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  • Author or Editor: J.F. Price x
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A new disorder of fruit has been observed on tomato (Lycopersicon esculentum Mill.) in Florida. The disorder, termed irregular ripening, was associated with field populations of the sweetpotato whitefly, Bemisia tabaci (Gennadius) and is characterized by incomplete ripening of longitudinal sections of fruit. An increase in internal white tissue also was associated with whitefly populations. In field cage studies, fruit on tomato plants not infested with the sweetpotato whitefly exhibited slight or no irregular ripening, whereas fruit from infested plants did. Fruit from plants on which a whitefly infestation had been controlled before the appearance of external symptoms exhibited reduced symptoms compared to fruit from plants on which an infestation was uncontrolled.

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The sweetpotato whitefly, Bemisia tabaci (Gennadius), was associated with symptoms of a silverleaf disorder of acorn squash (Cucurbita pepo L. cvs. Table King Bush and Table Ace) in cage studies in the greenhouse. Symptoms appeared on uninfested leaves that developed after plants were infested with the whitefly. When the infested lower leaves were removed and the young leaves protected from infestation with insecticides, new growth was asymptomatic or nearly so and symptomatic leaves remained symptomatic. Symptom expression was related more to nymphal density than to adult density since the relationship between log nymph density and symptoms was linear when adult densities were equal.

Free access

Abstract

Leaf water potential (LWP) data for cut-flower chrysanthemums (Crysanthemum morifolium Ramat.) collected from 5 different irrigation rate treatments throughout the growing season were compared to the final plant characteristics and yield in order to evaluate the usefulness of LWP for estimating water stress effects on ultimate yield. Significant treatment differences for LWP response measured during high evaporative demand periods were similar to treatment differences for yields and final plant characteristics. Treatment differences for LWP response measured during low evaporative demand periods were not significant and did not reflect the significant treatment differences for yields and final plant characteristics. Results indicate that LWP measurements vary with changes in atmospheric conditions, such as cloud cover, and are difficult to interpret relative to water stress effects on final plant characteristics. Plant growth parameters, such as height or growth rate, when monitored during the season, were found to be more adequate indicators of stress effects on final yield.

Open Access

Abstract

The numbers of twospotted spider mites (Tetranychus urticae Koch) per unit of leaf area on ‘Manatee Yellow Iceberg’ chrysanthemum (Chrysanthemum X morifolium Ramat.) grown with 13.6, 20.3, 27.1, 33.9, or 40.7 cm of water during the crop cycle were inversely related to amounts of water provided on both of 2 sampling dates. The numbers of mites per leaf were inversely related to amounts of water provided on the first of the 2 sampling dates. There was no significant response of leafmine densities with various amounts of water provided.

Open Access

Abstract

The minimum water requirement to produce the greatest number of marketa- bie cut flowers of Chrysanthemum × morifolium Ramat. ‘Manatee Yellow Iceberg’ was 35 cm with trickle irrigation, a 91% reduction in water uses as compared to overhead irrigation systems. Linear responses for fresh weight, dry weight, leaf area, leaf number, and flower number between 13.6 and 40.7 cm of water supplied during production indicated that an additional 6 cm of water would improve marketable stem's quality.

Open Access

Abstract

Damage by leafminer [Liriomyza trifolii (Burgess)], increased linearly as leaf nitrogen increased from 2.2% to 4.0% in spring and fall plantings of Chrysanthemum x morifolium Ramat. ‘Manatee Yellow Iceberg’. The number of marketable stems was related quadratically to leaf nitrogen with maximum yields estimated to occur at 3.6% at harvest.

Open Access

Abstract

Interactive effects of trickle irrigation rates, cultivars and culture (single or pinched stem), on Chrysanthemum × morifolium Ramat. cut flower yield and quality were evaluated. The minimum amount of water required to produce the greatest number of marketable stems of high quality was estimated to be from 0.96 to 1.07 cm/day. Responses to irrigation rate were similar regardless of culture or cultivar variables. Seasonal water use, however, would vary due to differences in cropping time influenced by the production method and choice of cultivars.

Open Access

Abstract

Experiments were designed to develop information on commercial production systems for Episcia cupreata (Hook.) Hanst. (flame violet) encompassing nutrition, propagation, light intensity, and insect pest management. A 200–250 ppm N and 150 ppm K solution applied at a rate of 50 ml/10-cm pot per week provided adequate nutritional requirements for these major elements. Propagation techniques involving combinations of rooted or unrooted plantlets 5–13 cm in canopy diameter provided crop turnover rates from 4 to 12 weeks for production in 10-cm pots. Optimum light intensity was established at 17–22 klx. Acephate and oxamyl eliminated mealybugs (Ferrisia virgata) on Episcia plants and were not phytotoxic to the foliage.

Open Access

Abstract

A study was conducted to investigate environmental factors which affect leaf water potential (LWP) response of chrysanthemums (Chrysanthemum × morifolium Ramat). Meteorological parameters, including air temperature (TEMP), relative humidity (HUM), total solar radiation (RAD), and photosynthetically active radiation (PAR) were measured simultaneously as LWP determinations were made diurnally for plants grown with 5 different irrigation rates. Stepwise multiple regression analyses using the meteorological parameters as independent variables and LWP as the dependent variable showed that models developed for each irrigation rate included TEMP, HUM, and PAR as statistically significant (P = 5%) independent variables. Coefficients of determination (R2) for the models ranged from 0.83–0.87. A combined model, including irrigation rate (R) as an independent variable along with the meteorological parameters, revealed that TEMP, PAR, HUM, and R were statistically significant at P = 1% and had an R2 = 0.84. Results reveal environmental factors which must be considered in studies involving LWP measurements for chrysanthemums in order to avoid misinterpretation of data.

Open Access

Abstract

In Florida, most producers of cut chrysanthemums (Dendranthema grandiflora Tzvelev.) use overhead irrigation systems and fertilize with soluble fertilizer injected through the system. Trickle irrigation can be used to produce cut chrysanthemums with substantial savings in water (2). Controlled-release fertilizers can be successfully used to produce cut chrysanthemums (1) and may be advantageous in certain production situations (3). Direct yield comparisons influenced by the four possible combinations of irrigation and fertilization practices have not been researched in previous studies. We, therefore, evaluated main and interactive effects of overhead or trickle irrigation in conjunction with soluble or controlled-release fertilization on the yield and postharvest quality of cut chrysanthemums.

Open Access