The Effect of Various Fungicides on Leaf Rust, Leaf Retention and Yield of Coffee

Dispersal and Plant Arrangement Condition the Timing and Magnitude of Coffee Rust Infection

“…Besides, Boudrot et al (2016) and Gagliardi et al, (2020) reported that the functional traits of plants related to shade (foliage density, shade percentage) modify the relative importance of wind and rainfall in uredospore dispersal across the plot. Understanding the role of the initial infection and dispersal rate on the time lag is also relevant for rust-control procedures that rely heavily on the timing of the epidemic, such as pruning, management of shade (Boudrot et al, 2016; Liebig et al, 2019; Soto-Pinto et al, 2000), or fungicide application (Burdekin, 1964; Mulinge and Griffiths, 1974). Additionally, the leaf-fall rate of infected leaves can also be modified with management practices but may have an ambiguous effect on the maximum infection: on the one hand, farmers could decrease the maximum infection by removing and bagging away the infected leaves continuously (thus decreasing the source of new reinfections from infected leaves either on the ground or in the plant system); but on the other hand, due to the farmers’ movement between the trees, removing the leaves could trigger the dispersal of uredospores by contact and further propagate the epidemic.…”

“…leaf production and leaf-fall rate of susceptible leaves) is represented by the so-called monomolecular growth (Cunniffe and Gilligan, 2010) , where the natural (or non-infected) leaf-fall rate is represented by ρ and leaf production rate is equivalent to Kρ where K is the carrying capacity of susceptible leaves. We took K = 1 for simplicity but our results can be rescaled by using reported values for K (Burdekin, 1964). This assumes that the new leaf production rate equals the leaf-fall rate of susceptible leaves.…”

“…One central issue in coffee rust epidemiology is to understand what determines the intensity of a one-year infection (Avelino et al, 2006; Gagliardi et al, 2020; Kushalappa and Eskes, 1989, Motisi et al, 2022). Similarly, many epidemiologists have sought to estimate the time to maximum infection for the design of specific control practices (Ananth, 1969; Burdekin, 1964). Both questions have been studied within the “disease triangle” framework (Stevens, 1960).…”

“…Intuitively higher local dispersal should lead to more severe epidemics in a plot. However, despite the importance of a nuanced understanding of rust epidemic dynamics within plots, most empirical studies on coffee rust epidemics report rust prevalence in terms of averages within a plot and not on individual trees (Bock, 1962a;Burdekin, 1964) . This method reduces the sampling errors and smooths the epidemic curves but may obscure the relationship between plant and plot dynamics mediated by dispersal.…”

Método de amostragem para a avaliação do índice de infecção da ferrugem do cafeeiro (>i<Hemileia vastatrix>/i< Berk. e Br.)

“…A técnica da amostragem por ramos marcados foi desenvolvida por TAPLEY (citação de BURDEKIN, 1964),em Lyamu� ku, Tanganyika, para a avaliação da incidência do "bicho minei ro", de ferrugens e de outras doenças. Consiste na marcaçao de um ramo primário, ao acaso, por planta, no qual são conta das as folhas de dez nós (contados a partir da extremidade do e o lote i de queijos; l q.. e o queijo j no lote i lJ e a amostra k , no queijo j, do lote i.…”