2024 Student Flash Talks Viticulture

Lauren Picone | Charlotte Decock | Cristina Lazcano

Assessing Long-Term Effects of Regenerative Management Practices on Vineyard Soil Health

Lauren Picone,* Charlotte Decock, and Cristina Lazcano
*Cal Poly, San Luis Obispo, 1802 14th St., Los Osos, CA, 93402 
(laurenmpicone@gmail.com)

Vineyards are often developed on slopes or marginal lands, which results in soils that are particularly susceptible to erosion and degradation. To mitigate these impacts, regenerative management methods—including the use of cover crops, no-till, compost application, and livestock integration— can be used to improve soil health and increase soil organic matter. These practices can improve crop productivity and quality, water infiltration, nutrient availability, and carbon sequestration within soils. Because building soil health is a slow process, there is little knowledge regarding the effects of long-term use of regenerative management practices on vineyard soil health.
To improve soil health and create more resilient agricultural systems, this project aims to assess the effects of long-term management practices on vineyard soil health across an edaphoclimatic gradient in California. Soils were collected from 87 different vineyard blocks across CA, specifically targeting vineyard blocks where one or several regenerative practices have been adopted for five or more years. Following recommendations from the Soil Health Institute, all samples were analyzed for a minimum suite of soil health indicators, which included soil organic carbon concentration, carbon mineralization potential, and aggregate stability. For each vineyard block, growers completed a qualitative survey on the management history and the performance of the vineyard, including yield, crop quality, water, nutrient, and pest management. Our preliminary results show that finer-textured soils had more total soil carbon concentrations than coarse-textured soils in the vine and alley row.  Total soil carbon concentrations in the vine and alley rows increased significantly with the number of years livestock integration had been adopted. Additionally, the years of livestock integration and adoption of no-till increased aggregate stability indices within the vine row. Texture class and location were more important in predicting total carbon and aggregate stability indices than the duration of practice adoption.

Funding Support: Foundation for Food and Agricultural Research, and CDFA

Rushil Patel | Satyanarayana Gouthu | Laurent Deluc

Exploring Auxin Responsive Factor 4’s Influence on Timing of Ripening Initiation Using Molecular Breeding

Rushil Patel, Satyanarayana Gouthu, and Laurent Deluc*
*Oregon State University, 2750 SW Campus Way, Room 4121, Corvallis, OR, 97331 (delucl@oregonstate.edu)

Genetic manipulation is a major tool in determining gene function and its relationship with traits of interest in plants. For any crop, it requires a tractable genetic transformation system and a reliable expression system to turn on or switch off expression of targeted genes. We implemented the microvine system for Agrobacterium tumefaciens-mediated transformation and a plant gene switch system to control the transgene expression by supplying transgenic greenhouse plants (through root-drenching) a chemical inducer, methoxyfenozide. As proof of principle, we conducted gain and loss of function studies on Auxin Responsive Factor 4, a transcription factor that may contribute to the timing of ripening initiation in grape berries. We developed three types of constructs. In construct 1, we aimed to induce over-expression of the native endogenous ARF4. In construct 2, we generated transgenic lines containing a synthetic ARF4 resistant to miRNA-mediated gene silencing (miRARF4). In construct 3, we created ARF4-silencing lines using artificial miRNA technology. To pinpoint plants with the most response to the chemical inducer, eight plants from each construct were grown to maturity and induced over a month with leaf collections at select points. Six collection times were chosen to comprehend both the short-term responses (days 0, 3, 7, and 10) and the reversibility of the system (days 14 and 31). The data extracted using qPCR allowed us to characterize the time period of greatest induced transgene expression. Expression levels of the most responsive plants were eight-fold in the native construct, 100-fold in miRARF4, and 1000-fold increase in the ARF4 silencing line. Ongoing experiments quantitatively compare expression levels in berry samples to verify the inducibility dynamics in the fruit. Once confirmed, the study intends to focus on comparing ARF4’s targetome among the three constructs by using genome-wide transcriptomic analyses.

