Why Do We Monitor Pests
The monitoring of pests and diseases has become a science. Most monitoring systems are sophisticated scientific tools developed by experts for growers. An incorrectly installed or maintained monitoring system, or where the wrong insects are counted, will not be a true reflection of the pest situation in the field. In many of these systems, the decision on whether to spray or not rests on very small differences in the number of insects trapped or counted weekly. A monitoring system that operates sub-optimally will lead to incorrect control decisions.
Monitoring indicates the level of pests, diseases and biological control agents in the field, keeping growers up-to-date with their status.
Knowledge of the status of any pest, disease and biological control agent enables growers to make intelligent and rational decisions on the necessary control actions, based on the actual numbers.
By spraying according to Economic Threshold Values rather than by the calendar, growers can reduce the number of sprays and therefore their spraying costs. There is a constant and increasing need to minimize the use of pesticides, due to the adverse effect on both humans and the environment.
Compare False Codling Moth & Macadamia Nut Borer populations since 2003 – 2008 in Macadamia orchards. Average from 10 Yellow Delta Traps over a 52 week period.
Macadamia Nut Borer (M.N.B.) and False Codling Moth (F.C.M.) monitoring in a 100 Ha Macadamia orchard, South Africa. The graph above shows the value of monitoring these pests over time to determine the pest population and dynamic.
For both pests the Yellow Delta Trap® was used and placed at a density of one trap per 10 Ha using a total of 10 traps for M.N.B. and 10 traps for F.C.M. These traps were installed in the top one third of the tree and were monitored weekly. The M.N.B. PheroLure® was replaced every 5 weeks and the F.C.M. PheroLure® every 10 weeks. Monitoring period was January 2003 – December 2008.
In total each trap was monitored 312 times over the 6-year period. The graph above presents the average moth count from the 10 traps over a 52 weeks period; the average moth numbers collected was 520 counts per year.
Macadamia Nut Borer counts increased from an average of 6.2 moths per trap per week to 21.8 moths per trap per week, clearly showing an increase in pest population.
False Codling Moth numbers varied from year to year but did not show the same significant increase as Macadamia Nut Borer.