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Slowly but surely
If pea weevil was to establish permanently in this country and spread it could have a serious impact on our pea growing and processing industries and our export pea seed markets. As a result of response efforts to date, it appears that the Ministry for Primary Industries (MPI) and the pea growing industry are on track to eradicate pea weevil from NZ.
What is pea weevil?
Pea weevils are a small insect of 4-4.5mm long, brownish-grey in colour with white flecks. They lay elongated yellow eggs on the outside of pea pods and after one to three weeks the larvae hatch and burrow into the pea. Pea weevil larvae are white/cream in colour with a brown head and feed inside the green growing pea seed. The larval stage of the weevil may consume nearly the entire contents of the pea seed as they mature leaving just a seed membrane window for adult escape. There is one generation per year and the weevil will only infest green ripening peas, not dry peas. Though the pea weevil cannot reproduce in stored grain, sometimes the adults can remain concealed in grain for up to two years.
What has the eradication response involved?
Pea weevils depend on the pea species Pisum sativum for their entire lifecycle. This host-specificity has formed the basis of the response actions, with a ban on pea growing in the region. With the removal of the insect’s food source, it is expected that the population will die out. A ban has been placed on growing green peas (including sugar snap and snow peas) so the area is devoid of the weevils feeding host. MPI issuing a Controlled Area Notice (CAN) that indicates where peas can’t be grown (all of the Wairarapa including Pahiatua) and restricts the movement of pea seed and pea straw within, and in and out of the area.
Weevils spread by flying from one site to another, but can also be moved in infected pea seed, straw or dirty farm machinery which is why there are movement restrictions as well as growing restrictions. A permit may be obtained from MPI under certain circumstances to allow movement of risk goods (for example, feed peas) and this permit may specify requirements to mitigate any risk, such as fumigation of product before movement.
It looks like the restrictions are working. The trapping programme for the 2017/18 season found only 15 pea weevils from two neighbouring sites. That is significantly down compared with the previous season, during which 1735 pea weevils were found across 11 sites.
It is thought that this progress is largely due to the CAN that is currently in place. MPI have indicated that they intend to maintain these restrictions until they are confident that the pest can be eradicated from NZ.
Grower support is crucial
It is acknowledged that the restrictions have had an impact on the pea growing industry in the Wairarapa area. Grower efforts and support, including abiding by the growing and movement restrictions in the CAN and showing flexibility by finding alternate crops to plant, has been crucial for the response success to date.
It is important that the conditions of the CAN continue to be adhered to – after more than two years of hard work to eradicate the pest it would be disastrous to allow pea weevil to establish again by planting host material.
Is eradication possible?
As summer approaches there is a need to be especially vigilant - warmer temperatures and pea flowering mean the time is right for pea weevil flight and reproduction. If you see a pea weevil or if you see peas being grown in the controlled area report this to MPI on 0800 80 99 66. It’s important we all play our part to maximise the chance of successfully eradicating this pest. The eradication programme has been underway for over two years and it seems that, slowly but surely, the battle is being won. But we can’t afford to be complacent as the eradication programme is not over yet and the restrictions are still vital to maximise our chance of success.
After last season’s successful trap crop programme the response is well on the way to eradicating pea weevil and the CAN currently in place remains in force with additional awareness measures. As at the end of last summer 15 pea weevils were trapped from two sites out of 22 trap crop sites compared with 1652 weevils trapped from 11 sites during the previous season. Also no weevils were detected outside the controlled area in the Wairarapa.
New posters and signage
The public information campaign has started in local newspapers and on local radio. New roadside signs will be put up soon and posters and other information materials are being distributed.
The next round of trap crops for the 2018/19 season will be planted when conditions permit and daily temperatures increase. AsureQuality will have two staff members on the ground to work directly with trap crop growers who will introduce themselves to those growers over the coming weeks.
Watch out for growing pea plants We thank those who are assisting with surveillance and ask for more volunteers to scout within crops such as faba beans as well as in gardens to be sure that the remaining pea weevils are not newly hatched from eggs on unknown volunteer plants through crop checks by AsureQuality and further public awareness. It has been brought to our attention that a researcher from Canada noticed three pea plants growing within a field of faba beans in the Wairarapa. These bean plants were pulled out and destroyed but heightened the need to look for and dispose of volunteer pea plants.
Please also remind friends and neighbours that the growing of peas or the moving of pea straw into the Wairarapa region is still prohibited and if you see growing peas please call 0800 80 99 66.
There will need to be evidence that that there are no remaining pests before eradication can be declared, which will take time. By acting early, before the population may spread to other areas, we appear to have a good chance of eradicating pea weevil within our borders
For more information visit the MPI website: www.mpi.govt.nz/protectionand-response/responding/alerts/peaweevil
It has been brought to our attention that a researcher from Canada noticed three pea plants growing within a field of faba beans in the Wairarapa. These bean plants were pulled out and destroyed but heightened the need to look for and dispose of volunteer pea plants.
▶ The new Pea Weevil Restrictions poster. (Credit MPI)