Comparison of Application Methods of Systemic Fungicides to Suppress Branch Cankers in Clementine Trees Caused byPhytophthora citrophthora

Abstract

Since 2002, considerable losses of Clementine trees (Citrus clementina) have been observed in Spain due to Phytophthora branch canker of citrus caused by Phytophthora citrophthora. Due to the low efficiency of the available cultural and genetic control measures, application of fungicides is required for economic management of the disease. Fosetyl-Al, metalaxyl, and its enantiomer mefenoxam are the only systemic fungicides registered for control of Phytophthora diseases in Spain. However, their efficacy has not been tested against Phytophthora branch canker. Greenhouse and field experiments were conducted for 3 years in Spain to evaluate the ability of these fungicides and application methods to reduce lesion expansion. Nevertheless, with the inoculation technique used, it was not possible to evaluate the protective activity of fungicides, which can play an important role in their performance under field conditions. None of the fungicide treatments inhibited lesion expansion when applications were made on a curative basis. The residual effect was better on young than on mature trees. Paint treatments were generally more effective in reducing lesion expansion that drip chemigation or foliar sprays. However, this application method is laborious and becomes uneconomical in Spain. Trunk and branch sprays as well as long-term programs of foliar sprays or drip chemigation for control of spring and autumn infections are proposed as targets for future research.

Biocontrol Endotherapy with Trichoderma spp. and Bacillus amyloliquefaciens against Phytophthora spp.: A Comparative Study with Phosphite Treatment on Quercus robur and Fagus sylvatica

“…The endotherapy experiment confirmed that the inoculation method of P. plurivora was efficient as previous report with P. citrophthora [60]. The curative treatment did not show any significant results, but the preventive application did show promising results for T. atroviride ITEC, which was able to significantly reduce the necrosis size compared to the control and the phosphite treatment.…”

Genetic variation and host specificity of Phytophthora citrophthora isolates causing branch cankers in Clementine trees in Spain

“…Lesion size from branch inoculations with P. citrophthora is in general highly variable (Alvarez et al 2008b). This variability in lesion size accounts for the low r 2 values obtained in the pathogenicity tests.…”

“…Phytophthora branch canker has also been described in the winter rainfall citrus-growing areas of South Africa affecting mainly clementine cultivars (Schutte 2007). In contrast to other Phytophthora diseases, fungicide schedules currently applied in Spain showed a limited degree of control of branch cankers (Alvarez et al 2008b).…”

“…P. parasitica Dastur) have been present for many years in Spain (Fawcett 1936;Urquijo et al 1961;Tuset 1977Tuset , 1983Erwin and Ribeiro 1996). To date, these diseases have been managed effectively through cultural practices and fungicide applications (Tuset 1977(Tuset , 1983Alvarez et al 2008b). However, a new syndrome caused by P. citrophthora was first recorded in Spain in 2002 and, since then, considerable tree losses have been observed (Alvarez et al 2008a(Alvarez et al , b, 2009.…”

Role of the Helix aspersa snail as a vector of Phytophthora citrophthora causing branch cankers on clementine trees in Spain

“…Temperatures in these regions are moderate during these periods of the year, favouring the development of lesions. As a result of the severe tree losses recorded and the limited effectiveness of current strategies for managing the disease (Alvarez et al ., 2008b), this disease causes considerable concern among citrus growers.…”