Field and greenhouse studies were conducted to evaluate herbicides in pumpkin. Field experiments at three Illinois locations determined weed control and crop injury from clomazone, dimethenamid, ethalfluralin, sulfentrazone, imazamox, RPA 201772, flumiclorac, and halosulfuron applied preemergence. Clomazone plus sulfentrazone controlled redroot pigweed 78 to 99%, ivyleaf morningglory 80 to 97%, common lambsquarters 97%, common purslane 84 to 99%, and velvetleaf 55 to 99%. Imazamox plus clomazone commonly provided more consistent broadleaf weed control than did ethalfluralin plus clomazone. RPA 201772 when used on sandy soils killed the pumpkin. Sulfentrazone initially caused chlorosis and necrosis on pumpkin seedlings when soil organic matter was low (< 1%) or when soil moisture was high. However, plants recovered rapidly, and yields were not affected. In a greenhouse study pumpkin was more tolerant to clomazone plus sulfentrazone than to sulfentrazone.
Nomenclature: Clomazone; dimethenamid; ethalfluralin; flumiclorac; halosulfuron, imazamox; RPA 201772 (proposed name, isoxaflutole), 5-cyclopropyl-4-(2-methylsulphonyl)-4-trifluoromethyl-benzoyl isoxazole; sulfentrazone; common lambsquarters, Chenopodium album L. #3 CHEAL; common purslane, Portulaca oleracea L. # POROL; ivyleaf morningglory, Ipomoea hederacea (L.) Jacq. # IPOHE; redroot pigweed, Amaranthus retroflexus L. # AMARE; velvetleaf, Abutilon theophrasti Medicus # ABUTH; pumpkin, Cucurbita pepo var. pepo L. ‘Howden’.
Additional index words: Herbicide combinations, herbicide interactions.
Abbreviations: DAT, days after treatment; PRE, preemergence.