Sarah Jane Pethybridge’s research while affiliated with Cornell University and other places
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The legacy effects of crop diversity on maize ( Zea mays L.) tissue nutrient composition, weed community structure, and intensity of weed-crop competition were assessed through a field experiment at two sites in the northeastern United States. Fields were conditioned with crop diversity gradients from summer 2016 to spring 2019. The crop diversity gradients ranged from a single cultivar to sixteen intercropped cultivars (four species, four cultivars per species) and were established in organic annual and perennial cropping systems. Following the three-year conditioning phase, maize was planted across the entire experiment, and each conditioning-phase diversity treatment was split into weed-free, ambient-weed, moderate-weed, and heavy-weed treatments. Within each cropping system, the effect of crop diversity legacy on weed-crop competition was negligible. In contrast, weed-crop competition varied between the maize grown in soil conditioned by the annual and perennial cropping systems.
In New York, organic production of muskmelon ( Cucumis melo ) and other cucurbits is limited by pests, diseases, and weeds. Among the most important pests are striped ( Acalymma vittatum ) and spotted ( Diabrotica undecimpunctata howardi ) cucumber beetles that cause damage through feeding. Cucumber beetles also transmit the bacterium, Erwinia tracheiphila , the causal agent of bacterial wilt. Mesotunnels are a modified row cover system consisting of nylon mesh netting supported by hoops approximately 1-m high, which have potential for incorporation into organic muskmelon production systems. The netting is an effective barrier for pests and insect-vectored diseases and also prevents insect-mediated pollination and in-season weed management in inter-bed areas. Two separate experiments were conducted in 2021 and 2022 to: (a) evaluate mesotunnels for organic muskmelon production and methods to control weeds in inter-bed areas (experiment 1), and (b) evaluate selected pollination treatments for integration into a mesotunnel production system (experiment 2). In experiment 1, there were four treatments: (i) landscape fabric in the inter-bed area with a mesotunnel, (ii) landscape fabric in the inter-bed area without a mesotunnel, and a (iii) ryegrass/white clover in the inter-bed area with a mesotunnel; or (iv) ryegrass cover crop in the inter-bed area with a mesotunnel. In experiment 1, mesotunnels significantly reduced cucumber beetle populations and bacterial wilt epidemic progress but did not affect the incidence of the foliar diseases, powdery mildew, or Alternaria leaf spot. In the mesotunnel and non-covered treatments, landscape fabric, applied for weed control between beds, resulted in greater fruit weight and more marketable fruit compared to mesotunnels with cover crops in the inter-bed area. In experiment 2, treatments were on/off/on (removal of netting during flowering followed by replacement), open ends (open ends during flowering), and a closed mesotunnel (with the insertion of a commercial bumblebee hive). Although the on/off/on treatment increased cucumber beetle populations and bacterial wilt epidemic progress compared to the open ends and closed treatments, it conferred significant yield benefits in both years. These findings emphasize the importance of systems-level analysis for evaluating the suitability of mesotunnels in organic muskmelon production.
A collection of foliar diseases affects table beet production in New York. The predominant diseases are bacterial leaf spot (BLS) caused by the bacterium Pseudomonas syringae pv. aptata; Cercospora leaf spot (CLS) caused by the fungus Cercospora beticola; and Phoma leaf spot (PLS) caused by the fungus Phoma betae (syn. Neocamarosporium betae). Little is known of the potential to use host resistance in an integrated program for table beet disease management. Field trials evaluated the susceptibility of selected table beet cultivars (Bohan, Bresko, Manolo, Pablo, Red Cloud, Ruby Queen, Subeto, and Bazzu/Irazu) to BLS, CLS, and PLS. Bohan was one of the least susceptible to BLS but was moderately and highly susceptible to CLS and PLS, respectively. Bresko was moderately susceptible to BLS and CLS and was among the least susceptible to PLS. Manolo was one of the least susceptible to BLS and PLS but was highly susceptible to CLS. Pablo and Red Cloud were moderately or highly susceptible to all diseases. Subeto was moderately susceptible to BLS and CLS but was the least susceptible to PLS. Ruby Queen, the processing standard, was the least susceptible to BLS and PLS and was moderately susceptible to CLS. Bazzu and Irazu (2021 and 2022, respectively) were among the least susceptible to all diseases and were the only cultivars tested with reduced CLS susceptibility. These findings emphasize the need to evaluate table beet cultivar susceptibility to the spectrum of foliar diseases. This information may underpin cultivar selection based on the varying importance of diseases in specific production situations.
