Agricultural and Forest Entomology (2009) 11, 197-203

Rod P. Blackshaw (2009)
A comparison of management options for leatherjacket populations in organic crop rotations using mathematical models
Agricultural and Forest Entomology 11 (2), 197-203
Abstract: 1 Pest management in organic systems is challenged by the paucity of options for direct interventions to control damaging populations compared with conventional agriculture. Consequently, a greater emphasis has to be placed on managing pest numbers through a rotation. In the present study, simulation modelling is used to evaluate the effects of different management options on populations of Tipula paludosa (leatherjackets) in organic rotations.
2 The growth of leatherjacket populations in grass was simulated over 5 years for different starting numbers. A significant risk of leatherjacket attack to subsequent crops can be avoided by limiting the fertility building phase of a rotation to a maximum of 2 years.
3 The effect of cultural control through additional cultivation interventions was compared in rotations comprising a grass/clover fertility building phase with host and/or nonhost crops. It is concluded that the effects are marginal and that prophylactic use cannot be recommended.
4 The prophylactic use of biological control agents in permanent grass and grass/arable rotations was investigated. Maximum population reductions in grass were achieved through annual autumn applications but the optimal economic strategy was less frequent than this. Application in the autumn preceding a spring-sown arable crop provided the best risk reduction.
5 A model decision support system for the control of pests in organic systems using data for leatherjacket damage to spring barley is presented. Economic threshold concepts are used to define when cultural control (as additional cultivation) and biocontrol applications should be used.
6 The present study shows the potential benefits of simulation modelling for the rapid evaluation of a wide range of pest management options. Any conclusions drawn from such simulations, however, are provisional until they can be tested experimentally.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Rod P. Blackshaw

Research topic(s) for pests/diseases/weeds:
control - general

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Tipula paludosa	Grasses/turf/rangeland