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Grapes (Vitis spp.), globally cultivated for wine and other grape-based products, are susceptible to various diseases, pests, and disorders. These challenges are particularly pervasive in Virginia and viticultural regions in similar climates. Thus, growers routinely use insecticides and fungicides to protect their fruits. However, frequent or excessive use of these chemicals can pose environmental and human health risks and increase the chances of fungicide resistance. Many crop production systems use physical barriers to shield plant surfaces from biotic and abiotic environmental factors, particularly in Asian countries. This study evaluated the efficacy of paper bags, umbrella-style covers, and fruit-zone shelters in mitigating fungal diseases, insect infestations, and other factors that damage grape clusters. A series of field experiments were conducted at four commercial vineyards in Virginia and one research experiment station at Virginia Tech in five years with eight grape cultivars. Our results highlighted the importance of bag and fruit-zone shelter applications. Especially when these protection measures were applied around bloom, we observed reductions in the level of multiple diseases and insect- and bird-related damages. Fruit bagging resulted in significantly lower (P ≤ 0.05) mean severity and incidence of black rot, sour rot, sooty mold, and grape berry moth damage. Similarly, we found a significantly lower mean incidence of black rot, ripe rot, sour rot, and bird damage with the application of fruit-zone shelters. Thus, fruit bagging and fruit-zone shelter can be an effective cultural method for safeguarding grape clusters from different diseases, potentially reducing pesticide use and offering economic advantages to growers. / Master of Science / Grapes are produced for making wine and other grape-based products worldwide. However, grape production often faces challenges from diseases, pests, and environmental factors, especially in humid regions like Virginia. Grape growers use pesticides (insecticides and fungicides) to protect their crops. However, these chemicals can harm the environment and human health; moreover, these disease organisms and pests can become resistant to pesticides. In many parts of the world, especially in Asia, farmers use physical barriers like bags or covers to protect their crops from various harmful factors. In this study, we tested the effectiveness of paper bags, umbrella-style covers, and special shelters around the fruit area of grape plants against fungal diseases, insect problems, and other damages. We conducted a series of experiments over five years in four commercial vineyards and a research station in Virginia, using eight grape cultivars. Our findings showed that using bags and shelters around the grapes, especially during the blooming period, was effective. Bagging the fruit led to significantly fewer cases of diseases (black rot, sour rot, and sooty mold) and grape berry moth damage. Likewise, using shelters around the fruit area resulted in significantly lower diseases (black rot, ripe rot, and sour rot) and bird damage. Therefore, these protective methods could offer more options for grape growers to protect yield from factors damaging their high-value crops.

京都大学 / 新制・論文博士 / 博士(農学) / 乙第13409号 / 論農博第2892号 / 新制||農||1085(附属図書館) / 学位論文||R3||N5319(農学部図書室) / (主査)教授 吉村 剛, 教授 藤井 義久, 教授 杉山 淳司 / 学位規則第4条第2項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

Lopholeucaspis japonica (Cockerell) (Hemiptera: Diaspididae), commonly known as Japanese maple scale (JMS), is an invasive pest established in the United States in 1914. Over the past decade, JMS infestations have escalated, posing a significant threat to the nursery industry, and resulting in economic losses from unsellable infested plants. The limited understanding of JMS hampers the development of effective management strategies, intensifying the financial impact of this destructive pest. To contribute to the development of a sustainable pest management program, it is crucial to acquire knowledge of JMS's natural history, biology, and dispersal capabilities. Management costs can be reduced by determining the optimal timing for scouting and spraying through peak crawler emergence and the identification of overwintering life stages. Understanding JMS dispersal patterns within tree canopies can lead to the refinement of scouting methods, such as strategically placing the tape method (for monitoring crawlers). A two-year study took place at two separate locations and on boxwoods (2022-2023) and red maples (2023). Our phenology findings indicated that there were two generations and prolonged crawler presence which can extend over a period of 34 weeks (March-October) during the growing season. The first generation of crawler emergence on boxwoods started as early as the second week of March [110-114 Growing Degree Days in base 50°F (GDD50)], with the first peak occurring in mid-June [1179-1514 GDD50]. The second generation depending on the year began in July and peaked between early September and mid-August due to overlapping from prolonged presence of crawlers. Crawler emergence on maples indicated the first peak during the second week of July, followed by the second peak during the third week of August. Management practices, including monitoring and chemical control and based on phenology data, could be suggested to begin early March and continue throughout the season putting high pressure on crawlers during the peaks of activity. Overwintering studies from this project suggested JMS could be developing throughout winter with immatures found in January and February while in March the highest population was adults. Using horticultural oil during the winter months may help with JMS infestations. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparative analysis of JMS crawler densities within the canopies of maples indicated that the middle canopy sections exhibited higher crawler densities compared to the top sections. However, when evaluating all three sections (top, middle, and bottom), the bottom sections displayed the highest crawler densities. Examination of cardinal points within the top and middle canopies of maples revealed a widespread distribution pattern. In contrast, no significant differences in crawler densities were observed between the various canopy sections of boxwoods, indicating a uniform distribution across the plant. / Master of Science in Life Sciences / Japanese maple scale (JMS), scientifically known as Lopholeucaspis japonica, is an invasive pest damaging ornamental plants in the United States since 1914, particularly affecting the nursery industry in the Southeast, including Virginia. This study aimed to enhance the understanding of JMS phenology, overwintering biology, and dispersal patterns. A two-year study took place at two separate locations and on boxwoods (2022-2023) and maples (2023). Phenology and dispersal patterns were monitored using the tape method to count crawlers per cm². Over two years, 100 JMS specimens were inspected monthly for three consecutive winter months to record overwintering life stages. Across both years and crops there were two peaks of activity with the first peak being between June and July and the second falling in between August and September. For overwintering, higher numbers of JMS immatures were found in January and February, and adults in March. To investigate dispersal patterns, the canopy of experimental plants of maples and boxwoods were divided into top, middle, and bottom sections based on plant height. Comparing JMS crawler densities in maples between the top and middle canopy sections revealed higher densities in the middle. However, when all three sections in maples were compared, the bottom had the highest density of crawlers. Cardinal points within the top and middle canopies were investigated for maples only and showed a widespread distribution when examining those points. For boxwoods, no significant difference was found in crawler densities between plant sections. This knowledge will empower nursery growers to make informed decisions, optimize their efforts in monitoring and control, and minimize the economic impact caused by JMS infestations.

The hemlock woolly adelgid (HWA) (Adelges tsugae [Annand]) (Hemiptera: Adelgidae) is a non-native lethal pest to eastern hemlock (Tsuga canadensis [L.] (Pinales: Pinaceae), and Carolina hemlock (Tsuga caroliniana [Engelmann]) (Pinales: Pinaceae). In the early 2000's, a robust biological control initiative using Laricobius spp. (Insecta: Coleoptera) was launched with the goal of decreasing HWA's impact to hemlock and the associated ecosystems on landscape level. Since then, two Laricobius agents, Laricobius nigrinus Fender (Coleoptera: Derodontidae) and Laricobius osakensis Montgomery and Shiyake (Coleoptera: Derodontidae) have been evaluated, approved, and released. The production and subsequent release of these agents has largely occurred through mass rearing efforts by Virginia Tech. A descriptive analysis of these rearing and release data over the past 16 years at Virginia Tech revealed that the mass production of these agents has been consistently limited by: 1) excessively high rates of subterranean mortality and 2) early subterranean emergence. Very little is known about the subterranean life cycle of these species in the field in terms of survivorship and timing of emergence. Additionally, the thermal limits and rates of development are unknown for L. osakensis and were thus further investigated. In 2019, surveys within the urban environment in two counties in southwest Virginia were conducted to determine if these agents have dispersed from their original release location. Laricobius nigrinus was documented to have established outside of release sites in 100 and 75% of the surveyed grids containing HWA infested hemlocks. The establishments of these species in easily accessible locations allowed for the use of field-caught larvae, in addition to laboratory-produced larvae, for experiments. Experiments were conducted in 2019-2020 to determine the overall subterranean survivorship in relation to site condition, differences in survivorship between field-caught vs. laboratory-reared, and the seasonal timing of emergence. We found that the average field subterranean