Effect of Chamomile Essential Oil on Gnomonia comari Control and Strawberry Fruit Production under Organic System

The strawberry crop is host of several pathogens and pests. The Gnomonia leaf spot (Gnomonia comari) is an emergent disease that has been occurring and limiting the production of this small fruit in the Rio Grande do Sul state, Brazil. However, there is no information about any efficient control method of this disease and also, no resistant strawberry cultivar available to organic production systems. Therefore, an experiment was carried out in order to evaluate the effect of the chamomile oil (Matricaria chamomiilla) on the control of G. comari and on yield of six strawberry cultivars ('Camarosa', 'Galexia', 'Earlibrite', 'Festival', 'Plarionfre' and 'Sabrosa'). The work was conducted at the Embrapa Temperate Climate Research Center, in Pelotas-RS, Brazil. Sixty days after the planting, the strawberries were sprayed weekly with chamomile oil at 500 ppm during 40 days. After appearing the first symptoms, the disease severity (%) of Gnomonia and some parameters which one related to fruit production were evaluated. After appearance of the first symptoms, the disease severity (%) of Gnomonia and some parameters related to fruit production were evaluated. Based on the severity values, the area under disease progress curve (Audpc) was calculated for each material tested. Thereafter, the Audpc and fruit yield data were submitted to Anova and Duncan test at 5%. It was verified that the disease severity was reduced in the 'Festival', 'Galexia' and 'Sabrosa' cultivars when plants were sprayed with chamomile oil. Although the use of chamomile oil has not affected fruit yield, 'Camarosa' and 'Galexia' showed the highest yield and 'Plarionfre' was the lowest yielder and the most susceptible to leaf spot of Gnomonia, independently of the application of chamomile essential oil.