The effects of inter-crop cultivation Between rows of citrus crop on spreading of Guignardia citricarpa Ascospores and in the citrus black spot occurrence

Abstract

-This study highlighted the effect of planting coast-cross grass and forage peanut cv. Amarilis between rows of Natal oranges on spreading of Guignardia citricarpa ascospores and consequent citrus black spot control. Treatments evaluated were: 1-conventional cultivation, free of fungicides; 2-conventional cultivation, using protective fungicides; 3-inter-crop cultivation of coast-cross grass between rows of citrus crops and; 4-inter-cropping cultivation of forage peanut between the rows of citrus crops. Quest Volumetric Spore System TM traps were set in order to determine the number of ascospores released. A total of 33 inspections were conducted weekly, from the end of August until early September the following year. A diagrammatic scale was used to determine the severity of the disease as well as the percentage of fruits having a commercial standard. The coast-cross grass was more effective in reducing the number of ascospores produced, whose average statistics were lower than in the conventional treatments, free-fungicides. The intercrop and conventional cultivation method coupled with fungicide treatment was more effective in reducing the severity of citrus black spot symptoms, and differs statistically from the fungicide-free control method. These methods also resulted in a higher percentage of fruits of a commercial standard, ranging from the 89% through the 91% percentile, and the cultivation, free of fungicides, fell within the 73%. Index terms: Citrus sinensis; Cultural control; Phyllosticta citricarpa; Arachys pintoi; Cynodon dactylon EFEITO DE CULTIVOS INTERCALARES NAS ENTRELINHAS DOS CITROS NA LIBERAÇÃO DE ASCÓSPOROS DE Guignardia citricarpa E NA OCORRÊNCIA DA MANCHA PRETA DOS CITROSRESUMO -No presente, foi avaliada a influência do amendoim-forrageiro cv. Amarillis e da gramínea coastcross nas entrelinhas de plantas de laranjeira 'Natal' quanto à produção e liberação de ascósporos de G. citricarpa, e consequente controle da mancha-preta dos frutos cítricos. Os tratamentos avaliados foram: 1-cultivo convencional, sem utilização de fungicidas; 2-cultivo convencional, com utilização de fungicidas; 3-gramínea coastcross, e 4-amendoim forrageiro entre as linhas das plantas. O monitoramento de ascósporos deu-se mediante armadilhas caça-esporos do tipo Quest Volumetric Spore System™. Um total de 33 inspeções foi realizado semanalmente, a partir do final de agosto até início de setembro do ano seguinte. A quantificação da doença deu-se mediante utilização de escala diagramática de notas, sendo também determinada a porcentagem de frutos com padrão comercial. A gramínea coastcross foi o melhor tratamento em reduzir o número de ascósporos liberados, diferindo, estatisticamente, do convencional, porém não dos demais tratamentos. Cultivo intercalar e cultivo convencional associado com aplicações de fungicida foram os mais eficientes quanto à redução da severidade de sintomas da mancha-preta, diferindo do tratamento--testemunha, sem emprego de fungicida. Esses tratamentos foram os que também proporcionara...

Phyllosticta citricarpa and sister species of global importance to Citrus

“…In addition to chemical control, cultural control measures may be used to reduce the amount of P. citricarpa inoculum (Bellotte et al ., , 2013; Schutte and Kotzé, ), such as the removal of leaf litter with machines (Bellotte et al ., ; Scaloppi et al ., ; Spósito et al ., ; Truter, ), the acceleration of leaf litter decomposition with urea, ammonium sulphate, sugarcane bagasse (Bellotte et al ., ; Dewdney et al ., ; Kotzé, ; van Bruggen et al ., ), the mulching with plants that grow between rows of orchards to cover leaf litter (Bellotte et al ., ; Schutte and Kotzé, ), the pruning of dead twigs (Silva et al ., ; Silva‐Junior et al ., ), irrigation and balanced nutrition (Calavan, ; Dewdney et al ., ; Kotzé, ), and the harvesting for optimal fruit quality and prevention of overlapping fruit sets (Kotzé, ; Spósito et al ., , ). Biological control of CBS with fungi, including P. capitalensis , and bacteria have shown inhibitory effect against P. citricarpa in vitro and in vivo (Almeida, ; Kupper et al ., ; Pena et al ., ; Santos et al ., ; Tran et al ., ); however, there is no biocontrol agent that controls CBS with fungicide‐like efficiency under field conditions.…”

Scientific Opinion on the risk of Phyllosticta citricarpa (Guignardia citricarpa) for the EU territory with identification and evaluation of risk reduction options

“…the adoption of drip instead of sprinkler irrigation and the avoidance of citrus mono-cultures; Bellotte et al, 2013); targeted surveys at highrisk nodes in the trade network of fruit and plants for planting; and information campaigns aimed at local growers, stakeholders and the public to raise awareness of the disease and increase the likelihood of implementation of containment and preventative measures. cultural/fungicide control measures in orchards); preventative measures in areas suitable for new infection foci (e.g.…”

“…cultural/fungicide control measures in orchards); preventative measures in areas suitable for new infection foci (e.g. the adoption of drip instead of sprinkler irrigation and the avoidance of citrus mono-cultures; Bellotte et al, 2013); targeted surveys at highrisk nodes in the trade network of fruit and plants for planting; and information campaigns aimed at local growers, stakeholders and the public to raise awareness of the disease and increase the likelihood of implementation of containment and preventative measures. With regard to the fungicide programmes, the results of the meta-analysis (section 3.6.1) indicated that strobilurin fungicides (QoI) and benzimidazoles are the most effective for CBS control, but they are not currently authorised for use in citrus in the EU.…”

Assessment of economic and environmental performance in citrus-based intercropping systems

“…The field studies were carried out from July 2014 to October 2015, in 19 fruit farms whose main crop is citrus, with cropping combinations as presented in Table 2. A system of economic and environmental performance indicators was built following the approach used by Rodrigues et al (2009) for formulating the 'Traditional Agroforestry Performance Indicators System' (TAPIS). Aiming at improving farmers' management capacity (essentially a biophysical efficiency attribute) and fostering sustainability of landholdings (essentially a socioeconomic adequacy attribute), a set of appropriate field measurements was listed and selected to produce coherent indicators, as advocated by several authors (BOCKSTALLER et al 1997;BOSSHARD, 2000;GIRARDIN et al 1999;LEWANDOWSKI et al 1999;RODRIGUES et al, 2010).…”