engleski

Maximal weekly vs. average daily capture on PhAM as a tool for WCR risk assessment

Risk assessment (RA) for western corn rootworm (WCR) was done in the USA by various authors but till now few focused on European and a Croatian condition. Small scale (0.5-5ha) and high level of repeated maize require a better approach in providing RA for WCR in Croatia. The aim of the investigation was to develop a model for RA in continuous maize for WCR. For the study, the relationship between WCR adult population density on Pherocon AM (PhAM) traps in the field and the average number of larvae (ANL) per plant, root damage ratings (RR) and plant lodging the following year were investigated. Adult population densities were determined over a 74-day period (24th to 35th week of the year) each year consecutively from 2006 to 2009 in 30 corn fields per year. Trap inspections were conducted weekly. Soil and root sampling was carried out to determine the ANL per plant, as well as larval root damage ratings according to the Iowa State University scale of 1-6. The percentage of partially and fully lodged plants was visually determined. Significant interactions for maximal weekly (MWC) and average daily (ADC) capture of adults on PhAM and ANL and RR were determined. Climatic conditions (CC) were found to have an impact on these interactions. MWC of 66 and ADC of 2.32 predict an average 0.5 larvae per plant. MWC of 78 and ADC of 4.55 predict a common RR of 3.5 (ISU 1-6). Significant interactions for MWC and ADC of adults on PhAM and partially or fully lodged plants were not determined. CC had no impact on these relationships. MWC of 62 and ADC of 4.01 both predict a 10% chance of partially lodged plants in continuous maize fields. Fully lodged plants could not be predicted by MWC or ADC. Regression coefficients for the relationship of adult MWC and ADC and ANL per plant, RR and plant lodging were also calculated, compared and discussed. Results from this investigation are beneficial as management guideline of integrated maize production in Croatia.

PhAM; risk assessment; WCR

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