 Knowing when to treat grubs is one thing, and knowing what
product to use is another. Many grub control treatments are
combined with fertilizer products, and this is the appropriate
time to apply a fall fertilizer treatment.It seems each year
provides more "stand-alone" treatment options as well. Diazinon
used to be the product of choice for many homeowners, but the
cancellation of home horticulture uses of the product created
confusion in selecting a product. The other wild card was that
the use of diazinon helped eliminate mole problems (by driving
them to the neighbor's yard) since the product killed grubs and
reduced earthworm populations.
Many of the products currently used do not affect earthworm
populations, and on the whole that is a good thing since
earthworms greatly benefit lawns. There are now some "soft
baits" available that are effective for mole control.
Current recommended products are halofenozide (Mach 2),
Heterorhabditis bacteriophora (Cruiser), imidacloprid (Merit)
and trichlorfon (Dylox). Many of the chemicals have other brand
names in addition to the ones listed in parentheses. It is also
recommended to drench treated areas with a half-inch of water
within 30 minutes of application, and this is especially
important with liquid applications. Application just ahead of a
rain is usually best. Granular applications buy a few days of
time but still need to be watered into the root zone where grubs
are active. The products with Merit will take three weeks or so
to activate. Some reputable sources also list carbaryl (Sevin)
granules as an option for grubs from green June bugs and
Japanese beetles. Carbaryl does reduce earthworm populations to
some degree.
In good growing seasons, it normally takes at least 10 grubs
per square foot of lawn area to justify treatment. In less
favorable seasons, this number can be reduced to six to eight
grubs per square foot. As your gasoline bill for the lawn mower
can attest, this has been a good growing season to date.
Consider many factors when selecting a product. These would
include combination with fertilizer, effectiveness, species
controlled, cost and the effect on the environment.
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 The Cruiser product is actually a nematode and would be the most
environmentally safe. It also costs about $55 to treat about 3,000
square feet of lawn. The other organic product sometimes mentioned
for control of the Japanese beetle grubs is milky spore. This
product is a bacteria that takes several years to become very
effective and can cost around $35 for 2,500 square feet of lawn. You
can't apply any other controls with milky spore, since you need high
populations of grubs to increase the bacteria populations to high
levels and provide transmission between grubs.
Good luck as you decide your attack plans against grubs. The
choices are many, and the attainment of the "perfect" lawn is a goal
many strive for. Remember, you can live with some grubs. However,
too many can be devastating to a lawn. With Japanese beetle
populations at very high levels in many areas, odds are great there
will be grubs to battle.
Syrphid flies
The population of syrphid flies swelled enormously this past
week. Syrphid fly is a generic name given to an entire group of
flies. There are some differences in appearance and color, but the
yellow and black color is the major one in our area. The other names
for syrphid flies are hover flies or flower flies. They tend to
hover around your arms and face when you have been perspiring, and
they land to lap up the sweat. They are also commonly found on
flowers, hence the flower fly name, and they do a good job of
pollinating.
Syrphid flies are actually beneficial insects. Besides helping to
pollinate as flies, the larvae feed on dead organic matter and are
predators of aphids.
The syrphid flies cannot sting, but their mouthparts can usually
be felt when lapping up sweat from sensitive areas. You may feel a
slight pinch.
[By
JOHN FULTON,
University of Illinois Extension, Logan County]
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