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  TB56: Effects of Differing Abundance Levels of Aphids and of Certain Virus Diseases upon Yield and Virus Disease Spread in Potatoes

  W. A. Shands, Geddes W. Simpson, Barbara A. Seaman, and F. S. Roberts

  In eight years during the period 1944 to 1954, a study was conducted on Aroostook Farm, Presque Isle, Maine, to develop ways of obtaining and maintaining varying levels of aphid abundance on potato plants. Methods for measuring aphid abundance and their effects on yield and virus transmission were devised. These techniques were then used to determine the effects of varying all-season levels of abundance of the aphids and of virus reservoirs of two potat o diseases upon yield of potatoes and the spread of leaf roll and spindle tuber in four varieties of potatoes. The results of that study are reported in this bulletin.

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  TB57: Effects of Cultural Methods for Controlling Aphids on Potatoes in Northeastern Maine

  W. A. Shands, Geddes W. Simpson, and H. J. Murphy

  A study was conducted at Aroostook Farm, near Presque Isle, Maine, 1954 to 1958, inclusive, to determine the effects of certain agronomic cultural practices designed to delay emergence of potato plants and to decrease their exposure to infestation by spring migrants. This technical bulletin reports the results of that study.

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  TB58: Further Evaluation of Entomogenous Fungi as a Biological Agent of Aphid Control in Northeastern Maine

  W. A. Shands, Geddes W. Simpson, I. M. Hall, and Corinne C. Gordon

  An intensive survey and study were made each year from 1952 through 1962 to determine seasonal abundance of living and dead diseased aphids by species on potatoes and to collect many of the infected specimens for exact diagnosis. Results of the study disclosed that the action of entomogenous fungi was outstanding in reducing the size of aphid populations on potatoes. This technical bulletin reports on the results of the continuance of the study from 1963 through 1969. However, the collection of dead, diseased aphids throughout the summer was done only from 1963 through 1966 ; thereafter, diagnosis was limited to dead, diseased specimens intensively collected from potatoes during a 1-week period when fungal activity was greatest. This was usually in mid-August, near the seasonal peak of aphid abundance on potatoes not treated with insecticides.

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  TB59: Soil Characteristics of Nesting Sites of Solitary Bees Associated with the Low-Bush Blueberry in Maine

  E. A. Osgood

  During the course of ecological studies of certain native bees which pollinate the low-bush blueberry in Maine, it was noted that several species chose particular areas in which to construct their nests. It is the object of this bulletin to describe the characteristics of these chosen sites and to compare them to areas that are not conducive to nesting. This study was carried out in Deblois, Washington County, on areas known as "blueberry-barrens." The predominant soil in the area is Colton gravelly sandy loam.

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  TB60: Survey of Internal Parasites of Potato-Infesting Aphids in Northeastern Maine, 1963 through 1969

  W. A. Shands, Geddes W. Simpson, and Corinne C. Gordon

  This technical bulletin reports the results of an annual survey conducted from 1963 through 1969 of parasitized aphids on potatoes in northeastern Maine, chiefly on Aroostook Farm, near Presque Isle. The authors discuss the role of parasites in control of aphids on potato plants not treated with insecticides and list the primary parasites and hyperparasites reared from potato-infesting species of aphids collected during the survey.

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  TB61: Properties of Plantation Grown Red Pine Related to Its Utilization

  James E. Shottafer, Norman P. Kutscha, and Richard A. Hale

  This report describes a study that was conducted to evaluate the static bending and compression parallel to the grain properties evident within and among material from 19 plantation-grown red pine trees, and to determine what effect position in the tree, latewood percentage, fibril angle, specific gravity and rate of growth might have on these mechanical properties. The second phase of the study was conducted concurrently with the first to determine what effect position in the tree and specific gravity might have on the characteristics of red pine Kraft pulp. A third investigation evaluated the effect of three dry kiln schedules on the visual grade characteristics and on the static bending, compression parallel to the grain, shear parallel to the grain and toughness strength properties of plantation-grown red pine.

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  TB62: The Suitability of Using Fluorescence Microscopy for Studying Lignification in Balsam Fir

  Norman P. Kutscha and Raymond R. McOrmond

  This publication discusses the advantages and disadvantages of primary and secondary fluorescence when examining lignification in balsam fir.

