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Oral: Risk Assessment


Spatio-temporal aspects of rust and nutrition of coffee plants in different irrigation systems.
M. SILVA (1), M. Silva (1), E. Pozza (2), G. Vasco (2), P. Paula (2), E. Chaves (2), G. Dornelas (2), M. Silva (2), A. Pozza (2) (1) UFLA, Brazil; (2) Lavras Federal University, UFLA, Brazil

The rust (Hemileia vastatrix) is the most important disease of coffee and the intensity depends on productivity, cropping system, plant nutrition and water availability. Thus, the objectives were to evaluate the spatio-temporal disease progress and the relation with plant nutrition and soil fertility in coffee farms irrigated by drip and center pivot, using geostatistics. The drip and pivot areas were georeferenced with 52 points in 11ha and 50 in 17ha, respectively. The disease incidence was evaluated in 60 leaves, in five plants/point at 60-days intervals, from August 2012 to May 2015, totaling 17 evaluations. It was also evaluated at each point, productivity, mineral nutrition of the plants and soil fertility annually. These data were correlated with the rust incidence. The disease progress curves were plotted and the adjustment of semivariogram models was done. Then, the data were interpolated by ordinary kriging and the maps of disease and nutrients were constructed (ArcGIS 9.2®). The disease incidence in dripping was less than 3% over the years. In the pivot, the incidence reaching in August 2013 and from June to August 2014, between 21 and 27%. There was correlation between soil fertility and plant nutrition with rust for Ca, P and K. The spatial distribution of the disease and nutrients changed over the years. The exponential model was adjusted to coffee rust over the space. The disease gradient was observed from the foci in the kriging maps.