Grass Seed for grub infested lawn *


We have a bad grub problem on our lawn. We face south and southwest, large corner lot in mid town Toronto. Have tried nematodes but it has not worked. We are reseeding and currently have a mixture of ryegrass, red fescue and Kentucky blue. Had heard that there are grass seeds that have endophytes which is a type of fungus that grubs don’t like. Interested in knowing whether this is a recommended type of grass seed to use and where best to buy it. Thanks.


Thanks for getting in touch with the Toronto Master Gardeners.

You pose an interesting question about the use of endophytic grasses–these grasses do contain a fungus that doesn’t harm the plant, and has been found to deter some surface foliar-feeding insects in lawns, such as billbugs, chinch bugs and sod webworms. It seems that these grasses would not be “effective against root feeders such as white grubs”. However, growing these endophytic cultivars do result in grasses that seem to be more resilient and tolerant of drought conditions and other stresses; once established, one’s lawn might require less maintenance.

There are a number of endophytic-infected cultivars of grasses, such as perennial rye grass and a variety of fescues; combinations of these grasses are marketed as ‘low-maintenance’ mixtures. Unfortunately, attempts to incorporate the endophytic-fungus into Kentucky blue grass have not been successful. One should also be aware that seeds of endophytic grasses must be stored at cool temperatures (about 5° C.) and dry conditions to maintain the viability of the seed. It may be difficult to source viable seed for one’s lawn at most local stores.

The lack of success with using nematodes to deal with the grubs in your lawn may have been due to several factors. The timing of nematode use is crucial–the soil must be moist; nematodes should be applied on an overcast day; the temperature should be between 13°C and 30°C., generally from late April/early May through June, depending upon which species of grub one is trying to deal with, and from mid-August through September; the lawn should remain moist for several days after the application. Given the fluctuating weather conditions in the Toronto area, it can be difficult to time the application of nematodes for success in treating grubs.

Your decision to reseed your lawn is probably the best way to deal with the grub problem. Maintaining a healthy lawn is the best defense against grubs. Make sure you keep the lawn watered regularly to encourage more roots which will withstand some grub feeding; a less vigorous lawn will show grub damage even after smaller amounts of grub feeding. Grub eggs need moisture to hatch into grubs; even though there would be fewer grubs hatching during drought periods, the grass would be weaker, so the damage to the lawn would be greater.

As you are no doubt aware, lawns require a lot of maintenance. You may decide at some point to consider using groundcovers in place of some of your lawn.

Good luck with your lawn.