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  TB46: Chemical and Physical Properties of the Allagash, Hermon, Howland, and Marlow Soil Mapping Units

  R. V. Rourke and C. Beek

  The soils presented in this report were sampled at varying locations in Washington, Hancock, Aroostook and Piscataquis counties. This study was undertaken to ascertain the characteristics of the four mapping units so that their classification and interpretation as to use could be more sharply defined.

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  TB47: The Relationship of Fibril Angle to Certain Factors in Plantation-grown Red Pine

  R. S. Shumway, Norman P. Kutscha, and J. E. Shottafer

  The purpose of this study was to make an estimate of the average ring fibril angle within the stem of 48-year old plantation-grown red pine (Pinus resinosa, Ait.). It was also conducted to determine the degreed relationship between this estimated average ring fibril angle and various factors such as position in the tree, latewood percent, specific gravity, and growth rate.

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  TB48: The Water Beetles of Maine: Including the Families Gyrididae, Haliplidae, Dytiscidae, Noteridae, and Hydrophilidae

  Stanley E. Malcolm

  Relatively little is known about Maine's water beetle fauna. Material for this study was obtained from existing collections and from personal collecting by the author. Field collections were made throughout the state of Maine.

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  TB49: Puckerbrush Pulping Studies

  Andrew J. Chase, Fay Hyland, and Harold E. Young

  A study was made of the potential of weed trees and shrubs, called "puckerbrush," native to the state of Maine as a source of fiber for the paper industry. Six species—gray birch, red maple, pin cherry, aspen, alder, and willow—were used in the study. All components of each species were studied separately, including stemwood, branches, roots, and stump. In addition, two mixtures of components of each species were studied: Composite 1, a representative mixture of stem, branches, roots and stump, and Composite 2, a mixture of stem and branches.

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  TB50: Intestinal Absorption of Amino Acids In Vitro with Special Reference to the Chicken: A Review of Recent Findings and Methodological Approaches in Distinguishing Transport Systems

  Joseph Lerner

  The potential importance of the work reported in this bulletin centers about the need for a complete description of the initial step in the metabolism of amino acids, namely, their interaction or recognition by the brush border membrane which lines the intestinal lumen.

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  TB41: The Potential of Lignin Research

  Norman P. Kutscha and James R. Gray

  Lignin constitutes a vast natural resource, which can be found in various forms depending on where it is obtained and how it is isolated. To most easily isolate lignin, we must understand more thoroughly its chemical structure and how it is bound to the other wall components. To use lignin more effectively and develop new uses for it, we must understand its properties. Likewise, the most effective use of lignin-containing materials such as wood and wood products depends on understanding how their properties are affected by the properties of lignin.

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  TB42: The Mycotoxic Effects of Fungi Isolated from Poultry Feed Ingredients: The Response of Ducklings and Performance of Commercial Broiler Chickens Fed Experimentally Infected Corn Diets

  Elizabeth S. Barden, H. L. Chute, D. C. O'Meara, and Hilda T. Wheelwright

  The present work, planned to investigate the possibility of mycotoxins occurring in feed ingredients fed to poultry in Maine, was designed with the following objectives: (1) to isolate fungi from poultry feed ingredients; (2) to grow the m separately on corn (the carbohydrate source of poultry rations) for later mixing into the diets; (3) to test the variously infected lots of this corn substrate for mycotoxicity by feeding ducklings, a bioindicator for toxins; (4) to determine the effects of aflatoxin and other mycotoxins from feed ingredients, on the performance of commercial broiler chickens; and (5) to appraise this response as a measure of toxicity of the fungi found in feed ingredients.

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  TB43: Field Recognition of the Larvae of Native Coccinellidae Common to the Potato Fields of Aroostook County

  R. H. Storch

  The adult beetles of the family Coccinellidae are the well-known ladybird beetles or ladybugs. The larvae and adults of the subfamily Coccinellinae are considered beneficial because they feed on pest species, mainly aphids and scale insects. This study was undertaken to provide a means of recognizing the larvae of native coccinellids found in or around the potato fields of Aroostook County. For our purposes, it is desirable to be able to identify the insect quickly and without killing it. Thus, the larval color pattern was chosen as a possible means of identification.

