Premium
Temporal patterns of citrus greasy spot‐induced defoliation of sweet orange cultivars in Brazil
Author(s) -
Silva S.X.B.,
Soares A.C.F.,
Almeida D.O.,
SantosFilho H.P.,
Laranjeira F.F.
Publication year - 2015
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/aab.12208
Subject(s) - biology , pathosystem , cultivar , orange (colour) , canopy , horticulture , citrus × sinensis , agronomy , botany , inoculation
Recôncavo Baiano is an area favourable for the occurrence of citrus greasy spot ( CGS ) ( Mycosphaerella citri ), but there has been no study of this pathosystem in Brazil. This work aimed to characterise the temporal patterns of CGS ‐induced defoliation in sweet orange cultivars ‘Bahia’ (Washington Navel) and ‘Pêra’. Temperature, rainfall and relative humidity were recorded, as well as weekly defoliation (fallen leaves/canopy m 2 or m 3 ). Considering the mean of fallen leaves per canopy m 2 , and mean canopy area, the total annual defoliation was estimated to be around 32 000 leaves per plant for ‘Bahia’ and 18 500 for ‘Pêra’ sweet orange. Spectral density analysis showed that defoliation has a 5‐week‐long main cycle for both cultivars. The proportion of symptomatic fallen leaves was never below 0.97. The monthly number of fallen leaves per canopy area was positively correlated with the mean CGS incidence on leaves. Defoliation was significant, resulting in a low leaf density throughout the year. Many defoliation cycles and the very high proportion of symptomatic fallen leaves assure a constant inoculum supply. Based on these results, CGS cannot be considered a minor disease, at least in Recôncavo Baiano.