Erianthus arundinaceus as a trap crop for the sugarcane stem borer Chilo sacchariphagus: Field validation and disease risk assessment

The sugarcane internode spotted stem borer Chilo sacchariphagus (Bojer, 1856) (Lepidoptera: Crambidae) is a major pest of sugarcane. In a previous work carried out in Reunion, we showed that Erianthus arundinaceus (Retz.) Jeswiet (Poales: Poaceae), accession 28NG7, can be used as trap crop to control C. sacchariphagus. The aim of this study was to determine the efficiency of using E. arundinaceus 28NG7 as a trap crop to control C. sacchariphagus in commercial field conditions and to assess the susceptibility of E. arundinaceus 28NG7 to the three main sugarcane diseases in Reunion: smut, leaf-scald and gumming. Our results confirmed that E. arundinaceus 28NG7 effectively reduced C. sacchariphagus damage on sugarcane in large fields. The E. arundinaceus 28NG7 perimeter trap considerably reduced the mean number of bored internodes in the adjacent sugarcane fields, by a factor ranging from 2.8 to 4.4. Using on-station trials, we also showed that E. arundinaceus 28NG7 is tolerant or resistant to the three sugarcane diseases and is, therefore, unlikely to act as a disease reservoir and source of inoculum for contaminating sugarcane. The first step to encourage the use of E. arundinaceus 28NG7 borders in commercial fields described here was also successful in terms of growers' adoption. All ten growers involved in the experiment spontaneously increased the area of sugarcane protected by E. arundinaceus 28NG7 borders on their farm