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Require Treatment?

BioShield® Grass Grub is a biological control treatment that is effective against New Zealand grass grub. Bioshield® Grass Grub is available in an easy-flow granule format, and provides effective long-term control of New Zealand grass grub. However, as it is a biological control agent its effectiveness depends on accurate paddock selection and correct product usage.

The paddock selection decision tree overleaf and other information is this booklet will help you to determine whether or not you have a grass grub problem that can be treated with BioShield® Grass Grub. Only paddocks with between 100 and 300 grass grubs/m2 are suitable for treating with BioShield® Grass Grub. It may not be economic to treat paddocks with significantly higher populations.

The decision tree will identify paddocks most at risk of grass grub damage. For confirmation, it may be useful to sample the paddock. This is done by digging 10 or more spade squares to a depth of 10-15 cm from throughout the paddock, and hand-sifting through the soil to collect grass grub larvae. If a 20 cm (8 inch) width spade is used, an

average of four larvae per spade square is approximately 100/m2. (If a 15 cm (6 inch) width spade is used, 100/mis represented by about 2 larvae per spade square). With February sampling, larvae are small and hard to find.

Ideally sampling was conducted last season.

 


Paddock Selection Decision Tree

DecisionTree.jpg

 


Pasture Value

Should the pasture be protected with BioShield® Grass Grub, or renovated – depends on how productive it is.

Pasture ValueScore CriteriaAction
5Composition predominantly retaining sown species; high genetic merit cultivars. Less than 3 years since sowing. High value pasture with perceived risk from grass grub.Clear candidate for treatment with BioShield® Grass Grub to reduce grass grub population.
4Composition retaining a minimum of 80% of sown species; high genetic merit cultivars. Less than 3 years since sown. High value pasture with perceived risk from grass grub.Clear candidate for treatment to reduce grass grub population. Consider “stitching-in” grass seed with treatment.
3Composition retaining around 60% of sown species, but cover patchy and/or not likely to have high genetic merit cultivars.Close evaluation needed of potential return on investment in grass grub control and/or under- sowing with new pasture species.
2Composition retaining less than 50% of sown species.Will most likely require complete renewal.
1Low value pasture (low quality, low dry matter production).Requires complete renewal.


Click here to download the full BioShield Grass Grub brochure.