Relative Contribution of Windbreak, Copper Sprays, and Leafminer Control for Citrus Canker Management and Prevention of Crop Loss in Sweet Orange Trees

Abstract

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.

The Perfect Match: Adjusting High Tree Density to Rootstock Vigor for Improving Cropping and Land Use Efficiency of Sweet Orange

“…Over the evaluation period (four harvests), there was no relevant influence of tree density on the fruit quality, except by the trend to decrease the FW and the MI, but increase soluble solids and acidity, which was similar to previous reports in the USA [14,15]. Recently, there is an increasing concern in the Brazilian citrus industry about a notable reduction in the industrial index in the last years [68], which has been partially attributed to the increased tree density after HLB was first reported [10]. This belief is not supported by our data so far; in fact, we observed an opposite effect, as there was some improvement in the fruit quality parameters at higher tree densities.…”

“…The production efficiency over the evaluation period was estimated as a function of the tree row volume occupation (PEV) and area index (PEA) per hectare before pruning by Equations ( 9) and (10), respectively:…”

“…and Sunki mandarin [C. sunki (Hayata) hort. ex Tanaka] rootstocks [5,6]; better soil and nutrition management and use of cover crops [7,8]; improvements in pest and disease management that decrease spread rates and crop losses [9][10][11][12][13]; the expansion in the use of drip irrigation on about one third of the harvested area [14,15]; and the profile of the citrus farms, with those cultivating more than 200,000 trees responding for most production, which have been migrating to southern areas with milder climate and lower HLB incidence in the citrus belt of São Paulo, Paraná and Minas Gerais States [14,16,17]. In addition, the average tree density in the citrus belt increased from 370 to 564 trees per hectare in the 2000-2020 period [14].…”

A Fluorescent Reporter-Based Evaluation Assay for Antibacterial Components Against Xanthomonas citri subsp. citri

“…Citrus-producing regions without CBC rely mainly on quarantine measures to keep the groves free of Xcc . Windbreaks also have a positive control effect on CBC by reducing wounds ( Behlau et al, 2021a ). Diverse and integrated disease control can reduce the risk of the application of copper-based bactericides during CBC control and management, but chemical control is still the primary method for preventing Xcc worldwide.…”

Late-Season Sweet Orange Selections Under Huanglongbing and Citrus Canker Endemic Conditions in the Brazilian Humid Subtropical Region

“…In the last decades, advanced cultural practices in the citrus industry have been of utmost importance for Brazil to maintain the leadership in the global sweet orange production (FAO, 2019;Carvalho et al, 2019a;Bassanezi et al, 2020). These practices include irrigation, fertilization, high tree density, pest and disease controls, and planting of citrus cultivars that are more productive and adapted to a wide range of environmental conditions (Carvalho et al, 2019a;Bassanezi et al, 2020;Behlau et al, 2021;Girardi et al, 2021). The presence and progression of citrus diseases in orchards are frequent under the humid subtropical climate (Bassanezi et al, 2020;Carvalho et al, 2021a).…”