Abstract:First Report of black-sigatoka in the State of Minas Gerais, BrazilBack-sigatoka caused by Mycosphaerella fijiensis is the most economically important disease of banana (Musa spp.) and plantain. Mycosphaerella fijiensis causes early defoliation resulting in yield losses of about 100% in common bananas such as Prata, Prata Anã and Cavendish cultivars. Black-sigatoka has been occurring in the State of Minas Gerais since July 2004.A sigatoka-negra causada por Mycosphaerella fijiensis Morelet anormorfo Paracercosp… Show more
“…We set the PDD value to enable P . fijiensis to persist in known locations in Brazil [2], and the relatively wide range over which this value was tested (880–1320 degree-days) only has a small impact (0.42%), giving us confidence that our value need only be approximately correct for the model results to remain stable. All other parameter values have a 0.3% or less sensitivity to the modelled range, which is negligible.…”
Section: Discussionmentioning
confidence: 99%
“…The current CLIMEX model presently ignores such biotic interactions, and projects the highlands of Cameroon to be climatically suitable, since attempting to model the highlands of Cameroon as unsuitable conflicts with knowledge of the distribution of P . fijiensis in tropical highland regions of Brazil [2]. With more data for locations where both pathogens co-exist, it would be possible to use the 2-species interaction model in CLIMEX to examine the relative suitability of locations for each of the species, and to explicitly examine competition between them [23].…”
Section: Discussionmentioning
confidence: 99%
“…In Brazil, P . fijiensis occurs in the municipalities of Cristina (altitude between 950 m and 1 500 m), São Jose do Alegre (altitude between 800 m and 900 m), Gonçalves (altitude between 1 200 m and 1 400 m) and Piranguçu (altitude between 860 m and 940 m) [2]. As we geo-coded these locations at town centres, and we do not know exactly where the sampling was conducted, we need to ensure that the area around these location records is suitable.…”
Black leaf streak disease, or black Sigatoka, is caused by the fungus
Pseudocercospora fijiensis
, and has been identified as a major constraint to global production of banana and plantain. We fitted a climatic niche model (CLIMEX) for
P
.
fijiensis
to gain an understanding of the patterns of climate suitability, and hence hazard from this disease. We then calibrated the climate suitability patterns against the results of an expert elicitation of disease pressure patterns. We found a moderately strong non-linear relationship between modelled climate suitability for
P
.
°fijiensis
and the expert ratings for disease pressure. The strength of the relationship provides a cross-validation between the CLIMEX model and the expert elicitation process. The bulk of global banana production experiences high potential threat from
P
.
fijiensis
, and the higher yielding areas for banana and plantain production are at greatest threat. By explicitly considering the role of irrigation we have been able to identify how strategic irrigation could be used to support banana production in areas that are at low risk from
P
.
fijiensis
.
“…We set the PDD value to enable P . fijiensis to persist in known locations in Brazil [2], and the relatively wide range over which this value was tested (880–1320 degree-days) only has a small impact (0.42%), giving us confidence that our value need only be approximately correct for the model results to remain stable. All other parameter values have a 0.3% or less sensitivity to the modelled range, which is negligible.…”
Section: Discussionmentioning
confidence: 99%
“…The current CLIMEX model presently ignores such biotic interactions, and projects the highlands of Cameroon to be climatically suitable, since attempting to model the highlands of Cameroon as unsuitable conflicts with knowledge of the distribution of P . fijiensis in tropical highland regions of Brazil [2]. With more data for locations where both pathogens co-exist, it would be possible to use the 2-species interaction model in CLIMEX to examine the relative suitability of locations for each of the species, and to explicitly examine competition between them [23].…”
Section: Discussionmentioning
confidence: 99%
“…In Brazil, P . fijiensis occurs in the municipalities of Cristina (altitude between 950 m and 1 500 m), São Jose do Alegre (altitude between 800 m and 900 m), Gonçalves (altitude between 1 200 m and 1 400 m) and Piranguçu (altitude between 860 m and 940 m) [2]. As we geo-coded these locations at town centres, and we do not know exactly where the sampling was conducted, we need to ensure that the area around these location records is suitable.…”
Black leaf streak disease, or black Sigatoka, is caused by the fungus
Pseudocercospora fijiensis
, and has been identified as a major constraint to global production of banana and plantain. We fitted a climatic niche model (CLIMEX) for
P
.
fijiensis
to gain an understanding of the patterns of climate suitability, and hence hazard from this disease. We then calibrated the climate suitability patterns against the results of an expert elicitation of disease pressure patterns. We found a moderately strong non-linear relationship between modelled climate suitability for
P
.
°fijiensis
and the expert ratings for disease pressure. The strength of the relationship provides a cross-validation between the CLIMEX model and the expert elicitation process. The bulk of global banana production experiences high potential threat from
P
.
fijiensis
, and the higher yielding areas for banana and plantain production are at greatest threat. By explicitly considering the role of irrigation we have been able to identify how strategic irrigation could be used to support banana production in areas that are at low risk from
P
.
fijiensis
.
A thorough assessment of the distribution of Mycosphaerella spp. associated with banana in Minas Gerais State, Brazil, was conducted after Mycosphaerella fijiensis was first reported to occur in this region in 2005. From 2009 to 2011, 80 fields located in 20 municipalities including the same fields where the disease was first reported were sampled. A total of 800 samples of leaf tissue with symptoms similar to those of yellow or black Sigatoka diseases were examined, and 239 isolates were obtained. The identification of the fungi was based on morphological characters combined with DNA sequences obtained after amplification with species-specific primers and phylogeny inferred from the internal transcribed spacer region of Mycosphaerella strains from banana. All 239 isolates were identified as Mycosphaerella musicola. The absence of M. fijiensis in the samples may have been due to misidentification of M. fijiensis or the displacement of M. fijiensis by M. musicola. It is now apparent that yellow Sigatoka caused by M. musicola is the prevailing leaf spot disease of bananas in Minas Gerais State and that regulatory/legislative control measures need to be revised based on our findings.
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