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  • Author or Editor: Joseph C. Scheerens x
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Increasing fruit and vegetable consumption reduces risk factors for cancer, cardiovascular disease and a number of other diet-related chronic diseases. These foodstuffs contain relatively high levels of beneficial phytochemicals (plant-derived, biologically active compounds) among which the preventative activity of antioxidants are most well-known and well-documented. Since small fruit typically contain high levels of antioxidants, increasing their incorporation in the diet is a laudable goal. Media reports of medical studies pertaining to dietary intake and national education initiatives such as the USDA's Food Guide Pyramid and the 5 A Day—for Better Health program have successfully raised public awareness of the health benefits of increased fruit and vegetable consumption, but, as of yet, may not have altered dietary habits. The factors influencing food choice are complex and interrelated. They include: sensory preference, physiological factors (pre- and postingestion), age, gender, lifestyle, behavior, personality, education, income, social attitudes about diet and health, ethnicity and tradition, religious beliefs, social pressures, marketing pressures, available product information and knowledge (labeling, media coverage, etc.) or self-identity beliefs. Some of these factors offer opportunities for increasing fruit and vegetable consumption while others present challenges. With respect to small fruit, food choice factors that tend to increase consumption include public awareness of these products as being beneficial to health and longevity and their image as highly desirable, dessert-like commodities with exquisite flavors. The main factors that deter increased small fruit consumption include their relatively high price per serving and their relative perishability which affects cost, ease of transport and availability. Strategies to capitalize on small fruits' positive attributes and overcome negative attributes with respect to food choice include the application of innovative marketing strategies at all levels and the expansion of research efforts to optimize the health benefits and sensory quality of these products.

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Terbacil at 0, 0.8, 1.6, 3.2, and 6.4 oz/acre (0, 0.06, 0.11, 0.22, and 0.45 kg·ha-1) a.i. was applied immediately after planting, at the thee-leaf stage and at the six-leaf stage to greenhouse grown strawberry (Fragaria × ananassa) cultivars Jewel, Mira, and Allstar. Strawberry was most tolerant of terbacil when the herbicide was applied before leaf emergence. `Mira' was more tolerant of terbacil than was `Jewel'. `Jewel' and `Allstar' exhibited similar levels of tolerance. In a second experiment terbacil at 4.8 oz/acre (0.34 kg·ha-1) was applied to the soil, to the foliage, and to the foliage followed by a water rinse. Injury was greatest when terbacil was applied directly to the strawberry foliage rather than to the soil, but was minimal when foliage was rinsed after application. In a final experiment terbacil at 4.8 oz/acre was applied to greenhouse-grown `Jewel' strawberries at the thee-leaf stage followed by a water rinse 0.5, 1, 2, or 4 hours after application. Rinsing the foliage of strawberry plants after application significantly reduced leaf injury. Delaying the rinse up to 4 hours did not lead to increased injury. Over all, the results from our study indicate the potential for using terbacil as an effective herbicide on newly established strawberries, especially if the compound is rinsed from leaves (if present) after treatment.

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Field experiments were conducted in newly planted strawberry (Fragaria ×ananassa) with terbacil applied at rates of 0 to 6.4 oz/acre a.i. either 4 days after planting but before appearance of new growth, or at the three-leaf stage. Irrigation of 0.4 inch was applied to half of the plots immediately after application of terbacil. Injury was greater when terbacil was applied before new growth than when applied at the three-leaf stage. Injury symptoms increased linearly with terbacil rate. Irrigation immediately following terbacil application reduced injury relative to non-irrigated plots. Weed control was reduced when terbacil was applied at the three-leaf stage than when applied before new growth. Irrigation did not reduce weed control. Herbicide injury symptoms were not detected the spring following terbacil application. Fruit yield was not affected by herbicide and irrigation treatments applied the previous year. The combination of low rates of terbacil, 0.8–1.6 oz/acre a.i., followed by irrigation to remove the herbicide from foliage is a safe option that growers can use to improve weed control and reduce hand weeding costs in the planting year.

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Identical trials were conducted in a multibay high tunnel and an adjacent open field in southwestern Michigan to compare primocane-fruiting cultivars (Autumn Britten, Caroline, Chinook, Heritage) and floricane-fruiting cultivars (Canby, Encore, Heritage, Nova) of red raspberry (Rubus idaeus). Floricane-fruiting plots of ‘Heritage’ were pruned to produce fruit on floricanes and primocanes (double cropping). The most productive cultivars in both environments were ‘Nova’ and ‘Canby’ (floricane) and ‘Caroline’ and ‘Heritage’ (primocane). These cultivars produced annual yields of 5.5 kg·m−1 row in the tunnel and 2.5 kg·m−1 row in the field. The order of primocane harvest (earliest to latest) was the same in the tunnel and field: ‘Autumn Britten’, ‘Caroline’, ‘Chinook’, and ‘Heritage’. Cultivars with the greatest average berry weight in the tunnel and field were Encore and Nova (floricane) and Autumn Britten and Caroline (primocane). ‘Chinook’ and ‘Autumn Britten’ tended to have the highest incidence of gray mold (Botrytis cinerea) of primocane-fruiting cultivars, but incidence was similar in floricane cultivars. Overall mold incidence was 1% in the tunnel and 13% in the field. Leaf spot (Sphaerulina rubi), cane anthracnose (Elsinoe veneta), spur blight (Didymella applanata), and botrytis cane blight (B. cinerea) were common in the field but absent in tunnel. Phytonutritional analyses of primocane fruit indicated that genotype differences were not consistent across the two environments. Relative cultivar characteristics (harvest season, yield, berry quality) were similar in the field and tunnels, but the tunnel environment tended to increase plant vigor, yield, and fruit quality and suppress several diseases.

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Shading effects on chlorophyll a (ChlA), chlorophyll b (ChlB) and anthocyanin (Antho) concentrations were examined at three developmental stages in four varieties of lettuce (Lactuca sativa) grown under contrasting temperature regimens in the greenhouse. Seedlings were transplanted to pots and grown at 30 °C (86.0 °F) day/night (D/N) (Study 1) or 30/18 °C (86.0/64.4 °F) D/N (Study 2). One-half of all plants in each study were positioned under bottomless shade boxes which reduced incoming light intensity by 50%. Pigment concentrations were measured in leaf tissue 9, 16, and 23 days after transplanting. Each study was repeated twice. Regardless of temperature regimen, variety influenced all pigment concentrations, while shading affected, primarily, Antho concentrations. ChlA and ChlB concentrations were influenced by growth stage. In Study 1, chlorophyll concentrations were significantly greater in `Green Vision' than `New Red Fire' or `Rolina', but not `Galactic'. Also, Antho concentrations were significantly greater in `Galactic' than the other varieties. In Study 2, chlorophyll concentrations were greatest in `Green Vision', with similar concentrations among the remaining varieties. Antho concentrations were greatest in `Galactic', intermediate in `New Red Fire' and `Rolina', and lowest in `Green Vision'. Shading significantly reduced Antho concentrations in `Galactic' and `Rolina' under both temperature regimens and `New Red Fire' at 30/18 °C D/N, but increased Antho concentrations in `Green Vision'. Chlorophyll concentrations tended to decrease with plant age. Pigment concentration data clarified what was apparent to the unaided eye—namely, that the amount and intensity of green and red color varied among plants subjected to different shading and temperature treatments. Therefore, these data may aid in developing strategies to achieve targeted levels of pigmentation (especially red) in lettuce, an important criterion of crop quality and potential market value.

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