I spread a 14 pound bag of Bayer Merit granulated on my yard last night, and
watered the lawn afterward with between 0.25 and 0.5 inches of water to wash
it in. I'm attempting to kill Japanese beetle grubs - have had a bad
problem for the last tow years. I applied the Merit at a heavier rate than
recommended. The recommended rate is 2.8 lbs/1000, I used 3.8 lbs/1000. My
soil is clay and perculates a little slow.
Tonight we had a heavy thunderstorm and heavy rain. We got about 1 inch of
rain in about 15 minutes.
My question is; did all of my Merit wash away? Should I reapply?
Heh, what do you think those beetles are doing when they're not
feeding?... That's right, laying eggs for the next generation.
The Merit will protect Peter's lawn from grub damage this fall
and consequently next spring too.
I really doubt it has washed away, Peter. It clings to organic
material real well.
Thanks for you reply Steveo.
Will it hurt my lawn to reapply? I *really* need to wack the grubs bad.
They got me the last two years before I realized what was going on. I want
the mothers dead.
Here in Ontario you are not permitted to reapply. Merit has a very long
residual... and you have already admitted to applying above the recommended
application rate. You should leave it alone.
Keep in mind that the application will not do anything about the existing
grubs in your lawn. Merit will only prevent a new infestation. I have
applied it many times and have seen it watered in, not watered in and
drenched. It has still been effective in preventing a new infestation every
Thanks Peter -
But why won't it do anything for existing grubs? I read that it kills
grubs. Also, the new infestation is under way, the beetle population peaked
last week and the eggs shouls start hatching grubs any day now. What I
understand, now is the best time to apply Merit.
I also understand Merit is not harmful to people and pets, so
overapplication doesn't have any *real* adverse effects.
Merit has a very long residual. It hangs around for about 3 months. This is
why they don't permit a second application in a season here. You may as well
just double the application rate initially 'cause the first application is
Merit works to prevent the new, young grubs from feeding. They ingest it in
very small quantities and then can't feed again which causes them to starve
to death. I have found it to be virtually 100% effective even when the
application is not perfect. Unfortunately the adult grubs are just too big
and strong to be effected. Fortunately they will pupate into June Bugs and
fly off and bother someone else in the next spring, or following one. Merit
should eliminate your grub problem, but you have to be patient.
You are right when you say now is the right time to apply it.
I can't tell you the science behind it, but do know that that is how it
works. You are not permitted to reapply because it has such a long residual.
When I used to spray Dursban and Diazinon and had spraymix left over the
next day I would just count it as water. The 1/2 life on that stuff is very
short, depending upon water ph, sunlight exposure etc. Merit is different.
It hangs in there.
Large grubs have too much body mass/fat, they can survive the
very mild active ingredient in Merit.
We use dylox to kill bad infestations of large grubs, not Merit.
As was mentioned, merit is designed as a preventative.
Part of the answer is on the package label for Bayer Advanced Lawn
Season-Long Grub Control, which says:
"HOW TO USE TO CONTROL GRUBS:
"WHEN TO APPLY: Apply once anytime from May through mid-August. For
best results, apply Season-Long Grub Control before grubs... hatch.
Contact your County Extension Agent for the ideal dates to apply in
What the label doesn't say is that if you already have any but the
smallest of grubs chewing on your grass roots, the Merit stuff won't
have any significant effect on them. However you can kill them with
something else, such as Bayer Advanced Lawn 24 Hour Grub Control (in
which the active ingredient is Dylox). If you have yellow or brown
patches developing in your lawn, check to see whether there are grubs
in the soil below. If there are, zap the whole lawn with Dylox, which
will clear out all the active grubs. The Merit you already applied
should take care of any new grubs that hatch this year.
Next year you may do better to apply the Merit product earlier in the
year, before any grubs hatch - exactly when depends on your location,
but there's no harm in being two or three weeks early, and a lot to
lose by being two or three weeks late.
Steveo, you are only half right. The Merit will protect Peter's lawn
from grub damage this fall (to the extent that the lawn is not already
damaged by grubs that had hatched and started growing before he
applied the Merit).
But next spring is a different story. Even if there are no grubs in
Peter's lawn this fall, there may be lots of them happily munching
away on the grass roots next spring unless Peter applies Merit again
in the spring before the eggs hatch. Remember it's not the grubs that
lay the eggs, it's beetles, and beetles can fly in from anywhere.
Merit in the grass roots this fall won't prevent beetles from
depositing eggs that lie dormant in Peter's lawn until next spring.
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