Search Results

You are looking at 1 - 10 of 11 items for

  • Author or Editor: G. Lightner x
  • Refine by Access: All x
Clear All Modify Search
Free access

G. Lightner

The personal computer has become a standard research tool and is used in the research process from data collection to publication of results. The volume of computer software increases as personal computers proliferate. Most tasks are accomplished with off-the-shelf products available at any computer store. More specific needs are usually met with commercial software packages supplied by the company providing the research equipment or from a specialized software provider. However, there are specific research needs that are best fulfilled with a custom computer program. An interface between data collection and storage that is more comfortable to the user or a model developed with a narrow scope might be better served with software developed for that application. The development of software for the MARYBLYT fire blight system is presented.

Full access

G.W. Lightner

MARYBLYT is a computer model system that was developed to assist growers when making management decisions regarding the control of fire blight. This disease is potentially devastating to pome fruit orchards and has traditionally been difficult and expensive to control. The collaboration between the Univ. of Maryland and the USDA Agricultural Research Service to develop MARYBLYT is reviewed to provide information that should be considered when such an effort is undertaken to address any research need using computer applications. Specifically, the development of the software for the MARYBLYT system is presented.

Open access

Ralph Scorza, G.W. Lightner, and A. Liverani

Abstract

Branch growth of compact (CT) and “Pillar” (PI) peach [Prunus persica (L.) Batsch.], a columnar growth type, and progeny of CT × PI was analyzed. PI trees were distinguished from CT trees by narrower branch angles and relatively fewer and longer branches. CT × PI hybridization produced two distinct classes of trees in a 1:1 ratio—globe shape (GL) and upright (UP). GL trees had a large number of branches, resembling CT trees, but had narrower branch angles. UP trees resembled PI trees, but with wider branch angles. Analysis of seedling growth at 1, 2, and 3 months indicated that height and number of lateral branches could be used to classify UP and GL mature tree form. Branch angle measured at 2 months was important in distinguishing GL from CT seedlings. Such measurements on young seedlings may be used for early selection of growth habit. The reported results indicate that peach tree form, in respect to branching density and branch angle, can be readily manipulated through hybridization of the appropriate growth types. The columnar form of the PI tree suggests its potential for high-density production systems and its use as a parent in developing narrow canopied trees.

Open access

F. B. Abeles and G. W. Lightner

Abstract

This report presents optimal harvest data equations (OHDE) calculated for 6 cultivars for apples at 3 locations in eastern West Virginia. In general, the equations predicted the observed harvest date one day better than the technique of using average calendar days for fruit development. The equations also indicated that bloom date was more important for determining the harvest date than the mean temperature during the growing season. Nonetheless, because of variability between equations, the overall usefulness of using the historical approach to the development of OHDE is limited.

Open access

Ralph Scorza, Li Zailong, G.W. Lightner, and Lenard E. Gilreath

Abstract

In the article “Dry Matter Distribution and Responses to Pruning Within a Population of Standard, Semidwarf, Compact, and Dwarf Peach Seedlings”, by Ralph Scorza, Li Zailong, G.W. Lightner, and Lenard E. Gilreath (J. Amer. Soc. Hort. Sci. 111:541–545, July 1986), Table 2, under the “Variable” column, which reads “Avg length of shoots (cm)”, should read “Avg length of shoots (mm)”.

Open access

E. N. Ashworth, G. W. Lightner, and D. J. Rowse

Abstract

A method for large scale evaluation of flower bud hardiness in apricots using a thermal analysis system interfaced to a computer is described. The technique measures the heat released during the lethal freezing of supercooled water within the bud primordia. Nine thermoelectric junctions wired in series were used to monitor the temperature of 10 individual buds. Bud temperature was scanned every 30 seconds and the data recorded on magnetic tape. The data were subsequently transferred to a minicomputer which analyzed and stored data and produced graphics. Computer assisted thermal analysis can accommodate a large number of samples and simplifies handling and storage of data. This technique has applications as a research tool, for determining critical bud temperatures and in screening selections from a breeding program.

Open access

E.N. Ashworth, J.A. Anderson, G.A. Davis, and G.W. Lightner

Abstract

Ice formation was initiated between –0.6° and –2.6°C in mature Prunus persica (L.) Batsch trees growing in the field. Trees supercooled very little. Ice formation was initiated at several locations in the tree and subsequently spread throughout. The release of the latent heat of fusion following ice formation in the tissue maintained tissue temperatures 1° to 3° above air temperature for several hours and mitigated the tissue's response to ambient temperatures.

Open access

H. W. Hogmire, T. A. Baugher, M. Ingle, and G. W. Lightner

Abstract

A sampling plan was developed and used along with a modified grading scheme as a tool to predict apple (Malus domestica, Borkh.) fruit quality, thus providing a means to evaluate the impact of orchard management practices on market potential. Apple extra fancy/fancy packout was predicted to within 10% by examining a 100-fruit sample from each of five bins at the submersion tank. Packout loss factors were predicted to within 5% by sampling 100 fruit from each of four bins. A modified Russo/Rajotte grading scheme in chart format proved to be a useful tool for assessing packout losses. An evaluation of downgraded fruit, comparing the grading scheme to grower practice, yielded coefficients of determination ranging from 0.83 to 0.94 for five of six fruit lots sampled. The grower’s marketing intentions and the tendency of packinghouse staff to give more attention to the most obvious defects during grading influenced the ability to predict packout and the severity of loss factors.

Open access

Ralph Scorza, Li Zailong, G.W. Lightner, and Lenard E. Gilreath

Abstract

Three-year-old limbs of unpruned standard (ST), semidwarf (SD), compact (CT), and dwarf (DW) seedling peach [Prunus persica (L.) Batsch] trees were separated into component parts at harvest. CT and DW trees had allocated higher percentages of dry matter to one- and 2-year-old branches than ST and SD trees. Although the proportion of dry weight in current season shoots was highest in CT trees compared with the other tree types, fruit dry weight was relatively low. In a separate study ST, SD, and CT trees were pruned and left unpruned, and current season shoot and fruit growth was recorded. Pruning increased the wood dry weight per trunk cross sectional area in current season growth in ST trees and increased the average length of shoots and lowered light penetration in ST and SD trees, but pruning did not affect current season shoot dry weight or length in CT trees. Shoot dry weight and shoot length were greatest in pruned ST trees. The number of shoots was not affected by pruning in any tree type. Total fruit dry weight did not differ with pruning or tree type.

Open access

R. Scorza, E.N. Ashworth, R.L. Bell, and G.W. Lightner

Abstract

Sample sizes for detection of differences of flower bud survival in peach and nectarine [Prunus persica (L.) Batsch] were chosen on the basis of theoretical confidence intervals (Cl) and least detectable differences (LDD) for the binomial distribution. Theoretical Cl and LDD for 1000-bud samples were comparable to Cl and Duncan's multiple range test separation computed from an analysis of variance for 1000 buds, based upon 10 replicates of 100 buds. Variability in survival was a function of eultivar, height of bud in canopy, and bud type. Variability may be minimized by sampling a given bud type (single, double, distal) at >1.5 m above ground level.