Search Results

You are looking at 1 - 10 of 27 items for

  • Author or Editor: George J. Hochmuth x
Clear All Modify Search
Full access

George J. Hochmuth

Efficient N management practices usually involve many potential strategies, but always involve choosing the correct amount of N and the coupling of N management to efficient water management. Nitrogen management strategies are integral parts of improved production practices recommended by land-grant universities such as the Institute of Food and Agricultural Sciences, Univ. of Florida. This paper, which draws heavily on research and experience in Florida, outlines the concepts and technologies for managing vegetable N fertilization to minimize negative impacts on the environment.

Free access

George J. Hochmuth

Vegetable producers are under increasing pressure to minimize production inputs such as water and fertilizers. Research on fertilizer placement and scheduling, soil testing, and drip irrigation fertigation has provided technologies to enable vegetable growers to produce profitable yields of high-quality vegetables while reducing nutrient inputs. Plant tissue testing has been an integral part of nutrient management on the farm. Although plant sap testing has been evaluated for more than 70 years, only recently has testing technology been developed to the point where farm use is facilitated. Researchers in several states, including Florida, have evaluated various methods for determining nitrate-N and K concentrations in petiole sap. Researchers in Florida have developed petiole sap sufficiency ranges for the major vegetable crops and strawberries, and these guidelines are widely used by vegetable growers and crop consultants as an aid for making informed fertilization decisions. In this workshop, research results and field experiences with fresh sap testing for N and K will be discussed, including field test equipment, testing methods, and current test applications.

Full access

Robert C. Hochmuth and George J. Hochmuth

The evolution of plastic uses (excluding glazing) in the production of greenhouse vegetables is presented. Plastics are used in almost every aspect of crop production, including providing a barrier to the soil, lining crop production troughs, holding soil and soilless media, and providing a nutrient film channel. Irrigation systems have become very elaborate, with various plastic products used to transport water and nutrients and to provide a means of emitting nutrient solution to the crop. The greenhouse environment is managed from several plastic components, including air distribution tubes, shade materials, and energy curtains. Plastics are now common in greenhouse vegetable crop training, insect monitoring, postharvest handling, storage, and marketing.

Full access

Stephen M. Olson, George J. Hochmuth and Robert C. Hochmuth

Studies were conducted at the NFREC, Quincy, and AREC, Live Oak, Fla., to compare watermelon {Citrullus lanatus [(Thumb.) Matsum & Nakai]} plant establishment by transplanting and direct-seeding. Cultivars used were `Charleston Gray' in 1984, 1985, 1986, and 1989; `Jubilee' in 1988 and 1989; and `Crimson Sweet' in 1987 to 1990. Early yields were greater with transplants for all three cultivars in all years. With `Charleston Gray', total yields with transplants were higher in 1985 and 1989, but not in 1984 or 1986. The average fruit weights with transplants were also greater in 1985 and 1989 than in 1984 or 1986. With `Jubilee', total yield with transplants was higher in 1989, but not in 1988. Average fruit weight with transplants was greater in 1989 than in 1988. With `Crimson Sweet', total yields were higher with transplants in 1989 and 1990, but not in 1987 or 1988, but fruits were larger with transplanting compared to direct-seeding only in 1990. In all experiments, yields with transplants were never less than those with direct-seeded plants.

Full access

George J. Hochmuth and Donald N. Maynard

Delivery of modern extension programs involves considerable expenses that are becoming scarce from traditional sources. Successful extension educational programs will need to find additional revenue sources to fund educational materials, speaker costs, conferences, and other needs. It is important to become as financially efficient as possible and sometimes this means consolidating some programs and eliminating others. Charging fees to attendees is one means of covering costs of delivering programs. The University of Florida is partnering with the agriculture industry and trade journal publishers to provide resources and publishing for educational programs and materials.

Free access

Puffy Soundy, Daniel J. Cantliffe and George J. Hochmuth

Phosphorus applied at frequent rates via the flotation irrigation system affected growth of both roots and shoots of lettuce transplants grown with a flotation irrigation system. After an initial P addition of 15 mg·L–1, further P additions up to 90 mg·L–1 P resulted in a minimal growth response. Transplants produced with 0 P had similar poor growth, regardless of the amount of N applied. Nitrogen at 100 mg·L–1 improved the response of shoot growth to any level of P, but adversely affected root growth compared to N at 60 mg·L–1. Quality transplants had a root to shoot ratio of ≈0.25, total root lengths between 276 and 306 cm, and total root area between 26 and 30 cm2 in a 10.9-cm3 cell volume. Only 30% of the plants produced with 0 P could be pulled from the transplant flats, compared to ≈90% pulling success with added P. All pretransplant P treatments had a similar effect of increasing head mass at harvest time, and in reducing time to maturity regardless of production season. At transplanting, plants produced with transplant P were larger than those produced with no transplant P. Thus, at least 15 mg·L–1, supplied every 2 days via flotation irrigation, is recommended for production of high quality lettuce transplants in a peat+vermiculite media containing low concentrations of water extractable P.

