Page 120 - AG 7-2011 Revised 2016

EARLY SEASON WEED CONTROL IN ESTABLISHED LANDSCAPES
(January, February, March)
By Gary King Ph.D.

Study the Growing Season Chart on page 106 to determine the proper timing for application
of pre-emergent herbicides. Pre-emergent herbicides should always be applied to flower
bed areas where many open spaces provide opportunity for weeds to grow. You must
put down the pre-emergent herbicide prior to weed seed germination. The spring growing
season may appear to be too early when looking at these charts, but if you provide service
on a monthly basis and will be away from the property, it’s better to start pre-emergent ap-
plications earlier than later. If you service weekly, you will be able to time your pre-emergent
applications with more precision.

Prior to herbicide application, prepare the area by hand pulling, hoeing or spot spraying the
existing weeds to kill them. When removing the weeds manually, be careful not to leave
flower heads as they may still drop seeds on the soil.

Remember pre-emergent herbicides, which kill the seeds as they germinate, are preventa-
tive and will reduce manual labor as the seasons rotate. After weed elimination, new land-
scape ornamentals can be planted and then weed-free soil mulches may be applied. You
can always check with your Univar representative for timing and treatment advice.

Do’s and Don’ts:

Do: Plant with weed free material.
Do: Wait for 1 to 2 irrigations to sufficiently settle the soil before applying the
pre-emergent herbicide.
Do: Avoid seeding new plants after pre-emergent herbicide, because some or all
of the seed will fail to emerge.
Don’t: Be late and allow weed seed germination ahead of the pre-emergent herbicide.
Don’t: Expect control of weeds that have already sprouted, most pre-emergent
herbicides are unable to affect seedlings after their germination.
Don’t: Use the same product repeatedly throughout the year.

ADDITIONAL WEED CONTROL SECTIONS: IDENTIFICATION- PAGE 100
MGMT BEFORE PLANTING- PAGE 112 LATE SPRING- PAGE 122
AT TIME OF PLANTING- PAGE 118 MID-SUMMER- PAGE 126
IN ESTABLISHED AREAS- PAGE 124 FALL- PAGE 134

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