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- Author or Editor: B.K. Harbaugh x
High quality Exacum plants suited for use as flowering house plants were produced in 10-cm pots using a 3 or 5 kg/m3 rate of a 3- to 4-month controlled-release fertilizer (Osmocote 14N-6.1P-11.6K) or an 8- to 9-month release Osmocote (18-2.6-10) with either capillary mat or overhead irrigation. Flowering plants placed in simulated home conditions had more foliar chlorosis at lower Osmocote rates while floral display decreased with higher Osmocote rates.
One pot study and 2 field experiments were conducted to evaluate the use of ethephon, acifluorfen, endothall, dinoseb, glyphosate, oxyfluorfen, and paraquat as harvesting aids (removal of root and shoot tissue) in caladium (Caladium × hortulanum Birdsey) tuber production. Of these 7 compounds, paraquat and oxyfluorfen showed the most potential with 2 applications at 15-day intervals reducing ‘Canadium’ and ‘Freida Hemple’ caladium root weight as much as 51% and shoot weight up to 90%. No residual effects were observed for these herbicide treatments when tubers were subsequently forced in a greenhouse. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon); [2-chloro-4-(trifluoromethyl)phonoxy]-2-nitrobenzoate (acifluorfen) (7-oxabicyclo[2.2.1]heptane-2,3-dicarboxylic acid (endothall); 2-(l-methylpropyl)-4,6-cinitrophenol (dinoseb); N-(phosphonomethyl)glycine (glyphosate); 2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluormethyl)benzene (oxyfluorfen); (1,1-dimethyl-4,4′-bipyridinium ion (paraquat).
Eight herbicides were evaluated for phytotoxicity to field grown ‘Candidium’ caladiums (Caladium × hortulanum Birdsey) in 1983. The 4 most promising or currently used herbicides were evaluated for weed control and phytotoxicity in 1984. During 1984, 4 applications of 2.24 kg/ha alachlor, 2.24 kg/ha simazine, 1.68 kg/ha oryzalin, and 0.56 kg/ha oxyfluorfen, all in combination with 1 postemergence application of 0.28 kg/ha fluazifop-butyl, were applied to caladiums. Alachlor and oxyfluorfen provided poor weed control and reduced plant vigor, tuber weights, and tuber size in 1984. Simazine provided good weed control, but reduced plant vigor and yield. Oryazlin provided excellent weed control without crop injury. Chemical names used: 2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide (alachlor); 6-chloro-N,N’-diethyl-1,3,5-triazine-2,4-diamine (simazine); 4-(dipropylamino)-3,5-dinitrobenzene sulfonamide (oryzalin); 2-chloro-l-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene (oxyfluorfen); butyl-2-[4-[[5-(trifluoromethyl)-2-pyridinyl]oxy] phenoxy] propanoate (fluazifop-butyl).
An easy method to estimate water requirements for poinsettia (Euphorbia pulcherrima Willd. ex Kl.) production with practical applications to commercial operations was developed to promote water conservation. A water-requirement prediction equation (P ≥ 0.01, R 2 = 0.78) that used pan evaporation along with plant-canopy height and width as input variables was generated. Equation verification was carried out by comparing plant quality of crops irrigated according to the generated water-requirement prediction equation to crops irrigated “on-demand” or with capillary-mat irrigation. Plants irrigated with the prediction equation were smaller than plants grown with capillary mat, but plant quality ratings for ‘Annette Hegg Diva’ and ‘Dark Red Annette Hegg’ were not significantly different. ‘Gutbier V-10 Amy’ plants grown with irrigation on-demand were of higher quality than plants grown using either the capillary mat or the prediction equation. Applied water was significantly lower for plants irrigated with the prediction equation than would normally be applied in a commercial operation using a conservative fixed daily irrigation rate.
Foliar chlorosis or bleaching, interveinal chlorosis, leaf edge and tip necrosis, a poor root system, and stunted growth of Eustoma grandiflorum (Raf) Shinn seedlings were associated with a medium pH of 5.0 or 5.5 but not when the values ranged from 6.4 to 7.5. The range in medium pH resulting in the best growth of seedings and flowering plants was 6.3 to 6.7. Responses to medium pH were similar, regardless of fertilizer solution pH or cultivar. Eustoma seedling and shoot fresh weights for pH 5.0 and 5.5 were only 23% to 66% of corresponding values for plants grown at pH 6.4. Leaf tissue Zn was extremely high (1050 mg·kg-l dry leaf tissue) at a medium pH of 5.0, but other macro- and micronutrients in leaves were not at abnormal levels.
Various rates, types, and formulations of controlled-release fertilizers were evaluated as potential components in a trickle irrigation production system for spray chrysanthemums (Chrysanthemum morifolium Ramat.). Optimum rates of total-N, with 34 kg N/ha as soluble 6-2.6-5 (N-P-K) and the remainder as 14-6.1-11.6 Osmocote, were estimated to be from 489-501 kg per planted hectare in 2 tests. Other formulations or ratios of Osmocote and urea formaldehyde fertilizers at similar rates did not improve production or were not comparable to Osmocote 14-6.1-11.6 or to the commercial practice of weekly overhead liquid fertilization. A water savings of 70-80% was estimated with the controlled-release fertilizer-trickle irrigation system compared to overhead irrigation, while yields (marketable stems and height) were similar to those produced with overhead-liquid fertilization practices.
Methodology was developed to estimate water requirements for production of 20 different potted ornamental plant species with practical application for water conservation in commercial operations. Water requirement prediction equations were generated using pan evaporation to estimate evaporative demand along with plant canopy height and width and flower height as input variables. Coefficients of determination (R2) for the prediction equations among plant species ranged from 0.51 to 0.91, with the lower values mostly associated with plant species with an open or less-uniform growth habit. Variation in water use among different cultivars of marigold also was associated with differences in cultivar growth habit. Estimation of the daily water requirements of potted Reiger begonia and Ficus benjamina using their developed prediction equations was compared to actual water use under common growing conditions to demonstrate the implementation of the method for plant species differing in growth habit.
A study was conducted to determine the effect of water table depth on water use and tuber yields for subirrigated caladium (Caladium × hortulanum) production. A field-situated drainage lysimeter system was used to control water table depths at 30, 45 and 60 cm (11.8, 17.7, and 23.6 inches). Water use was estimated by accounting for water added or removed (after rain events) to maintain the desired water table depth treatments. In 1998, tuber weights, the number of Jumbo grade tubers, and the production index (tuber value index) of `White Christmas' were greater when plants were grown with the water table maintained at 30 or 45 cm compared to 60 cm. In 1999, tuber weights, the number of Mammoth grade tubers, and the production index, also were greater when plants were grown at water table depths of 30 or 45 cm compared to 60 cm. The average estimated daily water use was 6.6, 5.1, and 3.3 mm (0.26, 0.20, and 0.13 inch) for plants grown at water table depths of 30, 45, and 60 cm, respectively, indicating an inverse relationship with water table depth. While current water management practices in the caladium industry attempt to maintain a 60-cm water table, results from this study indicate that, for subirrigated caladium tuber production, the water table should be maintained in at 30 to 45 cm for maximum production on an organic soil.
Daily water use for potted Chrysanthemum ×morifolium Ramat. ‘Spirit’ was estimated from pan evaporation and plant height data collected over 2 seasons using 3 different growing environments (glass greenhouse, saranhouse, and outside—no structure). Regression equations derived using pan evaporation and plant height were not significantly improved with the inclusion of plant width as an additional variable to estimate water use.