Figure 1. A fully constructed mesotunnel with pest exclusion netting, including conduit hoops over raised beds and sandbags to seal the netting. Figure 3. Severe symptoms of cucurbit yellow vine disease (CYVD) incidence in acorn squash, including rapid wilting and crop loss. Figure 2. Adult squash bug laying an egg mass on a cucurbit leaf. Top inset, late-stage instar. Bottom inset, newly-hatched nymph.
Onion thrips, Thrips tabaci Lindeman, is a global pest of onion crops, causing substantial economic damage by diminishing bulb yields and transmitting plant pathogens. Insecticides are used to manage T. tabaci infestations with control decisions traditionally based on action thresholds that require visually counting thrips on a fixed, predetermined number of onion plants per field. However, this approach for treatment decisions is inefficient when thrips populations are well above or below the action threshold. The aim of this research was to develop a sequential sampling plan that would provide a rapid and reliable classification of thrips populations in commercial onion fields above or below prespecified management thresholds. The study was conducted in a total of 24 commercial onion fields in New York in 2021 and 2022. Taylor’s power law and Wald’s Sequential Probability Ratio Test were used in concert to develop each sampling plan. Simulated and historical field data of thrips populations were used to further validate the efficacy of each sampling plan. Results demonstrated the sequential sampling plan required an average of 78% fewer samples to make a control decision compared with the traditional fixed-sampling approach. Treatment decisions were reached in 72% of cases after inspecting only 10 plants, while only 6% of the cases required examining more than 25 plants. Comparisons with fixed-sample sizes ranging from 23 to 68 plants revealed a 96% agreement in decision-making and a 78% reduction in sampling effort when using the sequential sampling plans.
In early August 2023, a disease outbreak on hot banana peppers (Capsicum annuum cv. Golden Dagger) was reported in Cattaraugus County, New York (NY). Disease incidence was at least 60%. Affected developing and mature fruit had at least one tan, soft, sunken lesion with salmon-colored spore masses surrounded by brown, necrotic margins. Microscopic observation of the lesions identified acervuli and setae typical of Colletotrichum spp. Isolations were made from these lesions by spreading conidia from the acervuli on 2% water agar (WA) + 0.02% (w/v) ampicillin. Colonies were hyphal tipped and transferred onto clarified V8 juice agar (CV8) and incubated at 20°C. The isolation frequency was 100% and a total of six isolates were obtained: Coll23Pep001, Coll23Pep003, Coll23Pep005, Coll23Pep007, Coll23Pep008, and Coll23Pep010. After 10 days, colonies were subcultured to potato dextrose agar (PDA) and CV8. On PDA, colonies appeared off-white to dark gray with sparse aerial mycelia. On CV8, the colony was pale gray with acervuli and orange-colored spore masses in the center. Conidia were hyaline, smooth and fusiform to round, and tapered at both ends. Mean conidial dimensions (n = 20) were 20.2 (13.75 to 25) µm long × 4.7 (3 to 6.25) µm wide. To confirm the identity of the isolates, DNA was extracted, and PCR performed to amplify the internal transcriber spacer (ITS) region (primers ITS1/ITS4; White et al. 1990), and actin (ACT) (primers ACT-512F/ACT-783R; Carbone and Kohn 1999) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes (primers GDF1/GDR1; Guerber et al. 2003). Pairwise alignment of the sequences showed all isolates had 100% similarity to C. scovillei ex. holotype CBS 126529 (Damm et al. 2012). Sequences from all isolates were deposited in GenBank with accessions PP556967 to PP556972 (ITS), PP565766 to PP565771 (ACT), and PP565772 to PP565777 (GAPDH). For pathogenicity testing, all isolates were grown on CV8 at 20°C in the dark for 10 days. Conidia were harvested by flooding the plates of each isolate with sterile distilled water and filtering the suspension through a double layer of cheesecloth. The concentration of the conidial suspension was adjusted to 5 × 105 spores per ml. Pathogenicity of the six isolates was tested on banana pepper fruit by using a sterile toothpick to pierce the skin at the two opposite ends. A droplet (10 µl) of the conidial suspension was placed on each wound. The same number of fruit were inoculated without wounding, and non-inoculated control fruit received a droplet of sterile distilled water (either wounded or unwounded). The experiment was repeated twice. All fruit were placed in a humid box at room temperature for 7 days. All wounded and inoculated fruit developed sunken lesions filled with salmon-colored conidial masses. Disease did not occur on the unwounded, inoculated fruit nor the non-inoculated controls. C. scovillei was recovered from all inoculated fruit by reisolating onto CV8 media and isolates had similar morphology and conidial dimensions to the original isolates. To the best of our knowledge, this is the first report of C. scovillei causing anthracnose on pepper in NY. C. scovillei has been reported in South Carolina (Toporek and Keinath 2021), Brazil (Caires et al. 2014), eastern Asia (de Silva et al. 2019), and Kosovo (Xhemali et al. 2023). The pathogen is particularly aggressive on pepper and poses substantial threats to pepper production around the world.