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  TB45: Foreign Woods Utilized in Maine

  Norman P. Kutscha and L. L. Emery

  The purpose of this study was to (a) evaluate the extent to which foreign woods are used in the state of Maine, (b) to see if any problems exist in the use of these woods, (c) to compile information on the characteristics of the species used and provide this information to the users by supplying them with a copy of this bulletin, and (d) to provide for a better understanding of the significance of foreign wood use in the state.

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  TB34: Chemical and Physical Properties of the Charlton, Sutton, Paxton, and Woodbridge Soil Mapping Units

  R. V. Rourke and C. Beek

  Charlton, Sutton, Paxton and Woodbridge soil series were each sampled at five locations. Chemical and physical properties evaluated included particle size distribution, soil reaction, moisture retention, bulk density, coarse fragment volume, exchangeable bases and acidity, saturated hydraulic conductivity, organic carbon and percolation. Properties were evaluated on a horizonal basis whenever possible. Sampling depth was to 40 inches. The samples represent a range of characteristics within each soil series. Each site is not to be considered modal for the particular soil series but was considered to within the range of characteristics of the series at the time of sampling.

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  TB35: Alpine Soils on Saddleback Mountain, Maine

  J. G. Bockheim and R. A. Struchtemeyer

  Alpine regions do exist in the Northeast, but are less extensive than in western United States and Alaska. Although the areal extent of alpine soils is not known in Maine, nearly 1.4 million acres of land are classified by the Soil Conservation Service as "mountainous." In Maine several mountains with subsidiary peaks greater than 4,000 ft in elevation support alpine zones, including Katahdin, Sugarloaf, Bigelow, North Brother, Saddleback, and Abraham.

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  TB36: Economic Analysis of Camping-oriented Recreation Firms: Part 1--Simulation of a Recreational Firm: Flow Chart and Computer Program

  Josef Grueter

  This computer program simulates the economic activities associated with the establishment and operation of a camping-oriented recreation firm and is designed for purposes of business analysis and decision making. The simulation model was developed for and tested by the author on the IBM 360 model 40 do-system computer at the University of Maine's computing center.

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  TB37: Economic Analysis of Camping-oriented Recreation Firms: Part 2--Manual for Maine Outdoor Recreation Firm Simulation

  Josef Grueter

  This manual provides a means for recording and directions for collecting information on a campground-oriented recreation firm, and preparing for computer input for purposes of business analysis and decision making.

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  TB38: Utilization of Amino Acids from Protein by the Growing Rat: Efficiency of Carcass Protein Formation

  Frederick H. Radke, Herman DeHaas, and Richard A. Cook

  Ten experiment stations in the Northeast have cooperated in investigating three sources of amino acids (pure amino acids, milk protein and wheat gluten) at two levels (1.2% and 1.6% dietary nitrogen) with different subjects (humans, rats, pigs and protozoa) under different conditions (growth, maintenance and stress) in order to study availability of amino acids in protein. The publication describes the effect of the three nitrogen sources containing equal amounts of essential amino acids and nitrogen on the growth of rats over two and four weeks.

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  TB39: Canada Plum, Prunus nigra Aiton, as a Primary Host of the Green Peach Aphid, Myzus persicae (Sulzer), in Northeastern Maine

  W. A. Shands, Geddes W. Simpson, and H. E. Wave

  Studies were conducted to determine the role of Canada plum as a host of the green peach aphid in northeastern Maine and to assess its importance as a source of infestation by the aphid on potatoes. The results relate chiefly to chronological and phenological aspects of the use of Canada plum as a primary host of this aphid; temperature developmental requirements of the aphid on this plant in spring; productiveness of spring migrants of the aphid in thickets and in cages; interrelationships between fall aphid populations on foliage, and egg deposition and overwintering to naturally occurring aphid colonies in spring and summer populations on potatoes.

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  TB40: Effect of Dietary Changes on the Tissue Composition of Rats

  Frederick H. Radke, Herman DeHaas, and Eileen K. Gabrielson

  The following experiments were done to study the effects of both long-term and day-by-day dietary changes of fat and protein on tissue fat and serum cholesterol levels.

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  TB29: Soil-Water, Chemical and Physical Characteristics of Eight Soil Series in Maine

  R. V. Rourke and C. Beek

  Eight soil series (Adams, Berkshire, Buxton, Colbath, Creasey, Hartland, Peru, Winooski) were sampled, each at five locations. The soil was sampled and analyzed on a horizon basis. Characteristics measured were organic carbon, moisture retention, water movement, particle size distribution, volume of coarse fragments, bulk density, soil reaction, exchangeable bases and exchangeable acidity. These data are important in the classification and interpretation of the soil resources of Maine.

