Life Sciences Commons^™

Designing A Remote Aerial System To Image And Analyze The Health Of Grape Crops At Cal Poly San Luis Obispo, Alexander D. Vice, Dylan Benton, Adipratnia Asmady, Andrew Mercier, Andrew Meyer, Eric Belfield, Aaron Drake

STAR Program Research Presentations

In the last decade the prevalence of unmanned aerial vehicles (UAVs) has exploded; however, the presence of UAVs in research situations is still a relatively new and untested field. The autonomous flight lab (AFL) at Cal Poly San Luis Obispo is a new lab site that is dedicated to using UAVs to benefit research for all backgrounds. Before AFL was able to fly missions we first needed to actually receive our vehicles, create a lab space that would provide all of the necessary resources and equipment necessary to fly, and to be granted permission by the Federal Aviation Administration (FAA) …

Nitrogen Utilization Efficiency Of Creeping Bentgrass Genotypes, Y. Kuo, David J. Wehner, T. W. Fermanian, John M. Swiader

Office of the Dean (CAFES) Scholarship

A greenhouse study was conducted in a hydroponic system to determine the nitrogen (N) utilization efficiency (NUE) of 14 creeping bentgrass cultivars. There were significant differences among cultivars in plant tissue dry weight, tissue N content, root absorption efficiency (RAE), and NUE. Considering all plant tissue (whole plant), 'Penncross' accumulated the highest N accompanied with the highest whole plant dry weight (WPDW), while 'Allure' accumulated the lowest total Nand WPDW than all the other cultivars. The proportion of WPDW and total N partitioned to shoots was higher than partitioned to roots in each cultivar. On a whole plant basis, 'Regent' …

Nitrogen Utilization In Creeping Bentgrass, Y. Kuo, T. W. Fermanian, David J. Wehner

Office of the Dean (CAFES) Scholarship

N utilization, including plant dry weight (DW) production, total N and nitrate N (NO₃-N) content accumulation, N utilization efficiency (NUE), root absorption efficiency (RAE), reduced N accumulation, and nitrate assimilation capacity (NAC) were determined for creeping bentgrass cultivars grown in hydroponic culture. Possible mechanisms affecting N utilization including nitrate reductase activity (NRA) and root morphology were also examined. Four cultivars, selected from an initial screening of creeping bentgrasses were grown under both low and high levels of N in a flowing solution culture system. The relationship between NUE and plant growth for two different creeping bentgrass cultivars was …

Dry Weight Production And Nitrogen Efficiency Traits In Kentucky Bluegrass Cultivars In Nutrient Solution And Soil, Anthony F. Bertauski, John M. Swiader, David J. Wehner

Office of the Dean (CAFES) Scholarship

Because of the importance of such factors as appearance and vigor in turf management, genetic selection of Kentucky bluegrass (Poa pratensis L.) is often conducted at high levels of N application. This process can mask potential differences between genotypes in N efficiency, especially under low N levels. The case is also made that because soil is the medium in which plant selections ultimately must perform, cultivar screening for N efficiency in solution culture should relate to results in soil. This study was conducted to evaluate N-utilization efficiency (NUE – mg plant dry matter mg^-1 plant N) in six …

A Computer-Based Tool For Introducing Turfgrass Species, T. W. Fermanian, David J. Wehner

Office of the Dean (CAFES) Scholarship

An essential component of an introductory turfgrass management course is the description of how turfgrass species are adapted to different cultural systems and environments. The objectives of this project were to develop an interactive program to introduce the characteristics of turfgrass species and their optimum environments and to evaluate the students' gain in understanding turf species characteristics through this approach. A self-contained application, Turf Species, was constructed using the SuperCard development tool. Turf Species consists of three sections including a self-paced tour of the species, a what if establishment section, and randomly composed reinforcement quizzes with automatic grading. Turf Species …

Models For Predicting The Lower Limit Of The Canopy-Air Temperature Difference Of Two Cool Season Grasses, Dennis L. Martin, David J. Wehner, C. S. Throssell

