White Grubs: How to Prevent and Treat Them
Is your lawn of poor quality because it has brown and withered areas, patches of dead grass, lots of weeds, and irregular growth? Do the diseased parts lift easily? The cause of your problem is probably what is commonly known as the "white grub."
White Grubs: What Are They?
They are the larvae of beetles: common chafer, European chafer, and Japanese beetle. They feed on the roots of grasses, including our lawns. The larvae of all these species have a soft, milky white body and a brown head. At rest, they are curled up in a "C" shape.
Why do white grubs invade certain lawns? The excessive use of fertilizers and pesticides creates a natural imbalance that leads to the proliferation of this pest. Kentucky bluegrass is also one of their favorite foods.
Situation Analysis
The best solution to combat white grubs is to detect the infestation early. Cut three sides of a 30 cm square of turf with a knife and roll it back:
If you count more than 5 to 10 larvae, there is a significant infestation.
If the infestation is severe, you may even need to replace the damaged area.
7 Tips to Prevent the Appearance of White Grubs
Tip 1: Aerate Your Lawn
In the spring, you should aerate your lawn to allow water and nutrients to penetrate the soil. The oxygen that the roots of our grass need for good growth will thus be available in greater quantity than if the soil is compacted. Do a test with a pencil: if you have difficulty inserting it, your soil needs aeration.
Tip 2: Turn Off Your Outdoor Lights
During the mating and laying period of these pests, from mid-June to mid-July, you can turn off your outdoor lights to avoid attracting them to your yard.
Tip 3: Amend Your Lawn
A good amendment in May with organic matter, like compost (topdressing), helps achieve a vigorous lawn that blocks these pests during laying. A thin layer of compost, 0.5 to 1 cm thick, is sufficient. Organic fertilization is preferable to chemical fertilization because it nourishes the soil microorganisms and ensures long-term treatment.
Tip 4: Reseed Your Lawn
A reseeding of grasses or legumes in a mix, after spring topdressing, strengthens the lawn. You can also reseed from mid-August to mid-September (the best reseeding period) by using endophyte grass, which contains a fungus that repels white grubs.
Tip 5: Avoid Mowing Too Short
During the summer, especially in June and July, the lawn should be cut to a height of 6 to 8 cm (2 to 3 inches) to complicate the laying of chafer beetles, as they prefer short-cut lawns. Broad leaves also promote photosynthesis and prevent weeds from germinating.
Tip 6: Avoid Watering Too Often
During dry periods, do not water frequently, but rather infrequently and deeply, to stimulate growth.
Tip 7: Remove Weeds and Plant Debris
In the fall, remove plant debris and weeds.
Note: If you see adult grubs, collect them and destroy them by crushing them or plunging them into soapy water.
What to Do in Case of White Grub Presence?
Biological products containing nematodes are somewhat effective when the population has not reached a critical threshold. In preventive control, combined with good cultural practices, they allow effective control of the white grub population. These nematodes feed on the tissues of the larvae. Their optimal use is from late August to early September. You can also achieve good results with an application from mid-May to mid-June.
If the problem persists, there are, of course, chemical pesticides specifically designed to combat white grubs.
Application of an Insecticide
- Water the lawn several days before application so that the white grubs come out of the ground to feed on the surface;
- Watering the lawn also allows your insecticide to penetrate the soil better and thus reach these root grazers;
- You should use a pesticide that is as harmless as possible to your health and the environment;
- Seek advice from experts by visiting your nearest Passion Jardins garden center.
Note: For pesticide purchase, it is important to get informed to avoid having to treat repeatedly! The right product at the right time!
Tips and advice
