, although large, the lesions had a smaller diameter, were located farther from the peduncle, and were less numerous than those observed on dropped fruit. Small canker lesions neither reduced the detachment force nor the survival of fruit in the tree. The earlier a fruit expressed canker symptoms, the higher the probability the fruit developed large lesions near the peduncle and/or developed lesions in greater numbers. This study provides a better understanding on the relationship between the time of appearance of lesions of citrus canker on fruit and premature fruit drop. This information defines the critical period for fruit protection and may be used to improve disease management.

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Regrowth and flowering in sweet orange after pruning

Australian Journal of Agricultural Research ◽

10.1071/ar9730101 ◽

1973 ◽

Vol 24 (1) ◽

pp. 101 ◽

Cited By ~ 2

Author(s):

GI Moss

Keyword(s):

Sweet Orange ◽

Practical Investigations ◽

Growth Cycle ◽

Growth Cycles ◽

The Third ◽

Second Growth ◽

Subsequent Flowering ◽

Orange Trees ◽

Practical Implications ◽

Cool Conditions

Sweet orange trees, cv. Late Valencia, 6 m in height were moderately pruned in the spring of 1969, up to 8 % of the canopy being removed. Over 2 years, three or four growth cycles were completed. The amount of regrowth was correlated with the size of the first growth cycle flush after pruning, and this was correlated with the diameter of the pruned branch. No flowers were found on regrowths 1 year after pruning; only 75% of regrowths produced flowers 2 years after pruning, and only 50 % produced fruit. Small plants (rooted cuttings) were used to investigate pruning responses in the phytotron. Low temperatures (18/13�C) immediately after pruning for 8 weeks resulted in smaller first growth cycle flushes after pruning, and even after transfer to warm (27/22�) conditions the original height was not regained after three growth cycles. Plants that received cool conditions after the first or second growth cycles regained their original height after the third growth cycle. The amount of regrowth was correlated with the length of the first growth cycle flushes, which was correlated with the original height of the plants and the height after pruning. Flowers could not be induced on the old wood after pruning or on the first growth cycle flushes, and only few flowers were formed in the second growth cycle flushes. Many inflorescences were produced on third growth cycle flushes following inductive conditions (18/13�C) for 8 weeks. Light pruning of less vigorous plants did not inhibit subsequent flowering. The practical implications of this work are discussed. Moderate pruning will remove part of two crops, not one, because of the inability of regrowth flushes to flower until several growth cycles have formed. The tree relatively quickly replaces the growth removed, and this depends on the vigour of the first growth cycle flushes after pruning. Pruning in autumn or winter would be expected to result in less vigorous regrowth. Our lack of knowledge on the pruning responses of orange trees is emphasized, with suggestions for future practical investigations.

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Accumulation and Metabolism of Bromacil in Pineapple Sweet Orange (Citrus sinensis) and Cleopatra Mandarin (Citrus reticulata)

Weed Science ◽

10.1017/s0043174500025716 ◽

1981 ◽

Vol 29 (1) ◽

pp. 1-4 ◽

Cited By ~ 6

Author(s):

L. S. Jordan ◽

W. A. Clerx

Keyword(s):

Citrus Sinensis ◽

Sweet Orange ◽

Citrus Reticulata ◽

Minor Metabolite ◽

A Minor ◽

Orange Trees ◽

Conjugated Metabolites ◽

Cleopatra Mandarin

Young orange [Citrus sinensis (L.) Osbeck ‘Pineapple sweet orange’] trees are more sensitive to bromacil (5-bromo-3-sec-butyl-6-methyluracil) than young mandarin (Citrus reticulata Blanco ‘Cleopatra mandarin’) trees. Pineapple sweet orange roots absorbed twice as much 14C from bromacil, and accumulated three times as much in the leaves, as did Cleopatra mandarin. The amount of conjugated metabolites formed was the same in the roots of the two cultivars, but twice as much formed in the leaves of Cleopatra mandarin as in the leaves of Pineapple sweet orange. The principle metabolite was 5-bromo-3-sec-butyl-6-hydroxymethyluracil; a minor metabolite was tentatively identified as 5-bromo-3-(3-hydroxyl-1-methylpropyl)-6-methyluracil. No 5-bromouracil was detected. Citrus cultivars differ in their ability to accumulate and metabolize bromacil into conjugated nonphytotoxic compounds.

