HOPHORNBEAM COPPERLEAF (ACALYPHA OSTRYIFOLIA) BIOLOGY AND CONTROL

Little is known about the biology and control of hophornbeam copperlea f, a weed of increasing importance in the Midwest. More than 2 wk of c old stratification and a 0.2% KNO3 solution increased germination of h ophornbeam copperleaf. Germination at constant 30 C was 47% and altern ating 30/20 C was 65%. Scarification did not increase hophornbeam copp erleaf germination. Within the first 600 growing degree days after soy bean planting, plant height, leaf area, and dry matter accumulation of hophornbeam copperleaf grown in soybean and alone were similar. Subse quently, leaf area and dry matter accumulation of hophornbeam copperle af grown alone were greater than of those grown in soybean. In contras t, plant height of hophornbeam copperleaf grown in soybean was greater than when grown alone. Hophornbeam copperleaf grown alone produced up to 12,510 seeds/plant, whereas hophornbeam copperleaf grown with soyb ean produced 980 seeds/plant. Of 13 postemergent herbicides evaluated on hophornbeam copperleaf in soybean, only lactofen, acifluorfen, and fomesafen controlled 80% or more. Lactofen at 210 g ai/ha consistently controlled more than 95% of the hophornbeam copperleaf.