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  TB30: A Critical Evaluation of Results from Spectographic Analysis of Plan Tissue

  Paul N. Carpenter, Alice Ellis, Harold E. Young, and Thomas E. Byther

  For this study, samples of wheat, corn, timothy, orchardgrass, alfalfa, Bermuda grass, and tomato were analyzed for eleven elements. A statistical study of these data was undertaken to determine the precision of the spectrographic analyses and to determine the precision that could be expected from analyses by this method.

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  TB31: The Chemical Properties of Seven Agricultural Soil Series and Their Relationship to Soil Fertility

  Frederick E. Hutchinson

  In recognition of the importance of soil in a crop and forest production program, the Maine Agricultural Experiment Station initiated a research project in 1962 to determine the chemical properties of seven important agricultural soil series found in the state (Bangor, Caribou, Charlton, Conant, Buxton, Plaisted, Thorndike). The ultimate goal of the research was to relate the chemical properties of the soil series to the most appropriate fertility practices for their wise economic use.

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  TB32: Evaluation of Soil Sites for White Pine in Maine

  Kenneth G. Stratton and Roland A. Struchtemeyer

  To understand environmental combinations required to produce high-quality white pine, studies of both the species and its sites have been undertaken. Increased demands on land use have also stimulated the search for species and varieties of trees that will best adapt themselves to the relatively permanent factors of the site. The purpose of this study, as undertaken originally in 1962, was to add to the basic knowledge of soil factors controlling tree growth and specifically, provide information for evaluation of soil-site quality or white pine. This investigation was designed to consider a wide range of stands, sites, and soil characteristics.

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  TB33: Utilization of Amino Acids from Proteins: Manual of Procedures

  Hermon DeHaas and Ellen H. Morse

  To meet the protein needs of the newly developing countries and the increasing world population, plant proteins and protein mixtures will be required in larger and larger amounts. The proteins studied in this investigation included an animal and a vegetable protein that are important agricultural products of the United States. While general information about the nutritive quality of these proteins is available, this regional study was designed to contribute to an understanding of the reasons for the quality differences and to provide a basis for formulating protein mixtures of high quality using various protein sources.

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  TB25: The Effect of Stand Factors on the Productivity of Wheeled Skidders in Eastern Maine

  Ernest B. Harvey III and Thomas J. Corcoran

  The objective of this study was to determine what forest stand factors, as they constitute a set of operating conditions, affect skidder and skidder crew productivity and the degree of their effect.

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  TB26: Native Bees Associated with the Low-Bush Blueberry in Maine and Eastern Canada

  L. W. Boulanger, G. W. Wood, E. A. Osgood, and C. O. Dirks

  Native bees are particularly important pollinators of lowbush blueberry. Changes in certain cultural practices since the 1930s, however, have caused substantial reductions in the native bee populations. Recent observations, however, have shown that adjustments in these practices can have a beneficial effect on native bees with accompanying increases in their numbers. Collections of native Apoidea were made in various areas of Maine and eastern Canada from 1961 through 1965 to determine the species present and their relative abundance in blueberry fields. Of the 89 species collected, 59 were taken on lowbush blueberry blossoms, and 10 in close association with lowbush blueberry. Species in the families Halictidae and Andrenidae were by far the most numerous (32 and 23 species), followed in decreasing occurrence by species in the families Bombidae, Anthophoridae, Colletidae, and Xylocopidae.

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  TB27: Fresh and Dry Weight, Nutrient Elements and Pulping Characteristics of Northern White Cedar, Thuja occidentalis

  Richard F. Dyer

  Northern white cedar was selected as an eighth species for complete tree investigation of weight, nutrient elements and pulping characteristics because it comprises approximately 13% of the total softwood growing stock in Maine, but only amounts to about 2% of the total softwood timber cut for all purposes. It is hoped that the information in this bulletin will provide basic information permitting northern white cedar to become a more meaningful segment of the Maine forest economy.

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  TB28: Weight, Nutrient Element and Productivity Studies of Seedlings and Saplings of Eight Tree Species in Natural Ecosystems

  Harold E. Young and Paul M. Carpenter

  The objective of this study was to obtain weight and nutrient element information on complete trees ranging from 1 to 35 ft in height above ground for the same eight species (red spruce, balsam fir, white pine, hemlock, northern white cedar, white birch, red maple and aspen) as a downward extension in size classes.