survivorship (17.1 ± 0.4%) was significantly less than the historical production of these agents in the laboratory (37.5 ± 13.6%). We found that as soil pH and organic matter depth increased, survivorship decreased. While the majority of emergence occurred as expected in the fall, a surprising amount of emergence also occurred in spring and summer. The rate of development and the minimum threshold temperature for each life stage were determined through constant temperature experiments, and were used in the construction of a phenological forecast model. Laricobius osakensis minimum threshold temperature (3.6°) from egg to adult was similar to that of other Laricobius spp., but completed development at higher a constant temperature (22°C). Our results suggest L. osakensis can handle the same colder climates as L. nigrinus, but may be better adapted for warmer locations than L. nigrinus. Laboratory rearing, establishment, subterranean survivorship, and thermal requirements of Laricobius spp. (Coleoptera: Derodontidae), biological control agents released for Adelges tsugae (Hemiptera: Adelgidae) / Doctor of Philosophy / Eastern and Carolina hemlocks are long lived, shade tolerant evergreen tree species that support a unique ecological assemblage of plants and animals. However, following the accidental introduction of a highly invasive aphid-like insect pest first found in the 1950s, known as the hemlock woolly adelgid (HWA), significant mortality of hemlocks in the eastern U.S. was eventually observed. In order to mitigate this pest's impact and to prevent the further collapse of this unique ecological system, a robust management program was initiated. Today, the primary management strategy to reduce HWA's deleterious effects is through the use of chemical and biological treatments. Biological treatments in the form of insect biological control agents, have focused on the use of two closely related beetle species in the genus Laricobius spp. These species were imported from their respective native ranges, biologically evaluated, and approved for release by federal and state agencies. Since then, the beetles have been mass-produced by multiple governmental and academic agencies and released on infested landscape on mostly public land. Key aspects of these species' biology in terms of their population patterns, development, distribution capabilities, and potential supplementary diet remains unknown. Therefore, investigations into these aforementioned aspects were conducted from 2018-2021 in both laboratory and field experiments. In order to supply beetle larvae for field experiments and to better understand how well these predatory beetles were establishing across the landscape, we investigated heavily urbanized areas for their presence. We found that L. nigrinus was established outside of release locations, in 100 and 75% of the surveyed grids containing HWA in southwest Virginia. Laricobius spp. spend a significant amount of their lives in a presumed dormant state beneath the soil during the summer months. Observations over the past 17 yrs. of rearing Laricobius spp. revealed relatively high rates of subterranean mortality and subterranean early emergence, both of which are substantial mortality factors. Through field experiments, the survivorship of these beneficial beetles was found to be 17.1 ± 0.4% and their seasonal emergence was not limited to fall.Comparing the average survivorship from our field study (17.1 ± 0.4% ) to that of the past 17 yrs. of laboratory production (37.5 ± 13.6%), there was significantly less survivorship. The developmental and phenological biology of one of the two Laricobius spp., L. osakensis was determined and found to be similar to that of other beetles. However, L. osakensis was able to complete development at 22°C, the highest developmental temperature recorded for any Laricobius spp. The similar phenological biology of these two predators will allow for precise larval sampling as a metric for establishment. Results and conclusions from these data have provided further knowledge to scientists, land managers, and public stakeholders regarding the benefits of Laricobius spp.

For the first time in many decades, a hemp pilot program was initiated in Virginia in 2016. Outdoor surveys were conducted in the 2017 and 2018 field seasons to record insect presence and feeding injury to plants. Multiple insect pests were present, including corn earworm (Helicoverpa zea [Boddie]) (Lepidoptera: Noctuidae), brown marmorated stink bug (Halyomorpha halys [Stål]) (Hemiptera: Pentatomidae), and cannabis aphid (Phorodon cannabis) (Hemiptera: Aphididae). In 2019, indoor production surveys revealed that cannabis aphid, twospotted spider mite (Tetranychus urticae Koch) (Acari: Tetranychidae), and hemp russet mite (Aculops cannabicola [Farkas]) (Acari: Eriophyidae) would likely cause production issues. Very little is known about the impact of insect defoliation in hemp so studies were conducted in 2018-2020 to determine impacts on yield and cannabinoid content of grain and cannabinoid variety hemp due to leaf surface area loss. In Virginia over two growing seasons, manual removal of leaf tissue in grain and CBD cultivars did