Pumpkins (Cucurbita sp.) grown in North Carolina are a nascent specialty crop that has only risen to a national production level in the past 10 years. There are only general cultural management guidelines for this region, resulting in variation in plant density and inefficient production. Production field studies of the cultivar Kratos were conducted to investigate the impact of plant density and row width on marketable yield and individual fruit size for large carving pumpkins. Plant densities of 2691, 3588, 5382, and 10,764 plants per hectare with row widths of 1.5 and 3.0 m were grown in 2020 and 2021 in North Carolina. Data regarding fruit size, fruit size variance, and yield per area were collected. Fruit size in terms of weight, length, and diameter increased as plant density decreased. There was no difference in fruit size variation between plant densities and row widths. The fruit number per hectare and fruit weight per hectare increased as plant density increased, with the highest production at 10,764 plants per hectare. For years combined, reducing the row width from 3.0 to 1.5 m increased the fruit weight and diameter, but not the length. Additionally, the 1.5-m row width produced more fruit weight per hectare than the 3.0-m row width for both years. Growers can optimize fruit weight per area and fruit number per area by using a density of 10,764 plants per hectare. Overall, using a row width distance that is more equidistant to the in-row spacing promotes higher fruit yield and larger fruit size.
Hot and humid conditions create challenges for tomato production under a controlled environment. Low tomato productivity is related to the lack of stress tolerance of existing cultivars and their ability to maximize fruit set and yield. The aim of this study was to evaluate the effectiveness of three management strategies, cultivar selection, grafting, and plant density, for the growth and production efficiency of organically grown hydroponic tomatoes under adverse environmental conditions in Qatar. The experiment used a split-split plot design with ‘Velocity F1’ and ‘Sigma F1’ as the main plot treatments and a factorial arrangement of grafting combinations and planting densities (3.5 and 5.5 plants/m2) as subplots. Tomato cultivar Velocity F1 grafted on Maxifort F1 resulted in greater vegetative growth and improved phenological attributes than nongrafted Velocity F1. Grafted ‘Velocity F1’ plants grown at 3.5 plants/m2 had an increase in leaf photosynthetic rates (18%), less transpiration loss (16%), and less electrolyte leakage (15%) while maintaining stomatal conductance and intercellular CO2 concentrations. At 9 weeks after transplanting, canopy growth was higher (24%) and flowering occurred earlier (3 days) with grafted ‘Velocity F1’ transplants than with nongrafted transplants. Higher fruit sets (20%), pollen viability (22%), and fewer flower drops (17%) were also observed for grafted ‘Velocity F1’ transplants than for nongrafted transplants. Marketable fruit yields were higher (26%) with grafted ‘Velocity F1’ grown at 3.5 plants/m2 than with nongrafted ‘Velocity F1’. Both grafted ‘Velocity F1’ and ‘Sigma F1’ fruits retained acceptable fruit color (L*, a*, b*, C*, °h), firmness, °Brix, titratable acidity, weight, and prolonged shelf life by 4 additional days than nongrafted ones. We conclude that grafted tomato ‘Velocity F1’ grown at a plant density of 3.5 plants/m2 was the best management strategy for enhancing seedlings quality, plant growth, and postharvest quality and alleviating abiotic stresses under this protected environment and hydroponic system.
Ornamental rhizoma peanut (Arachis glabrata Benth.; ORP) is a low-maintenance groundcover for use in urban and residential landscapes. Despite its availability since 2002, consumer insights on ORP have never been assessed. Online surveys are readily accepted by academic researchers as a valuable research tool. An online survey was distributed to 5820 Floridians with the objective to assess the use and perceptions of ORP by consumers. A total of 907 survey responses were received. Most respondents identified themselves as home gardeners (89%), white (93%), female (75%), and over age 65 (60%). Out of several turfgrass alternative benefits, respondents most valued reducing herbicide/pesticide and fertilizer/water usage and preventing weed establishment (χ2 = 204, df = 6, P < 0.001). The ORP selection purchased by respondents was predominately unknown. Most preferred ORP to flower heavily and frequently and maintain a canopy height below 20 cm in the landscape with infrequent mowing. Survey data show there is a potentially large consumer demand for ORP in Florida, but product availability, branding, and consumer access and engagement with information sources require additional focus in the coming years.
