Browsing by Author "Lopez, Lorena"

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    Can the introduction of companion plants increase biological control services of key pests in organic squash?
    Lopez, Lorena; Liburd, Oscar (2021-07)
    Florida (USA) is a major producer of squash, Cucurbita pepo L. (Cucurbitaceae), with approximated 16% of the US production in 2019, valued at about 35 million USD. Major insect pests, including the sweetpotato whitefly MEAM1, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae), and the melon aphid, Aphis gossypii Glover (Hemiptera: Aphididae), jeopardize plant development and transmit viruses of economic importance that can cause up to 50% yield loss in squash crops. Pesticides are generally used for insect management in squash, but the development of insecticide resistance and their non-target effects are major concerns. A combination of non-pesticidal approaches was evaluated, including intercropping flowering plants, augmentation, and conservation biological control to manage key pests in organic squash. Refugia increased natural enemies around the squash; however, only a few beneficial arthropods moved from the companion plants towards the squash plants. Whitefly densities and squash silverleaf ratings were reduced, whereas natural enemies were more abundant when the predatory mite Amblyseius swirskii Athias-Henriot (Acari: Phytoseiidae) was released alone or together with sweet alyssum, Lobularia maritima (L.) Desv. (Brassicaceae). All companion plants used in this study increased natural enemies, but only African marigolds and sweet alyssum ultimately increased biological control activities.
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    Early Results of Kaolin Clay Applications in the Dominican Republic
    Torres, Emmanuel; Mancebo, Jorge; Lara, Ambrosio; Maurer, Willy; Geraldo, Yohana; Pilar, Martha; Torres, Isabel; Caro, Jose; Lopez, Lorena (2020-12-30)
    Sustainable approaches for fruit fly control are desirable to reduce resistance development and ease the entry of the commercial fruit to international markets. Kaolin clay foliar applications ares a suitable option for sustainable insect control in agriculture. Kaolin clay has shown to reduce plant stress and increase yield under high-temperature conditions. Adequate kaolin clay treatment could mitigate detrimental effects of high temperatures on guava flowering and fruiting while reducing fruit losses due to Caribbean fruit fly. However, the efficiency of kaolin clay may be affected by the rate and time of application as well as growing conditions and plant morphology. The objective of this study was to evaluate the effect of three kaolin clay rates in combination with three frequencies of application on fruit fly control and guava yield. Kaolin clay was applied to the foliage of guava trees using 19, 38, and 57 kg/ha, and were reapplied either weekly, biweekly, or monthly. Additionally, one control treatment was maintained with no kaolin clay application. Fruit yield, larvae infestation, and foliage temperature were recorded. Guava marketable fruit number was influenced by the kaolin clay compared to the control, although no increase in the overall yield was recorded. Weekly and biweekly applications of kaolin clay reduced fruit fly infestation by 69%, compared to monthly applications. Additionally, application rates of 57 kg/ha reduced larvae infestation by 59%, compared to 19 kg/ha. Biweekly applications of 57 kg/ha reduced fruit fly larvae infestation in guava fruit in 95.5%, compared to the untreated control. This technology showed potential as a sustainable tool for management of Caribbean fruit flies in guava when the recommended field rate (57 kg/ha) is used at least every two weeks.
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    Effect of Kaolin clay, Planting Dates, and Color Mulches on Summer Tomato Production in the Eastern Shore of Virginia
    Gandini Taveras, Ricardo Jose (Virginia Tech, 2024-04-15)
    As climate change exacerbates heat stress during the summer season, it becomes increasingly critical to develop effective strategies to safeguard the productivity of tomato plants (Solanum Lycopersicon L.). This research delves into the tools and techniques aimed at enhancing the cultivation of summer tomatoes in the coastal region of Virginia. The study explores the optimization of transplant dates, the implementation of reflective mulches, and the application of kaolin clay particle films. Field trials spanning two seasons were carried out, comparing different planting dates in May, June, and July, as well as the use of reflective, black, and white plastic mulches, both with and without foliar kaolin sprays. The findings of this study underscore the impact of transplanting tomatoes in May, demonstrating a substantial increase in yields when compared to transplanting in June and July. Reflective mulches enhanced plant height and fruit production relative to the conventional black plastic mulch. The combination of kaolin clay sprays with standard black mulch, resulting in yield increases of over 35%, rivaling the outcomes achieved with reflective and white mulch treatments. The application of kaolin did not significantly affect leaf-level physiological processes. These results highlight the significant potential of strategic early planting and the adoption of emerging heat mitigation technologies, such as kaolin clay films, in sustaining and enhancing the productivity of summer tomatoes. This becomes particularly relevant as growing conditions continue to evolve due to rising temperatures and the increasing extremity of weather events resulting from climate change.