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Citrus tristeza virus infection in sweet orange trees and a mandarin × tangor cross alters low molecular weight metabolites assessed using gas chromatography mass spectrometry (GC/MS)

Metabolomics ◽

10.1007/s11306-016-0959-z ◽

2016 ◽

Vol 12 (3) ◽

Cited By ~ 6

Author(s):

Alberto Pasamontes ◽

William H. K. Cheung ◽

Jason Simmons ◽

Alexander A. Aksenov ◽

Daniel J. Peirano ◽

...

Keyword(s):

Mass Spectrometry ◽

Molecular Weight ◽

Gas Chromatography ◽

Virus Infection ◽

Citrus Tristeza Virus ◽

Sweet Orange ◽

Gas Chromatography Mass Spectrometry ◽

Low Molecular Weight ◽

Orange Trees ◽

Tristeza Virus

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EVALUATION OF SUSCEPTIBILITY OF 'PERA' SWEET ORANGE GENOTYPES TO CITRUS CANKER UNDER FIELD AND GREENHOUSE CONDITIONS

Acta Horticulturae ◽

10.17660/actahortic.2015.1065.62 ◽

2015 ◽

pp. 511-516

Author(s):

Aline M.O. Gonçalves-Zuliani ◽

William M.C. Nunes ◽

Carlos A. Zanutto ◽

José Croce Filho ◽

Paula T.R. Nocchi

Keyword(s):

Sweet Orange ◽

Citrus Canker

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Increased Resistance Against Citrus Canker Mediated by a Citrus Mitogen-Activated Protein Kinase

Molecular Plant-Microbe Interactions ◽

10.1094/mpmi-04-13-0122-r ◽

2013 ◽

Vol 26 (10) ◽

pp. 1190-1199 ◽

Cited By ~ 15

Author(s):

Maria Luiza Peixoto de Oliveira ◽

Caio Cesar de Lima Silva ◽

Valéria Yukari Abe ◽

Marcio Gilberto Cardoso Costa ◽

Raúl Andrés Cernadas ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Sweet Orange ◽

Plant Immunity ◽

Gene Promoter ◽

Citrus Canker ◽

Hypersensitive Reaction ◽

Mitogen Activated Protein Kinase ◽

Defense Gene Expression ◽

Defense Gene ◽

Mitogen Activated Protein

Mitogen-activated protein kinases (MAPK) play crucial roles in plant immunity. We previously identified a citrus MAPK (CsMAPK1) as a differentially expressed protein in response to infection by Xanthomonas aurantifolii, a bacterium that causes citrus canker in Mexican lime but a hypersensitive reaction in sweet oranges. Here, we confirm that, in sweet orange, CsMAPK1 is rapidly and preferentially induced by X. aurantifolii relative to Xanthomonas citri. To investigate the role of CsMAPK1 in citrus canker resistance, we expressed CsMAPK1 in citrus plants under the control of the PR5 gene promoter, which is induced by Xanthomonas infection and wounding. Increased expression of CsMAPK1 correlated with a reduction in canker symptoms and a decrease in bacterial growth. Canker lesions in plants with higher CsMAPK1 levels were smaller and showed fewer signs of epidermal rupture. Transgenic plants also revealed higher transcript levels of defense-related genes and a significant accumulation of hydrogen peroxide in response to wounding or X. citri infection. Accordingly, nontransgenic sweet orange leaves accumulate both CsMAPK1 and hydrogen peroxide in response to X. aurantifolii but not X. citri infection. These data, thus, indicate that CsMAPK1 functions in the citrus canker defense response by inducing defense gene expression and reactive oxygen species accumulation during infection.

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