Sherbrooke adopts ‘integrated approach’ to white grub management

Sherbrooke City Council approved changes to municipal bylaws to encourage an integrated approach to controlling the spread of white grubs.

In 2017, the number of sites infested with white grubs in Sherbrooke increased significantly. More than 2,700 preventive treatments with non-low impact pesticides were allowed, sometimes on land that was not dealing with grubs. The treatments were tolerated since the concept of infestation was not properly defined in the municipal regulations.

The situation will be corrected as of October 1, 2018. From that point on, only land damaged by white grubs in the past year will be considered "infested". Owners will then be able to take advantage of the exception allowing the use of pesticides that are not low impact. Before this point, however, the City of Sherbrooke is encouraging citizens to act proactively and use biological control agents to prevent infestation.

The City also reminds residents that the presence of a few white grubs will not damage a healthy diversified lawn that includes clover.

In summary, the City’s Integrated Pest Management Policy contains four main features:

1. Preventing the arrival of white grubs by promoting healthy lawns and using preventative methods like turning off outdoor lights and reducing watering, especially in July, since those conditions attract the pesky insects during their egg-laying period. In addition, it is recommended to maintain a mowing height of 8 cm (3.15 inches) and avoid over fertilizing.

2. Repairing damage and keeping the problem in perspective. Lawn repair in some areas is part of the normal maintenance schedule.

3. Using biological control agents (nematodes) to prevent and reduce the spread of the grubs. Nematodes are small worms that infect white grubs as parasites For best results, this ecologically-friendly treatment must be applied in August, rigorously following the application directions. It is important to be well informed.

4. As a last resort, after trying the first three methods, pesticides that are not low impact are tolerated in ‘exceptional’ circumstances. This must be done by a commercial applicator, because the only such pesticide allowed for use in Sherbrooke is not available over-the-counter. All neonicotinoid pesticides are prohibited because of their harmful effects on bees.

In the meantime, the City will provide more information to educate citizens on ways to effectively fight against these pests.