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Paropsisterna beata - an update

Scion is the leading provider of forest-related knowledge in New Zealand
Formerly known as the Forest Research Institute, Scion has been a leader in research relating to forest health for over 50 years. The Rotorua-based Crown Research Institute continues to provide science that will protect all forests from damage caused by insect pests, pathogens and weeds. The information presented below arises from these research activities.

From Forest Health News 237, June 2013.

In an attempt to eradicate a new pest to New Zealand, a eucalyptus leaf beetle (Paropsisterna beata), the Ministry for Primary Industries carried out two insecticide spray operations at Whiteman’s Valley near Wellington (see FH News 233, February 2013). The spraying was done in late April and early May 12 days apart and each lasted less than 20 minutes. However, a great deal of planning was needed before those short operations could be carried out. For instance, the surrounding area was surveyed to determine if the insect had spread from where it was first detected and communication with property owners and other parties was undertaken. Technical aspects of the spray operation needed to be addressed. As spray droplets increase in size, drift reduces but so too does coverage of the target plants. A reduction in coverage severely compromises efficacy. In an urban environment it is even more important that spray drift is minimised, but maximum efficacy is needed for a successful eradication.

Scion assisted with this eradication response by using the aerial spray simulation model, AGDISP, to evaluate those tradeoffs between drift and efficacy. A total of 32 model runs were completed and used to compare the differences in efficacy and drift between all combinations of: three droplet size ranges (spectra), two wind speeds, two release heights, and two aircraft speeds. The results were presented to MPI and a spray nozzle set up was agreed that would deliver the required droplet size. As a result, both operations resulted in good coverage and limited drift. The outcome of the operations in terms of eradication won’t be known for several months but the exercise did highlight the need for methods of applying sprays from the air to a very concise target such as a single tree. Development of such methods is being considered for inclusion in our 2013-14 aerial applications research programme so that this valuable tool is available for future responses.

Lindsay Bulman

This information is intended for general interest only. It is not intended to be a substitute for specific specialist advice on any matter and should not be relied on for that purpose. Scion will not be liable for any direct, indirect, incidental, special, consequential or exemplary damages, loss of profits, or any other intangible losses that result from using the information provided on this site.
(Scion is the trading name of the New Zealand Forest Research Institute Limited.)


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