Managing resistance to protect our crops
The development of pest, weed and disease resistance to crop protection compounds threatens the sustainability of our
primary production and is already a major problem overseas.
Agcarm and the New Zealand Plant Protection Society (NZPPS) recently brought together industry and agricultural experts
to discuss the proactive management of pest resistance to crop protection compounds in New Zealand.
Crop protection compounds include herbicides, insecticides and fungicides. They are used to control weeds and to protect
crops from damaging pests and diseases.
Examples of resistance in New Zealand include blackspot on apples, powdery mildew (a fungal disease that affects a wide
range of plants), glysophate resistant ryegrass, and diamond back moth - which is resistant to a range of insecticides.
In some areas, these are now resistant to major chemical groups.
Agcarm chief executive, Mark Ross says “New Zealand is not facing a catastrophe, but we need to be ahead of the game.”
A pesticide resistance management workshop, sponsored by AGMARDT, was held to review, update and develop New Zealand’s
resistance management strategies and identify possible new threats. Plans for implementing the strategies and
identifying issues were discussed.
The workshop, hosted by Agcarm and NZPPS, also identified priorities for research as well as potential funding sources.
“We will be working with our members, government, farmers and agrichemical users to ensure solutions are developed for
potential problems,” said Ross.
NZPPS president, Lisa Jamieson says “Managing resistance requires an understanding of the factors that influence its
development, and having strategies in place to manage the risk of resistance developing.
“We need to understand what is happening in the field. This is done by developing test methodology for resistance and
monitoring.”
“With good monitoring and early detection, we can adjust strategies to evade resistance,” says Ross.
A good resistance strategy includes alternating crop protection products with different modes of action, crop rotation
as well as other management practices such as good hygiene.
What is pesticide resistance?
Among the billions of individuals that make up a pest population (be it disease, insect, mite, weed etc), there may
exist some individuals that are more tolerant to a pesticide than others. If the same pesticide is continually applied,
then the more susceptible individuals will be killed, leaving only resistant individuals to breed and multiply. If the
resistance is heritable then eventually a large proportion of the population may be resistant to the pesticide. The
resistant pests may then cause unacceptable damage to crops. See http://resistance.nzpps.org/ for more information.
ENDS