Funding Support: Oregon Wine Board, Erath/Family Foundation, Oregon Wine Research Institute

Abram Smith | Satyanarayana Gouthu | Charles Dearing | Laurent Deluc

Identifying Protein-Protein Interactions in Red Blotch Infected Vines

Abram Smith, Satyanarayana Gouthu, Charles Dearing, and Laurent Deluc*
*Oregon State University, 2750 SW Campus Way , Corvallis, OR, 97331 (laurent.deluc@oregonstate.edu)

Grapevine red blotch virus (GRBV) poses a significant threat to winegrape production. Host factors critical for red blotch infection remain largely unknown in grapevines, impeding attempts to use CRISPR technology to generate red blotch-resistant grapevines. Our project seeks to identify these host factors. Our two main objectives are to identify the host factors using the yeast two-hybrid (Y2H) system and to validate their interaction with viral proteins in planta. For the Y2H experiment, we will conduct a comprehensive genome-wide screen using GRBV replication-associated proteins (C1, C2, C3, and C1-2) as baits against a comprehensive grapevine cDNA library from GRBV-infected plants as preys. Based on the strength of the interactions and their biological relevance from previous studies, we will select the top two most promising interactors for each bait (C1, C2, C3, C1+2) to conduct bimolecular fluorescence complementary assays from isolated grapevine protoplasts. All four baits have been successfully cloned into yeast, initiating the screening process. A prey library using coding-gene related RNA is currently being constructed. The next step will be to carry out mating of the bait and prey, as well as isolation of mated yeast. Further screenings on a series of selective media will identify high-confidence interactors, followed by Sanger sequencing to identify their biological function. To get ahead of the work on objective 2, we have optimized a protocol to isolate protoplasts from tissue cultured cells of microvines. If we reach our goals, we will lay the groundwork for further studies to produce CRISPR-engineered, GRBV-resistant grapevines.

Funding Support: California Department of Food and Agriculture

Vincenzo Cianciola | Luca Pallotti | Alessandro De Rosa | Peyton Peralez | Desiree Hernandez | Luis Ortiz | William Whalen | Eve Laroche-Pinel | Luca Brillante

A Two-Year study of 12 Sustained and Regulated Deficit Irrigation Schedules for Cabernet Sauvignon in Central California

Vincenzo Cianciola, Luca Pallotti, Alessandro De Rosa, Peyton Peralez, Desiree Hernandez, Luis Ortiz, William Whalen, Eve Laroche-Pinel, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Amidst escalating drought conditions in the San Joaquin Valley, where grapegrowers face an urgent need for effective water management strategies, this study contributes valuable insights for sustainable viticulture practices. Recognizing the pressing importance of optimizing water use in vineyards, particularly in the context of the West San Joaquin Valley, this research aims to unravel the physiological responses of grapevines under varying intensities and timings of sustained and regulated deficit irrigation.

Focused on a singular commercial Cabernet-Sauvignon × 1103 Paulsen vineyard, this study explored the impact of irrigation treatments administered during 2022 and 2023 seasons. Employing a semi-autonomous irrigation approach, actual water quantities were recorded using flow meters. The study incorporates sustained deficit irrigation (SDI) schedules with varying percentages (40, 60, 80 and 100% of ET_c) and regulated deficit irrigation (RDI) strategies in both preveraison and postveraison periods (e.g., 100/40, 80/60, 60/100).

Stem water potential and gas exchange were measured from June to harvest, grape composition from veraison to harvest and yield components were also assessed at harvest time. Results show that while the 40% SDI significantly underperformed 100% ET_c, it is possible to obtain similar or better results while saving water with RDI and SDI treatments with lower ET_c reductions.

This research determined the primary effects of these irrigation regimes on plant water status, gas exchange, berry composition, and yield components. The findings aim to provide a nuanced understanding that can inform advanced developments in water management strategies, offering practical insights for grapegrowers navigating the challenges of water scarcity in the San Joaquin Valley.

Funding Support: American Vineyard Foundation, California State University – Agriculture Research Institute

Alessandro De Rosa | Luca Pallotti | Eve Laroche-Pinel | William Whalen | Luca Brillante

Enhancing Water Use Efficiency and Berry Ripening in Cabernet Sauvignon: Effects of Irrigation Regimes and Biostimulants

Alessandro De Rosa, Luca Pallotti, Eve Laroche-Pinel, William Whalen, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Water availability is a key factor for agriculture, as rising temperatures increase plants’ water demand, while water resources become increasingly limited.

