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  • Author or Editor: C. D. Stanley x
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Combinations ofvarious vegetable crop species grown in multiple-cropping sequences using microirrigation on a sandy soil were evaluated for production potential and changes in normal cultural management An initial fall-season fresh-market tomato crop was followed immediately by a winter-season crucifer crop (cauliflower, broccoli, or cabbage), which was followed by a spring-season cucurbit crop (cucumber, zucchini squash, or muskmelon). Studies were conducted over a 3-year period in southwestem Florida. Results showed that when cropping sequences were compared on a basis of a derived relative value index (RVI), the sequence of tomato-cauliflower-zucchini squash significantly outperformed other sequences. Several management concerns particular to the production system (crop residue removal and interference, plastic mulch deterioration and damage, and weed control) were identified and discussed. The potential savings when cropping sequences are compared to individual crop production resulted in net savings (dollar savings less additional production costs) that ranged from $565 to $1212/acre ($1396 to $2993/ha) and $614 to $1316/acre ($1516 to $3251/ha) for the 1986-87 and 1988-89 seasons, respectively.

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A number of mass—diameter equations were compared for their potential use in indirect measurement of fruit masses of `Royal Gala' apple (Malus ×domestica). The fruit fresh-mass—diameter relationship changed with time during the season, hence no single function fitted the data well. Smooth piecewise functions that assume different relationships for intervening segments of a curve bounded by knots on the x-axis are particularly useful for modeling such data. The curve is said to be smooth because the first derivative of the function is continuous on the interval, including the knots. Two such equations, a three-parameter piecewise power function and a five-parameter spline exponential function, provided good fits to data. For both equations, the estimated mean bias on individual fruit predictions was within 5% of predicted mass over the two validating data sets. As for the precision conditional on no bias, a sample size of 20 fruit gave standard errors within 2.5% of mean predicted mass. These precisions are adequate to meet the industry requirements for monitoring fruit mass through the growing season. There was evidence of a seasonal difference in the estimated bias, but we were unable to confirm that this variation resulted from seasonal differences in fruit shape. Application of these two equations to data from other regions suggested that divergence from the estimated functional form may in fact be greater under increasingly different climatic conditions. Hence, further investigations to identify possible sources of these differences are necessary before the proposed equations can be applied across climatically different regions.

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Field studies were conducted over three seasons to determine the effect of N and K on susceptibility of tomato to bacterial spot. A factorial randomized complete block design consisting of four rates of N (167, 334, 501, and 668 kg·ha–1) and three rates of K (334, 668, and 1335 kg·ha–1) were used. Liquid fertilizer was injected via trickle irrigation. Increasing N rates reduced disease severity, whereas the effect of increasing K was inconsistent from season to season. The concentration of N in leaf tissue showed a significant negative correlation with disease severity, whereas the concentration of Ca in leaf tissue exhibited significant positive correlation with disease severity and negative correlation with N rate during two seasons of data collection.

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Modeling the growth of field-grown tomato (Lycopersicon esculentum Mill.) should assist researchers and commercial growers to outline optimal crop management strategies for specific locations and production systems. A generic crop-growth model (CROPGRO) was previously adapted to simulate the growth of fresh-market tomato under field conditions. Plant growth and development of field-grown tomato, and fruit yields, will be outlined and compared to model predictions for a number of locations in Florida, nitrogen fertilizer rates, and irrigation management practices. Possible application of the model to quantify effects of crop management on crop production will be discussed using simulated yield values for a wide range of environmental conditions.

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Recent concerns over the environmental impact of peat harvesting have led to restrictions on the production of peat in Florida and other areas. The objectives of this study were to evaluate the use of composted dairy manure solids as a substitute for sphagnum or reed-sedge peat in container substrates on the growth of Solenostemon scutellarioides L. Codd ‘Wizard Velvet’, Tagetes patula L. ‘Safari Queen’, and Begonia ×hybrida ‘Dragon Wing Red’ and to examine the nutrient content in leachate from pots. Plants were grown for 5 weeks in a greenhouse in 15-cm plastic pots with seven substrates containing various proportions of sphagnum peat (S) or reed-sedge peat (R) and composted dairy manure solids (C), each with 20% vermiculite and 20% perlite. Substrate composition had no effect on plant quality ratings, number of flowers, or root dry mass for any of the plant species evaluated. Substrate composition did not affect the growth index (GI) or shoot dry mass of S. scutellarioides ‘Wizard Velvet’ or the GI of T. patula ‘Safari Queen’. However, growth of B. ×hybrida ‘Dragon Wing Red’ (GI and shoot dry mass) and T. patula ‘Safari Queen’ (shoot dry mass only) was highest in the 3S:0R:0C substrate. The substrates containing sphagnum peat and/or composted dairy manure solids (3S:0R:0C, 2S:0R:1C and 1S:0R:2C) had the highest NH4-N losses through the first 7 d of production. The 0S:3R:0C substrate had the highest initial leachate NO3+NO2-N losses and this trend persisted throughout most of the production cycle. Significantly more dissolved reactive phosphorus was leached from substrate mixes containing composted dairy manure solids than mixes containing only sphagnum or reed-sedge peat materials through 19 d after planting. All substrates tested as part of this study appeared to be commercially acceptable for production of container-grown bedding plant species based on plant growth and quality. However, nutrient losses from the containers differed depending on the peat or peat substitute used to formulate the substrates.

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The urban soil environment is usually not conducive to healthy root growth and function, leading to problems with plant establishment, growth, and aesthetic quality. The objective of this study was to determine if the addition of compost with or without the application of shallow tillage or aeration will improve soil physical and chemical properties and plant growth compared with an unamended control in simulated new residential landscapes. Twenty-four mixed landscape plots were established in a randomized complete block design to simulate new residential landscapes. Each plot was constructed using 10 cm of subsoil fill material over a compacted field soil and planted with Stenotaphrum secundatum and mixed ornamental plant species. Composted dairy manure solids were applied as an organic soil amendment at a depth of 5 cm (≈256 Mg·ha−1) in combination with two mechanical soil treatments (tillage to 15 cm and plug aeration) for a total of five soil management treatments plus an untreated control. Soil physical and chemical properties, plant growth, and quality and plant tissue nutrient concentrations were assessed periodically to determine the effect of soil treatment on soil and plant quality. Applications of compost to soils significantly reduced soil bulk density and pH and increased soil organic matter, electrical conductivity, and Mehlich-1 phosphorus and potassium concentrations. All ornamental plant species, with the exception of Raphiolepis indica (L.) Lindl. ex Ker Gawl., exhibited more growth when grown in soils amended with composted dairy manure solids. In most instances, plant tissue nitrogen and phosphorus concentrations were higher for plants grown in soils receiving compost. Results of our study suggested that the addition of composted dairy manure solids to soils can improve soil properties and enhance plant growth in residential landscapes when sandy fill soils are used. In contrast, shallow tillage and aeration had little effect on soil properties or plant growth.

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The Florida horticulture industry (vegetables, ornamentals, citrus, and deciduous fruit), valued at $4.5 billion, has widely adopted microirrigation techniques to use water and fertilizer more efficiently. A broad array of microirrigation systems is available, and benefits of microirrigation go beyond water conservation. The potential for more-efficient agricultural chemical (pesticides and fertilizer) application is especially important in today's environmentally conscious society. Microirrigation is a tool providing growers with the power to better manage costly inputs, minimize environmental impact, and still produce high-quality products at a profit.

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