Temporal progress of coffee leaf rust and environmental conditions affecting severity in Veracruz State, Mexico

Abstract

Coffee is an important crop in Mexico. Unfortunately, coffee production has been affected by coffee leaf rust (CLR). The severity of this infection occurs with variations along the year described before in different coffee-producing regions worldwide. For Veracruz, there are available reports of weekly CLR severity, but this information is only descriptive. We analyzed variations along the year of CLR severity in Veracruz with data from municipal weekly reports provided by Mexico’s federal government phytosanitary epidemiological monitoring coffee program. We selected reports dated in 2018 from nine municipalities and after calculations of mean monthly severity values, we conducted a one-way ANOVA (months as factors) of severity data. We compared this information with other coffee-producing regions. Additionally, we explored the association of temperature, rainfall, and altitude with CLR severity using Principal Component Analysis and multiple linear regressions. Temperature and rainfall data were obtained from Mexican National Meteorological Service. We found that CLR severity in January, October, November, and December (months of harvest period) was significantly higher than values from March-June. During the harvest period, coffee plants allocate resources mainly for fruiting which competes in resources for other tasks such as defense and leaf growth, so this competition of resources can explain the positive relationship found between fruit load and CLR severity. This monthly variation of severity was similar to those reported in Chiapas, Guatemala, Colombia, Uganda, and Ethiopia. Our model (R2 = 0.401) showed a significant and negative effect of altitude and medium temperature on CLR severity, while the effect of rainfall was positive. With our study, we suggest applications of fungicides in March-June when coffee plantations are in leaf phenophase. Key words: Altitude; Coffea arabica; Hemileia vastatrix; phenophase.