Evaluation of the PFD model and PFD-FAD for timing of fungicide applications for postbloom fruit drop of citrus in Brazil
Peres, N.A.R.; Souza, N.L.; Furtado, E.L.; Timmer, L.W.
Phytopathology 93(6 Suppl): S70-S71
2003
ISSN/ISBN: 0031-949X Accession: 034884843
Postbloom Fruit Drop (PFD), caused by Colletotrichum acutatum, infects petals of citrus flowers and induces the abscission of fruitlets. The PFD model was developed in Florida to schedule fungicide applications based on the amount of inoculum, rainfall and leaf wetness. This model was evaluated for 4 yr in Itapetininga, SP, Brazil. A new advisory system (PFD-FAD) was developed to be more widely applicable by incorporating factors such as disease history, varietal susceptibility and the stage of bloom. Applications following the PFD model provided good control of PFD and saved 2 sprays compared to the calendar program in 1999, and 1 to 2 sprays compared to the grower's choice in 2000, 2001 and 2002. In field tests in 2001 and 2002, PFD-FAD provided good control of the disease with only one spray. The PFD model and the PFD-FAD were equally effective for timing fungicide applications to control PFD in Brazil. PFD-FAD is simpler to use than the PFD model, eliminates unnecessary sprays, and reduces expenses.