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  TB21: Relationships of Proteins, Essential Fatty Acids and Cholesterol in the Rat and the Mouse

  Frederick H. Radke, Herman DeHaas, Eileen K. Gabrielson, and Mary E. Norburg

  This report describes extensive experiments to search for effects of various types and levels of dietary protein and dietary fat, especially linoleic acid, on such parameters of well-being as growth, appearance, tissue moisture and lipid content, tissue and serum cholesterol levels and lipid iodine numbers. Inbred mice were used in initial experiments and inbred rats were used in later experiments.

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  TB22: Design, Construction and Calibration of a Laboratory Rainfall Simulator

  Eliot Epstein and Walter J. Grant

  The use of field plots under natural rainfall conditions to evaluate factors that cause or contribute to erosion requires a long period of study to cover a range of climatic variations. To shorten the time required for erosion studies, field plot and laboratory rainfall simulators have been developed. The rainfall simulator at the University of Maine was designed for the study of soil characteristics as related to soil erodibility, and for the determination of soil erodibility factor (K) as used in the universal soil loss prediction equation.

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  TB23: Studies Concerning the Retention of Organic Materials by Clays

  David C. Frost and Harold W. Gausman

  The purpose for conducting this research reported was to investigate interlattice adsorption of organic materials by montmorillonite clay and clays obtained from Merrimac sandy loam and Suffield silt loam soils.

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  TB24: The Caddisflies (Trichoptera) of Maine Excepting the Family Hydroptilidae

  R. L. Blickle and W. J. Morse

  A survey of the Trichoptera taken from light trap collections made during July and August, 1959, form the basis of the present paper. A checklist of the family Hydroptilidae known from Maine has been published. The collections were made for the most part in the Boreal Region of Maine.

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  TB15: The Standardization of Symbols in Forest Mensuration

  International Union of Forestry Research Organizations

  This technical bulletin reprints the recommendations on the standardization of symbols in forest mensuration, originally published in 1959. The recommendations were made by a small working group in Section 25 of the International Union of Forestry Research Organizations, which was appointed at the Congress of the Union held in Rome in 1953. Members of the group were asked to enquire into the possibility of standarizing the use of symbols (and the systems of measurement) in forest mensuration and to make recommendations.

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  TB16: The Effect of Stress on the Formation of Tissue Lipid from Dietary Protein

  Frederick H. Radke, Herman DeHaas, and Sally C. Jacobs

  Rats were stressed in a black, enclosed, motor-driven drum by being rotated at random intervals during half of a forty-eight hour period. They were stressed for two out of every six days for six weeks, while receiving a casein diet.

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  TB17: Fiber Weight and Pulping Characteristics of the Logging Residue of Seven Tree Species in Maine

  Harold E. Young and Andrew J. Chase

  This publication presents information on fiber weight and pulping characteristics of the logging residue of red spruce, red maple, white birch, white pine, balsam fir, hemlock, and aspen. The accumulation of evidence concerning the amount of fiber in the present logging residue and the pulping potential of that residue justifies this synthesis of the various studies in a single publication.

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  TB18: Mensuration Methods for Site Classification of Shade Tolerant Tree Species

  Leigh E. Hoar Jr. and Harold E. Young

  All of the climax tree species in Maine are shade tolerant. This means that they have the capacity of surviving and growing slowly in the seedling, sapling and pole-size stages. As a result none of the established methods employing total age are applicable. In searching for a way to overcome this problem an entirely new approach to quantitative site evaluation was conceived. This study evaluates this new mensurational approach to site evaluation for shade-tolerant trees.

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  TB19: Parasites of Potato-Infesting Aphids in Northeastern Maine

  W. A. Shands, Geddes W. Simpson, C. F. Muesebeck, and H. E. Wave

  This publication presents brief synopses of the biology of several of the more common species or genera of primary parasites and of hyperparasites occurring in northeastern Maine. Three approaches are discussed for increasing effectiveness of insect parasites against the potato-infesting species of aphids, including (1) the introduction of new species of parasites or strains of species better adapted and more effective against each species of aphid than the naturally occurring ones, (2) the mass releasing of parasites in potato fields at times critical for the population dynamics of the aphids, and (3) a combination of these. The combined-effort approach is considered most likely to succeed.