not significantly impact observable effects on physical yield (seed or bud weight) or cannabinoid content (CBD or THC) at time of harvest. Corn earworm is the major pest of hemp produced outdoors and studies occurred to evaluate monitoring and management strategies. Pheromone traps may be valuable in determining when corn earworm moths are present in the vicinity of hemp fields but are not useful in predicting larval presence in buds or final crop damage. Larval presence and final crop damage are related. Brown marmorated stink bug does not appear to be a concern in hemp, at least at this time. / Doctor of Philosophy / For the first time in many decades, a hemp pilot program was initiated in Virginia in 2016. Outdoor surveys were conducted in the 2017 and 2018 field seasons to record insect presence and feeding injury to plants. Multiple insect pests were present, including corn earworm, brown marmorated stink bug, and cannabis aphid. In 2019, indoor production surveys revealed that cannabis aphid, twospotted spider mite, and hemp russet mite would likely cause production issues. Very little is known about the impact of leaf area loss due to insect feeding in hemp so studies were conducted in 2018-2020 to determine impacts on yield and cannabinoid content of grain and cannabinoid variety hemp due to leaf surface area loss. In Virginia over two growing seasons, manual removal of leaf tissue in grain and CBD cultivars did not significantly impact observable effects on physical yield (seed or bud weight) or cannabinoid content (CBD or THC) at time of harvest. Corn earworm is the major pest of hemp produced outdoors and studies occurred to evaluate monitoring and management strategies. Pheromone traps may be valuable in determining when corn earworm moths are present in the vicinity of hemp fields but are not useful in predicting larval presence in buds or final crop damage. Larval presence and final crop damage are related. Brown marmorated stink bug does not appear to be a concern in hemp, at least at this time.

Systena frontalis (F.) (Coleoptera: Chrysomelidae), the red headed flea beetle (RHFB), is a ubiquitous pest of ornamental nursery crops in the eastern United States. Defoliation by adults renders plants unsaleable. Control costs and economic losses from injured plants have become a top concern among Virginia nurseries in the past decade. Current management tactics include spraying insecticides up to three times a week during the adult active season. The frequent use of insecticides poses a risk to the environment, non-target organisms, and evolution of resistance within the targeted beetle population. To develop a sustainable pest management program, more information is needed to understand pest biology, quantify the injury potential, and explore control tactics. Methods to monitor this beetle were used to observe peak activity throughout the growing season as well as the adult daily activity levels. There were three observed generations with population peaks in late June, late July, and late August into early September. Within the scale of one day, adult beetles were found to be diurnal with peaks in activity in the middle of the day. These findings will inform growers of the most efficient times to scout and spray, ultimately reducing insecticide usage. Quantification of feeding damage to individual leaves, the entire plant, and preference between older and newer growth may relate plant injury with specific population densities. The use of phenyl ethyl alcohol as an attractant lure, was explored to bolster pest control. Finally, insecticide bioassays were performed to compare those currently used to others yet untested. / Master of Science in Life Sciences / The red headed flea beetle (RHFB) is an important pest of ornamental crops in open-field nurseries along the Eastern United States. Defoliation caused by adult feeding renders plants unsellable. Japanese hollies, hydrangeas, and sweetspire iteas are among the most affected plants. Infested nurseries suffer severe economic losses due to insecticide costs and plant inventory reductions. Growers are spraying insecticides up to three times a week to manage RHFB. Frequent use of insecticides poses risks to the environment non-target organisms. This study will help improve control tactics for this pest and potentially minimize non-target effects by reducing insecticide usage. Understanding when beetles are active throughout the day, and throughout the growing season, may inform timing of scouting and insecticide sprays to maximize effectiveness. With populations highest in late June, late July, and late August, RHFB is estimated to have three generations per year. Adults are most active in the middle of the day and sedentary at night. It was observed how different densities of beetles cause injury to individual leaves and entire plants, and compared feeding preference on older versus newer growth. Chemical control tactics were explored including insecticides labeled and not labeled for RHFB such as iscycloseram. Finally, the effectiveness of phenyl ethyl alcohol as an attractant lure for RHFB was assessed and found ineffective within the open-field nursery ecosystem.