Office of the Dean (CAFES) Scholarship

Estimation of the lower limit of the canopy-air temperature differential, (T_c–T_a)_LL, is required for calculation of an empirically-based crop water stress, index. This research determined the complexity of model needed for accurate estimation of (T_c–T_a)_LL for several field grown cultivars of Kentucky bluegrass (Poa pratensis L.) and for creeping bentgrass (Agrostis stolonifera L. var. palustris (Huds.) Farw.). Regression models using vapor pressure deficit of the air (VPD), net radiation load (R_n), and wind speed (WS) were developed for predicting (T_c–T_{a …}

Utilizing Iron In Turfgrass Management, David J. Wehner

Office of the Dean (CAFES) Scholarship

The purpose of this article is to review some of the basic information on iron, look at one of the discoveries made during the 1980s, and present some of the published research studies that have been conducted with iron on turfgrasses. Additional information on the use of iron can be found in popular magazines and in the proceedings of turfgrass conferences.

Iron Fertilization Of Kentucky Bluegrass, David J. Wehner, Jean E. Haley

Office of the Dean (CAFES) Scholarship

Iron applications are sometimes used to enhance the color (darker green) of turfgrass stands even when iron is not deficient. A study was conducted to determine the feasibility of replacing a portion of the total yearly N applied to Kentucky bluegrass (Poa pratensis L.) with iron. Turfgrass response to iron chelate (Sequestrene 330) applications at 2.2 kg Fe ha^-1 in combination with three liquid-applied N sources (urea, Formolene, and FLUF) at 25 kg N ha^-1 was compared to turf response from applications of the N sources at 49 kg N ha^-1. Iron was substituted for …

Melamine/Urea And Oxamide Fertilization Of Kentucky Bluegrass, David J. Wehner, Dennis L. Martin

Office of the Dean (CAFES) Scholarship

The commercial lawn care industry represents a large market for N sources. A formulated melamine (2,4,6-triamino-s-triazine) plus urea combination (MLU) (45% melamine by weight) and oxamide were evaluated for use by the lawn care industry by comparing turfgrass response from these fertilizers to that from urea, sulfur coated urea (SCU), ureaformaldehyde (Nitroform), and a non-fertilized check. Fertilizers were applied four times per year to field plots of Kentucky bluegrass (Poa pratensis L.) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) at a rate of 49 kg N ha^-1 per application. Color ratings and clipping weights …

Late Fall Fertilization Of Kentucky Bluegrass, David J. Wehner, Jean E. Haley, Dennis L. Martin

Office of the Dean (CAFES) Scholarship

Many turfgrass managers apply a portion of the total yearly N to cool-season turfgrasses in the late fall (November). The purpose of this field study was to compare fertilization programs with and without N applications in November using both slow-release and soluble N sources. Turfs of two different cultivars of Kentucky bluegrass (Poa pratensis L. cv. Baron and cv. Newport) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) received 10 fertilization programs utilizing urea, isobutylidene diurea (IBDU), or sulfur-coated urea (SCU). Urea was applied four times per year with either a spring application or a late-fall application …

Effect Of Temperature, Moisture, And Soil Texture On Dcpa Degradation, J. S. Choi, T. W. Fermanian, David J. Wehner, L. A. Spomer

Office of the Dean (CAFES) Scholarship

Turf managers sometimes experience poor or early loss of control of targeted weeds, even when herbicides are applied at recommended rates. This study was conducted to determine the influence of soil temperature and moisture on the rate of DCPA (dimethyl tetrachloroterephthalate) degradation in soil. The effect of six soil temperatures, three soil moistures, and three soil textures on the degradation of DCPA was measured in the laboratory through HPLC analysis. Soil temperature influenced the rate of DCPA degradation in the following order: 10<<15<<20<25=30>35°C. The average half-life ranged from 92 d at 10°C to 18 d at 30°C. Soil moisture …