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  TB20: Preliminary Tables of Some Chemical Elements in Seven Tree Species in Maine

  Harold E. Young, Paul N. Carpenter, and Russell A. Altenberger

  These tables show the amount in grams for each of twelve elements for the complete tree and the merchantable bole, for seven tree species (red spruce, balsam fir, hemlock, white pine, white birch, red maple, aspen) in terms of five height classes and ten diameter classes.

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  TB10: A Comparison of Arch-yarding and Ground-skidding of Pine Sawlogs in the University of Maine Forest

  Henry A. Plummer and Roger F. Taylor

  The decision whether to use a trailing-arch or operate by ground-skidding methods may face many sawlog producers. This case study attempted to determine statistically whether there existed significant differences between the two methods of operation by examining the various activities performed by a crawler-type tractor within the arch-yarding and ground-skidding phases of a harvesting system.

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  TB11: Speculation on Recovery of Rubidium–86 from Clays

  Harold W. Gausman and David C. Frost

  A very short publication on efforts to recovery Rubidium–86 from clays.

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  TB12: Preliminary Fresh and Dry Weight Tables for Seven Tree Species in Maine

  Harold E. Young, Lars Strand, and Russell Altenberger

  The studies on which the tables in this publication were based establish that data on the complete tree can be obtained by employing modern harvesting equipment thus eliminating a problem of measurement that has been impossible or difficult for hundreds of years. The tables in this publication are based on a limited amount of data obtained in a small area. However, these indicate the method and they can be useful guides for professional foresters and helpful to research workers who are seeking improved techniques for biological investigations such as site productivity. They are a beginning in an approach to a fuller use of the whole tree. Species covered: aspen, red maple, red spruce, white birch, balsam fir, hemlock, and white pine.

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  TB13: The Use of Aerial Photographs in Studies of Marsh Vegetation

  David P. Olson

  This publication describes a study using aerial photographs of marsh habitat in Merrymeeting Bay, Maine, to determine the kind of information relative to marsh vegetation that could be obtained from them, and also to determine the accuracy of the photographic interpretation.

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  TB7: Scheduling of Pallet Trucks in Pulpwood Operations

  Thomas J. Corcoran

  This study illustrates a method of scheduling pallet trucks using data obtained from pallet operations in Maine. The method, which is based upon a linear programming technique, can be employed in the determination of the minimum number of trucks required to handle a continuous flow of pulpwood in situations involving multi-pickup and multi-delivery points. In addition, the program establishes times and places of pulpwood pickup and delivery for each required truck.

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  TB8: Enzyme Levels in Birds

  Lois S. McDaniel, Helen A. Dempsey, and Harold L. Chute

  This technical bulletin describes a research project relating to enzymes and chickens during health and disease. This project was started in 1957, and with the aid of a National Institutes of Health grant #C-4957 in 1959 the work was accelerated. This bulletin covers some of the work that has not been published and at also summarizes some of the literature relating to enzyme activity levels in birds.

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  TB9: Newcastle Disease Virus Activity and Volume of Amniotic Allantoic Fluid in Chicken Embryos from Flocks with Different Vaccination Histories

  Harold L. Chute, D. C. O'Meara, D. B. Reardon, and H. T. Wheelwright

  Breeding hens of similar age, 9 to 11 months old, were selected from four flocks, each with a different vaccination history. One flock received no vaccinations, the second received spray and wing web Newcastle disease (ND) vaccine, the third was given three ND dust vaccinations, and the fourth received two dead ND viral vaccinations.

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  TB5: Effects of Factorially Combined Levels of Sulfur and Magnesium on Potato Plants (Solanum tuberosum)

  Harold W. Gausman and George O. Estes

  Katahdin potatoes were grown in the greenhouse in 2-gallon, crocks containing a virgin Caribou loam soil. Factorially combined levels of S and Mg, each at an equivalent rate of 0, 10, 20, and 30 pounds per acre, were imposed as treatments for the first five of seven crops. The sixth and seventh crops of potatoes were grown primarily to further deplete the soil of S and Mg and to enhance or accentuate plant deficiency symptoms which occurred quite intensively during growth of the fifth crop of potatoes. The objective was to evaluate effects of factorially combined levels of sulfur and magnesium on the growth, quality, and chemical composition of the white potato.