Page 128 - AG 7-2011 Revised 2016

LATE SPRING WEED CONTROL IN ESTABLISHED LANDSCAPES
(April, May, June)

By: Gary King Ph.D.

Germinated weeds will grow rapidly as the weather warms April through June. Pre-emer-
gent herbicides used in the previous season may prevent most, but not eliminate all new
weeds. There are several reasons you may still have weeds after careful planning and use
of pre-emergent herbicides:

1. Some weed seeds may not have been affected by the herbicide selected in the first ap-
plication (early spring).
2. Some weed seeds may have been missed just by chance.
3. Other emerging weeds may be from taproots, rhizomes, tubers, and other vegetative
parts that will sprout in spite of the pre-emergent herbicide.

A second application of the same pre-emergent herbicide may extend your weed prevention
into July and August. If your first treatment was early enough and you still have a heavy
population of weeds, you may need to try a different pre-emergent this time that targets
your specific weeds.

Areas requiring special treatments:
Newly seeded or re-seeded turf areas: Proper soil preparation (see page 112) to eliminate
weeds and proper maintenance of newly seeded turf areas will encourage vigorous turf
growth which will not allow weeds to compete. Pre-emergent herbicides should be avoided
because they may damage seedlings and should be unnecessary to use in this situation.

Established turf: Normally pre-emergent herbicides are not necessary in well-maintained
turf. Ideally turf is so thick it crowds out the weeds by itself. Most of the time people only
have problem spots in their lawns and weeds get into those problem areas. See page 126
for more details.

Ground cover areas: Once groundcover is established it will also crowd out some weeds.

Flower beds: Generally need regular treatment season to season.

For established weeds, see tips and techniques for spot spraying listed under Mid-Summer
Weed control on page 126.

ADDITIONAL WEED CONTROL SECTIONS: IDENTIFICATION- PAGE 100
MGMT BEFORE PLANTING- PAGE 112 EARLY SPRING- PAGE 114
AT TIME OF PLANTING- PAGE 118 MID-SUMMER- PAGE 126
IN ESTABLISHED AREAS- PAGE 124 FALL- PAGE 134

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