From the results of this study the following conclusions can be drawn. All conclusions are based on statistical ABOVA tests at a five percent level of significance. 1. Baaed on 108 detachment tests, it can be concluded that the difference in rate at which the loads were applied to the stem, which were 0.175 and 0.350 in./sec did not affect the force of removal. 2. Based on 108 detachment tests, it can be concluded that the angle at which the load was applied to the stem did affect the force of removal. The loading angles used were 90, 60, 30 and 0 degrees. 3. Two, 4-day differences in the stage of maturity did not affect the detachment force. 4. Each individual stem exhibited non-linear stress-strain properties since the calculated apparent elastic modulus in bending decreased as stem deflection increased. S. The rate of applying the load to the stem influenced the calculated apparent elastic modulus values. / Master of Science

The anthocorid, Orius insidiosus (Say) is a common polyphagous predator in Virginia apple orchards, particularly in orchards under reduced pesticide programs. The purpose of this research was to contribute to the basic knowledge of the biology and ecology of O. insidiosus in Virginia orchards and to evaluate the potential for its incorporation into IPM programs currently being developed. Egg and nymphal development of O. insidiosus was studied at 17°, 23°, 29°, and 35°C. Nymphs were supplied with an excess of the European red mite, Panonychus ulmi (Koch). There was a linear relationship between development rate (l/Days) of O. insidiosus and temperature. Developmental threshold temperatures were calculated as 10.2°C for the eggs; 8.9°, 7.5°, 10.7°, 12.5°, and 9.9°C for nymphal instars 1-5 respectively; and 10.0°C for total nymphal development. Mean degree-days (DD) requirements were 75.8 for eggs; 45.0, 38.0, 27.8, 28.8, and 64.9 for instars 1-5 respectively: 201.7 DD were required for total nymphal development. Nymphal development was also studied using aphids and pollen as food sources. Mean time (days ± S.E.) for total nymphal development at 23°C was 19.0 ± 0.0 with aphids and 20.0 ± 0.5 with pollen. As already mentioned, O. insidiosus is a polyphagous predator. Extensive laboratory and field observations established a number of small, soft-bodied insects and mites as well as the eggs of several lepidoptera are acceptable as prey. O. insidiosus also feeds on other beneficial species including predaceous thrips and mites. O. insidiosus falls prey to a number of other general orchard predators, particularly spiders, chrysopids, and other predaceous Heteroptera. During 1977-1978, the population dynamics of O. insidiosus along with a complex of predators and pests in orchards under three different pesticide programs was studied. O. insidiosus underwent 2-3 generations per year in Virginia orchards, depending on the availability of prey. Adults overwintered in the orchard, but most migrated into the orchard during May-early June from other areas. O. insidiosus first responded to aphid populations, but as this prey became scarce in late June, O. insidiosus fed on the European red mite whose populations were usually building up at that time. This study indicated that O. insidiosus responded numerically to increasing mite densities. Numerous weeds and crops serve as alternate sites for 0. insidiosus populations. Corn and alfalfa are often adjacent to orchards in Virginia and apparently serve as a reservoir for O. insidiosus throughout the season. Thistle (Carduus spp.) harbors large numbers of O. insidiosus which prey on thrips. These natural and cultivated alternate sites may be important to the management of O. insidiosus populations. Since pesticides are an important component of an IPM program for apples, the relative toxicity of 14 compounds (2 rates of each) to adult O. insidiosus was evaluated. Common cover-spray materials, aphicides, miticides, new materials such as synthetic pyrethroids, and fungicides were tested. Generally, O. insidiosus tolerated many of the compounds being considered for use in our developing IPM programs--especially at the lower rates. The functional response of O. insidiosus to densities of the European red mite was studied at 18.3°, 23.9°, 29.4°, and 35.0°C. Prey densities ranged from 5-80 mites/ cage. Mite consumption was recorded during five, three-hour intervals during the day. O. insidiosus did exhibit a functional response and increasing temperatures resulted in increased feeding at most prey densities. The data provided a good fit to both the type-2 and type-3 functional response models. The interspecific interactions of 5th instar O. Insidiosus and 2nd instar larvae of another mite predator, Leptothrips mali (Fitch) was studied in the laboratory. L. mali is a potential prey for O. insidiosus, but has a defensive anal secretion which repels predator attacks. Most contacts between well fed O. insidiosus and L. mali resulted in mutual avoidance. Most attacks by O. insidiosus were unsuccessful, especially if the approach was from the rear. Contact with the thrips' anal secretion resulted in immediate repelling of O. insidiosus with subsequent cleaning activity lasting 1-3 minutes. This study supports earlier work that indicated these two predators were compatible, especially in the presence of another food source such as the European red mite. / Ph. D.

