Plantpro 45, an iodine-based compound, was evaluated as a seed treatment for management of fusarium wilt caused by Fusarium oxysporum f.sp. basilici on basil (Ocimum basilicum) in greenhouse assays and for effects on growth of the pathogen in vitro. Plantpro 45 at a concentration of 300 mg·L-1 (ppm) prevented fusarium hyphal growth in vitro. Seed treatments of 800 to 1000 mg·L-1 eliminated fungal contamination of seed and increased germination by 27% compared to the nontreated control. Basil transplants grown from seed treated with 400, 800, and 1000 mg·L-1 were significantly taller, weighed more, exhibited larger leaf area, and had reduced wilt severity in the greenhouse compared to the nontreated control. Transplants grown in soil treated with increasing concentrations of Plantro 45 had correspondingly decreased wilt severity, regardless of whether or not the seeds had been previously treated with Plantpro 45. Further research and optimization of soil and foliar applications in combination with seed treatments are needed to provide a complete program for management of fusarium wilt of basil.
Pamela D. Adams, Nancy Kokalis-Burelle, and William H. Basinger
J. Pieters, B. Van Assche, and A. Buekens
The solid waste streams specific to soilless horticulture (substrate slabs, propagation cubes, and plastic films to cover the soil and to wrap the substrate slabs) were determined quantitatively and qualitatively, while methods to reduce these waste streams without yield loss were evaluated in a case study applied to the Flanders region of Belgium and based on an explorative inquiry among horticulturists. Rockwool used for substrate slabs and propagation cubes was found to be by far the most important waste stream. The use of long-lived, polyurethane (PUR) slabs could reduce the total slab waste stream by ≈90%. Moreover, if substrate blocks are used instead of slabs, this reduction could even increase to 95%. The introduction of new cultivation techniques could further reduce the required volume of substrate slabs. Rockwool propagation cubes could be successfully replaced with peat pots that can be composted after 1 year of use. The reuse of plastic films to cover the soil or to wrap the substrate slabs cannot be considered because of the danger of plant diseases. Due to the susceptibility of these films to contamination, they cannot yet be recycled on a large scale. The use of thinner films and the cultivation on profiled concrete floors were found to allow drastic reductions (of up to 80%) of the quantity of plastics used.
H.H. Krusekopf, J.P. Mitchell, T.K. Hartz, D.M. May, E.M. Miyao, and M.D. Cahn
Overuse of chemical N fertilizers has been linked to nitrate contamination of both surface and ground water. Excessive use of fertilizer also is an economic loss to the farmer. Typical N application rates for processing tomato (Lycopersicon esculentum Mill.) production in California are 150 to 250 kg·ha-1. The contributions of residual soil NO3-N and in-season N mineralization to plant nutrient status are generally not included in fertilizer input calculations, often resulting in overuse of fertilizer. The primary goal of this research was to determine if the pre-sidedress soil nitrate test (PSNT) could identify fields not requiring sidedress N application to achieve maximum tomato yield; a secondary goal was to evaluate tissue N testing currently used for identifying post-sidedress plant N deficiencies. Field experiments were conducted during 1998 and 1999. Pre-sidedress soil nitrate concentrations were determined to a depth of 60 cm at 10 field sites. N mineralization rate was estimated by aerobic incubation test. Sidedress fertilizer was applied at six incremental rates from 0 to 280 kg·ha-1 N, with six replications per field. At harvest, only four fields showed a fruit yield response to fertilizer application. Within the responsive fields, fruit yields were not increased with sidedress N application above 112 kg·ha-1. Yield response to sidedress N did not occur in fields with pre-sidedress soil NO3-N levels >16 mg·kg-1. Soil sample NO3-N levels from 30 cm and 60 cm sampling depth were strongly correlated. Mineralization was estimated to contribute an average of 60 kg·ha-1 N between sidedressing and harvest. Plant tissue NO3-N concentration was found to be most strongly correlated to plant N deficiency at fruit set growth stage. Dry petiole NO3-N was determined to be a more accurate indicator of plant N status than petiole sap NO3-N measured by a nitrate-selective electrode. The results from this study suggested that N fertilizer inputs could be reduced substantially below current industry norms without reducing yields in fields identified by the PSNT as having residual pre-sidedress soil NO3-N levels >16 mg·kg-1 in the top 60 cm.
L. Carolina Medina, Thomas A. Obreza, Jerry B. Sartain, and Robert E. Rouse
Most Florida citrus is grown on extremely sandy soils inherently low in fertility, cation exchange capacity, and ability to retain applied plant nutrients. Traditionally, the main way of providing nitrogen (N) to Florida citrus trees has been
Allen V. Barker
materials and have been altered drastically by anthropogenic activities. They explain that in general urban soils are not favorable to plant growth due to compaction and contamination. The book addresses the poor quality and presents discussions of food
Robert H. Stamps
One of the most difficult times to balance crop nitrogen (N) requirements with concerns about nitrate-N leaching occurs during crop establishment, when root systems are poorly developed and not widely distributed in the growing medium. This dilemma can be exacerbated when producing a slow-growing plant such as leatherleaf fern (Rumohra adiantiformis [Forst.] Ching) on sandy soils in shadehouses in areas with significant rainfall. Rhizomes were planted in 36 drainage lysimeters containing Tavares fine sand located in a shadehouse. Nitrogen fertilizer was applied at nine rates using liquid and/or controlled-release fertilizer. Nitrogen application rates were varied as the rhizomes became established and spread into unplanted areas of the lysimeters. Irrigation and rainfall were monitored and the amount of water not lost to evapotranspiration was determined. Nitrogen (ammoniacal, nitrate/nitrite, total Kjeldahl) concentrations in leachate collected below the rootzone were determined. Stipe sap nitrate and frond total Kjeldahl nitrogen (TKN) were determined to try to develop a production monitoring technique. Initially, only leachate samples from controlled-release fertilizer plots treated at 21 and 42 kg of N/ha per year and liquid fertilizer at 28 kg of N/ha per year were consistently below the maximum contamination level (MCL) of 10 mg·L–1. As the fern became established, leachate nitrate/nitrite-N concentrations from higher N application rate treatments also remained below the MCL. Leachate N concentrations decreased as rainfall increased. Fern growth increased with increasing N application rate. Stipe sap nitrate-N and frond TKN concentrations were not well-correlated during establishment.
