Grub damage notoriously begins in the spring and becomes more intense in the summer. So if you don't follow proper grub treatment by applying grub control, this may be a yearly problem and a source of migraine.
If you're still wondering what the best time to treat grubs with a preventer or a killer is– this is sometime during the early spring and late summer, when there's visible increased grub activity on the lawn. Grub preventers must be applied ideally sometime between June and July, just before the pests hatch. Meanwhile, grub killers will need to be used in the spring (late March to late April) or once you see visible signs of lawn damage.
Grubs grow into adult Japanese beetles in the late spring to the early summer season, making it an excellent time to apply grub preventer for the following season.
Grub Treatment Timing: The Best Time to Apply Grub Control
Commonly, grub control is available in two types: grub preventers and grub killers. For healthy, lush lawns, prevention is ideal for maintaining your picture-perfect turf. But if you are already dealing with visible signs of lawn grub damage, you may want to use an insecticide for a more immediate control.
The ideal time to apply grub control is during the early spring (April to May) to prevent any grub damage in the fall.
On the other hand, use grub killers to treat your lawn as soon as you see visible brown patches in the grass. Some homeowners also like to apply the treatment sometime during June and July to prevent unwanted grub growth for the next season.
When is it too Early to Apply Grub Control?
If you want to treat your lawn early to avoid grub damage next season, avoid doing so in the early spring as it may be too early. In this case, the pesticide may quickly disintegrate into the soil and eventually lose its potency in July through August– the usual time for hatching grubs.
Insecticides offer the best results when used in high concentrations at the root zone where eggs are starting to hatch, and young grubs are around. You may control about 80 percent of your lawn's grub worm infestation in the next season with the right timing.
Signs of Grub Damage
Many homeowners are still confused as to whether (or not) their lawn problems are related to a grub infestation.
To make it easier for you, here are some signs to keep an eye out for:
Choosing between Grub Prevention or Grub Removal (Killing)
First, ask yourself if you want to prevent grubs or remove those already pestering your lawn. This will allow you to select the best grub control approach for your situation.
Grub preventers must be applied between April through mid-July, as this is when the grub eggs are starting to hatch. But if you want to correct grub damage immediately, you can apply grub killer to your lawn once signs of damage become visible. Be vigilant around mid-summer through September, when the grub larvae tend to feast on your healthy turf the most.
What to Do after Putting down Grub Control Pesticide
To get the most out of your chosen lawn pesticide for grub control, here are some expert-backed tips to follow:
Water the lawn as soon as you're done applying grub control. Since most grub killers and preventers are designed in granular formulations, water your lawn to at least 1-inch for them to be effective. Continue to monitor the lawn for grub worm activity, even after post-treatment. Grub killer application usually completes the eradication within a few days to a week. But if the grubs somehow still thrive and the lawn damage continues, your grub treatment may have been insufficient.
Expert Tip: Choose proven grub control pesticides such as Scotts GrubX, which can be applied at any season. This pesticide offers long-term control to remove adult beetles and reduce their population on your lawn.
Frequently Asked Questions
Why does my lawn have grubs but not my neighbor's?
The adult stage in a grub’s life cycle is a beetle– which flies. So, a random chance may be why your lawn has grubs, unlike your neighbor’s. If the recent weather is dry, but your lawn is adequately watered and surrounded by dry lawns, your turf is the prime spot for grub egg-laying.
Do I need to apply grub control each year?
Unless you notice grub damage, you do not need to use grub control every year. If you've been using a grub preventer and killer on your lawn for a few years, it's time to stop until you see grubs and European chafers again.
Grub preventers aid in grub management for the next season. A grub preventer will not eliminate grubs that are already causing damage to your lawn. A grub preventer will not eliminate the pests that may be present on your turf between mid-October and mid-May.
How often should I apply grub control?
When used at the right time, grub treatments are effective. To remove grubs from your lawn altogether, you may need to use the insecticide two or three seasons in a row. In most cases, though, you'll only need to use grub control twice during the season: once as a grub killer when you notice indications of infestation and once as a grub preventer around June and July to break the cycle.
When is it too late to treat for grubs?
Late summer (September) is too late to treat for grubs because white grubs have developed into adult beetles that are difficult to kill.
Using a grub killer on your lawn may not be enough to eliminate 60% of the beetles already feasting on the leaves and laying eggs on your turf. However, putting down a grub-killer pesticide will only be too late if the grass is already dead since you won't be able to restore grass that has been dead for more than five weeks.
When the grubs are actively causing damage to your lawn, use the grub killer. That will not require any timing. A grub preventer, for example, requires exact timing since it must be in the soil before or when the eggs develop into larvae (white grub worms).
How long do grub killer insecticides last?
The majority of grub preventers remain 60 to 90 days in the soil, allowing them to inhibit grub worms from when they hatch until they grow into larvae. However, because different products have different half-lives, it's critical to schedule them correctly before applying them to get the best grub control.
For example, Syngenta's Acelepryn pesticide can take 3-4 weeks to penetrate thatch in your lawn and access the root zone, where grub worm activity is present. Once inside, it can kill grubs and provide season-long control of these pests with only one treatment.