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( Lactuca sativa L.), the predominant crop in this region ( Bottoms et al., 2012 ; Breschini and Hartz, 2002 ; Hartz et al., 2000 ; Jackson et al., 1994 ). Less attention has been given to cole crops (broccoli, cabbage, and cauliflower), which are

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80 POSTER SESSION 12 (Abstr. 635-649) Crop Protection

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Cole crop [broccoli, cabbage ( Brassica oleracea var. oleracea L.), and cauliflower ( Brassica oleracea var. botrytis L.)] and leafy green [collards and kale ( Brassica oleracea var. sabellica L.)] production in the United States

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Abstract

Over a 6-year period (1969-1974) the efficacy of 3 insecticides and 24 herbicides and their interactions in combination were investigated when applied to field-seeded broccoli (Brassica oleracea L. Italica group), cabbage (Capitata group) and cauliflower (Botrytis group). Of these, broccoli was the most susceptible to injury. Of 212 herbicide-insecticide combinations, 26 caused phytotoxic symptoms in broccoli, 20 in cabbage and 8 in cauliflower. The insecticides, thionazin, fensulfothion and carbofuran, were each involved in 1 or more phytotoxic combinations in each of the 3 crops. Ten herbicides were involved in phytotoxic reactions: alachlor, aziprotryn, benefin, CDEC, chlorpropham, cycloate, prometryne, propachlor, prynachlor and PP493. Root maggot damage was reduced markedly by the insecticides. Carbofuran allowed less damage than either fensulfothion or thionazin. None of the herbicides showed any insecticidal properties, and some decreased the effectiveness of the insecticides.

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These studies were initiated to investigate severe growth inhibition observed when some vegetable crops were infested with corn spurry (Spergula arvensis L.). Interference by a natural population of the weed reduced the shoot weights of English pea (Pisum sativum L.) and collard (Brassica oleracea L.) by 93% and 72%, respectively. In a greenhouse experiment where light competition by corn spurry was prevented, broccoli (Brassica oleracea L.) shoot weights were reduced by corn spurry, but pea weights were not different from the controls. Homogenized corn spurry shoot tissue incorporated into a greenhouse potting medium inhibited the growth of both species, and a concentration effect was observed. Sequential hexane, dichloromethane, methanol, and 50% aqueous methanol extracts of corn spurry root and shoot tissue were tested for inhibitory activity using millet seed germination and broccoli seedling growth bioassays. Dichloromethane, methanol, and aqueous methanol shoot extracts were inhibitory to broccoli; whereas all shoot extracts inhibited millet germination. Shoot extracts were more inhibitory than root extracts. Further fractionation of the inhibitors using a combination of reversed-phase sephadex LH-20 and silicic acid column chromatographic procedures showed that a major portion of the millet germination inhibition was due to sucrose esters (SE). Preliminary characterization of the esters showed that there were four different SE groups. The major groups contained either octanoic or dodecanoic acid along with butanoic and petanoic acids. All groups inhibited seed germination at concentrations as low as 20 ppm. This is the first report of the SE class of defense chemicals in plant species outside of the solanaceae family.

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The North Carolina Agricultural Research Service supported this research. Emeritus Professors Thomas R. Konsler and Frank L. Haynes provided leadership in cole crops and potatoes. Anthony D. Cole and George B. Cox provided technical

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the results of previous studies showing the weed-suppressive activity of sorghum-sudangrass cover crop on following cole crops production ( Creamer and Baldwin, 2000 ; Finney et al., 2009 ; Mennan et al., 2009 ) and demonstrate that in the case of

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Drip irrigation used in conjunction with plastic mulches and other intensive production technologies continues to expand in the Midwestern states. The vegetable crops being produced on the greatest acreages using drip irrigation/plastic mulch are tomatoes, peppers, muskmelons and watermelons. Summer squash, eggplant, cucumbers and some cole crops are also grown using drip irrigation and plastic mulches but to a much lesser extent. The estimated acreage for drip irrigation in the Midwest is 43,209 acres which includes both vegetable and fruit crops.

Special consideration in using drip irrigation in this region of the country are high pH of the water, amounts of calcium salts, and iron levels in the water.

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The development of polyethylene as a plastic film in 1938 and its subsequent introduction as a plastic mulch in the early 1950s revolutionized the commercial production of selected vegetable crops. Throughout the succeeding years, research, extension, and industry personnel, together with growers, have documented the advantages of using plastic mulch as one component of a complete intensive vegetable production system. Although a variety of vegetables can be grown successfully using plastic mulches, muskmelons, honeydews, watermelons, squash, cucumbers, tomatoes, peppers, eggplant, okra, sweet corn, and cole crops have shown significant increases in earliness, total yield, and quality. Research continues on field evaluation of new formulations of degradable, wavelength-selective, and colored plastic mulches and on cropping systems to use best these specific improvements. The use of plastic mulches for the production of vegetable crops continues to increase throughout the United States and the world.

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