Juan Carlos Díaz-Pérez

Silverleaf whitefly ( Bemisia tabaci ), silverleaf disorder (SLD), and whitefly-transmitted viruses (WTVs) are major constraints to cucurbit production in the southeastern United States. Two field trials were conducted in Tifton, Georgia, U.S.A., during the fall of 2023 and 2024 to evaluate yellow squash and zucchini ( Cucurbita pepo L.) cultivars for tolerance to SLD and WTVs. In one experiment, 10 yellow squash cultivars (8 straight neck: ‘Cougar’, ‘Lioness’, ‘Multipik’, ‘Lazor’, ‘Grand Prize’, ‘Gold Prize’, ‘Enterprise’, and ‘Fortune’; and 2 semicrook neck: ‘Gentry’ and ‘Gold Star’) were evaluated. In another experiment, 10 zucchini cultivars: 3 spineless (‘Spineless Perfection’, ‘Spineless King’, and ‘Spineless Supreme’), 2 gray types (‘Hurakan’ and ‘Rocio’), and 5 green types (‘MGO477’, ‘Everglade’, ‘Cardea’, ‘Fortress’, and ‘Renegade’) were evaluated. Gold Star and Spineless Perfection served as susceptible controls. In yellow squash, Lioness and Cougar displayed the lowest SLD progression. Area under symptom progress curve (AUSPC) values for SLD were 203 in 2023 and 202 in 2024 for Lioness and 446 in 2023 and 490 in 2024 for Cougar. Virus incidence was also lowest in Lioness (area under disease progress curve [AUDPC] values of 315 in 2023 and 403 in 2024) and Cougar (AUDPC values of 548 in 2023 and 516 in 2024). Aligned rank-transformed (ART) values for virus severity were smallest in Lioness (7), followed by Enterprise and Grand Prize (27) and Cougar (31). Cougar and Lioness cultivars produced the highest marketable yields (25,986 and 24,565 kg ha ⁻¹ , respectively, in 2023). In zucchini, Rocio and Hurakan had the lowest AUSPC values (204 in 2023 and 197 in 2024 for Rocio and 497 in 2023 and 427 in 2024 for Hurakan). Rocio, Hurakan, and Renegade recorded the lowest AUDPC values and virus severity (ART = 13). Marketable yields were highest in Renegade (40,421 kg ha ⁻¹ ), followed by Hurakan and Rocio. Across crops and years, cucurbit chlorotic yellows virus predominated over cucurbit yellow stunting disorder virus and cucurbit leaf crumple virus. Overall, Lioness, Cougar, Renegade, Hurakan, and Rocio demonstrated superior performance with tolerance to SLD and WTVs while maintaining high yield.

Biochar and poultry litter have been proposed as soil amendments to improve soil health in coarse-textured agricultural soils, yet their field performance under southeastern U.S. conditions remains inconclusive. This two-year field study evaluated five biochar application rates (0–44.8 Mg ha⁻¹) combined with inorganic fertilizer or poultry litter on selected soil health indicators in a sandy loam Ultisol under sweet corn production in the Georgia Coastal Plain. Treatments were arranged in a randomized complete block design with four replications and analyzed using linear mixed-effects models. Biochar application did not significantly affect aggregate stability, pH, cation exchange capacity, soluble salts, organic matter, active carbon, or estimated nitrogen mineralization, with only a marginal three-way interaction observed for microbial respiration. Poultry litter significantly increased microbial respiration relative to inorganic fertilizer, whereas responses for the remaining soil health indicators were broadly similar between fertilizer sources. Year was the dominant source of variation, with extreme rainfall in 2024 reducing aggregate stability, soluble salts, microbial respiration, and nitrogen mineralization while increasing organic matter and active carbon. These findings indicate that short-term soil health responses were driven primarily by environmental conditions rather than management practices. Under the conditions of this study, either fertilizer source can be used successfully, whereas longer-term studies are needed to determine whether biochar aging enhances soil function in sandy loam Ultisols.

