Know your enemy because lawn problem may not be grubs but
lack of water
I've read conflicting advice as to just when to apply
grub killer (such as Diazinon granules) for this area.
Just what date, and how often, should this grub control
item be applied?
The best time is in late July or the first of August, so the
grub killer is there for the early stages of development of the
various lawn-damaging grub species. The younger the insect, the
easier it is to kill and the less damage it can do before your
treatment ends its feeding.
Diazinon has been widely used but Merit, more recently
developed, is currently in favor since it works at lower
concentrations. Mach2, which can't be purchased at a retail level
but pest control companies can apply for you, affects only beetle
grubs so it's a better choice for those trying to avoid unwanted
side effects such as reduced worm activity that can mean hardened
soil and weakened lawn roots. The active ingredient, such as
Merit (imidacloprid) or Diazinon, is listed on the grub
One well-timed application should suffice. If you're a
greenskeeper who knows precisely which beetle is doing the most
damage, you might alter the application time for what you know of
that species and its development in that year. If you're dealing
with an enormous problem or missed the July application you treat
the lawn in spring, although your choice of product is more limited
then since Merit and Mach2 are not effective on older, springtime,
Regardless of timing and type of killer, water it in so it
reaches the grubs. Keep a sprinkler running after your application
until a collection can or rain gauge placed there catches an inch
of water. If your soil is hard packed, apply the water slowly or in
several closely spaced episodes so it can soak in rather than run
off. An inch of water will push the grub killer down through 3 or 4
inches of soil, good placement for most grub activity.
Water. So many of us in this business wish those concerned about
their lawns would jump to the conclusion "water" before thinking
"grubs." Today, I'm writing while I tend sprinklers. I
crossed paths witha fellow landscaper as I came in and we
commiserated over how dry the soil is and how hard it's been to
keep things watered this summer.
I mentioned grubs as my topic of the day. "Grubs! I wonder about
people who look at their lawns every August and figure they have
grubs," they sad. "They might just need to water better. Kick the
sod, and if it rolls up like a carpet, that's a grub problem.
Otherwise, water's probably the answer."
Grubs eat roots and that kills the lawn. The damage is at its
worst by late spring when grubs are oldest, before they emerge as
beetles. The grass dies or limps along on severely damaged roots
until the hot, dry weather comes, then gives up the ghost. If an
August-brown lawn still has enough root to anchor it against a
kick, you don't have enough grub activity to warrant grub
Studies show that a well watered lawn can sustain three or four
times as many grubs as one that's not irrigated, and is healthier
in many other ways. Greenskeepers respect these reports, so why
It's dry! Brown lawns, mildewed Pulmonaria, non-blooming
Astilbe, scorched ferns, faded Astrantia and flattened Anemone need
water, not pesticide. It takes a great deal of irrigation to make
up for lack of rain, so even if your sprinklers have been on
regularly, your plants may be parched. Poke your fingers an inch or
two into the soil, below the mulch or the lawn and see if it's warm
there -- that means it's dry, time to drag out the hoses.
The year of the bellflower
That's the title F.K. proposes for the year. "My peach leaf
bellflowers (Campanula persicifolia) have never stopped
blooming and are standing up tall. The clustered bellflowers
(C. glomerata) are blooming down their stems and preparing
to start all over again. The carpet bellflowers (C.
carpatica'Blue Clips' and 'White Clips') have bigger blossoms
than usual. Bellflowers are not exotic but they sure are neat!"
Black spot time!
Paul Emanuelsen, a zoo Adopt a Gardener who specializes in
roses, reports black spot beginning to show up now. One of his
floribunda roses is looking so bad he may just cut it down
and let it start over. Since it blooms just once a year in late
spring he won't lose any flower by doing this now but may net a
cleaner, neater look.
Overall rose health is as important in black spot control as
spraying. That means keep up with watering and fertilizer.
Emanuelsen's just applying his last Rose-Tone fertilizer for the
Green thumbs up
to putting a bucket under that leaky hose connection, if you
can't fix it yet. Use what you catch to hand water where sprays
Green thumbs down
to hose wrestling. How do hoses always manage to kink and
stiffen in ways that defy even the best hose reel and most agile
Originally published 8/2/03