Methomyl at seven concentrations, 0.051 to 0.204 kg ai/378.5 l water, was evaluated against eggs of pest and beneficial insects and mites associated with apples. The pest eggs studied were: Laspeyresia pomonella, Panonychus ulmi, Platynota spp., aphids, and Argyrotaenia velutinana. For A. velutinana, five rates of methomyl ranging from 0.013 to 0.204 kg ai/378.5 l water were used. Platynota spp., aphid, and A. velutinana eggs were highly susceptible to the material. P. ulmi eggs were not susceptible. Eggs of beneficial syrphid flies, Aphidoletes aphidimyza, Leptothrips mali, and Stethorus punctum were highly susceptible to methomyl. Eggs of Orius insidiosus were moderately susceptible. Chrysopa spp. eggs appeared to be unaffected by the material. LC₅₀ values for methomyl on eggs of Platynota spp. L. pomonella, O. insidiosus, Chrysopa spp., and S. punctum were generated. LC₅₀ values for P. ulmi eggs were unobtainable. Three rates of methomyl, used as an ovicide, were evaluated in the field for control of the Platynota spp. complex on apples compared to two formulations of FMC 45806, permethrin, and Bacillus thuringiensis. Methomyl provided the best control. Seasonal activity of P. flavedana and P. idaeusalis were monitored in reference to degree-day accumulations. Regression equations for male moth flights and egg deposition of the species are presented. Seasonal activity and prospects for development of a phenology model to predict seasonal activity of the species is discussed. / Master of Science

I. Scanning and transmission electron microscopy were used to investigate damage to apple leaves caused by the white apple leafhopper (WALH), Typhlocyba pomaria McAtee. Feeding holes created by WALH were found in the lower epidermis, with no visual exterior evidence of cell injury to the upper epidermis. The feeding holes were located in areas of the leaf with high stomatal density, and were therefore in close proximity to stomata. Groups of cells in the palisade layers were empty, or contained coagulated cell contents; adjacent palisade cells were apparently uninjured. These uninjured cells contained an abundance of starch granules, however, possibly indicating that they were not functioning properly. Spongy mesophyll cells dorsal to the feeding area were left intact as were the epidermal cells ventral to the feeding area. There was no evidence of cell wall collapse from the external view of either epidermis, or from internal leaf views. II. Scanning and transmission electron microscopy were used to investigate damage to apple leaves caused by the white apple leafhopper (WALH), Typhlocyba pomaria McAtee. Feeding holes created by WALH were found in the lower epidermis, with no visual exterior evidence of cell injury to the upper epidermis. The feeding holes were located in areas of the leaf with high stomatal density, and were therefore in close proximity to stomata. Groups of cells in the palisade layers were empty, or contained coagulated cell contents; adjacent palisade cells were apparently uninjured. These uninjured cells contained an abundance of starch granules, however, possibly indicating that they were not functioning properly. Spongy mesophyll cells dorsal to the feeding area were left intact as were the epidermal cells ventral to the feeding area. There was no evidence of cell wall collapse from the external view of either epidermis, or from internal leaf views. III. Two nine-year-old "Campbell Redchief Delicious’/MM.111 apple trees growing on the Virginia Tech Horticulture Research Farm were used to evaluate gas exchange characteristics of leaves injured by the white apple leafhopper (WALH). Two groups of leaves were used for gas exchange measurements. One group of 42 leaves had three leaves each with 0, 1, 2, 3, 5, 7, and 10 WALH per leaf on each of the two trees. This injury corresponded to 0, 12, 21, 28, 53, 70, and 100 cumulative WALH days, respectively. Gas exchange was measured both in the field and in the lab. A second set of leaves was selected which were visually rated as having zero, low, medium or high amounts of WALH damage, corresponding to approximately 0, 3, 7, and more than 10 WALH per leaf. Gas exchange measurements on the selected leaves were made in the field periodically through an entire day. When measured in the lab, photosynthesis (Pn) was reduced and transpiration (Tr) was increased by WALH feeding. Field gas exchange measurements indicated that WALH feeding reduced Pn and increased Tr before 1200 hrs, but no differences in Pn or Tr were measured after 1200 hrs. No explanation for the conflicting results is offered, and clear conclusions about feeding damage could not be made. / Master of Science