Denitrification Losses From Kentucky Bluegrass Sod, C. F. Mancino, W. A. Torello, David J. Wehner

Office of the Dean (CAFES) Scholarship

Denitrification may represent an important mechanism in the fate of N applied to turf. Denitrification losses were directly measured from fertilized 'Baron' Kentucky bluegrass (Poa pratensis L.) sod samples sealed in acrylic chambers using the acetylene inhibition technique. Losses were correlated with soil texture, percent soil saturation (SAT), and temperature. Losses from turf on a Hadley silt loam soil and Hadley silt soil (both coarse-silty, mixed, nonacid, mesic Typic Udifluvents) incubated at 22°C did not exceed 0.4 and 0.1%, respectively, of the applied potassium nitrate fertilizer (4.5 g N m^-2) when soil water levels were less than …

Influence Of Prestress Environment On Annual Bluegrass Heat Tolerance, Dennis L. Martin, David J. Wehner

Office of the Dean (CAFES) Scholarship

Annual bluegrass (Poa annua L.) turf quality is reduced during periods of high temperature. To predict heat stress injury and develop improved prestress maintenance practices, an understanding of the seasonal variation in annual bluegrass heat tolerance and the influence of soil moisture on heat tolerance is crucial. Annual bluegrass growing in the field on a Drummer silty clay loam (fine silty, mixed, mesic Typic Haplaquolls) was sampled on 23 dates over two growing seasons and brought to a laboratory for exposure to high temperature. Prestress environmental conditions (air and soil temperature, soil matric potential, plant water potential, daylength, rainfall and …

Evaluation Of Liquid-Applied Nitrogen Fertilizers On Kentucky Bluegrass Turf, B. G. Spangenberg, T. W. Fermanian, David J. Wehner

Office of the Dean (CAFES) Scholarship

Solution and suspension N sources have been developed as substitutes for urea in spray solutions used by lawn-care professionals. A field study was conducted to evaluate the response of Kentucky bluegrass (Poa pratensis L.) growing on a Catlin silt loam (Typic Argiudoll), to applications of the new solution and suspension N sources, alone or combined with urea, by comparison to turf response from application of the traditional fertilizer materials ammonium nitrate (AN), Nitroform (ureaform), sulfur-coated urea (SCU), ammonium sulfate (AS), granular urea, spray-applied urea (US), and urea-ammonium nitrate (UAN) solution. Also, urea and AS treated with dicyandiamide (DCD) were …

Heat Tolerance Of Kentucky Bluegrass As Influenced By Pre- And Post-Stress Environment, David J. Wehner, D. D. Minner, P. H. Dernoeden, M. S. Mcintosh

Office of the Dean (CAFES) Scholarship

An understanding of the natural variation in heat tolerance of Kentucky bluegrass is needed to develop predictive models for stress tolerance. The variation in heat tolerance of ‘Adelphi’ Kentucky bluegrass (Poa pratensis L.) over the growing season and the effect of recovery environment on the perceived heat tolerance of the plants was determined. Field-grown plants (Chillum silt loam, fine-silty, mixed, mesic Typic Hapludults) were exposed to heat stress on 11 dates over two growing seasons by immersion in a water bath for 30 min at either 42, 44, or 46°C and then placed in either a greenhouse, or one of …

A Microecosystem For Fertilizer And Pesticide Fate Research, B. E. Branham, David J. Wehner, W. A. Torello, A. J. Turgeon

Office of the Dean (CAFES) Scholarship

A microecosystem was designed to study the behavior of pesticides, fertilizers, or related compounds applied to plant stands. The system consists of three parts: a brass base that holds the plant growth media, a glass atmospheric chamber that rests on the base, and a set of analytical traps. The brass base is fitted with a porous ceramic plate so that tension can be applied to the water in the growing media. Air enters the bottom of the glass atmospheric chamber and exits through the top into appropriate trapping systems to recover volatilized pesticides, ammonia, or metabolized ¹⁴CO₂ from …

