Southeastern U.S. Vegetable Crop Handbook - 2022 - 351

WEED CONTROL
TABLE 4-17. CHEMICAL WEED CONTROL IN ONION (cont'd)
Weed
Herbicide,
Mode of Action Code*
and Formulation
ONIONS, Preplant and Preemergence (cont'd)
Annual grasses and
broadleaf weeds, yellow
nutsedge suppression
S-metolachlor, MOA 15
(Dual Magnum) 7.62 EC
8 to 16 oz
0.47 to 0.96 Dry bulb onion and green onion. This is a Section 24(c) Special Local Needs
Label. Growers must obtain a label. Irrigation following the application of Dual
Magnum will increase the risk of crop injury. Use lower rates on coarse-textured
soils and higher rates on fine-textured soils. See label for more information.
Seeded Application. Do not apply before 4-leaf stage. Once onion has reached
the 4-leaf stage, apply 8 oz per acre. When onions reach 6-leaf stage, rate can be
increased to 12 oz per acre.
Transplant Dry Bulb. Transplant and then irrigate to seal soil around the root ball.
Apply within 48 hours of planting. Heavy irrigation following the application of Dual
Magnum will increase the risk of crop injury.
ONIONS, Postemergence
Most annual broadleaf
weeds
oxyfluorfen, MOA 14
(Galigan) 2 E
(Goal 2 XL) 2 EC
(Goaltender) 4 E
Common lambsquarters,
common chickweed,
common purslane,
black nightshade,
ladysthumb, Pennsylvania
smartweed, redroot
pigweed, and some
annual grasses
Most broadleaf weeds
less than 4 in. tall or
rosettes less than 3
in. diameter; does not
control grasses
Most emerged weeds
ethofumesate, MOA 8
(Nortron) 4 SC
0.12
0.5 pt
0.5 pt
0.25 pt
0.5 to 1
16 to 32 oz
Dry bulb only. May be used as a postemergence spray to both the weeds and
crop after the onions have at least two fully developed true leaves. Some injury to
onions may result. Injury will be more severe if the chemical is applied during cool,
wet weather. Weeds should be in the 2- to 4-leaf stage for best results. Do not
make more than four applications per year. PHI = 45 days.
Apply at planting or just after planting prior to weed emergence. Can be used
postemergence at 16 oz per acre. See label for more information. Rainfall of at
least 0.5 in. is needed for activation.
Amount of
Formulation
Per Acre
Pounds Active
Ingredient
Per Acre
Precautions and Remarks
carfentrazone-ethyl,
MOA 14
Up to 0.031
(Aim) 1.9 EW or 2 EC
glyphosate, MOA 9
(numerous brands and
formulations)
Annual and perennial
grasses only
fluazifop, MOA 1
(Fusilade DX) 2 EC
sethoxydim, MOA 1
(Poast) 1.5 EC
clethodim, MOA 1
(Arrow, Clethodim,
Intensity, Select) 2 EC
(Intensity One, Select Max)
1 EC
Up to 2 oz
See labels
See labels
Apply post-directed using hooded sprayers for control of emerged weeds. If crop is
contacted, burning of contacted area will occur. Use a nonionic surfactant or crop
oil with Aim. See label for rate. Coverage is essential for good weed control. Can
be tank mixed with other registered herbicides.
Row middles only. Apply as a hooded spray in row middles, as shielded spray in
row middles, as wiper applications in row middles, or postharvest. To avoid severe
injury to crop, do not allow herbicide to contact foliage, green shoots, stems,
exposed, roots, or fruit of crop. PHI = 14 days.
0.1 to 0.25
6 to 16 oz
0.2 to 0.3
1 to 1.5 pt
Dry bulb and green onion. Apply to emerged grasses. Consult manufacturer's
label for specific rates and best times to treat. Do not apply on days that are unusually
hot and humid. PHI= 45 days.
Dry bulb and green. Apply to emerged grasses. Consult manufacturer's label
for specific rates and best times to treat and adjuvant and rate. Adding crop oil to
Poast may increase the likelihood of crop injury at high air temperatures. Do not
apply Poast on days that are unusually hot and humid. PHI = 30 days.
6 to 16 oz
9 to 32 oz
0.09 to 0.25
0.07 to 0.25
*Mode of action (MOA) code developed by the Weed Science Society of America.
Dry bulb only. Apply to emerged grasses. Consult the manufacturer's label for
specific rates and best times to treat. Adding crop oil may in- crease the likelihood
of crop injury at high air temperatures and high humidity. Do not apply Select on
unusually hot and humid days. PHI = 45 days for dry bulb onion. Intensity One may
be applied to dry bulb onions or green onions (leeks, scallions or spring onions,
Japanese bunching onion, shallots or eschalots). Do not exceed 16 ounces of
Intensity One per acre on green onions. For green onions, PHI = 14 days.
2022 Vegetable Crop Handbook for Southeastern United States
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