Greenfield Lakes Neighbors

Weed Control

Fall and Winter Weeds and How to Manage Them

A plant growing where you don't want it to - this is a working definition
of a weed. Weed seeds arrive in your yard either by wind or carried in by
birds. There are two basic groups of weeds, those that are grasses and
those that are broadleaf. In Arizona, weeds are usually annual or
perennial. Annual weeds grow from seeds each year and grow, flower,
produce seed and die within one season. Perennial weeds can live for
several years. The control methods you choose will depend on what type of
weed you are dealing with.

Control

Control
If you only have a few weeds in a relatively small area, mechanical removal
is often the most desirable. This can be accomplished with sharp hoes,
shovels, or hand pulling. C'mon, this is good exercise - therapeutic
even. If applications of herbicides are warranted, it is important to
select one that will target the weed you are dealing with and not harm
surrounding vegetation. If you use grass killer on the crabgrass or
nutsedge growing in your hybrid Bermuda lawn, it won't discriminate and
will kill any "grass" it contacts.

In gravel areas both annual and perennial weeds can be controlled with the
application of a post-emergent herbicide. Post-emergent meaning weeds that
have already sprouted and are growing. The most common products for this
application contain Glyphosate (Roundup) or Glufosinate (Finale). These
herbicides work by translocating the product through the leaves to the
roots where they interfere with the growth process. Both these products
are non-selective, meaning they will kill any growing vegetation, both
grass and broadleaf.

In lawn areas the best weed control is a healthy lawn. Turf will
out-compete most weeds and regular mowing will remove the growing tips of
the weeds, preventing them from forming seeds. Any chemical weed control
should be practiced only on well established lawns as newly installed or
seeded lawns are often injured by weed control agents. Spot treatment with
Glyphosate is effective, especially in dormant winter Bermuda.

Pre-emergents work very well in preventing weed seeds from sprouting and
work best in gravel areas. Do not use a pre-emergent if you plan to
overseed your hybrid Bermuda or Bermuda grass lawn - it will prevent the
winter rye grass seeds from sprouting! Common pre-emergents are marketed
under the trade names of Gallery, Surflan or Barricade. Apply twice a year
in September/October for control of winter weeds and in April/May for
summer weeds.

For control of nut sedge (nut grass) in lawns, several applications in
September of the product Manage will provide effective control. Some
follow-up may be necessary.

Caution: Never use a total vegetation killer that is a soil
sterilant. These products kill existing vegetation, persist in the soil
for many years and can leach into surrounding areas seriously affecting or
killing plants there. If you have an area in your yard where nothing will
grow, a soil sterilant like Triox may have been applied there in the past.

Be careful when using products that contain 2-4-D. They are designed to be
applied when the temperatures are cool. During most of the year this
product volatilizes (turns to a gas) and can cause damage to surrounding
vegetation as it drifts through the air
.
Remember! Always follow label directions exactly! We sometimes think if a
little is good, more is a whole lot better. With herbicides and
insecticides, this can be deadly - to plants, pets and humans. Wear
protective clothing and avoid skin contact with the product.

Common broadleaf weeds: Purslane, goosefoot, pigweed, puncturevine, London
rocket, bur clover, cheeseweed, tumbleweed, silver nightshade.

Common grass type weeds: crabgrass, Bermuda grass, nutgrass (not really a
grass), bromegrass, orchardgrass.



Catherine Rymer
Instructional Specialist, Sr., Urban Horticulture
Certified Arborist