Effects of Fungicide Treatments for the Control of Epidemic and Exotic Calonectria Diseases in Italy

Abstract

Aiello, D., Cirvilleri, G., Polizzi, G., and Vitale, A. 2013. Effects of fungicide treatments for the control of epidemic and exotic Calonectria diseases in Italy. Plant Dis. 97:37-43.The efficacy of 11 fungicides was evaluated for the control of Calonectria infections on bottlebrush (Callistemon "Masotti") and feijoa (Acca sellowiana), with special emphasis on Calonectria pauciramosa and C morganii, which are the most destructive species in Italian ornamental nurseries. Three nursery experiments were performed with the selected fungicides in order to determine their ability to prevent leaf spot caused by C. morganii on bottlebrush and leaf spot and crown and root rot caused by C. pauciramosa on bottlebrush and feijoa. All fungicides were effective in reducing disease infections, except for cyproconazole, propamocarb + fosetyl-Al, and K phosphite that were the least effective in reducing C. morganii leaf spot. In contrast, K phosphite proved more effective in reducing crown and root rot caused by C. pauciramosa. Fungicides were also evaluated in growthcabinet experiments for their ability to reduce incidence and severity of leaf spot on bottlebrush caused by the exotic pathogens C. pseudomexicana, C tunisiana, C. pollzzii, and C. mexicana. Copper hydroxide, fosetyl-Al, prochloraz, prochloraz + cyproconazole, and tebuconazole were always effective in reducing Calonectria leaf spot on bottlebrush. However, some differences in levels of control might be attributable to Calonectria isolate. Overall, this study clearly indicates that new fungicides can be employed for chemical management of Calonectria infections in ornamental nurseries.

Emergence of Prochloraz-Resistant Populations ofCalonectria pauciramosaandCalonectria polizziiin Ornamental Nurseries of Southern Italy

“…infections, as confirmed by our in vivo experiments. For example, antiresistance strategies could include the use of copper compounds, phosphonate, and quinone outsideinhibitor fungicides that showed good activity in controlling Calonectria diseases (1). The lack of prochloraz efficacy in controlling Calonectria diseases could be avoided by increasing the fungicide rate (6,14), because a small shift in reduced sensitivity to prochloraz over time was detected in this study.…”

“…This article helps explain the variations in field efficacy of prochloraz against Calonectria diseases in Italy since the mid-2000s (1,51,66), and worldwide (5,8,23,33,37). Calonectria populadons in nurseries of Southern Italy have altered toward resistance to prochloraz.…”

“…However, as decrease in prochloraz-sensitivity within Calonectria populations occurs, prochloraz may not be able to provide an adequate control of Calonectria spp. infections in ornamental nurseries (1). Therefore, the emergence of resistant populations could result in heavy losses in ornamental production which can occur more frequetitly if prochloraz is ap- plied alone.…”

“…Prochloraz (IUPAC name; Af-propyl-A'-[2-(2,4,6trichlorophenoxy)ethyl]imidazole-l-carboxaniid), an imidazole member of the DMIs, has been used successfully worldwide against various plant pathogens (17,21,28,60). Recent surveys in the same areas, however, revealed that prochloraz treatments produce variable disease control efficacy (1). This compound, although with poor systemic activity and short-term effects (24), was effective in controlling Calonectria diseases in southern Italy when it was used on a large scale (43,51), thus confirming previous data on its effectiveness (8,33,37).…”

Two novel species of Calonectria isolated from soil in a natural forest in China

“…Calonectria species include many notorious plant pathogens and are widely distributed in tropical and subtropical areas of the world (Crous 2002, Lombard et al 2010d, Aiello et al 2013, Alfenas et al 2015. These species can cause serious plant epidemics on a wide range of plant hosts (Peerally 1991, Crous 2002, and result in considerable economic losses to agriculture and forestry.…”