Grubs in the Lawn

Grubs in the Lawn

The grub is the larval stage of a variety of beetles: Japanese beetles, European chafer and June beetles are the three most common.

grubsDamage Identification:
Grubs feed on grass roots thus causing your lawn to die. The key symptom of grub invasion is irregular dead patches which lift up quite easily if tugged on. These patches have had the roots severed off and thus there is nothing to anchor the sod or lawn in place. The lawn may also have patches that have been burrowed in or been turned over by skunks or raccoons feeding on the grubs. The highest concentration of grubs will be found in dead turf bordering green areas. The grub is “C” shaped with a brown head, white body and six legs on its upper half.

Life Cycle:
-the grub’s life cycle is very simple. The grub feeds on grass roots from mid-March to late-May, and then develops into its pupal form. The adult beetle then emerges in mid-June, mates over a two week period and then retreats back into the soil to lay its eggs. The grubs hatch and begin to feed in late July/early August. The grubs will burrow below the frost line in the late fall and stop feeding but resume feeding if there is a thaw at anytime during the winter. The grubs continue to feed in the spring, constantly growing larger.

Cultural Control:
-Grubs are in every lawn, this is common and expected but within a limited, balanced ecosystem. What is harmful to lawns is when there is an infestation of grubs and there is no longer a balance in this ecosystem. Lawns that are well maintained and healthy are more likely to resist infestations and to recover by growing more roots when some roots are destroyed. A lawn care program to maintain a healthy lawn-soil ecosystem is vital. Harmony Gardens Landscaping can assess your lawn’s health and requirements and provide an appropriate, specific lawn care program.

Nematode Treatments:
-make sure the nematodes being applied are specifically to treat white grubs which are the larvae of European chafer, Japanese beetles and June beetles.

Nematodes are alive, tiny, microscopic, eel-shaped organisms. They are parasitic to white grub larva. In general, nematodes should be applied when grubs are actively feeding from mid-March until early June and then again late July/early August through to late October. This being said one must remember that these live parasitic organisms are susceptible to frost, need moisture and are most beneficial and effective in soil temperatures between 10 to 30 degrees Celsius. Therefore in Ottawa one should not apply nematodes until all danger of frost has past in the spring(late May) and before frost in the fall (September).

Nematodes are best applied when lawn is wet. Time applications around rainy periods or water lawn prior to and after applications. Irrigation system can be set to benefit nematode applications. After nematodes are applied with a sprayer attached to garden hose the lawn must be kept moist for the next 3 to 7 days to ensure the nematodes are flushed down into the root zone of lawn where the feeding grubs are present and to ensure the nematodes remain viable. If soil and weather are dry then ensure nematodes are watered daily x7 days.

For grub control Harmony Gardens Landscaping offers applications of nematodes late May/early June, late July/early August and again up to mid- September. All three applications are important throughout the season with the September application being most vital.

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