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Surveillance of plantations on State forest to detect pest and disease problems

Surveillance of plantations on State forest to detect pest and disease problems has been done annually since 1997 - 98. Research done over the past few years has provided an understanding of the type and level of damage that can be reliably detected by surveillance. This has allowed us to refine surveillance to use the most costeffective methods for detecting damage likely to require management. We are now turning our attention to the linkage between detection and the management of pests and diseases. In particular, we want to better understand and document the value of averting potential future losses from pests and diseases, as a result of management actions triggered by health surveillance.

Information from surveillance can avert future losses from pests and diseases in several ways. The simplest is when detection leads to a direct response to prevent damage. For example, the detection of an emerging outbreak of autumn gum moth in an E. nitens plantation in western Tasmania this year resulted in the decision to spray the plantation with insecticide to prevent severe defoliation. That detection and management response was calculated to have averted $103 000 in future losses, and protected 47 800 m3 of future sawlogs and veneer logs that would otherwise have been used for pulpwood.

Pictured:Severe late-season defoliation of a high-altitude plantation of E. nitens by chrysomelid leaf beetles.

Severe late-season defoliation of a high-altitude plantation of E. nitens by chrysomelid leaf beetles.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Another way in which losses can be averted is when surveillance identifies sub-optimal management in operational pest management programs. For several years, the issue of late-season defoliation by leaf beetles has been identified through health surveillance. Studies done this year identified that insecticide spraying of over-threshold larval populations is largely effective in preventing late-season damage by adult beetles. However, many plantations that are beyond the current age-range targeted by the operational program, particularly those at high altitude, are suffering severe defoliation.

Calculations based on levels of moderate and severe defoliation assessed last year indicate that, by extending the operational leaf beetle program to include plantations in high-risk areas up to the age when they are thinned, we could increase annualised financial returns by about $150 000 and the annual yield of sawlogs and veneer logs by about 8 000 m3.