Mulching landscape beds is a common task for landscapers seeking to affect soil conditions and reduce weed pressure. This study investigated the effects of three pine (Pinus sp.) straw mulch depths (5, 10, and 15 cm) on soil moisture/temperature modulation during late winter/spring. No differences in soil volumetric water content were observed; however, increasing mulch depth to ≥10 cm decreased fluctuations in temperature. This research provides a better understanding of the effect of mulch depth and potential environmental benefits so that landscape contractors can determine cost-benefits of mulching applications.
The newly released “Plant This Not That: A Guide to Avoiding Invasive Plant Species in Florida” booklet emerges as a crucial tool in cultivating a comprehensive understanding of invasive species, facilitating informed decision-making in plant selection. Its unique focus on illustrating alternatives to invasive plants, coupled with its accessible format, can empower individuals to contribute to the preservation of Florida, USA, ecosystems. The booklet’s impact was displayed through an in-service training for 58 University of Florida/Institute of Food and Agricultural Sciences extension personnel. Following the in-service training, attendees demonstrated statistically significant improvements in their perceived knowledge of four key invasive species concepts. This study highlights the booklet and accompanying training’s potential as a valuable resource for mitigating the impacts of invasive plant species.
Allyl isothiocyanate (AITC) is a colorless aliphatic oil that naturally occurs in many plants of the cabbage and mustard family (Brassicaceae). It has antimicrobial activity and is used as pesticide for a variety of applications. However, AITC as a soil disinfectant has exhibited inconsistent weed and pathogen control, mainly because of its higher viscosity and low vapor pressure (5 mmHg at 25 °C). Steam, however, effectively controls soil-borne pathogens if soil temperatures of 65 °C or more are reached for a minimum duration of 30 minutes. We hypothesized that steam applications targeting lower temperatures, when combined with soil-injected AITC, will provide sufficient weed and pathogen control. We further hypothesized that the combination of AITC and steam will lead to higher strawberry yields compared with either of the components on their own. Two strawberry (Fragaria ×ananassa cv. Camarosa) trials were conducted during two consecutive seasons (2020–21 and 2021–22). The trials were conducted at the Central Crops Research Station in Clayton, NC, USA, and the Horticulture Research Station in Castle Hayne, NC, USA. Eight treatments and a nontreated control were established in a randomized complete block design (four replicates each). The treatments were Pic-Clor 60, AITC, AITC followed by 60 minutes of steam injection, AITC followed by 30 minutes of steam injection, AITC followed by 10 minutes of steam injection, 60 minutes of steam injection, 30 minutes of steam injection, and 10 minutes of steam injection. Soilborne pathogen control efficacy was assessed using wet Pythium sp. plating assays. Weed control was assessed through weed seed/tuber germination assays. Our results showed that combining ATIC with steam did not reduce weed or pathogen levels or improve yield when compared with AITC alone or Pic-Clor 60. Moreover, treatment comprising steam alone did not provide sufficient control. However, AITC alone controlled weeds and pathogens as effectively as Pic-Clor 60 during both years and both locations of the study. These results showed that AITC alone could be a potential alternative soil disinfectant for Eastern North Carolina strawberry production.
Armillaria root rot (ARR), caused by Armillaria species and Desarmillaria tabescens, is a severe disease that affects stone fruit trees in the United States. One strategy to mitigate the impact of this disease is to develop ARR-resistant rootstocks. However, current techniques to screen Prunus species for resistance to ARR are time-consuming, labor-intensive, and may not fully replicate field conditions. To address these limitations, we developed a new rapid in vitro screening assay, which uses roots of 2-year-old Prunus rootstock genotypes. We screened 12 Prunus genotypes against Armillaria mellea, Armillaria solidipes, and Desarmillaria tabescens in vitro. Freshly excavated root segments were placed next to or on top of fungal cultures. After 21 days, the circumferential percentage and horizontal length of the fungal colonization and the ability of the fungus to enter through root periderm were evaluated. The root tissue surrounding the infection was also evaluated to assess any response reactions against the ARR pathogens. Our results showed that inoculated root tissues displayed signs of fungal infection, and infection and host responses varied among the Prunus genotypes. Host responses similar to those observed in the field, such as compartmentalization of infected tissue with barrier zones, necrophylactic periderm formation, and callus formation on root surfaces, were observed and were more evident in less susceptible genotypes. In conclusion, our newly developed assay, which uses freshly excavated roots from 2-year-old rootstocks, can rapidly screen Prunus genotypes for resistance to ARR.