Optimizing water use efficiency is essential to enhance vine tolerance to heat stress and ensure high productivity. This study examines the effects of four distinct irrigation regimes: vines irrigated at 50, 75, and 100% of estimated crop evapotranspiration (ET_c), alongside regulated deficit irrigation (RDI), employing 50% of vine ET_c from fruit set to veraison and 100% from veraison to harvest, both independently and in combination with a biostimulant during the 2023 growing season. Measurements were taken for stem water potential, gas exchange, berry ripening, and yield at harvest of Cabernet Sauvignon vines. The biostimulant did not affect vine physiology, as stem water potential, gas exchange, and water use efficiency remained unchanged between treated and untreated vines. There were differences related to irrigation amount, with greater water supply leading to lower stress conditions and increased photosynthetic activity. However, this improvement came at the cost of reduced water use efficiency when compared with the 50% irrigation and RDI treatments, which had the greatest efficiency. The biostimulant increased berry and cluster weight without affecting berry ripening in combination with 50, 75, and 100% irrigation, but not with RDI. The water regime had a significant effect on juice composition, with the 50% treatment hastening berry ripening and the 100% treatment delaying it. Interestingly, RDI had the most pronounced effect on ripening, slowing down sugar accumulation and preserving organic acids.

Even though the effects of the biostimulant were limited, this study underscores that restricting water during periods when vine demand is limited represents a sustainable approach to enhance water use efficiency and delay berry ripening.

Funding Support: N/A

Desiree Hernandez | Alessandro De Rosa | Eve Laroche-Pinel | Luca Brillante

A Comparative Study of Traditional Drip Irrigation and Deep Underground Irrigation to Improve Water Use Efficiency

Desiree Hernandez, Alessandro De Rosa, Eve Laroche-Pinel, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Water efficiency is crucial for grapevine cultivation, especially in regions like California where water scarcity poses significant challenges. In 2023, a comprehensive project was initiated in Madera, CA, aimed at comparing the efficacy of traditional drip irrigation with a novel, deep-underground irrigation system in sustaining grapevine water status. The experiment comprised eight blocks, each with four vines, with four blocks irrigated conventionally using drip irrigation and the remaining four with a deep underground irrigation setup.

From June to August 2023, three water-related metrics were measured five times: stem water potential (Ψ_stem), stomatal conductance (g_s), and net assimilation rate (AN). Ψ_stem measurements showed a discernible disparity in mid-July, coinciding with peak water stress conditions. During this critical period, vines under traditional drip irrigation exhibited lower average Ψ_stem (-1.24 MPa) than those under deep irrigation (-1.13 MPa). Throughout the observational period, vines subjected to deep irrigation consistently demonstrated superior physiological performance. Specifically, AN remained consistently higher under deep irrigation, with an average difference of 2.6 µmol CO²/m²sec compared to drip irrigation. Similarly, g_s values were consistently elevated under deep irrigation, with an average difference of 65.9 mmol H₂O/m²sec except during the initial stages of the trial.

These findings underscore the efficacy of deep irrigation in mitigating water stress and enhancing grapevine physiological functions compared to traditional drip irrigation methods. The study provides valuable insights into the potential of deep underground irrigation systems to optimize water usage and sustain grapevine health and productivity in water-scarce environments. Ultimately, such innovative irrigation approaches hold promise for improving water efficiency and promoting sustainable viticulture practices in CA and beyond.

Funding Support: N/A

Tingting Ye | Michael Qian | Alexander Levin | Yanping Qian

Effect of Irrigation Initiation Time on Methoxypyrazine and C13-norisoprenoid Composition in Pinot noir Wine

Tingting Ye, Michael Qian,* Alexander Levin, and Yanping Qian
*Department of Food Science and Technology, Oregon State University, 100 Wiegand Hall, Corvallis, OR, 97331 (michael.qian@oregonstate.edu)

