As soon as they hatch, they develop into grubworms and start eating the grass roots throughout the warm seasons. So, throughout this life cycle of Japanese beetles and European chafers, what is the best time to treat for grubs with a preventer or a killer? It is usually best to put down grub preventers in June and July just when the grubs are about to hatch. This will provide the best preventative control of grubs for the next season.
If you want to stop grub damage immediately, the best time to apply grub killer insecticide in your lawn is as soon as you see signs of damage. This is usually any time between early spring to early August when the grub worms are most active eating and damaging grass in your lawn.
When treating your lawn to prevent grub damage for the next season, it would be too early to apply grub preventer on your turf in early spring. The pesticide will easily disintegrate into the soil and lose its potency by the time the grubs hatch in July through August.
For the grub killers, you can stop lawn damage almost immediately especially if you follow the right application guidelines on the label of the pesticide. You want to get the best effects after applying the pesticide on your lawn. Here are a few tips on what to do after the application:. Pro tip : Some grub control pesticides such as Scotts GrubX provide long-term control and can be applied almost any time of the season.
It can kill adult beetles and reduce their population in your yard. Did you find grubs in your lawn last spring? Then you may need to apply a grub preventer for lawns. You do not need to apply grub control every year successively unless you see grub damage. Grub preventers help control grubs for every next season.
You cannot apply a grub preventer to kill grubs that are already damaging your lawn. It is important to realize that healthy turf, supported by frequent rain or irrigation, can support a grub population of five or more grubs per square foot with no visible turf damage.
In fact, most well-maintained lawns do not have visible damage from grubs. A lawn should be mowed at 3 to 4 inches in height and properly fertilized for maximum root growth. However, if the grub population is high or if there is a history of damage in an area, it may be necessary to consider using an insecticide for grub control. Finding one or two grubs does not indicate you need to apply a grub control product. Check for the active ingredient in a grub product.
I went to several of the local lawn and garden centers in the Lansing, Michigan, area to see what kinds of products are available that specifically claim they will work to control grubs. I found five to nine different products at each store. The profusion of different products can be rather mystifying.
The critical issue with any grub control product is the active ingredient. There are many products available, some with the same active ingredients.
The active ingredients are usually shown on the bottom right or left of the front of the bag and listed as a percent of composition. Water the lawn immediately after applying the insecticide. The second major concern is to make sure the insecticide is thoroughly watered into the ground with at least a half-inch of irrigation or rain immediately after the chemical is applied. You can measure how much irrigation is applied by putting out several coffee cups in your lawn and run the irrigation until they fill to a half-inch level above the bottom.
Research tests over the last 25 years have clearly shown that watering immediately after application helps to obtain good results. This also moves the chemical off the grass and will make the yard safe for children, pets and wildlife after the yard is dry.
A third concern is the rate at which the insecticide is applied. The label lists the legal rate at which the product can be used. There is little benefit to exceeding this rate, and doing so is also illegal. There are also products for sale that list grubs on the label that do NOT work for grubs.
Insecticides used for grubs can be separated into two groups based on how they work: preventive chemicals and curative chemicals. These products are used to prevent future grub problems, not to control the grubs present in the lawn in the spring. They will not work on grubs found in the lawn from the middle of October through the middle of May. However, when applied in June or July they provide excellent protection against the next generation of grubs.
So, if you need to apply the preventive insecticide BEFORE the grubs are there, how do you know if you need to use an insecticide or not? If you confirmed grub damage the previous fall or spring, meaning you found lots of grubs, then you may want to use a preventive insecticide for one or two years to build a more dense turf that will be tolerant of grubs.
There is an erroneous philosophy being perpetuated that because we have European chafers and Japanese beetles in the area, it is necessary to treat every year or your lawn will be damaged by grubs. This is not true. Preventive products are the most effective. Products containing imidacloprid, thiamethoxam, clothianidin or chlorantraniloprole will not control grubs in the spring. They are preventive products that work very well on newly hatched grubs present in July, but do not work well for large grubs found from September to May.
There are different recommended timings for application depending on the active ingredient. Although the bag often says apply anytime from May to Aug. If applied in early spring, the pesticide may move through the soil or partially degrade by the time the grubs hatch in late July. If applied too late, preventative products may not be effective as they work best on small grubs. Lawn sprinklers can be used if you do not have an irrigation system. There is another active ingredient in some insecticides called chlorantraniliprole that will also work in preventing grub problems, but it is less water soluble than the other preventive compounds mentioned above, so it can be applied any time after the grass turns green in the spring.
Chlorantraniliprole can be applied as early as April and up to mid-July. The grubs may feed on grass roots, killing the roots and making the grass thin, wilted and brown. Over time, irregular patchy areas in the lawn develop as the grubs eat more roots. Applying grub control products at the right time will help prevent the grubs from developing, helping to keep your lawn healthy. Before applying grub controls, make sure the lawn damage is caused by a grub infestation.
Dig up 3 or 4 inches of soil and sift through it. Grubs are C-shaped, creamy-white, with a brownish head and six legs. Grubs need to be controlled before they grow, become beetles and fly.
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