Postbloom fruit drop: definition of the action threshold for chemical control and identification of fungicide resistant strains

• Grant number: 15/06007-2
• Support Opportunities: Scholarships in Brazil - Master
• Start date: July 01, 2015
• End date: July 31, 2017
• Field of knowledge: Agronomical Sciences - Agronomy - Plant Health
• Agreement: Coordination of Improvement of Higher Education Personnel (CAPES)
• Principal Investigator: Lilian Amorim
• Grantee: André Bueno Gama
• Host Institution: Escola Superior de Agricultura Luiz de Queiroz (ESALQ). Universidade de São Paulo (USP). Piracicaba , SP, Brazil
• Associated scholarship(s): 15/19564-7 - Postbloom fruit drop of citrus: sensitivity to fungicides, molecular characterization and dispersal of secondary conidia of Colletotrichum spp, BE.EP.MS

Abstract

The Brazilian citrus industry is very important in the global citrus market, with high annual production and yield. Citrus crop in the State of São Paulo recently have migrated from the Northern to the Southwestern region of this state, because of the lower incidence of major diseases, such as canker, CVC and greening. The weather conditions of this region are also favorable to the development of this crop. However, the high occurrence of rain over this region during the blooming period favor the development of Postbloom Fruit Drop (PFD) in citrus, caused by Colletotrichum gloeosporioides and C. acutatum, especially in years of mild temperatures. Although the occurrence of rain during the blooming period varies from year to year, the growers perform preventive sprays to control the PFD every season. When a dry period occurs the fungicide sprays are usually unnecessary and the costs for disease control could be avoided. Besides the economic impact, the exaggerated application of fungicides increases their selection pressure. When resistant isolates to the fungicides are selected the efficiency of the chemical control might be reduced. One of the most commonly used fungicides in the state of São Paulo to control the PFD is a mixture of trifloxystrobin (strobilurin) and tebuconazole (triazole). Isolates of Colletotrichum resistant to strobilurins and triazole have already been reported in the literature in other crops. Recently, a grant was awarded by FAPESP to support a research that intends to develop and implement a user friendly epidemic forecasting system for the PFD in São Paulo state. This project aims to develop an online platform of disease risk prediction with remote access by the growers. In order to accurately predict the disease occurrence, it is essential to determine a threshold of action for the fungicides spraying in orchards of the Southwestern region of São Paulo. Thus, this study aims to establish a threshold of action for the application of fungicides that controls the disease equally or more efficiently than the spray system that is currently adopted by the citrus growers in the Southwest of São Paulo and intends to characterize the sensitiviy of isolates of C. gloeosporioides and C. acutatum to trifloxystrobin and tebuconazole in vitro and molecularly. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

GAMA, ANDRE B.; SILVA JUNIOR, GERALDO JOSE; PERES, NATALIA A.; MOLINA, JUAN EDWARDS; DE LIMA, LILIAN M.; AMORIM, LILIAN. A Threshold-Based Decision-Support System for Fungicide Applications Provides Cost-Effective Control of Citrus Postbloom Fruit Drop. PLANT DISEASE, v. 103, n. 9, p. 2433-2442, SEP 2019. (14/19933-0, 15/06007-2)

GAMA, ANDRE B.; BAGGIO, JULIANA S.; REBELLO, CAROLINA S.; LOURENCO, SILVIA DE AFONSECA; GASPAROTO, MARIA CANDIDA DE G.; DA SILVA JUNIOR, GERALDO JOSE; PERES, NATALIA A.; AMORIML, LILIAN. Sensitivity of Colletotrichum acutatum Isolates from Citrus to Carbendazim, Difenoconazole, Tebuconazole, and Trifloxystrobin. PLANT DISEASE, v. 104, n. 6, p. 1621-1628, JUN 2020. (15/06007-2)

Academic Publications

(References retrieved automatically from State of São Paulo Research Institutions)

GAMA, André Bueno. Postbloom fruit drop: definition of the action threshold for chemical control and survey of isolates sensitivity to tebuconazole and trifloxystrobin. 2017. Master's Dissertation - Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) Piracicaba.