This study investigated the influence of initiated irrigation time on the methoxypyrazine and C13-norisoprenoid compositions of Pinot noir wine. The experiment was conducted in three subregions of the Rogue Valley in southern Oregon for two years, and the Pinot noir vines were irrigated at different irrigation initiation times based on normalized vine water status thresholds (ΔSWP). The ΔSWP was defined as the departure of measured midday stem water potential from the calculated non-water-stressed baseline, varied from 0.2 MPa (control) to the most delayed irrigation (1.0 MPa) in five irrigation initiation times, while the irrigation amount was set at 70% ET_c, based on industry standard. Wines produced in each of the two vintages were analyzed. Methoxypyrazines and C13-norisoprenoids in the wine were analyzed by headspace solid-phase microextraction gas chromatography-mass spectrometry and stable-isotope labeled compounds were used as internal standards for quantification. The results showed that the delayed irrigation initiation time decreased the methoxypyrazine levels and increased C13-norisoprenoid levels in the wines, although the trends depended on vintage and subregion. These changes in volatile composition in response to irrigation initiation timing could affect aroma perception and overall wine quality. Determination of the optimal irrigation initiation timing can provide a guideline for grapegrowers to produce high-quality winegrapes and reserve water resources.

Funding Support: Northwest Center for Small Fruits Research Commission, USDA

Kenneth Donsky, | Benjamin Ramsell | Britt Eubanks | Laurent Deluc

Accelerating Molecular Breeding via Development of a Novel Multiplexed Gene-Editing Method for Vitis vinifera

Kenneth Donsky,* Benjamin Ramsell, Britt Eubanks, and Laurent Deluc
*Oregon State University, 1450 NW Division Street, Apartment 32, Corvallis, OR, 97330 (donskyk@oregonstate.edu)

Genome editing can aid breeding programs dedicated to delivering genetically improved material from crops that will not be able to adapt to rapidly evolving climate change. Using the microvine system, we developed a research program to produce high-throughput gene-edited collections of grapevine mutants for easy gene-to-trait interrogations. To achieve this goal, we pursued the following three primary objectives: i) improve plant regeneration from Agrobacterium tumefaciens-mediated transformation events in somatic embryogenic grapevine cells, ii) increase the editing rate using a specific variant of the CRISPR/Cas9 protein, and iii) evaluate the potential of a new nanomaterial, carbon nanodots (CDs), to deliver multiple single guide RNAs for multiplexed editing. The approach to achieve objective 1 involves using the conditional expression of the morphogenic and synthetic gene, miRGRF_GIF4, from Vitis vinifera. For objective 2, we will compare the editing rate of different versions of the CRISPR/Cas9 editing system. In objective 3, we propose to identify the ratio of CD:sgRNA for optimized delivery to embryogenic grapevine cells. Zinc-functionalized CDs have been selected for their ease of synthesis and zinc’s affinity for nucleic acids. If we achieve our goals, we will give the scientific community a new tool for generating KO mutant collections that could expand beyond the grapevine model.

Funding Support: USDA NIFA

Christian Mandelli | Laurent Deluc

Spray-Induced Gene Silencing (SIGS) with Carbon Dots for Enhanced RNA Delivery in Grapevine

Christian Mandelli* and Laurent Deluc
*Oregon State University, 2750 SW Campus Way, Corvallis, OR, 97331 (mandellc@oregonstate.edu)

Spray-induced gene silencing (SIGS) is a recent technology that enhances a plant’s immune system. It involves the ectopic application of double-stranded RNAs (dsRNAs) to trigger a plant’s defense mechanism, known as RNA-interference (RNAi). Unlike traditional methods relying on the generation of transgenic plants, SIGS offers a rapid and targeted disease management solution. By transiently enhancing RNAi, it eliminates the need for resources and time-consuming development of resistant plants. However, SIGS application in tree crops encounters significant challenges, including limited cellular uptake and environmental stability of dsRNAs. To address these limitations, we explored an innovative approach that combines SIGS with branched polyethyleneimine-functionalized carbon dots (CDs) as nanocarriers, which enhanced dsRNA stability and cellular uptake. We developed a cost-effective, microwave-assisted protocol to synthesize 10 nm monodispersed CDs, that achieved >50% protection of dsRNA against RNase III degradation at a 200:1 (w/w) ratio. These CDs effectively improved cellular uptake, demonstrated by the successful delivery of CD-complexed fluorolabeled-dsRNAs (Cy3-RNA) into intact plant tissue-cultured cells. To prove the applicability of this formulation in planta, we sprayed Cy3-RNA with CDs on the abaxial surface of greenhouse grapevine leaves via low-pressure spray. Fluorescence microscopy revealed penetration of Cy3-RNA into stomata and neighboring cells. Additionally, the efficacy of CD-complexed dsRNA in triggering RNAi was validated using a 21-mer dsRNA targeting eGFP in eGFP-expressing microvines. Notably, no cytotoxic effects were observed following CD application. Ongoing research quantitatively compares eGFP expression of microvine leaves sprayed with CD-complexed and naked dsRNA through qPCR, to demonstrate the improvement in nucleic acid delivery associated with CDs. This innovative approach aims to overcome critical barriers for dsRNA delivery, particularly those associated with cell wall-related constraints in plants. Through optimization of RNAi-based defense strategies in grapevine, this research contributes to advancement of sustainable viticulture practices.