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    Effect of Nitrogen Rates, Planting Dates, and Irrigation Regimes on Potato Production in the Eastern Shore of Virginia
    Suero Mirabal, Alexis Emanuel (Virginia Tech, 2024-01-04)
    Potatoes in the Eastern Shore of Virginia are traditionally planted between late February and early April and harvested between early June and late August. Potato prices are usually higher early into the harvest season and decrease slowly as the season progresses. Early planting dates are desirable for farmers, as it allows them to perceive higher prices for their product, but early planting is also associated with lower air temperature during the early season, which in turn can affect plant development, water and nutrient uptake, and overall yield. Additionally, variations in soil properties often affect nutrient and water availability for plants, as well as the distribution of soil-borne insect pests. Additionally, several techniques are available to map the variations of soil properties in commercial potato fields, but little effort has been made to relate this information to the potential presence of soil-borne pests. Hence, the objective of this project was to evaluate the effect of planting dates, nitrogen (N) rates, and irrigation regimes on potato production. Two comprehensive studies were conducted between February and July 2022 and 2023. The objective of the first study was to evaluate the effect of N rates, planting dates, and soil physicochemical properties in potato production and the presence of soil-borne pests. This study was established in a split-plot design with four replications, with planting dates on the main plot and N rates and time of application on the sub-plot. Late March planting resulted in the highest total tuber yield, while early planting produced significantly larger tubers. Early March planting reduced plant development and emergence, probably due to lower air and soil temperatures. There was no interaction between planting dates and N applications. Using N rates higher than 147 kg ha-1 resulted in no significant differences in total tuber yield. Regression analyses showed that the Normalized Differences Red Edge (NDRE) is an excellent predictor of N content in plant tissue and tuber yield. Moreover, Ca and H saturation percentages were linked to wireworm damage levels using classification algorithms. Similarly, K saturation percentage was identified as a potential predictor of nematode presence in this region. A second study was established with the objective of evaluating the effect of N rates and irrigation regimes on potato production. The study was established in a split-plot design with four replications, with the irrigation method on the main plot and total N rate on the subplot. Results from these experiments showed higher growth and tuber yield when combining overhead irrigation with crop evapotranspiration (ETc) estimation. Moreover, there were no significant differences when using N rates higher than 112 kg ha-1. Overall, results from these experiments suggest no changes in current N rate recommendations for this region. Additionally, these results suggest planting in late March and using irrigation regimes based on evapotranspiration with overhead irrigation systems. Future research should focus on adaptive fertilization based on growing degree days and refinement irrigation determination practices.
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    Miticidal Tools for Management of Southern Red Mites Infesting Southern Highbush Blueberries
    Lopez, Lorena; Liburd, Oscar E. (MDPI, 2023-06-21)
    Tetranychid outbreaks have been detected since 2016 in southern highbush blueberries (SHB); however, it was not until 2019 that the southern red mite (SRM), Oligonychus ilicis (Acari: Tetranychidae) was confirmed as the pest causing severe bronzing and stunting, in multiple Florida and Georgia commercial blueberry plantings. To date, only three miticides (fenazaquin, fenpyroximate, and acequinocyl) have been registered for use in SHB and there are no clear guidelines on how to manage SRM in SHB. Similarly, there is no knowledge regarding the existence of natural enemies of SRM in SHB. This is the first report of naturally occurring predatory mites (Amblyseius sp. and Neoseiulus ilicis) associated with SRM in SHB. Predatory mites were recorded in blueberry bushes after treatment with seven miticides used to suppress SRM populations including spiromesifen, acequinocyl, sulfur, sulfur + molasses, bifenazate, fenpyroximate, and fenazaquin. The number of SRM recorded per leaf and averaged plant damage ratings (0 = no bronzing–4 = 100% bronzing) were used to evaluate miticide efficacy. Additionally, the presence or absence of predatory mites per sample was recorded. Fenpyroximate used as the standard miticide, significantly reduced mite numbers seven days after application, as well as acequinocyl and fenazaquin. Fenpyroximate and fenazaquin demonstrated the best performance for managing O. ilicis on SHB and treated bushes demonstrated significantly less bronzing compared with the control plants. These miticides were also safe to naturally occurring predatory mites. Lastly, the level of growers’ awareness regarding SRM was assessed using surveys in 2020 to design adequate educational materials available to the grower community.
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    Virginia Vegetable Specialist Team
    Reiter, Mark S.; Kuhar, Thomas P.; Lopez, Lorena; Mullins, Chris; Nartea, Theresa; Rideout, Steve; Singh, Vijay; South, Kaylee; Strawn, Laura K.; Torres Quezada, Emmanuel; Vallotton, Amber; Githinji, Leonard; Higgins, Doug; Zeng, Yuan; Rashed, Arash; Mersha, Zalalem; Gu, Sanjun (2023-03-15)
    Specialists on the Virginia Vegetable Team are committed to assisting growers, regardless of business size, with obtaining the freshest, highest quality, and most efficiently produced vegetables with the idea of safety and economic viability in mind. Please reach out to your local Cooperative Extension agent and/or vegetable team specialist to answer any vegetable related questions important to Virginia growers. Please click on the specialist’s name to be directed to their university’s webpage. The team routinely conducts applied research, presents information to growers and industry, publishes farmer friendly fact sheets, and works towards training Agriculture and Natural Resource (ANR) Extension agents and governmental employees through in-service trainings to ensure information is disseminated to the masses.