Abstract
Moniliophthora Pod Rot (MPR) caused by the fungus Moniliophthora roreri (Cif.) Evans et al., is one of the main limiting factors of cocoa production in Latin America. Currently insufficient information on the biology and epidemiology of the pathogen limits the development of efficient management options to control MPR. This research aims to elucidate MPR development through the following daily microclimatic variables: minimum and maximum temperatures, wetness frequency, average temperature and relative humidity in the highly susceptible cacao clone Pound-7 (incidence = 86% 2008–2013 average). A total of 55 cohorts totaling 2,268 pods of 3–10 cm length, one to two months of age, were tagged weekly. Pods were assessed throughout their lifetime, every one or two weeks, and classified in 3 different categories: healthy, diseased with no sporulation, diseased with sporulating lesions. As a first step, we used Generalized Linear Mixed Models (GLMM) to determine with no a priori the period (when and for how long) each climatic variable was better related with the appearance of symptoms and sporulation. Then the significance of the candidate variables was tested in a complete GLMM. Daily average wetness frequency from day 14 to day 1, before tagging, and daily average maximum temperature from day 4 to day 21, after tagging, were the most explanatory variables of the symptoms appearance. The former was positively linked with the symptoms appearance when the latter exhibited a maximum at 30°C. The most important variables influencing sporulation were daily average minimum temperature from day 35 to day 58 and daily average maximum temperature from day 37 to day 48, both after tagging. Minimum temperature was negatively linked with the sporulation while maximum temperature was positively linked. Results indicated that the fungal microclimatic requirements vary from the early to the late cycle stages, possibly due to the pathogen’s long latent period. This information is valuable for development of new conceptual models for MPR and improvement of control methods.
Highlights
Cacao (Theobroma cacao) diseases are the main threat for production, causing losses estimated at 30 to 40% worldwide [1]
This study aims to apply advanced statistical modeling to establish the relationships between three microclimatic variables and Moniliophthora Pod Rot (MPR) development
Based on the results of a pair correlation analysis presented in S3 and S4 Figs, we discarded Wetness Frequency from three to 25 d.a.t. (WF3 to 25) and Amplitude of Temperature from eight to 23 d.a.t. (Tamp8 to 23) for H!D change, and Amplitude of Temperature from 37 to 47 d.a.t. (Tamp 37 to 47) for D!S change
Summary
Cacao (Theobroma cacao) diseases are the main threat for production, causing losses estimated at 30 to 40% worldwide [1]. At the beginning of the 20th century, more than 50% of global cocoa production (approximately 29 400 tons) occurred in mainland tropical America, followed by the Caribbean islands, Africa, Asia and Oceania[3]. Diseases such as Moniliophthora Pod Rot (MPR) and Witches’ Broom caused a decline in American cocoa production. MPR has been reported as the most destructive, invasive and difficult-to-control cacao disease in the area [4, 5]. The disease has swept many plantations in countries where it has been reported
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call