This study evaluates the cost-effectiveness of alternative Integrated Pest Management (IPM) training methods and programs aimed at diffusing IPM innovations to farmers in Bangladesh. Various IPM innovations are categorized as being simple, intermediate or complex, while dissemination methods used to extend these innovations are classified as being less intense, moderately intense, or more intense. Examples of less intense diffusion methods include mass media and field day demonstrations, and moderately intense methods include visits from agents. A "farmer field school" (FFS) is considered a more intense type of training method. The study evaluates the effectiveness of these IPM diffusion methods based on a number of criteria such as a methods ability to reach the greatest number of farmers with a given budget, their capability of reaching farmers quickly, and their ability to influence adoption of IPM. Additional components of effectiveness include influencing appropriate use of IPM, influencing retention of IPM, providing a level knowledge that participants can adapt to other areas on the farm, and providing accessibility to limited resource farmers. Data used in the analysis come from a field survey conducted on 350 rice and vegetable farmers in Bangladesh during July and August of 2004. Three ordered probit models are used to measure adoption of simple, intermediate and complex technologies. Results from these models indicate that FFS participants are more likely than non-participants to adopt simple, intermediate and complex practices, while farmers visited by agents are more likely than non-participants to adopt simple and intermediate practices. Field day attendees are more likely to adopt intermediate and complex practices than non-participants. These results may be influenced by endogeneity of unobserved factors that influence participation in FFS but also affect adoption. The study uses a binary probit model to measure appropriate use, but it does not detect any significant differences among farmers trained through different methods, nor does it find any significant differences in retention rates among farmers who have been to different training programs. Another probit model identifies farmers who have been visited by an agent as being more likely to discover an IPM practice through their own experimentation, indicating that farmers who have been visited by an agent have received enough knowledge to adapt IPM to different problems on their farm. Results of the study indicate that limited resource farms are well represented by their participation in the various training methods, but that a higher percentage of large farmers than small farmers in the sample have been visited by an agent or been to FFS. Informal diffusion of IPM information is found to be occurring among people in FFS villages for simple practices. However, for intermediate and complex practices, farmers who participated in FFS are no more likely to spread information to other people in their villages than are less intense formal training methods such as field days and agent visits. This result indicates that while FFS graduates may be likely to share simple practices with others, they should not be relied upon as the primary means of informally diffusing more complex practices to other farmers. The cost-effectiveness estimation incorporates components of the effectiveness evaluation along with the cost of administering the methods. The study calculates that agent visits are the most cost-effective method for diffusing simple and complex technologies and practices, while field days are the most cost-effective methods for extending intermediate technologies and practices. / Master of Science

Adoption of new agricultural technologies by farmers in developing countries is sometimes limited, despite the associated benefits. Potato farmers in Carchi, Ecuador rely heavily on pesticides to limit pest and disease damage, rather than adopting a more sustainable and economically viable alternative: Integrated Pest Management (IPM). One reason IPM adoption is limited is that farmers are uncertain about the benefits of the complex technology. Information provision builds knowledge that reduces that uncertainty and leads to adoption. Another reason for limited adoption is that other farming activities compete for time, and farmers may forget or delay IPM adoption. One way to transfer information and remind farmers to adopt IPM practices is through text messages. To evaluate the impact of text messages on IPM adoption, we conducted a Randomized Control Trial (RCT) among potato farmers in Carchi, Ecuador. The RCT allowed us to identify the causal impact of text messages by comparing adoption rates and knowledge scores between farmers who received text messages (treatment), and farmers who did not (control). After attending a one-day training, the treatment received tailored IPM messages for approximately five and a half months. At the conclusion of the trial period, treatment and control farmers reported their adoption of individual IPM practices, and were tested on their IPM knowledge. Treatment farmers adopted both simple and complex practices at higher rates than the control. Farmers who received text messages also possess more knowledge about IPM techniques than non-recipients, which is evidence of the knowledge-building effect of text messages. Furthermore, text messages were shown to be effective in encouraging the adoption of practices for which no separate inputs were required, and ineffective in encouraging practices where a separate input was required. Text messages are an positive supplement to an in-person training program because they build knowledge and remind farmers, both of which encourage the adoption of IPM, which benefits the farmer, his community, and the environment. / Master of Science

An instructional guide for high school science and agricultural education courses was designed around the topic of integrated pest management (IPM) and the gypsy moth (Lymantria dispar [L.]) problem in Virginia. Construction of the guide followed three phases—design, development, and evaluation—of the Instructional Development Institute (IDI) model of instructional design. Lessons were developed using information from Virginia agricultural education course competencies, national science standards, a conceptual model of IPM, and gypsy moth management references and contacts. A validation panel consisting of two educators and two gypsy moth managers provided a review of the guide. / Master of Science