Master of Science

Our present knowledge, as indicated by the above data, proves that fire blight is due to a specific organism, a bacterium known in science as Bacillus amylovorus, which manifests itself in the following ways: 1. Blossom blight, due to the bacterial infecting the nectary of the flower and multiplying therein, later passing down into the stem by way of the ovary and pedicel. Apparent by the browning of the flowers, which later become blackened. 2. Twig blight, due to inoculation infections through wounds made by insects or other agencies on the young and tender shoots, blighting from the tips downward, the leaves turning brown and appearing as though scorched by fire. 3. Fruit blight, due to the progress of the bacteria up the pedicel into the pulp of the fruit; appearing as brownish or much darkened areas, later involving the entire fruit. 4. Canker blight, due to the entering of the larger branches by bacteria, conveyed by insect, bird, or mechanical agents, or by the bacillus working back from infected twigs, fruit-spurs, or water-sprouts. These cankers vary in size from barely visible areas to a girdling of the entire limb; they appear roughened and depressed with a distinct line separating the canker from the apparently healthy tissue. They are called "hold-over cankers." 5. Collar blight is nothing more than canker blight which attacks the base of the trunk usually through an infected water-sprout, borers, or mechanical injury. Trees afflicted with collar blight soon take on the sickly appearance of half starved trees, prematurely defoliating (partially or wholly), and finally dying. 6. Leaf blight, due largely to insect injury, the majority of infections the margin, either lateral or terminal, although central lesions are found. The blighted portion of the leaf being a light or yellowish brown with a faint purplish border at the advancing edge, which when active shows a narrow watery zone. During the warm sunny days soon after rains, when the trees are in blossom and the pollen gathering insects are busy visiting the flowers, and the hold-over cankers are exuding drops of the blight bacterial, fire blight begins its havoc. Insects come in contact with this gummy substance and later visit the blossoms, thereby inoculating the flowers with the active organism, blossom blight resulting. Bees are awarded first place in spreading the blight to the flowers but flies and all other insects which visit the bloom are also liable to spread the germ. Later on in the season, as long as the tree is in a vigorous stage of growth, the aphids, ants, leaf hoppers, borers, beetles, and in fact any of the biting or sucking insects which inhabit the apple tree, may spread the organism to the succulent tissue, causing twig blight, fruit blight, leaf blight, or body blight. It is a fact that the insect, which in one section of the country is most troublesome in disseminating blight-bacillus, may not be so important an agent in another section. Different varieties of apple trees may also vary in different sections as to their powers of resistance or susceptibility; the York Imperial being listed as a susceptible variety in Pennsylvania and Virginia while in West Virginia it seems to be quite resistant. We cannot control weather conditions which play so important a part in the spread of blight. The weather may put a tree in a responsive or susceptible condition to inoculation and may also control insect life to a great extent. And it is indeed difficult to try to "harden up" a tree by the application of phosphate and potash fertilizers and by the discontinuing of cultivation, especially when the soil is strong and rains are frequent. Hence the more practical methods must be followed: 1. Fight the insects which spread the disease. Spray with nicotine sulphate or some other tobacco extracts in combination with the early scab or codling moth sprays. Where "Black leaf 40" is used, the recommended strength is 1 to 800 parts of water. 2. Cut out the source of infection,- the hold over cankers--cutting back an inch or two into healthy bark, and disinfect the wound with bichloride of mercury (1-1000). Prune out all blighted branches and if possible cut out all blighted twigs, cutting back several inches into the healthy wood. A severe winter often kills the germs in the twigs. All the waste material should be hauled out of the orchard and burned. 3. It is well to discontinue cultivation and application of manure or nitrogenous fertilizers as soon as blight its appearance. 4. The trees are most susceptible to the attack when planted in low wet ground; hence drain the low spots in the orchard. Many bulletins have stated that winter pruning is inducive to wood and thus favors fire blight. Little attention should be paid to such recommendations for we need trees with good growth which will carry a crop of fruit and allow the sun to penetrate throughout the tree and color up the apples. Many fruit growers have bearing orchards and are not anticipating new ones, so to such,the talk of susceptible and resistant varieties means little. Then too, some of the susceptible varieties are the best commercial apples to raise, and when such is the case it means careful inspection for the hold-over cankers. It is however well to pay some attention to this fact when planting an orchard. What is needed badly is community spirit or cooperation in this difficult work of controlling fire blight. For if one's neighbor does not keep the disease out of his orchard, it is sure to spread to the adjoining orchard. So everyone should "pull together" and control blight which has and is now causing the apple grower heavy losses. / Master of Science

