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Elvis A. Takow, Edward W. Hellman, Andrew G. Birt, Maria D. Tchakerian, and Robert N. Coulson

dynamic layers comprising the AVATXIS geographic information system developed to describe the eight American Viticultural Areas (AVAs) of Texas. Climate data. Data were obtained from Daymet, a collection of algorithms and computer software that interpolate

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A.G. Snelgrove, J.H. Michael, T.M. Waliczek, and J.M. Zajicek

A geographic information system (GIS) was used to create an interface to evaluate the relationship between the amount of greenness and the crime level within the city of Austin, Texas. Results indicated a statistically significant negative correlation between the incidence of crime committed in the Austin greater metropolitan area for the year 1995 and the amount of vegetation within the area in which those crimes occurred. Areas with less than the average mean greenness level in Austin had an increased amount of crime. Results indicated no statistically significant relationship between the level of greenness of the crime sites and the severity of the crimes committed, and income level appeared to have no statistically significant effect on the severity of crimes committed.

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Gary W. Stutte

Effective management of site variability has been shown to improve efficiency of chemical use, enhance of fruit quality, optimize irrigations and increase profits. Techniques for localizing and quantifying spatial variation through computer analysis of aerial imagery exist, but the detailed knowledge of soils, site history, and nutrition required for effective management of the variation often are not available in a readily accessible or timely fashion. As a consequence, the benefits of site-specific management have not been fully realized by horticultural managers. These limitations have been partially overcome by developing an information management system which integrates image analysis functions to identify crop stress, a geographic information system to relate stresses to resident and nonresident site factors, and custom spreadsheets that provide a cost/benefit analysis of various management decisions. The system allows a manager to visualize the probable impact of an intervention on variability, yield, and profits in a timely manner.

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Ronnie W. Heiniger

New technologies such as differential global positioning systems (DGPS) and geographical information systems (GIS) are making it possible to manage variability in soil properties and the microenvironment within a field. By providing information about where variability occurs and the patterns that exist in crop and soil properties, DGPS and GIS technologies have the potential of improving crop management practices. Yield monitoring systems linked to DGPS receivers are available for several types of horticultural crops and can be used in variety selection and/or improving crop management. Precision soil sampling and remote sensing technologies can be used to scout for infestations of insects, diseases, or weeds, to determine the distribution of soil nutrients, and to monitor produce quality by measuring crop vigor. Combined with variable rate application systems, precision soil sampling and remote sensing can help direct fertilizer, herbicide, pesticide, and/or fungicide applications to only those regions of the field that require soil amendments or are above threshold levels. This could result in less chemical use and improved crop performance. As with any information driven system, the data must be accurate, inexpensive to collect, and, most importantly, must become part of a decision process that results in improvements in crop yield, productivity, and/or environmental stewardship.

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Amy Barr, Mark Bennett, and John Cardina

The objective of this study was to ascertain if stand establishment of sh2 sweet corn (Zea mays L.) would benefit from variable planting depths determined by the use of geographic information systems (GIS). Spring and fall research plots were established in a field [80 × 20 m (262 × 66 ft)] containing Crosby silt loam and Kokomo silty clay loam soil series in Columbus, Ohio. Three sh2 sweet corn cultivars (Starship, Skyline, and Confection) were planted at three depths on the two soil types in the fall study, with an additional transition soil added in the spring. Emergence counts as well as soil moisture and temperature were monitored. In the spring, sites were also sampled for nutrient levels and soil compaction. Significant variability was found within the field with respect to soil moisture, temperature, nutrient levels, and compaction. Seedling emergence fluctuated with average soil moisture increasing in blocks with up to 24% moisture and then leveling off. Daily minimum soil temperatures impacted stand establishment. Although heat units accumulated faster on the Crosby soil, emergence was slower and less complete on these soil series than on Kokomo soil series. Further investigation determined that although temperatures of the Crosby soil were 3 to 4.5 °C (5.4 to 8.1 °F) warmer during the day than the Kokomo soil, temperatures on the Crosby soil averaged 2 °C (3.6 °F) cooler at night. Analysis of emergence patterns and field variability was performed on ArcView mapping software. Although `Skyline' planted at 2 cm (0.8 inches) had the best emergence overall, final stand would have been increased with `Skyline' planted variably at 2 and 4 cm (1.6 inches). Mapping the field under these different scenarios showed that although area with less than 70% stand would exist with a 2-cm uniform planting depth, the entire field would have a stand of 70% or greater with variable planting depth using a high vigor seedlot.

