Proceedings of the Sixty-first Annual Meeting of the Northeastern ...

121
WEED CONTROL IN NO-TILL SWEET CORN. D.D. Lingenfelter, The Pennsylvania
State Univ., University Park and D.H. Johnson, The Pennsylvania State Univ.,
Manheim.
ABSTRACT
Field studies were conducted in 2006 at two locations in PA to evaluate annual
and perennial weed control in no-till sweet corn (Zea mays L., succharata var.
'Attribute'). Atrazine (1.24 lb ai/A) and s-metolachlor (0.96 lb ai/A) were applied PRE to
most of the treatments followed by a POST application of one or a combination of the
following herbicides: 2,4-D (0.25 to 0.5 lb ai/A), atrazine (0.25 to 0.5 lb ai/A), bentazon
(0.52 lb ai/A), mesotrione (0.094 lb ai/A), topramezone (0.0164 lb ai/A), tembotrione
(0.12 lb ai/A), carfentrazone (0.012 lb ai/A), clopyralid (0.19 lb ai/A), halosulfuron (0.032
lb ai/A), foramsulfuron (0.033 lb ai/A), glufosinate (0.4 lb ai/A), and KIH-485 (0.18 lb
ai/A). Adjuvants were included in the POST spray mixtures.
In general, herbicide treatments provided >90% control of annual weeds
including, giant foxtail (Setaria faberi), fall panicum (Panicum dichotomiflorum), common
lambsquarters (Chenopodium album), and velvetleaf (Abutilon theophrasti). Canada
thistle (Cirsium arvense) was the only perennial weed species that was common at both
locations. Clopyralid, mesotrione plus atrazine, and glufosinate plus atrazine provided
80 to 85% control of Canada thistle. Other treatments that provided >80% control of
Canada thistle included, tembotrione plus atrazine (92%) at Rock Springs and
topramezone plus atrazine (83%) at Landisville. At Landisville, field bindweed
(Convolvulus arvensis) control ranged from 82 to 92% control with treatments
containing 2,4-D, clopyralid, and glufosinate plus atrazine, while the other treatments
only provided 45 to 77% control. At Rock Springs, tembotrione plus atrazine,
halosulfuron plus 2,4-D, and foramsulfuron provided between 70 and 81% control of
hemp dogbane (Apocynum cannabinum) and common milkweed (Asclepias syriaca).
Glufosinate plus atrazine also provided adequate suppression (80%) of hemp dogbane.
Aside from carfentrazone, clopyralid, and KIH-485, most of the other POST treatments
provided 77 to 95% control of common pokeweed (Phytolacca americana).
No crop injury occurred from any of the treatments at Landisville. At Rock
Springs, negligible crop injury was noted on most treatments except for halosulfuron
plus 2,4-D and foramsulfuron which ranged from 15 to 20%. Sweet corn yields at Rock
Springs were generally better than at Landisville. At Rock Springs, sweet corn in the
untreated check yielded about 5,300 lb/A compared to the other treatments which
ranged from 9,100 to 13,000 lb/A. The one exception was the halosulfuron plus 2,4-D
treatment which reduced the yield to about 5,800 lb/A. At Landisville, sweet corn yields
also benefited from better weed control in the herbicide treated plots and ranged from
about 5,800 to 9,000 lb/A compared to the untreated check (2,700 lb/A).
In summary, production of no-till sweet corn can be enhanced by newer herbicide
options. Compared to a decade ago, PRE and POST annual weed control in sweet
corn has greatly improved. Perennial weed control can still be challenging for sweet
corn producers, especially in no-till settings. However, with the introduction of some
newer herbicide chemistries, these can complement other product choices to provide
better weed management.
103