Soil biological processes are important drivers of crop productivity in agroecosystems. Soil microarthropods play key roles in nutrient cycling and plant nutrient acquisition, though little is known about how these effects manifest in crop production under different organic fertilizer amendments. We explored the interactive effects of microarthropods and fertilizers on crop productivity in two greenhouse experiments: experiment one involved a single Collembola species, and experiment two involved diverse microarthropod communities. Oats were grown as a model crop in both experiments under one of three initial fauna abundance levels (none, low, and high). In both experiments, four organic fertilization treatments were compared: alfalfa green manure, Kreher's Poultry Litter Compost, Chilean nitrate, and a nonamended control. Oat growth and development were evaluated weekly. During each experiment, 48 pots were selected randomly for destructive harvest at two separate times to mimic forage and grain harvest stages. At each harvest, multiple soil metrics (microarthropods, microbial biomass, microbial enzymes, and soil carbon and nitrogen) and plant metrics (biomass, reproduction, and tissue carbon and nitrogen content) were evaluated. Our findings indicated that microarthropods, both single species and diverse communities, stimulated nitrogen cycling and enhanced crop nutrient status. As microarthropod abundance and diversity increased, microarthropods exerted more effects on soil microbial activity. The effects of the microarthropods enhance the breakdown of fertilizers, ultimately making fertilizer choice less important for soil processes and plant nutrient availability. Our findings suggest that microarthropods drove oat production yields primarily through their effects on soil biological processes.
Cercospora leaf spot (CLS), caused by the hemibiotrophic fungus Cercospora beticola, is a destructive disease affecting table beet. Multiple applications of fungicides are needed to reduce epidemic progress to maintain foliar health and enable mechanized harvest. The sustainability of CLS control is threatened by the rapid development of fungicide resistance, the need to grow commercially acceptable yet CLS-susceptible cultivars, and the inability to manipulate agronomic conditions to mitigate disease risk. Nighttime applications of germicidal ultraviolet light (UV-C) have recently been used to suppress several plant diseases, notably those caused by ectoparasitic biotrophs such as powdery mildews. We evaluated the efficacy of nighttime applications of UV-C for suppression of CLS in table beet. In vitro lethality of UV-C to germinating conidia increased with increasing dose, with complete suppression at 1,000 J/m2. Greenhouse-grown table beet tolerated relatively high doses of UV-C without lethal effects despite some bronzing on the leaf blade. A UV-C dose >1,500 J/m2 resulted in phytotoxicity severities greater than 50%. UV-C exposure to ≤750 J/m2 resulted in negligible phytotoxicity. Older (6-week-old) greenhouse-grown plants were more susceptible to UV-C damage than younger (2- and 4-week-old) plants. Suppression of CLS by UV-C was greater when applied within 6 days of C. beticola inoculation than if delayed until 13 days after infection in greenhouse-grown plants. In field trials, there were significant linear relationships between UV-C dose and CLS control and phytotoxicity severity, and a significant negative linear relationship between phytotoxicity and CLS severity at the final assessment. Significant differences between UV-C doses on the severity of CLS and phytotoxicity indicated an efficacious dose near 800 J/m2. Collectively, these findings illustrate significant and substantial suppression by nighttime applications of UV-C for CLS control on table beet, with potential for incorporation in both conventional and organic table beet broadacre production systems.
Citations (17)
... Alternaria leaf spot incidence with the on-off-on treatment also exceeded that in other treatments every year; however, the difference was statistically significant only in 2020. The nylon mesh material does not block the entry of fungal spores, nor does it substantially alter microclimatic conditions on the crop (Nelson et al. 2023); therefore, mesotunnels may be expected to have little impact on the progress of diseases caused by foliar fungi (e.g., Alternaria leaf spot and powdery mildew (Podosphaera xanthii)) or oomycetes [e.g., downy mildew (Pseudoperonospora cubensis)], as observed during a study performed in New York by Pethybridge et al. (2023). An important practical advantage of the mesh fabric over the spunbonded polypropylene typically used in low tunnels is that pesticide sprays can be applied through the mesh (Nelson et al. 2023). ...
