White Grub Control Alternatives
It is very difficult to use an IPM (Integrated Pest Management) approach to white grubs in turfgrass. Turfgrass often has a very high value – either monetary value (golf courses and sod farms) or aesthetic/emotional value (home lawns). White grub infestations are highly variable from year to year and from place to place. Damage is spotty, localized and impossible to predict.
Monitoring,
one of the keystones of IPM is not practical for white grubs under most
circumstances. Inspection for grubs requires cutting and lifting flaps
of turf and looking for grubs below the thatch level. This is
difficult, time consuming and potentially damaging. Research has
indicated that the number of samples necessary is too large to be
practical.
Studies at Cornell University
have shown that over 70 percent of all grub control treatments were
applied needlessly because there were no grubs in the lawn. Many
homeowners are frightened into applying grub controls because of
advertisements on TV, in plant centers, or because of horror stories
they have heard about grub damage. Most grub treatments are not only
expensive but hard to justify from an environmental standpoint.
There
are 3 approaches to grub management in the home lawn, depending on your
tolerance for damage, comfort with pesticides and willingness to spend
the cash.
#1. The Golf Course Approach: Treat
every part of the lawn, every year because you might have white grubs
and heavy use of high-price insecticide is preferable to ANY white grub
damage. The available insecticides for grub prevention are imidacloprid
(Merit®, Grub-Ex®) and halofenozide (Mach 2®, Grub-B-Gon®). These must
be applied before early August to prevent damage. A compromise
modification of the Golf-Course Approach is to treat only those areas of
previous damage. Grubs tend to return to the same areas in successive
years, so it is logical to treat the areas where you had grubs last year
or the year before.
#2. Wait-And-See
Approach. Watch the lawn carefully during August - September for early
signs of damage (wilting, turning brown). Apply a curative insecticide
such as trichlorfon (Dylox, Bayer Advanced 24-Hour Grub Control) only
where needed and when needed. The risk is that you might still lose
some sod, especially if summer rainfall or irrigation keeps the grass
growing and vigorous through July and August. Damage symptoms may not
appear until after it is too late for effective treatment (late
September through late October). Unfortunately, raccoons and skunks are
much better at locating grub populations than we are and the first hint
of a grub problem in your turf is likely to be that your lawn was
"plowed" by varmints overnight.
#3. The
Do-Nothing Approach. Count up how many years you DID NOT have grub
damage. Divide the cost of replaced sod by that number of years. If
the yearly-averaged cost of sod is less than the price of insecticide,
do nothing and take your lumps in the occasional year when damage
occurs. This approach is much easier to follow if your attitude is
"it's just grass, anyway."
White grub management decisions are difficult and frustrating. There is no one right answer for everyone.
White Grub Control Alternatives
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