A survey was conducted in 2000 across 38 counties in Mississippi on 192 randomly selected soybean fields to assess the most common occurring weeds. Statewide, prickly sida, which was present in 40% of the fields sampled, was the most common. Pitted and entireleaf morningglory were present in 34 and 29% of the soybean fields, respectively. Broadleaf signalgrass and barnyardgrass were the most common annual grasses, and yellow nutsedge was the most common sedge observed. Trumpetcreeper and redvine were the most common perennial vines. In the Mississippi Delta region of Mississippi, prickly sida was present in 45% of the fields sampled. The trend of occurrence of other species in the Delta mirrored statewide results. In eastern Mississippi, prickly sida and broadleaf signalgrass were found in 43% of soybean fields. Sicklepod, common cocklebur, and balloonvine were more prevalent in eastern Mississippi, when compared with the Mississippi Delta. Since 1982, there has been a sevenfold decline in the occurrence of common cocklebur and a fourfold decline in the occurrence of johnsongrass in Mississippi soybean. Also, the occurrences of redroot pigweed, common ragweed, and fall panicum have declined. Conversely, the occurrences of yellow nutsedge and broadleaf signalgrass have increased. The occurrences of barnyardgrass, prickly sida, redvine and trumpetcreeper have been relatively static over the past two decades.
Nomenclature: Balloonvine, Cardiospermum halicacabum L. #3 CRIHA; barnyardgrass, Echinochloa crus-galli (L.) Beauv. # ECHCG; broadleaf signalgrass, Brachiaria platyphylla (Griseb.) Nash # BRAPP; common cocklebur, Xanthium strumarium L. # XANST; common ragweed, Ambrosia artemisiifolia L. # AMBEL; entireleaf morningglory, Ipomoea hederacea var. integriuscula Gray # IPOHG; fall panicum, Panicum dichotomiflorum Michx. # PANDI; johnsongrass, Sorghum halepense (L.) Pers. # SORHA; pitted morningglory, Ipomoea lacunosa L. # IPOLA; prickly sida, Sida spinosa L. # SIDSP; redroot pigweed, Amaranthus retroflexus L. # AMARE; redvine, Brunnichia ovata (Walt.) Shinners # BVRCI; sicklepod, Senna obtusifolia (L.) Irwin and Barneby # CASOB; trumpetcreeper, Campsis radicans (L.) Seem. Ex Bureau # CMIRA; yellow nutsedge, Cyperus esculentus L. # CYPES; soybean, Glycine max (L.) Merr.
Additional index words: Annual grasses, common weeds, Mississippi Delta, nutsedge, perennial vine, weed survey.
Abbreviations: ALS, acetolactate synthase; EM, eastern Mississippi; MASS, Mississippi Agricultural Statistics Service; MD, Mississippi Delta.