... Onions are cultivated in both regions [37], which are around 500 km apart, and hardly in the in-between region. In both regions, T. tabaci has been a serious pest since 1952 [38,39], causing direct and indirect damage [40][41][42][43][44][45]. In the Netherlands, T. tabaci is also a major pest in Allium spp. ...
... There were some results were investigated by Miceli et al. (2019) that GAs can promote seed germination, leaf expansion, stem and root extension, and dormancy. Our results are analogous to the work of Pethybridge et al. (2023) who illustrated that the effects of gibberellic acid (GA) on hormone transcriptional regulatory systems resulted in root growth suppression. GA has also been reported to stimulate the formation of secondary xylem, reduce secondary phloem production, and improve lignification in roots. ...
... Squash bugs vector the Gram-negative bacterium, Serratia marcescens, which causes cucurbit yellow vine disease (CYVD; Bruton et al., 2003;Rascoe et al., 2003). In NY, CYVD is a newly reported and emerging disease of cucurbit (Rodriguez-Herrera et al., 2023). CYVD-affected plants appear stunted and chlorotic, and rapidly wilt and/or decline, usually dying around 2 weeks before harvest. ...
... Cultural, morphological and pathological variations have been reported to occur among different isolates of S. vesicarium [24]. Prasad et al., 2024 and Heck et al. [25]. Further studies are required using molecular markers to decipher the nature, extent and type of variations in different isolates of S. vesicarium for better understanding of the pathogen and management of the disease under field conditions. ...
... Blotch Virus Using the LAMP Assay (Al Rwahnih et al. 2013) and the unintended dissemination of infected plant material (Sudarshana et al. 2015). Secondary spread has been reported in southern Oregon (Dalton et al. 2019, KC et al. 2022 and Northern California (Cieniewicz et al. 2017a, Flasco et al. 2023a). The highest rates of in-field GRBV spread can be alarming, with an increase of up to 30% reported over three years (KC et al. 2022), or a two-to ten-fold increase over two years (Dalton et al. 2019), as observed in study vineyards in Oregon. ...
... Strong and healthy foliage with an upright architecture is therefore critically important to facilitate harvesting. Table beet root yield and sizes are strongly influenced by cultivar (Goldman & Navazio, 2008), disease management (Chancia et al., 2021;Khan et al., 1992;Pethybridge et al., 2017;Shah & Stivers-Young, 2004), plant populations (Benjamin, 1987;Benjamin & Bell, 1985;Goldman, 1995;Kikkert et al., 2010;Warne, 1953), light intensity (D'Egidio et al., 2019), light interception (Chancia et al., 2021;Saif et al., 2023) and plant nutrition (D'Egidio et al., 2019;Mampa et al., 2017). However, despite optimization of agronomic inputs (Kikkert et al., 2010;Shah & Stivers-Young, 2004), in-field variation can result in a substantial proportion of roots that do not fall within the acceptable size range for processing. ...
... Our sequential sampling plans will be implemented in an application called "Sampling by Cornell" (Heck et al. 2023). This free web-based application will provide growers access to the sequential sampling plans outlined in this study and useful features like personalized storage of previously sampled fields, all of which can be stored and reviewed on a field-by-field basis. ...
... Because of this, historical records have significantly augmented and enhanced our knowledge of historical climatic variability (Norrgård, 2014). Advances in historical climatology have drawn attention to the widespread use of documentary materials like weather diaries, private correspondence, trip journals, ship logs, and official and missionary records (Andrijevic et al., 2020). Increases in global temperature are predicted to significantly affect several countries, with disastrous consequences for agriculture systems in developing countries that rely solely on rainfall (Klutse et al., 2020a). ...
... They identified Leaf Area Index (LAI) and Height and Aboveground Biomass (AGB) [4]. The LiDAR-derived Leaf Area Index (LAI) is compared against the Multi-Spectral Instrument (MSI) derived LAI, and it identified LiDAR as a viable modality since 3D point clouds approximate LAI with minimal variables [5]. The comparison studies conducted in precision viticulture to assess vine canopy size parameters using LiDAR scan revealed that canopy height and LAI strongly correlate to canopy volumes [6]. ...