Coffee leaf rust (Hemileia vastatrix) is spread by rain splash from infected leaf litter in a semi-controlled experiment

Abstract

The coffee leaf rust disease (CLR), caused by the fungus Hemileia vastatrix, is an economically significant phytopathogen of cultivated Coffea species. Since coffee plants with CLR drop their infected leaves, rain splash from infected leaf litter could be one way H. vastatrix spores are dispersed, but this mechanism has not been demonstrated. Here we experimentally verify that splash from leaf litter can lead to H. vastatrix dispersal and infection. In a semi-controlled experiment, we compared the infection rates of pairs of potted uninfected, susceptible C. arabica plants with leaf litter that was either infected with CLR (experimental treatment) or without CLR (control). Plants with CLR litter became infected sooner than control plants by a median difference of 2.5 weeks. On average, CLR litter treatment plants had 18% of their leaves infected, while control plants had 9% of leaves infected, though later patterns could reflect leaf turnover and reinfection. Future research should investigate the dynamics of leaf litter splash for CLR in the field. Possible management measures to limit the effect of splash from leaf litter could include planting cover crops or restoring natural groundcover, techniques known to provide additional benefits as understood in general practices of agroecology.

Revolutionizing Coffee Farming: A Mobile App with GPS-Enabled Reporting for Rapid and Accurate On-Site Detection of Coffee Leaf Diseases Using Integrated Deep Learning

“…As the disease advances, it impairs the plant's photosynthetic capabilities, potentially affecting its overall health and yield. Severe infections can stunt coffee plant growth, impacting both the quantity and the quality of coffee beans [12][13][14][15][16][17].…”

Interplay between harvesting, planting density and ripening time affects coffee leaf rust dispersal and infection

“…The urediniospores may also ascend to the atmosphere and travel to other plantations (Becker and Kranz, 1977;Vandermeer and Rohani, 2014). For each of these ways of dispersal, there are agroecological management proposals to reduce the spread, like reducing the density or clustering of the plantations (Beasley et al, 2022;Ehrenbergerová et al, 2018), avoiding regular or extremely dense patterns that can make the epidemic thrive through contact or splash-mediated dispersal (Hajian-Forooshani and Vandermeer, 2021;Mora Van Cauwelaert et al, 2023a;Li et al, 2023), but also planting different trees within the plots and in the borders to reduce local and regional wind dispersal (Avelino et al, 2022;Boudrot et al, 2016;Gagliardi et al, 2020) It has been observed that workers can also disperse CLR within the plot and between regions (Becker and Kranz, 1977;Ramírez-Camejo et al, 2022;Schieber and Zentmyer, 1984).…”

“…& Br is one of the principal coffee diseases and has caused devastating loss of production in different coffee sites around the globe (McCook and Vandermeer, 2015; Talhinhas et al, 2017). Its mechanisms for dispersal have been amply studied (Becker and Kranz, 1977; Kushalappa and Eskes, 1989; Li et al, 2023; Vandermeer et al, 2018) and thus provide a great model to explore the disease’s spatially explicit dynamics and its relations with the host’s spatial arrangement and density (Beasley et al, 2022; Gagliardi et al, 2020; Hajian-Forooshani and Vandermeer, 2021; Mora Van Cauwelaert et al, 2023a). CLR forms urediniospores that can travel to neighboring coffee plants through direct contact, water splash, or local turbulent wind conditions (Kushalappa and Eskes, 1989).…”