Funding Support: Erath Family Foundation, Oregon Wine Board

Bronwyn Riddoch | Myroslava Khomik | Richard Petrone

Testing the Application of a Novel Technology for Assessing Grape Maturity using Spectrometry

Bronwyn Riddoch, Myroslava Khomik, and Richard Petrone*
*University of Waterloo, 200 University Ave W, N2L3G1, Canada
(rpetrone@uwaterloo.ca)

The Niagara region wine industry in Ontario, Canada, is already experiencing the effects of climate change, and more extreme weather events are expected. It is predicted that the changing climate will result in significant consequences for quality wine production. Consistent monitoring of grapes will help maximize their enological potential. However, most monitoring techniques are either destructive to the grapes or time-consuming (e.g., UAV flights). Past research on soft fruits and Chardonnay grapes suggests that the use of the visible light spectra can predict fruit/berry ripeness in a time-efficient and non-destructive manner.

PRecent advancements in compact and inexpensive technology for monitoring individual woody plant health and growth conditions, called TreeTalker, have been adapted to vines (TreeTalker Wine; TTW). This adapted technology allows continuous, real-time monitoring of grape status using spectrometry. Here, we present results from experiments that tested TTW’s ability to monitor grape veraison. We developed empirical relationships between spectral signatures measured by TTWs and berry total soluble solids (TSS) and investigated the possibility of using TTWs to predict berry TSS in situ and continuously on the vine until harvest.

Funding Support: Sources are University of Waterloo, Nature 4.0, and Ontario Grape and Wine Research Inc.

Edgar Godoy-Monterroso | Shunping Ding | Marco Fernandez | Quinn Cahoon | Shijian Zhuang | Qun Sun

Optimizing Biofungicide Use for Control of Grapevine Diseases on the Central Coast of California

Edgar Godoy-Monterroso,* Shunping Ding, Marco Fernandez, Quinn Cahoon, Shijian Zhuang, and Qun Sun
*Department of Viticulture and Enology, California Polytechnic State University-San Luis Obispo, Cal Poly 1 Grand Ave, San Luis Obispo, CA, 93407 (egodoymo@calpoly.edu)

Biofungicide efficacy in grapevine disease management is enhanced by selecting the right active ingredients and modes of action, optimizing application timing and understanding the pathogen’s biology, then integrating them properly into fungicide programs. The efficacy of biopesticides in vineyard production is influenced by local climate and environmental conditions. The objective of this study was to investigate the efficacy of biofungicides applied at different intervals in controlling powdery mildew and Botrytis bunch rot, and their effect on grape quality. The study was conducted in the San Luis Obispo Coast AVA on mature Chardonnay vines. Twelve fungicide programs were designed, with three biofungicides containing different active ingredients and modes of action, application intervals, and integration strategies. A grower-standard program and an untreated control were also included in the experiment. Fungicide applications started at bloom in May 2023 and finished at veraison in August 2023. Fungicide program efficacy was determined based on disease incidence and severity. Yield was measured by weighing all clusters from each plot. Berry chemistry (total soluble solids, pH, and titratable acidity) was assessed following standard laboratory protocols. Biofungicide active ingredient and mode of action significantly affected program efficacy, while the interval of application did not. All programs integrating biofungicides with synthetics had efficacy comparable to the grower standard which, with the exception of one biofungicide stand-alone program, resulted in significantly higher powdery mildew and Botrytis bunch rot disease control than biofungicide stand-alone programs. Yields were also significantly greater in these programs. This suggested that when designing a program with biofungicides in this AVA, integration with synthetics can significantly improve the efficacy of the programs. Berry chemistry was affected significantly by the fungicide program, but results did not necessarily correlate with their efficacy.