Master of Science

The effects of sterol-inhibiting fungicides (SIFs) on the free sterol and free fatty acid composition of apple leaves of Red Delicious and Jonathan cultivars were examiried over a 2 year period. Trees were treated in mornings vs evenings throughout each season and samples collected after 24 and 72 hours after each treatment. Generally, SIFs appeared to have an effect on the free sterol content of apple leaves after 24 hours, but the concentrations of free sterol returned to normal after 72 hours in the leaves of both cultivars. Morning versus evening application had little or no influence on leaf free sterol concentrations. There were increases in unsaturated and total fatty acid concentrations in Red Delicious leaves 24 hours following applications with the SIF, etaconazole, and the non-sterol-inhibiting fungicide (NSIF), metiram, early in the season. There were also increased concentrations of linoleic, linolenic and total free fatty acids in fenarimol and triadimefon-treated Jonathan leaves 72 hours after treatment. Early in the season, the SIF, fenarimol, caused an increase in linolenic acid in both Red Delicious and Jonathan leaves 72 hours after either morning or evening applications. Generally, both the Red Delicious and Jonathan leaves exhibited a decrease in saturated fatty acids following morning application whereas, an increase in saturation following evening application. Although SIFs may have had an effect primarily on the unsaturated fatty acids, particularly linolenic acid, early in the season, particularly linolenic acid, the fatty acid composition of the leaves appeared to return to normal later in the season. Ultrastructural observations were made of Red Delicious leaves 12, 24 and 72 hours after treatment with the SIF, bitertanol. Twelve hours after treatment thylakoids of chloroplasts appeared swollen and irregular resulting in loss of integrity of the organelles. However, after 24 and 72 hours, thylakoids of chloroplasts of treated leaves were similar to the controls. Infection of bitertanol-treated Red Delicious leaves by Spilocaea pomi was also examined at the fine structural level. Nuclear envelopes were not well defined and mitochondrial matrices appeared washed-out after 12 and 72 hours post treatment. There was dissolution of normally plate-like cristae of mitochondria, accompanied by the accumulation of minute electron dense bodies around their periphery. Invaginations and proliferations of the plasmalemma were observed as well as increased vacuolization of the cell. Further electron microscopic observations were made of the in vitro conidial state of Venturia inaequalis following the application of fenarimol. Conidia treated 2 hours with the fungicide for had necrotic areas throughout the cytoplasm. The plasmalemma was not well defined, and appeared to be degrading. Increased vacuolization was observed as were numerous lipid bodies and multivesicular complexes (MVCs) which contained vesicles of varying electron densities. Structural integrity of the organelles was such that they were difficult to discern. After 12 hours, the entire fungal cell was necrotic accompanied by the degradation of the cell wall. Detection of a selected number of SIFs in apple leaf tissue using bioassay procedures were also evaluated. It was found that the leaf disk and leaf extract bioassays examined in this study were ineffective in determining the presence of SIFs in apple leaves. / Ph. D.