The Fate Of Diazinon Applied To Thatched Turf, B. E. Branham, David J. Wehner

Office of the Dean (CAFES) Scholarship

Diazinon (0,0-diethyl-0-(2-isopropyl-6-methyl-4-primidinyl) phosphorothioate) is widely used to control turfgrass insect pests. Poor control of soil-inhabiting insects has been found where diazinon has been applied to thatched turfgrass stands. The purpose of this study was to evaluate the environmental fate of diazinon applied to turfgrass stands. A microecosystem was used to follow the fate of radiolabeled diazinon surface applied to Kentucky bluegrass (Poa pratensis L.) turfs, with or without a thatch layer, growing on Flanigan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) irrigated daily or every 4 days. Loss of diazinon by volatilization, leaching, and degradation accompanied by release of …

Foliar Application Of N And Fe To Kentucky Bluegrass, A. K. Yust, David J. Wehner, T. W. Fermanian

Office of the Dean (CAFES) Scholarship

The goal of the professional lawn care industry is to provide the homeowner with a dark green weed-free lawn. Members of this industry are interested in techniques to enhance the color of a turfgrass stand in lieu of excessive N fertilization. The purpose of this research was to evaluate the use of foliar applications of Fe alone or in combination with N on the color response of Kentucky bluegrass (Poa pratensis L.). Iron sulfate or an iron chelate was applied at the rate of 1.1, 2.2, or 4.5 kg Fe ha^–1 in combination with either 0, 25, or 49 …

Heat Stress Effects On Protein Synthesis And Exosmosis Of Cell Solutes In Three Turfgrass Species, David J. Wehner, T. L. Watschke

Office of the Dean (CAFES) Scholarship

Kentucky bluegrass (Poa pratensis L.), annual bluegrass (Poa annua L.), and perennial ryegrass (Lolium perenne L.) differ in their heat tolerance as determined by plant dry weight 2 weeks after exposure to heat stress. The status of the plants at that time depends on the degree of injury that occurs during the stress treatment and the repair or tolerance of that injury. The purpose of this research was to evaluate species differences in the degree of initial injury due to heat stress. The incorporation of radio-labeled leucine as an indicator of the net rate of protein synthesis …

Heat Tolerance Screening Of Field-Grown Cultivars Of Kentucky Bluegrass And Perennial Ryegrass, D. D. Minner, P. H. Dernoeden, David J. Wehner, M. S. Mcintosh

Office of the Dean (CAFES) Scholarship

The quality of cool-season turfgrasses frequently declines during periods of high temperature stress. Simple tests are needed to rapidly identify heat tolerant germplasm for incorporation into breeding programs. Facilitative screening tests have been devised, however, in the few studies that have been performed only immature and greenhouse or growth chamber-grown plants have been evaluated. To be of practical value, results of screening tests, employing plants grown under artificial conditions, should correlate closely with results of tests involving field grown plants. The objective of this research was to evaluate the heat tolerance of several cultivars of Kentucky bluegrass (Poa pratensis …

Urease Activity In A Kentucky Bluegrass Turf, W. A. Torello, David J. Wehner

Office of the Dean (CAFES) Scholarship

The components of a turfgrass ecosystem, including plants, an intervening layer of thatch and the underlying soil, influence the fate of topically applied urea fertilizer. The loss of urea N by ammonia volatilization may be governed by the rate of urea hydrolysis. The main objective of this study was to determine the extent of urease activity associated with turfgrass plant tissue, thatch, and the underlying soil. This information may help elucidate the mechanism of ammonia loss following urea application. Because a turfgrass stand frequently possesses an extensive thatch layer that may serve as the primary plant growth medium, additional objectives …

Ammonia Volatilization From Fertilized Turfgrass Stands, W. A. Torello, David J. Wehner, A. J. Turgeon