Cover crops are defined as crops grown primarily for agroecosystem improvement rather than for market or sale. The use of cover crops to decrease the negative effects of weeds and improve soil and ecosystem health is increasing, but unanticipated allelopathic responses to those cover crops by subsequent crops is sometimes a problem. Allelopathy is broadly defined as the biochemical interactions between all types of plants, including microorganisms. Because allelopathic effects include both inhibitory and stimulatory responses and may be species- and cultivar-specific, a method of rapidly screening donor and recipient crops for allelopathic interactions is needed. The objective of this research was to evaluate a growth chamber bioassay for rapidly screening spinach (Spinacia oleracea L.) cultivars for allelopathic interactions with an aqueous extract from fresh whole-plant tissue of sorghum-sudangrass [Sorghum bicolor (L.) Moench; SSG] cultivars. The bioassay exposed the seed of 10 spinach cultivars to the aqueous extract of three cultivars of SSG during the imbibition and germination processes and evaluated the consequent root and stem development. Compared with the control, the extract from all three SSG cultivars decreased the root length of all spinach cultivars. A subsequent field screen where spinach cultivars were planted into decomposing SSG residue resulted in a similar pattern of growth suppression. These results demonstrate that the growth chamber bioassay is suitable for predicting allelopathic interactions between cultivars of SSG and cultivars of spinach and can be used by growers for making cultivar selection decisions when spinach follows SSG in a cropping sequence. This rapid-screening growth chamber bioassay protocol eliminates many of the environmental and other challenges frequently associated with field trials and may be adaptable for predicting allelopathic interactions among other cover crops, weeds, and subsequent market crops.
Indoor vertical farms that grow lettuce commonly encounter tipburn, which is an environmental disorder caused by calcium (Ca) deficiency during the late head-forming stages of lettuce. Characterized by marginal leaf necrosis of young expanding leaves, tipburn reduces marketable yield because of the appearance of these necrotic lesions. Lowering the daily light integral (DLI) to slow the plant growth rate has been a widely practiced approach to avoid tipburn in lettuce, but it largely reduces the final yield. We assessed the effect of lowering the DLI only during the end of production, which is a critical time because it is when tipburn is typically observed. Lettuce plants of tipburn-sensitive cultivars Klee and Rex were grown under a tipburn-inducing condition in growth chambers. Sixteen days after transplanting, the DLI was varied to 100% (L100), 85% (L85), 70% (L70), or 55% (L55) of the original 17.4 mol⋅m−2⋅d−1 to grow the final 12 d. At harvest, tipburn severity was reduced by lowering the DLI, but the magnitude of reduction was cultivar-specific. For ‘Klee’, the lowest tipburn severity was found at L55 (8% ± 2.1% of leaves), but the severity was similar for all other DLI levels (33% ± 3.5% of leaves). For ‘Rex’, tipburn severity was highest in the control (L100; 14% ± 2.8% of leaves) but similar for all other DLI levels (2% ± 0.9% of leaves). Reducing the end-of-production DLI to 55% resulted in a linear decrease in yield by up to 22% and 26% for ‘Klee’ and ‘Rex’, respectively. When the increase in marketable yields and decrease in the electricity cost were considered, decreasing the end-of-production DLI yielded a profitable contribution only for ‘Klee’ (L55). For moderately tipburn-sensitive ‘Rex’, revenue losses attributable to the yield decrease were too large to justify this approach of end-of-production reduced DLI.