This study is based on consumers' perceptions of two different types of cider. Cider can be produced from apples or pears and is enjoyed by consumers, but the differences in tasteprofile and production are drastic. The types of cider in this study are referred to as traditional artisanal cider, which contains 95% apple or pear juice, and industrially flavored cider, which contains 15% fruit concentrate. Despite these differences, both fall under the same official definition according to the Swedish food Agency and are included in the same cider category at the retail monopoly of alcohol beverages in Sweden, called Systembolaget. This contributes to the formulation of the study's problem. The problem is that consumers lack knowledge about traditional artisanal cider, leading them to choose industrially flavored cider instead.The sustainability of the latter can be questioned due to the long transport distances of fruit concentrate from abroad. The study aims to investigate what consumers appreciate in the different types of cider and what would be required for them to choose traditional artisanal cider more frequently. Information about consumers' cider preferences was collected through a survey distributed on social media. The results show, among other things, that the respondents have interest in traditional craft cider. However, respondents feel they lack knowledge about this type of cider and therefore buy industrially flavored cider more frequently. This also affects the sales of traditional artisanal cider, as Systembolaget bases its sales on consumer demand, which is higher for industrially flavored cider. The study's results also show significant differences in cider preferences correlated with age and place of residence. There is also a significant correlation between the pricing of traditional artisanal cider and both age and place of residence. The conclusion drawn from the study is that the majority choose to drink industrially flavored cider, but there is interest in drinking traditional artisanal cider, especially if the two types of cider were priced the same.

This study is a comparative analysis of how two forms of capitalist production intersect with gender to shape the labor process in apple packing houses of Virginia, United States and the VI Region, Chile. It illustrates how differences in growers' production systems, as well as traditional undervaluation of women's work, shape the organization of the apple-packing workplace. A theoretical framework based on the notion of labor processes was developed to study growers' farming systems and their use and management of labor. Production is conceptualized as a system based upon the relation of labor process and value-creating process. The study focused on two interrelated dimensions: 1) production as difference between exchange and use value and 2) the intersection of gender inequality and capital and its effects on the organization of the workplace and on women's ability to increase control and autonomy. Five apple farms were selected in each of two regions - one in Chile and the other in the United States. From these farms one hundred-twenty workers were chosen to be interviewed by stratified random sampling. In addition, the farm operator of each farm was interviewed. Labor in both regions is gendered and tightly controlled. However, the manner in which sample growers approach gender relations and the nature of labor control mechanisms differ from one region to the other. Such differences are associated with the type of production systems, the degree of articulation of farming systems with the modern economy, the type of ownership, the relation the owner had with the workers, and traditional undervaluing of women’s’ work expressed in wage differential according to gender and job segmentation. Explanations that propose an association between women’s income and autonomy are inadequate. First, women often worked because their family demanded that they do so, and, second, the type of work done by women in packing houses does not increase their economic power relative to men because a) the majority earn less than men, b) women’s packing-house work is commonly viewed as an extension of women’s housework, and c) women themselves think of their wage-work contribution as secondary and supplemental. Although women’s work choices are prediucpoan treeasdon s other than personal satisfaction, the majority value the possibility of meeting other women at work. Understandiwnhgy women enter packing-house employment needs to go beyond questioning women whether they do or do not need to work for wages. Explanations of how the contradictions in women’s roles and attitudes affect how labor power is reproduced within the workplace are needed when addressing gender and work. / Ph. D.