Office of the Dean (CAFES) Scholarship

Nitrogen applied to turfgrass stands can be lost through leaching, denitrification, or ammonia (NH₃) volatilization. The purpose of this investigation was to evaluate the effects of N carrier and mode of application on NH₃ volatilization from a Kentucky bluegrass (Poa pratensis L.) turf growing on an acidic (pH 6.4) Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) soil. The NH₃, which volatilized after application of any of several sulfur-coated ureas (SCU), prilled urea, spray-applied solubilized urea, and two liquid N products was measured by passing the airstream from microecosystems, in which the treated turfs …

Heat Tolerance Of Kentucky Bluegrasses, Perennial Ryegrasses, And Annual Bluegrass, David J. Wehner, T. L. Watschke

Office of the Dean (CAFES) Scholarship

Use of cool-season turfgrasses in transitional environments is limited, in part, by their heat tolerance. Development of a rapid heat tolerance screening technique would be of value in determining the potential of turf•grasses for use in warmer areas.

The heat tolerance of 22 Kentucky bluegrass (Poa pratensis L.) cultivars, Poa annua L., and four perennial ryegrass cultivars (Lolium perenne L.) was evaluated by exposing plants for 30 min to temperatures ranging from 41 to 49 C in single degree intervals. Ten-week-old plants, which had been grown under a low level of N fertilization and watered infrequently to maximize …

Occurrence Of Farming Practices In Idaho: With Special Reference To Remote Sensing, Mark D. Shelton, Joseph Ulliman

Office of the Dean (CAFES) Scholarship

This survey of information was initiated and compiled because of the needs of remote sensing interpreters to identify crops throughout the year on various types of remote sensing imagery. A fairly comprehensive guide to what crops grow in a county and the specific cropping practices has been developed.

Effect Of P, K, And Lime On Growth, Composition, And P Absorption By Merion Kentucky Bluegrass, T. L. Watschke, D. V. Waddington, David J. Wehner, C. L. Forth

Office of the Dean (CAFES) Scholarship

Information is needed concerning the effects of different soil fertility levels on the activity of turfgrass roots in that part of the soil profile sampled for routine soil tests. In Pennsylvania, a sampling depth of 5 to 7.5 cm is suggested for established turf. A study was conducted on 'Merion' Kentucky bluegrass (Poa pratensis L.) to determine relationships among lime, phosphorus, and potassium applications; soil test results; foliar growth and elemental analysis; and root activity as determined by ³²P uptake from three soil depths. In the field, soil pH values were 5.8 and 7.0, P ranged from 13 …

Separation Of Kentucky Bluegrass Cultivars Using Peroxidase Isoenzyme Banding Patterns, David J. Wehner, J. M. Duich, T. L. Watschke

Office of the Dean (CAFES) Scholarship

The peroxidase isoenzyme banding pattern of 15 Kentucky bluegrass (Poa pratensis L.) cultivars was investigated for use in identification. Isoenzymes were separated by polyacrylamide slab gel electrophoresis, stained with benzidine-H₂O₂, and the relative intensities of the bands evaluated with a densitometer. Cultivar separations were made on single seedling samples at the 1% level of confidence using band number, mobility, and intensity ratios. Overall variability of the procedure was evaluated using a horseradish peroxidase standard and the effects of seedling age and seedlot determined. Of the 15 cultivars, 11 could be separated individually, whereas the remaining 4 …

Separation Of Kentucky Bluegrass Cultivars Using Peroxidase Isoenzyme Banding Patterns, David J. Wehner, J. M. Duich, T. L. Watschke

Office of the Dean (CAFES) Scholarship

The peroxidase isoenzyme banding pattern of 15 Kentucky bluegrass (Poa pratensis L.) cultivars was investigated for use in identification. Isoenzymes were separated by polyacrylamide slab gel electrophoresis, stained with benzidine-H₂O₂, and the relative intensities of the bands evaluated with a densitometer. Cultivar separations were made on single seedling samples at the 1% level of confidence using band number, mobility, and intensity ratios. Overall variability of the procedure was evaluated using a horseradish peroxidase standard and the effects of seedling age and seedlot determined. Of the 15 cultivars, 11 could be separated individually, whereas the remaining …