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Sandra A. Balch, Cynthia B. McKenney, and Dick L. Auld

Geographically referenced information is an important aspect in the collection of wild plant species. It provides detailed information about the collection site as well as a method of relocating plant populations. In one project, native plants were collected and analyzed for the presence of gamma-linolenic acid, a valuable fatty acid used in medicinal products. In a second project, native wild-flowers were collected and evaluated for potential use as drought-tolerant ornamental landscape plants. All native plants were initially tagged in the spring while in bloom. Each collection site was revisited later for seed collection. Due to a lack of landmarks in the collection area, a GeoExplorer Global Positioning System (GPS) unit was used to capture coordinate data of latitude, longitude, and altitude. This was added to the passport file of each collection site. Differential correction was used to increase accuracy of GPS data to within a range of 10 m. ARC/INFO software was used to assemble, store, and display collection data in map form. This method has been used to document over 300 accessions and identify areas with a high frequency of plants possessing desired characteristics.

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Joanne Logan and David L. Coffey

Vegetable production has become a multi-million dollar activity in Tennessee. The large number of options of planting dates and maturity classes of different vegetable species and cultivars result in a flexible, yet confusing, situation for the grower. A plentiful supply of vegetables for the processor, fresh market, or family table can be assured by the proper scheduling of planting and harvest of different crops and cultivars. Growers have very limited access to climatic data oriented to vegetable production in their locations. For the most part, they depend on planting maps on the backs of seed packets, or on extension bulletins with very general planting and harvest date recommendations. Tennessee consists of 4 climatic divisions that do not adequately describe the multitude of climates due to the diverse topography. The objective of this research was to create GIS maps of climatic variables important to vegetable production. Maps of temperatures, growing degree days, and rainfall, freeze and heat stress probabilities based on data from 72 locations in Tennessee were used to characterize the growing seasons for different vegetables.

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Reginald S. Fletcher, James H. Everitt, Michael R. Davis, and David E. Escobar

Major citrus blackfly (Aleurocanthus woglumi) outbreaks occur periodically in the Lower Rio Grande Valley (LRGV) of Texas, causing a reduction in citrus (Citrus sp.) tree yields. This research reports on the integration of airborne color-infrared (ACIR) imagery and geographic information system (GIS) technology for mapping citrus blackfly outbreaks appearing in this area in separate years. For this study, the 1993 and 2002 citrus blackfly infestations were mapped and compared. Outbreaks did not appear at the same sites for 1993 and 2002. In 1993, infestations occurred in the southern part of Hidalgo and Cameron counties compared with outbreaks primarily appearing in the western portion of Hidalgo County in 2002. For both years, Hidalgo County was affected more than the other citrus producing counties in the LRGV. This study demonstrated airborne remote sensing imagery integrated with GIS technology could be used to develop maps for comparing citrus blackfly infestations appearing in separate years.

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Kent D. Kobayashi

-related apps for research, extension, teaching, and industry are widely available. These apps deal with a myriad of subjects including food safety ( Albrecht et al., 2012 ), geographic information systems, image enhancement, hydroponics, scouting for insects

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Q.U. Zaman, A.W. Schumann, and H.K. Hostler

Many citrus groves in Florida were affected by hurricanes in Summer 2004. A commercial 42-acre `Valencia' sweet orange (Citrus sinensis) grove of 2980 trees was routinely scanned with an automated ultrasonic system to measure and map tree canopy volumes. We estimated tree damage by comparing canopy volumes measured before and after the hurricanes of 2004. Ultrasonically sensed tree canopy volume was mapped and the relative tree canopy volume loss percentage (TCVL%) for each tree was calculated and classified into six categories [≤0 (no damage), 1% to 24%, 25% to 49%, 50% to 74%, 75% to 99%, and 100%]. Authenticity of the ultrasonically sensed missing trees was established by ground truthing or matching visually observed and georeferenced missing tree locations with ultrasonically sensed missing trees in the grove. Ninety-one trees were found missing during ground inspections after hurricanes and they exactly matched with ultrasonically sensed missing tree locations throughout the grove. All of the missing trees were in TCVL% categories 5 and 6 (≥75% damage). Some canopy volume was still detected with ultrasonics at the missing tree locations because of the presence of tall grass, weeds, or branches of large adjacent trees. More than 50% of trees in the grove were damaged (completely or partially) and generally larger trees (>100 m3) were damaged more by the hurricanes than small or medium size trees in each tree canopy volume loss category. The automated ultrasonic system could be used to rapidly identify missing trees (completely damaged) and to estimate partial tree canopy volume loss after hurricanes.