Funding Support: CDFA-Specialty Crop Black Grant Program and CSU ARI

Sam Dudley | Isaac K. Uyehara | Andrew McElrone | Megan K. Bartlett

Characterizing Root System Architecture Traits for Drought Tolerance in Grapevine Rootstocks

Sam Dudley,* Isaac K. Uyehara, Andrew McElrone, and Megan K. Bartlett
*University of California, Davis, 750 Anderson Rd., Davis, CA, 95616 (sdudley@ucdavis.edu)

To reduce the effects of climate change on viticulture, breeding more drought-tolerant rootstocks is a promising, but difficult, strategy due to limited information on traits and genes of interest. Our goal is to use an F1 population produced from a drought-tolerant and a drought-sensitive rootstock (110 Richter × 101-14 MGT) to identify molecular markers for root system architecture (RSA) traits in grapevine. Neutron radiography is an imaging technique that can non-destructively visualize entire small root systems. We subjected plants to two-week dry-down and rewatering treatments and used neutron radiography and new semi-automated root classification software to measure RSA. Here, we present preliminary results for a subset of 45 genotypes. We will complete measurements across the entire population and use genotyping by sequencing (GBS) to link RSA traits to molecular markers by next summer.

The 45 genotypes varied significantly (p < 0.001) in nearly all RSA traits, including total root length, mean root angle, aspect (total horizontal/vertical extent), root growth rate, and change in depth during drought. Roots were significantly steeper rooted and thicker in 110 Richter than 101-14 MGT, suggesting these are especially important traits for drought tolerance. Across genotypes, a more vertical aspect was correlated with a steeper root angle (r² = 0.47) and thicker mean root diameter (r² = 0.09), but independent of root system size and fibrosity (root system length/# of tips) (p > 0.05). Altogether, these findings suggest that this population is well-suited to identify genetic associations with RSA, and that selecting for a more vertical aspect, steeper root angles, and thicker roots could enhance drought tolerance in grape rootstocks, though more work is needed to evaluate how these phenotypes perform under field conditions. Genetic associations are pending current experimentation results.

Funding Support: California Department of Food and Agriculture

Luis Ortiz, Luca Pallotti | Eve Laroche-Pinel | William Whalen | Luca Brillante

Enhancing Vine Resilience and Delaying Ripening: Novel Late-Season Practices for Grape Production in Central California

Luis Ortiz, Luca Pallotti, Eve Laroche-Pinel, William Whalen, and Luca Brillante*
*Department of Viticulture and Enology, California State University Fresno, 
2360 E Barstow Ave, Fresno, CA, 93740 (lucabrillante@csufresno.edu)

Global warming is significantly compromising grape production in regions like central California. Late-season practices aimed at reducing the efficiency of the photosynthetic apparatus might be the solution to improve vine resilience and delay ripening. In this trial, an untreated control © was compared with applications of pinolene (P) and diatomaceous earth (D). A fourth treatment involved shoot twisting (T), seeking to achieve the benefits of traditional topping by breaking xylem tissue without overexposing clusters. Leaf area, light interception, midday stem water potential, and gas exchange were measured over the 2023 season. Berry ripening was followed and grape production at harvest was evaluated. Twisting determined the desiccation of the upper portion of the shoot, reducing leaf surface while maintaining a low level of irradiance in the fruiting zone. Stem water potential results showed that D, and especially T, partly alleviated stress conditions, while P led to a worsened vine water status. D had the most pronounced effect on gas exchange, especially transpiration and stomatal conductance, thereby leading to higher water use efficiency trend in the treated vines. D and T fruit exhibited greater berry weights during the first half of the season, likely due to the improved water status, while P berries had reduced weight. All applied treatments significantly affected berry ripening, resulting in increased titratable acidity and lower must pH, without compromising crop yield at harvest.

This trial highlights that innovating traditional, easily mechanizable practices such as topping, and introducing new products like diatomaceous earth can be effective techniques to mitigate summer heat stress and delay berry ripening, particularly in hot, dry regions such as CA’s Central Valley.

Funding Support: N/A