Dispersal and plant arrangement condition the timing and magnitude of coffee rust infection

Cauwelaert, Emilio Mora Van; González, Cecilia; Boyer, Denis; Hajian‐Forooshani, Zachary; Vandermeer, John; Benítez, Mariana

doi:10.1016/j.ecolmodel.2022.110206

Cited by 4 publications

(9 citation statements)

References 38 publications

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“…Concerning the CLR impact, we found that increasing the planting density where only contact-mediated dispersal was present increases the final CLR at the plot level. This is in line with other studies (Hajian-Forooshani and Vandermeer, 2021; Zambolim, 2016; Mora Van Cauwelaert, et al 2023) and emphasizes planting at lower densities to avoid big bursts of the pathogen (Ehrenbergerová et al, 2018). The harvest event magnifies the final CLR infection for all scenarios and densities.…”

Section: Discussionsupporting

confidence: 93%

“…We start the simulations with a small percentage of infected plants (T0 in Fig.1A) and run five cycles of contact-mediated dispersal and infection (these five cycles mimic the five months from the beginning of CLR buildup to the peak of harvesting; Mora Van Cauwelaert et al, 2023). At the time of harvest (TH = 5 time steps) almost all the plants in the same contact-mediated networks with one or more initially infected plants are infected (gray circles in Fig.…”

Section: Methodsmentioning

confidence: 99%

“…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). At the plot scale, this relates to the fact that some foci of infection occur close to harvesting paths and human settlements (Waller, 1982, 1972) and that the build-up of the epidemic correlates with the harvesting season (Avelino et al, 1993, 1991; Mora Van Cauwelaert et al, 2023). However, it is unclear how relevant the dispersal by harvesters is for the whole epidemic in contrast to other modes of dispersal, and what agroecological measures could be implemented to reduce its impact.…”

Section: Introductionmentioning

confidence: 99%

“…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).…”

Section: Introductionmentioning

confidence: 99%

“…& 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).…”

Section: Introductionmentioning

confidence: 99%

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

Van Cauwelaert,

Li,

Hajian-Forooshani

et al. 2023

Preprint

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Coffee leaf rust (CLR; Hemileia vastatrix) is one of the principal coffee diseases and has caused devastating loss of production around the globe. This fungus disperses between plants or regions through direct contact, water splash, or local turbulent wind conditions. Some studies have proposed that coffee harvesters can also bear CLR during harvesting. Their different trajectories depend on management and coffee plant characteristics, like the planting density or the ripening synchronicity, but also on the social organization of the plantation. However, it is not clear how relevant these movements are for CLR dispersal and plot-level infection in plots with other modes of CLR dispersal and different planting densities. Here we present a qualitative computational model to explore the role of coffee ripening synchronicity and the number of workers per plot in reproducing the different movement trajectories observed in the field. We then evaluate how these trajectories modify rust dispersal and change CLR infection in plots with increasing planting densities. We found that interplant asynchronous ripening and tree scarcity generate trajectories with long steps. In our model, the number of workers does not modify the trajectories. The harvest dispersal significantly increases coffee plot infection (up to 15%) compared to scenarios where only local mechanisms for CLR dispersal (contact-mediated or splash) are present. This effect is maximal for trajectories with long steps and in plantations with medium planting densities. At larger planting densities, plants are all already infected due to the local CLR dispersal. Our results aim to spur discussion on practices that could reduce the impact of harvesting and specific trajectories, in scenarios where one can benefit from asynchronous maturation of berries and shaded plantations. Some examples of practices include reducing the long-distance movements during the same day, for instance, by avoiding harvesting at the end of the harvest season when trees ripening asynchronicity and CLR levels are higher.

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Section: Discussionsupporting

confidence: 93%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Van Cauwelaert,

Li,

Hajian-Forooshani

et al. 2023

Preprint

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

Hajian‐Forooshani

Vandermeer

et al. 2023

J Plant Pathol

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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.

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Spatial trajectories of coffee harvesting in large-scale plantations: ecological and management drivers and implications

Van Cauwelaert,

Boyer,

Jiménez-Soto

et al. 2023

Preprint

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0.AbstractCoffee is produced under different management systems and scales of production, which can be categorized as Syndromes of Production. The “Capitalist Syndrome” is characterized by a high use of inputs such as capital and labor to increase agricultural outputs. This syndrome results in practices like high planting density, that may promote the development and dispersal of important diseases like the coffee leaf rust (CLR). The arrangement of plants can drive the spatial movement of the harvesters, who can bear and disperse CLR across and within plantations. Furthermore, in most capitalist coffee plantations, harvesters work multiple hours to maximize the daily harvest, which might increase CLR dispersal. However, their spatial movement has not yet been described, nor its relationship with the scale or management of the plantation, and even less its ecological implications for CLR dispersal. We present a description and qualitative analysis of the daily spatial movement of harvesters in two large-scale capitalist coffee plantations: an organic and a conventional plantation. Using state-space models, we recorded and analyzed the spatial movements of harvesters. We then constructed a driver tree for harvest dynamics, which incorporated qualitative variables related to climate, coffee plants, and management aspects reported by the harvesters. Our model differentiated two kinds of movements: 1) when trees have berries, harvesters remain in the same rows or areas nearby (Collect state; 94-98% of the steps); 2) when not, harvesters make longer steps within the harvesting zone or move to another area (Search state; 2-6% of the steps). In the organic plantation, the Search state had a longer tailed step-length distribution than in the conventional plantation, resulting in a significantly higher visited area per worker (p<0.05). This might be related to a) a lower fruit load or percentage of trees with ripe fruits when we took the data or b) smaller harvesting locations (“pantes”) per number of harvesters. Harvesting movements that explore a wider area, either by visiting more plants or by changing locations on the same day, could create more foci of CLR infection across the plantation. To reduce the possible impact of human dispersal of pathogens, we suggest shorter trajectories by working fewer hours a day or avoiding harvesting at the end of the maturation season when few trees have berries and harvesters have to travel longer distances. This calls for an organic coffee management that could prevent diseases, increase diversity, and guarantee just and safe conditions for workers.

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Dispersal and plant arrangement condition the timing and magnitude of coffee rust infection

Cited by 4 publications

References 38 publications

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

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

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

Spatial trajectories of coffee harvesting in large-scale plantations: ecological and management drivers and implications

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