Full access

George J. Hochmuth, Jeffrey K. Brecht and Mark J. Bassett

Potassium (K) is required for successful carrot (Daucus carota) production on sandy soils of the southeastern United States, yet there is little published research documenting most current university Cooperative Extension Service recommendations. Soil test methods for K in carrot production have not been rigorously validated. Excessive fertilization sometimes is practiced by carrot growers to compensate for potential losses of K from leaching and because some growers believe that high rates of fertilization may improve vegetable quality. Carrots were grown in three plantings during the winter of 1994-95 in Gainesville, Fla., to test the effects of K fertilization on carrot yield and quality on a sandy soil testing medium (38 ppm) in Mehlich-1 soil-test K. Large-size carrot yield was increased linearly with K fertilization. Yields of U.S. No. 1 grade carrots and total marketable carrots were not affected by K fertilization. K fertilizer was not required on this soil even though the University of Florida Cooperative Extension Service recommendation was for 84 lb/acre K. Neither soluble sugar nor carotenoid concentrations in carrot roots were affected by K fertilization. The current K recommendation for carrots grown on sandy soils testing 38 ppm Mehlich-1 K could be reduced and still maintain maximum carrot yield and root quality.

Free access

George J. Hochmuth, Jeffrey K. Brecht and Mark J. Bassett

Nitrogen is required for successful carrot production on sandy soils of the southeastern United States, yet carrot growers often apply N in amounts exceeding university recommendations. Excessive fertilization is practiced to compensate for losses of N from leaching and because some growers believe that high rates of fertilization improve vegetable quality. Carrots (Daucus carota L.) were grown in three plantings during Winter 1994–95 in Gainesville, Fla., to test the effects of N fertilization on yield and quality. Yield increased with N fertilization but the effect of N rate depended on planting date; 150 kg·ha–1 N maximized yield for November and December plantings but 180 kg·ha–1 N was sufficient for the January planting. Concentration of total alcohol-soluble sugar was maximized at 45 mg·g–1 fresh root with 140 kg·ha–1 N for `Choctaw' carrots, whereas sugar concentration of `Scarlet Nantes' roots was not affected by N fertilization. Carrot root carotenoid concentration was maximized at 55 mg·kg–1 fresh root tissue with 160 kg·ha–1 N. Generally, those N fertilization rates that maximized carrot root yield also maximized carrot quality as determined by sugar and carotenoid concentrations.

Free access

Elio Jovicich, Daniel J. Cantliffe and George J. Hochmuth

In greenhouse crops, fruit yield and quality can be increased by managing shoot pruning and plant density. The effect of plant population density (2, 3, and 4 plants/m2 as function of in-row plant spacings of 66.5, 44.3, and 33.3 cm, respectively), and shoot pruning (one, two, and four main stems) was studied for effects on fruit yield, quality and plant growth of greenhouse-grown sweet pepper (Capsicum annuum L. cv. Robusta) during Summer 1998 in Gainesville, Fla. Red fruit were harvested 84 and 118 days after transplanting (14 Apr.). Additional fruit set was inhibited due to the high temperatures. Marketable yield (number and weight) per square meter increased linearly with plant density and was greater on plants with four stems than in those with two or one stem. Extra-large fruit yield per square meter was not affected by plant density, but was higher in four-stem plants. Total marketable yield and extra-large fruit yields per plant were greatest in the four-stem plants at two plants per square meter. The stem length and the number of nodes per stem increased linearly with the decrease in plant spacing. Stem length and number of nodes per stem were greater in single-stem than in four-stem plants. Number and dry weight of leaves, stem diameter, and total plant dry weight were higher in four- and two-stem plants than in single-stem plants. Results indicated that four plants per square meter pruned to four stems increased marketable and extra-large fruit yield in a short harvest period of a summer greenhouse sweet pepper crop in north central Florida.