Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a bacterial disease of citrus and results in peel blemishes rendering fresh fruit unsalable. Xcc is most active in warm, wet Florida summers where tiss...Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a bacterial disease of citrus and results in peel blemishes rendering fresh fruit unsalable. Xcc is most active in warm, wet Florida summers where tissues are infected during periods of active growth. Melanose, caused by Diaporthe citri, is common in citrus producing countries, but, like canker, is only important for fresh market fruit. To control canker and melanose, Florida growers spray trees with copper formulations (Cu), but these sprays are removed by strong rains and intense radiation of Florida summers. A study was undertaken in FL commercial grapefruit groves in 2009 and 2010 to assess the efficiency of a spray combining copper with a specially formulated, hydrating wax (WashGard?) (WG). Using a 21-day spray schedule for the season, fruit were sprayed with WG + Cu, Cu and Control (no spray). Fruit from trees sprayed with WG + Cu had approximately 10 and17% more canker free fruit in 2009 and 2010 respectively compared to trees sprayed with copper alone. Compared to control trees the canker free fruit incidence was increased by ≈10% in 2009 and 57% in 2010. For melanose there was 40% more disease free fruit (treated) over fruit from trees with no treatment in 2009 and approximately 20% more in 2010. Controlling infection with this spray significantly reduces citrus canker and melanose, increasing the percentage of marketable fruit.展开更多
Diaporthe species are important pathogens of a wide range of hosts including many economically important crops.Diaporthe citri is generally accepted to cause melanose of Citrus fruits,leaves and shoots;stem-end rot of...Diaporthe species are important pathogens of a wide range of hosts including many economically important crops.Diaporthe citri is generally accepted to cause melanose of Citrus fruits,leaves and shoots;stem-end rot of fruits and gummosis of perennial branches.In this study,147 strains of Diaporthe were isolated from diseased leaves,twigs,fruits and branches of Citrus from Shaanxi,Zhejiang,Guangxi,Fujian,Guangdong,Jiangxi,Hunan,Chongqing and Shanghai and identified by morphology and molecular analysis of nuclear ribosomal internal transcribed spacer(ITS),partial sequences of translation elongation factor 1-α(EF 1-α),tubulin(TUB)and calmodulin(CAL)genes.All strains from Citrus clustered in three clades.Diaporthe citri was the predominant species and is compared with strains from Florida,USA,where this species was first collected and described.Two new taxa differing from D.citri are described as D.citriasiana and D.citrichinensis in this paper.Inoculation tests indicate that all three species are able to cause stem-end rot of fruits,while only D.citri could cause melanose on leaves.展开更多
文摘Citrus canker, caused by Xanthomonas citri subsp. citri (Xcc), is a bacterial disease of citrus and results in peel blemishes rendering fresh fruit unsalable. Xcc is most active in warm, wet Florida summers where tissues are infected during periods of active growth. Melanose, caused by Diaporthe citri, is common in citrus producing countries, but, like canker, is only important for fresh market fruit. To control canker and melanose, Florida growers spray trees with copper formulations (Cu), but these sprays are removed by strong rains and intense radiation of Florida summers. A study was undertaken in FL commercial grapefruit groves in 2009 and 2010 to assess the efficiency of a spray combining copper with a specially formulated, hydrating wax (WashGard?) (WG). Using a 21-day spray schedule for the season, fruit were sprayed with WG + Cu, Cu and Control (no spray). Fruit from trees sprayed with WG + Cu had approximately 10 and17% more canker free fruit in 2009 and 2010 respectively compared to trees sprayed with copper alone. Compared to control trees the canker free fruit incidence was increased by ≈10% in 2009 and 57% in 2010. For melanose there was 40% more disease free fruit (treated) over fruit from trees with no treatment in 2009 and approximately 20% more in 2010. Controlling infection with this spray significantly reduces citrus canker and melanose, increasing the percentage of marketable fruit.
基金supported by China Agriculture Research System(CARS-27)Research Programs for Nonprofit Technology and Application of Zhejiang Province,China(2009CB119203)。
文摘Diaporthe species are important pathogens of a wide range of hosts including many economically important crops.Diaporthe citri is generally accepted to cause melanose of Citrus fruits,leaves and shoots;stem-end rot of fruits and gummosis of perennial branches.In this study,147 strains of Diaporthe were isolated from diseased leaves,twigs,fruits and branches of Citrus from Shaanxi,Zhejiang,Guangxi,Fujian,Guangdong,Jiangxi,Hunan,Chongqing and Shanghai and identified by morphology and molecular analysis of nuclear ribosomal internal transcribed spacer(ITS),partial sequences of translation elongation factor 1-α(EF 1-α),tubulin(TUB)and calmodulin(CAL)genes.All strains from Citrus clustered in three clades.Diaporthe citri was the predominant species and is compared with strains from Florida,USA,where this species was first collected and described.Two new taxa differing from D.citri are described as D.citriasiana and D.citrichinensis in this paper.Inoculation tests indicate that all three species are able to cause stem-end rot of fruits,while only D.citri could cause melanose on leaves.