Importance of the work: Research on habanero (Capsicum chinense Jacq.) chili production and physiology remain limited, despite their economic and culinary relevance. Objectives: To assess the effects of shade levels on the plant growth, fruit yield, and chemical composition of habanero. Materials and Methods: A two-season field experiment was conducted using five shade levels [0% (unshaded), 30%, 47%, 63%, 80%] and two cultivars (‘Kukulkan’ and ‘Kabal’). The experiment was conducted using a randomized complete block design with 4 replications and 10 treatments, comprising 5 shade levels and 2 cultivars. Response variables were environmental factors, plant height and stem diameter, leaf pigment content, fruit yield, postharvest water loss and fruit soluble solids, total phenolics, flavonoids, antioxidant capacity, and capsaicin concentration. Results: Shade-grown plants were taller and had thinner stems relative to unshaded plants. Shading decreased root-zone and canopy temperatures, lowered evaporative demand and reduced plant water use. Total and marketable yields under 30% and 47% shade were comparable to those under unshaded conditions; however, yields declined significantly at 63% and 80% shade levels. While the number of fruits decreased with increasing shade, the individual fruit weight increased. Kukulkan consistently produced higher total and marketable yields than Kabal. Shading reduced fruit soluble solids, total phenols and antioxidant capacity; however, it did not affect capsaicinoid or carotenoid contents, the incidence of fruit sunscald or blossom-end rot or the postharvest rate of fruit water loss. Main finding: Shading did not increase fruit yields compared to unshaded conditions. However, moderate shading (30% and 47%) did increase individual fruit weight and reduce crop water use. Therefore, moderate shading may be a viable strategy to mitigate environmental challenges without compromising habanero fruit yield or quality.

The pomegranate cultivar Barski slatki, the most widely cultivated on the Eastern Adriatic coast, was evaluated over one growing season across four growing areas to assess its pomological and chemical properties and antioxidant activity. Results showed that location significantly influenced fruit weight, volume, number of arils per fruit, and both total and individual aril weight, with the Kaštela (CRO) site producing the largest fruits and highest aril yields. Climatic factors, such as precipitation during bud differentiation, flowering, and early fruit development, were found to impact fruit set, aril number, and fruit size. Aril and juice yields, however, remained relatively stable across sites. Notable differences were observed in total soluble solids, titratable acidity, pH, total phenolic content, and anthocyanin profiles. Location with higher rainfall occurring during fruit growth favored enhanced phenolic accumulation. Although total anthocyanin content remained consistent among locations, significant variation occurred in aril coloration and composition of individual anthocyanins. In conclusion, microclimatic factors, particularly rainfall distribution, temperature, and altitude, play a decisive role in shaping the physical, chemical, and visual attributes of ‘Barski slatki’. Despite being cultivated under similar Mediterranean conditions, the observed differences across sites highlight the strong adaptability of this cultivar to diverse agroecological environments, while maintaining stable quality.

Colored shade nets have gained attention due to their ability to reduce light intensity and alter the light spectrum, thereby influencing vegetable crop quality and yield. However, limited research has examined their effects on jalapeño pepper (Capsicum annuum L.) growth and yield. This study evaluated the impact of four nets—black, red, silver, and white (40% shade factor)—compared to an unshaded control. The red net altered light quality by increasing the proportion of red and far-red wavelengths, while the other nets reduced light intensity without spectral modification. Although differences in mean air temperature were minimal between shaded and unshaded conditions, root zone temperatures were consistently lower under shade nets. Shade treatments significantly increased plant height, stem diameter, and leaf chlorophyll content relative to the unshaded control. The highest rates of leaf transpiration and stomatal conductance were recorded under unshaded and white net conditions. Net photosynthesis, electron transport rate, intercellular CO₂ concentration, or photosynthetic water use efficiency were similar among net treatments. Marketable and total yields did not differ significantly among net treatments in either year; however, in 2021, they were positively associated with light intensity. In conclusion, while colored shade nets promoted vegetative growth, they did not enhance fruit yield relative to unshaded conditions in jalapeño pepper.

Calcium (Ca²⁺) is a macronutrient essential for the growth, development, yield, and quality of vegetables and fruits. It performs structural, enzymatic, and signaling functions in plants. This review examines Ca²⁺ translocation from soil to the fruit via the plant xylem network, emphasizing the importance of Ca²⁺ compartmentalization within fruit cell organelles in the development of calcium deficiency disorders such as blossom-end rot (BER). The underlying causes of BER and potential control measures are also discussed. Soil-available Ca²⁺, transported by water flow, enters the root apoplast through membrane channels and moves toward the xylem via apoplastic or symplastic routes. The transpiration force and the growth of organs determine the movement of Ca²⁺-containing xylem sap to aerial plant parts, including fruits. At the fruit level, the final step of Ca²⁺ regulation is intracellular partitioning among organelles and cellular compartments. This distribution ultimately determines the fruit’s susceptibility to Ca²⁺-deficiency disorders such as BER. Excessive sequestration of Ca²⁺ into organelles such as vacuoles may deplete cytosolic and apoplastic Ca²⁺ pools, compromising membrane integrity and leading to BER, even when overall Ca²⁺ levels are adequate at the blossom end. Effective BER management requires cultural and physiological practices that promote Ca²⁺ uptake, translocation to the fruit, and appropriate intracellular distribution. Additionally, the use of BER-resistant and Ca²⁺-efficient cultivars can help mitigate this disorder. Therefore, a comprehensive understanding of Ca²⁺ dynamics in plants is critical for managing BER, minimizing production loss and environmental impacts, and maximizing overall crop productivity.

