For monitoring and decision making around whether or not control options are necessary, the following points are essential:

a) Knowing which crops are more susceptible to pest damage;

b) Knowing which areas on the farm are most problematic;

c) Recognising the conditions that lead to pest numbers increasing rapidly. For example, high moisture and mild temperatures and/or high levels of crop residue or a cloddy tilth can provide an ideal environment to support slug activity, survival and reproduction.

Clover root weevil may be present in second year clovers.

Check leaves for adult feeding damage, which can be identified by distinctive notches on the leaves.

High levels of feeding damage equates to high numbers of adult weevils. Some adult weevils (<40%) will be laying eggs, and larvae (small white maggots 2-3mm in length) may also be present around the plant roots.

Populations of the CRW biocontrol agent, a parasitoid wasp, are building up well this year, so additional control may not be required.

Growers are seeing a lot of feeding damage to the leaves, the CRW population could be high and chemical control could be considered. However, it may be wise hold off until later in March, when CRW adults stop flying. Chemicals registered for controlling CRW will impact on the biological control agent in the short term.

Argentine stem weevil numbers could be at reasonable levels in paddocks coming out of pasture, (especially low or no endophyte). Consider a fallow period to reduce numbers, and/or insecticide treated seed. Recent FAR supported research has shown the parasitoid wasp introduced as a biocontrol agent for ASW is losing efficacy and this may result in increased populations of the pest in some areas.

Slugs – Remember that a range of control options, both chemical and cultural is available. In order to maximise the value of natural slug predators, e.g. carabid beetles, growers should consider using EDTA based baits. For more information on this see page 23-24 in FAR Focus 12: Integrated Pest Management, which is available on the FAR website: https://www.far.org.nz/resources/publications/far_focus