Michael D. Orzolek and John H. Murphy
A long term study was initiated in 1993 to evaluate the effect of composted sewage sludge on growth, yield, and quality of different vegetables. The composted sewage sludge consisting of 40% hardwood sawdust and 60% clean municipal wastewater sludge was obtained from the University Area Joint Authority (UAJA) in State College, PA. The composted sewage sludge is currently sold by UAJA as a fertilizer amendment under the name CornposT. Two rates of the ComposT product (11 and 22 dry T/A) were compared to a granular fertilizer application of 800 lbs/A of 10-10-10. The low rate of ComposT also received half of the fertilizer rate. After incorporation of the amendments into a Hagerstown clay loam soil, lettuce, tomato, muskmelon, cabbage and pepper were transplanted in the field in a Randomized Block Design with 3 replications. ComposT application did not reduce yield or quality of cabbage, lettuce tomato,and muskmelon; in fact, yields were generally higher with the application of composted sewage sludge. The application of ComposT did not reduce the macro or micro nutrient concentration of leaf tissue below optimum levels nor did it result in any phytotoxic effects in plant growth. In addition, the application of ComposT did not increase the heavy metal (Cd, Ni, Pb) concentration in leaf tissue or increase the risk of microbial contamination in the edible portion of the vegetables.
W.H. Tietien, P. Nitzsche, and W.P. Cowgill Jr.
Environmental concerns about nitrate contamination of groundwater have prompted renewed interest in optimizing fertilizer rates. A field study was initiated to study the influence of preplant and drip fertigation rates of nitrogen on the yield of hell peppers grown on Quakertown (QkB) silt loam soil. Preplant nitrogen rates of 0, 56.7, and 113.5 kgha were incorporated into the plots before transplanting. The three fertigation rates (0, 17 and 34 Kg/mulched hectare) were injected through the drip irrigation starting one week after transplanting and repeated at three week intervals.
Proplant nitrogen applications variably influenced early pepper yield. and did not significantly influence total yield. Early pepper yield was not influenced by drip fertigation rate, however, total yield increased as the fertigation rate increased. The dry weather conditions of the 1993 growing season may have influenced the responsc of pepper yield to the fertilizer treatments. Further studies are required to determine the optimum fertilization program for bell peppers grown under Northern New Jersey's edaphic conditions.
Anne Plotto and Jan A. Narciso
Organic foods are produced using agricultural practices that emphasize renewable resources and conservation of soil and water. Horticultural crops are grown and processed without synthetic fertilizers, pesticides, ingredients and processing aids. Crops or ingredients derived from genetic engineering, and use of ionizing radiation are prohibited in organic production. The challenge is to deliver produce that has the same safety, quality and shelf life as conventional products, with a limited array of tools available for sanitation and postharvest treatments. Organic operators, professionals servicing the industry, as well as researchers involved in organic production practices, should be aware of all the points in the process of storing, handling and transforming horticultural crops where accidental contamination could occur, and thus compromise organic integrity. This presentation summarizes the major points of the National Organic Program for processing and handling, and gives suggestions for postharvest research. For example, finding organic alternatives for postharvest decay control is critical to maintain food safety. Additionally, ingredients compatible for fresh cut and produce coatings must be developed for the organic market for food safety and competitiveness.
James W. Rushing, Robert J. Dufault, Richard L. Hassell, and B. Merle Shepard
Feverfew has aspirin-like properties and has been utilized for the treatment of pain, particularly migraine headache. Parthenolide is the sesquiterpene lactone believed to be responsible for the medicinal properties. The potential for utilizing existing tobacco production and handling systems for the production and postharvest handling of feverfew was investigated. In year one, 8 commercial tobacco growers each planted about one-half acre of feverfew (Tanacetum parthenium L. Schulz-Bip.). The yield of dry herb varied among farmers from about 122 to 772 (55 to 350 kg) pounds per half-acre. The parthenolide content of the dried herb from most producers was within the range desired by industry, but four factors precluded its salability: a) presence of foreign matter, primarily weeds; b) excessive ash content due to contamination from sandy soils; c) mold resulting from processing with excessive moisture content, and; d) insect infestation (tobacco beetles Lasioderma serricorne) during storage. All of these limitations resulted from the failure to implement good agricultural aractices (GAPs) and good manufacturing practices (GMPs) during production and handling of the product. A second planting of the feverfew was carried out with strict attention to GAPs and GMPs. In this trial, all of the dried feverfew met the requirements for sale. Here we report on the management of production and handling systems for feverfew that can enable growers to produce high quality herbs that meet the high standards for medicinal use.