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Pamela B. Trewatha

Through contacts, observations, and travel throughout the midwestern United States during Spring and Summer 2004, a number of weed species were noted to be relatively new problems, or growing problems in turfgrass and/or horticultural cropping situations. These include hophornbeam copperleaf (Acalyphaostryifolia), garlic mustard (Alliaria petiolata), blackgrass (Alopecurus myosuroides), Palmer amaranth (Amaranthuspalmeri), waterhemp species (Amaranthus spp.), biennial wormwood (Artemisiabiennis), lambsquarters complex species (Chenopodium spp.), windmillgrass (Chlorisverticillata), showy chloris (Chlorisvirgata), Asiatic dayflower (Commelinacommunis), horseweed (Conyzacanadensis), redstem filaree (Erodiumcicutarium), toothed spurge (Euphorbia dentata), dovefoot geranium (Geranium molle), pitted morningglory (Ipomoealacunosa), purple deadnettle (Lamium purpureum), birdsfoot trefoil (Lotuscorniculatus), roundleaf mallow (Malvarotundifolia), star-of-bethlehem (Ornithogalumumbellatum), cressleaf groundsel (Packeraglabella), striate knotweed (Polygonum erecta), creeping yellow fieldcress (Rorippa sylvestris), lanceleaf sage (Salviareflexa), sibara (Sibaravirginica), white campion (Silene latifolia ssp. alba), hairy nightshade (Solanumphysalifoium), spiny sowthistle (Sonchusasper), and others. Possibilities for this increase or spread include natural invasiveness of the weeds, control of previous weed competitors, resistance to widely used herbicides, changes in cropping practices, and other weed adaptations to current weed management methods.

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Clydette M. Alsup and Pamela B. Trewatha

Many homeowners have difficulty establishing ornamental gardens in shallow, rocky soils. “Gardening in a Bag” (planting directly into bags of topsoil) offers a viable alternative for growing many herbaceous ornamental plants. This study compares the growth and appearance of several herbaceous bedding plants using “Gardening in a Bag” versus “in the ground” planting methods. Twenty-five cultivars of Alternanthera dentata R. Br., ornamental pepper (Capsicum annuum var. annuum L.), dianthus (Dianthus barbatus L.), gazania [Gazania rigens (L.) Gaertn.], marigold (Tagetes patula L.), petunia (Petunia hybrida hort. ex E. Vilm.), salvia (Salvia splendens Sellow ex Schult.), peek-a-boo plant (Spilanthes oleracea L.), verbena (Verbena hybrida hort. ex Groenl. & Rümpler), and vinca [Catharanthus roseus (L.) G. Don] were evaluated in 2002 under the two planting methods: in the ground versus in bags of topsoil. Wave petunias, dianthus, vinca, and rose moss (Portulaca grandiflora Hook.) were evaluated using the same methods in 2003. All plants were mulched with 7.5 cm coarse sawdust. In 2002, the planting method had no effect on the average height for 16 of the 25 cultivars tested. Seven cultivars were taller when grown in the ground whereas two cultivars were shorter during that treatment. Planting method had no effect on average plant spread of 13 of the cultivars. Plant spread was greater for nine cultivars grown in bags, whereas three cultivars were wider when grown in the ground. Visual ratings of overall appearance were similar for 14 of the cultivars regardless of planting method. In 2003, performance of the five species was evaluated on 3 July, 29 July, and 5 Sept. Planting method did not affect growth and appearance of rose moss or vinca. The two petunia cultivars and the dianthus tended to be taller and wider and had more flowers when grown in the ground compared with growth in bags. Visual quality of the petunias and the dianthus was unaffected by planting method until September when the `Purple Wave' petunias and the dianthus grown in the ground received better ratings than plants grown in bags.

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Clydette M. Alsup and Pamela B. Trewatha

In two experiments, seedlings of black-eyed susan were transplanted into 15-cm pots and after 1 week received one of the following treatments: media drench application of 0.1, 1, 10, or 100 mg·L-1 of paclobutrazol or pinching back of terminal growth once, twice, or three times. After plants reached salable size, plant height, lateral branch length and number, and flower counts were taken, and plants were harvested for dry weights. In the first experiment, all pinching treatments and 10 mg·L-1 paclobutrazol reduced plant height and increased lateral branching. Flower count at harvest was enhanced by paclobutrazol and reduced by pinching, due to delayed development of inflorescences. Lateral branching and flower bud count were greatest in the second study on plants receiving three pinches. The 100 mg·L-1 paclobutrazol-drenched plants had lowest height, dry weight, and bud count and were severely stunted. The most attractive plants appeared to be those that received the 10 mg·L-1 paclobutrazol drench treatments.

Open access

Clydette Alsup-Egbers, Patrick Byers, Kelly McGowan, Pamela B. Trewatha and William E. McClain

Commercial garlic (Allium sativum) is a relatively new crop for Missouri growers. While U.S. production is primarily in California, Oregon, Washington, and New York, little information is available regarding growing garlic in Missouri’s climate and soil conditions. Therefore, research is needed to investigate the optimum planting date for garlic in southwest Missouri. Comparisons between one spring and four fall planting dates using two garlic cultivars (Inchelium Red and German White) and the leek (Allium ampeloprasum) known as elephant garlic (A. ampeloprasum ssp. ampeloprasum) were planted at two replicated sites. Postharvest data were collected on bulb weight and diameter and clove weight and quantity. Although the numbers were not always statistically different, the overall results indicated that earlier planted garlic (September and early-October) had higher yields in 2016–17 than garlic planted later; however, in 2017–18, garlic planted in mid-October and early-November out-yielded garlic planted in September and early-October. Fall planting is preferred based on the results of our study, but spring-planted garlic can still yield a profitable crop for commercial growers. Future research on a variety of planting dates will give producers a better choice on when to plant in southwest Missouri.