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K.M. Kelley and J.A. Biernbaum

Eight species of edible flowers were grown in 12.5-cm (1.5-L) square containers during the months of November through May, in a root medium suitable for organic certification or a standard peat and perlite mixture with preplant fertilizer. Plants were fertilized with 200 mL of either a water-soluble fertilizer (19–1.8–19) at 300 ppm N, fish emulsion (5–0.4–0.8), or a certified organic, commercially available soluble fertilizer (6–2.6–5), each at 300 or 600 ppm N applied every 2 weeks. Shoot fresh and dry weights were measured and percent dry weight was calculated. The fresh weights for all species were highest for plants fertilized with the organic fertilizers. For all but one species the organic fertilizer treatments had the same or higher dry weights than the inorganic control. The percent dry weights for all species were the same or higher for the inorganic control treatment. The effect of the organic fertilizer rate on the dry weight was species-dependent. The highest flower production generally occurred with 300 ppm N. Flower size was measured for Viola tricolor and Viola ×. wittrockiana species. For both species flower size was smallest for plants fertilized with the 600 ppm certified organic fertilizer. Root media pH and EC were tested at 6-week intervals throughout the experiment. In general, the pH increased from the first to the second sampling date, but only increased or decreased slightly for later dates, and there was little effect of fertilizer type. Root media EC decreased initially with minimal change later.

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N.D. Clarke, J.L. Shipp, W.R. Jarvis, A.P. Papadopoulos and T.J. Jewett

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Logan S. Logendra, Thomas J. Gianfagna, David R. Specca and Harry W. Janes

Limited-cluster production systems may be a useful strategy to increase crop production and profitability for the greenhouse tomato (Lycopersicon esculentum Mill). In this study, using an ebb-and-flood hydroponics system, we modified plant architecture and spacing and determined the effects on fruit yield and harvest index at two light levels. Single-cluster plants pruned to allow two leaves above the cluster had 25% higher fruit yields than did plants pruned directly above the cluster; this was due to an increase in fruit weight, not fruit number. Both fruit yield and harvest index were greater for all single-cluster plants at the higher light level because of increases in both fruit weight and fruit number. Fruit yield for two-cluster plants was 30% to 40% higher than for singlecluster plants, and there was little difference in the dates or length of the harvest period. Fruit yield for three-cluster plants was not significantly different from that of two-cluster plants; moreover, the harvest period was delayed by 5 days. Plant density (5.5, 7.4, 9.2 plants/m2) affected fruit yield/plant, but not fruit yield/unit area. Given the higher costs for materials and labor associated with higher plant densities, a two-cluster crop at 5.5 plants/m2 with two leaves above the cluster was the best of the production system strategies tested.

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Ronald K. Jones, Ann R. Chase, Melvin P. Garber, William G. Hudson, Jeffrey G. Norcini and Kane Bondari

A national survey of the commercial ornamental industry was conducted to determine the current status of pest control including chemical and nonchemical disease control practices. The fungicides thiophanate methyl, chlorothalonil, mancozeb, and metalaxyl were used in the greatest quantity and by the largest percentage of growers. Metalaxyl was used in greenhouse and field operations by the highest percentage of growers, primarily to control root diseases but many growers reported using metalaxyl to control foliar disease. Overall, more fungicides were used in the field for foliar diseases, whereas almost equal amounts of fungicides were used for foliar and root diseases in the greenhouse.

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Jeffrey G. Norcini, William G. Hudson, Melvin P. Garber, Ronald K. Jones, Ann R. Chase and Kane Bondari

Growers in the American Association of Nurserymen and the Society of American Florists were queried as to their use of plant growth regulators (PGRs) and nonchemical alternative practices during 1993. Daminozide (B-Nine SP) and chlormequat chloride (Cycocel) accounted for 78% of the total pounds active ingredient and were used by 20% and 17% of the respondents, respectively. In contrast, the rooting compounds indolebutyric acid (Dip `N Grow, Rootone, and Hormoroot) and naphthaleneacetic acid (Dip `N Grow, and Hormodin I, II, and III) were used by 53% and 24% of the respondents, respectively, but combined accounted for less than 3% of total pounds active ingredient. Pruning/pinching was used by the greatest number of respondents (82%) and was the only alternative to PGRs rated as very effective by more than 60% of the respondents. Use of chemical PGRs and nonchemical alternative practices was influenced by region and firm size. In the northeastern United States, growers reported relatively low use of PGRs (frequency and total pounds) and the lowest use of mechanical brushing as an alternative practice. In contrast, mechanical brushing was used most in the western United States. Large firms (more than $2 million in annual sales) reported the greatest use of chemical and nonchemical means of regulating growth.

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Jeffrey G. Norcini, Melvin P. Garber, William G. Hudson, Ronald. K. Jones, Ann. R. Chase and Kane Bondari

Members of the American Association of Nurserymen and the Society of American Florists were surveyed as to their use of herbicides and nonchemical alternative weed control practices for 1993. Glyphosate was the top-ranking herbicide among the total of 37 reported, in terms of number of respondents and estimated total amounts of active ingredients applied. It was used by all but two of the respondents that used herbicides in their operations. Oryzalin was the top-ranked preemergent herbicide, and was second only to glyphosate in number of respondents and amount of active ingredient applied. The highest estimated use in amounts of active ingredient applied was in the southeastern (43% of total) and north-central (27% of total) regions, nearly two to three times the estimated use in the northeastern or western regions. However, there were only about 50% more respondents in the southeastern or north-central regions compared to the other regions. About 56% of herbicide active ingredients used were in field sites, 22% in container sites, 19% in perimeter areas, and 3% in green-houses. Large firms (annual sales more than $2,000,000) used the greatest estimated total amount of active ingredients, while small firms (annual sales more than or equal to $500,000) tended to use nonchemical alternatives the most. Nearly all respondents used handweeding or hoeing as part of their weed control program. Mowing was used by 84% of the respondents, 71% used tractor cultivation, and 66% used mulches (includes gravel and black plastic). Alternative methods were rated as somewhat effective to very effective by 65% or more of the respondents who used them.

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William G. Hudson, Melvin P. Garber, Ronald D. Oetting, Russell F. Mizell, Ann R. Chase and Kane Bondari

A national survey of the greenhouse and nursery industry provided data on insecticide/miticide use in 1993. Respondents reported using 46 different compounds, and the industry used an estimated 2.8 million pounds of active ingredients to control insect and mite pests. The most frequently used material was acephate: 52% of the respondents reporting use in 1993. The most heavily used material was a miticide, dienochlor, with an estimated 643,281 lb (292,400 kg) applied, or 28% of the total. Only three other compounds represented more than 5% of the total use—carbaryl (498,073 lb or 22%) (226,397 kg), diazinon (326,131 lb or 14%) (148,242 kg), and propargite (143,888 lb or 6%) (65,404 kg). Of the top four products, two (dienochlor and propargite) are miticides. Together these represented 34% of the total estimated insecticide/miticide use, demonstrating the importance of mites as pests in the industry.

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Michael D. Orzolek, Cathy Thomas, Robert D. Berghage and Paul R. Heller

82 POSTER SESSION 12 Greenhouse Management/Cross-Commodity