Calcium (Ca2+) is a macro-mineral essential for the growth, development, yield, and quality of vegetables and fruits. It performs structural, enzymatic, and signaling functions in plants. This review outlines Ca2+ translocation from soil to fruit via the plant xylem network, emphasizing the importance of Ca2+ compartmentalization within fruit cell organelles in developing the Ca2+-deficiency disorder, blossom-end rot (BER). The causes and possible control measures of BER are also discussed. Soil available Ca2+ enters the root apoplast with the water flow and moves towards the xylem via apoplastic or symplastic routes. The transpiration force and growth of organs determine the movement of Ca2+-containing xylem sap to aerial plant parts, including fruits. The final step of fruit-Ca2+ regulation is the partitioning among cellular compartments, which determines susceptibility to Ca2+-deficiency disorders such as BER. Depleting cytosolic and apoplastic Ca2+ due to excessive deposition in organelles such as the vacuole may lead to disintegration of the plasma membrane, resulting in BER, even at high Ca2+ availability at the blossom end of the fruit. BER management requires cultural and physiological practices that ensure Ca2+ translocation to the fruit and proper Ca2+ compartmentalization. The use of BER-resistant and Ca2+-efficient cultivars may also help in BER management. Therefore, a comprehensive understanding of Ca2+ dynamics in plants is crucial for managing BER, reducing production costs, minimizing environmental impact, and enhancing crop productivity.

Viruses are a major pathogen challenging the sustainable production of cucurbits worldwide. Pumpkin and winter squash showed severe virus-like symptoms during the fall of 2022 and 2023 in Georgia, USA. Symptomatic leaves were collected from the field and processed for small RNA sequencing for virus identification using high-throughput sequencing (HTS). HTS analysis revealed the presence of two aphid-transmitted viruses (ATVs), zucchini yellow mosaic virus (ZYMV) and papaya ringspot virus (PRSV), along with three whitefly-transmitted viruses, cucurbit chlorotic yellows virus, cucurbit yellow stunting disorder virus, and cucurbit leaf crumple virus. The results of our study suggest a significant shift in ATV’s abundance in these two crops between 2022 and 2023. According to the qPCR data in the fall of 2022, pumpkins experience an incidence of 56.25% and 31.25% of PRSV and ZYMV, respectively. Similarly, winter squash shows an incidence of 50% and 32.14% of PRSV and ZYMV, respectively. Mixed infection of both viruses was also observed in these two crops. In 2023, we observed a predominance of ZYMV in pumpkin and winter squash (61.25% and 42.50%, respectively). However, PRSV was not detected in pumpkins, and it was detected at a negligible level (0.62%) in winter squash using qPCR. Phylogenetic analysis of ZYMV-encoded coat protein (CP) and helper component-protease (HC-Pro) from Georgia suggests a close relationship with the European isolates. Conversely, PRSV-encoded CP and NIa-VPg show a more diverse evolutionary history. Overall, this research will provide valuable insights into the dynamics of ZYMV and PRSV in pumpkin and winter squash crops within the southeastern United States.

Cucurbit leaf crumple virus (CuLCrV), cucurbit yellow stunting disorder virus (CYSDV), and cucurbit chlorotic yellows virus (CCYV) are the major whitefly-transmitted viruses (WTVs) that infect cucurbit crops as mixed infections in Southern Georgia. Symptoms of WTVs mixed infections include leaf curling, crumpling, yellowing, and plant stunting. During fall 2023, we compared five commercial hybrid cultivars of pumpkin for their resistance to WTVs in an open field under natural virus disease pressure at the University of Georgia, Tifton Campus. This study revealed no WTVs had complete resistance among cultivars but found differences in WTV symptom severity levels and marketable fruit yield.