Browse

Breadfruit marketing is limited by its rapid ripening and deterioration after harvest; therefore, improved postharvest practices may facilitate breadfruit marketing. This study examined the effect of harvest maturity and 1-methylcyclopropene (1-MCP) on the postharvest quality of ‘Ma’afala’ breadfruit (Artocarpus altilis). Breadfruit was harvested at 13, 15, and 17 weeks after flowering, and half of each harvest was treated with 1 μL⋅L⁻¹ of 1-MCP for 20 hours. During storage, the weight of the fruit, hand feeling, skin color, respiration rate, and ethylene production rate were evaluated every other day until the fruit deteriorated. Compared with untreated fruit, 1-MCP treatment delayed the climacteric respiratory peak by 6 days (65% delay), delayed complete softening by 7 days (63% delay), and increased uniformity in the number of days to the climacteric respiratory peak and complete softening. Skin discoloration was delayed during the earliest harvest period by 5 days (108% delay). Picking breadfruit at early harvest maturity may be useful for preventing discoloration, and 1-MCP may be useful for preventing softening.

Bermudagrass (Cynodon sp.) is one of the most commonly used warm-season turfgrasses in the southern areas and transition zone of the United States. Due to the increasing demand for water resources and periodic drought, it is important to improve the drought resistance of bermudagrass for water savings and persistence under drought stress. This study was conducted to determine whether experimental bermudagrass genotypes have improved drought resistance compared with the standard cultivars Tifway and Riley’s Super Sport (Celebration^®) at Stillwater, OK. The trials were designed as randomized complete blocks with four replications in Expt. I and three replications in Expt. II. In each experiment, genotypes were subjected to progressive acute drought conditions using polyethylene waterproof tarps to exclude precipitation over a period of at least 72 d. Bermudagrass entries were evaluated for turfgrass quality, leaf firing, normalized difference vegetation index, and live green cover at least once each week during the dry-down. Substantial drought response variations were found in this study, and all parameters were positively and highly correlated. A turf performance index (TPI) was assembled based on the number of times an entry ranked in the top statistical group across all testing parameters on each date. ‘DT-1’ (TifTuf^®) and OSU1221 had the top TPI in both experiments. Most of bermudagrass experimental genotypes had equal or greater TPI than the standard Tifway, showing improved drought resistance through breeding effects. The identification of superior drought resistance experimental genotypes provided useful information to breeders on cultivar release.

Industrial insect rearing is expected to increase as a feedstock to meet growing global food demand. This will lead to greater production of insect excreta known as frass, a nutrient-dense organic material that has shown promise as a natural fertilizer source with potential environmental benefits. In this study, black soldier fly (Hermetia illucens) frass (BSFF) was compared with a synthetic fertilizer (SF) during production of containerized ornamentals grown under greenhouse conditions. Fertilizers were incorporated into a bark-based substrate at 0, 0.1, 0.2, or 0.3 kg⋅m^–3 nitrogen (N) planted with coleus (Plectranthus scutellarioides) plugs. Growth index, shoot dry weight, and leaf quality were assessed for a period of 6 weeks. In addition, coleus fertilized at 0.3 kg⋅m^–3 N and a control had leachate collected and analyzed weekly for volume, pH, electrical conductivity, and nutrient losses. Black soldier fly frass was found to produce marketable coleus plants at 0.3 kg⋅m^–3 N and reduce cumulative N leaching by 87% compared with coleus fertilized with SF at the same rate. Therefore, BSFF can be a suitable fertilizer source for coleus production without compromising growth and leaf quality while potentially decreasing nutrient leaching losses.

Surveys of blueberry [rabbiteye blueberry (Vaccinium virgatum) and southern highbush blueberry (Vaccinium corymbosum interspecific hybrids)] nurseries in the State of Georgia, USA, were conducted in 2007 and 2022 to determine the prevalence of and associations among propagation practices, especially related to disease management. As indicated by the reduction in surveyed nurseries in 2022 (7) compared with 2007 (18), the Georgia blueberry nursery industry has consolidated. However, cultural disease management practices have generally improved in these remaining nurseries. In 2007, in nurseries where cuttings were grown in containers, 77.8% reused containers and 66.7% did not sterilize them before use. The growing medium [pine (Pinus sp.) bark] was reused for subsequent production cycles in 29.4% of nurseries, although such reuse of media tended to be associated with production in beds as opposed to containers (P = 0.08). Nurseries used well water in 88.2% and pond water in 11.8% of cases. Cuttings were grown on benches (vs. the ground) in slightly fewer than half of the nurseries. In contrast, all nurseries surveyed in 2022 grew their cuttings in containers, used well water, and had increased bench use, albeit only slightly. Although all nurseries reused containers, only 28.5% did not sterilize containers before use, and only 14.3% of nurseries reported reusing media. Most nurseries surveyed in 2007 (83.3%) were on a routine, calendar-based fungicide program using a.i. targeted primarily against aboveground diseases (blights and leaf spots) and secondarily against soil-borne water molds (Phytophthora and Pythium species of the Oomycetes class). In contrast, 42.8% of those surveyed in 2022 were on a 2- to 3-week spray schedule, 42.8% used fungicides on an as-needed basis, and 14.4% were on a monthly schedule, indicating that fungicide scheduling varied dramatically among the remaining nurseries.

Growers have traditionally used mechanical pinching and other cultural practices to control height and encourage branching for full and uniform poinsettia (Euphorbia pulcherrima) plants. A total of six experiments were conducted over 5 years to evaluate the impact of chemically treating poinsettia on final height, branching, first color, visible bud formation, and anthesis. The first four experiments evaluated the potential of benzyladenine (BA) and gibberellins [GA₍₄₊₇₎] to increase height of treated poinsettia. Timing of the application was assessed during Expt. 1 using a combined concentration of 3 ppm BA and 3 ppm GA₍₄₊₇₎ applied at 5, 7, 9, or 11 weeks after pinching; some cultivars exhibited significantly more elongated inflorescences when treatment occurred 7 or 9 weeks after pinching. The application method and frequency was assessed during Expt. 2, and treatments were applied one or three times with either drench application at a concentration of 2 ppm or foliar application at a concentration of 5 ppm or untreated controls. All plants treated with three drench applications produced taller plants on average than when only applied once or when treated with a foliar application. Expt. 3 further assessed height gain and effects on flowering during late-season production with foliar applications of BA+GA_(4 + 7) applied 2 weeks after first color at a concentration of 2 ppm compared with untreated control plants. One cultivar, Mars Red, was observed to have a significant decrease in days to anthesis when treated (9 days) compared with untreated plants, but no cultivars exhibited a significant change in height resulting from treatment. Expt. 4 assessed both the application method (foliar and drench) and change in final environment when plants were either maintained in a greenhouse or relocated to a postharvest room before anthesis. Most cultivars experienced a significant height increase when treated with foliar application of BA+GA_(4 + 7) regardless of the final environment, but a significant delay in days to first color, visible bud, and anthesis was prevalent, and only one cultivar exhibited a treatment benefit from drench application with no significant delay in flowering or differences caused by changing environment. Expts. 5 and 6 were conducted over 2 growing years to evaluate the benefits of chemically pinching poinsettia using dikegulac sodium at a concentration of 800 ppm applied either once or twice (1 week apart) or 1600 ppm applied once to promote branching. The tallest plants were those treated one time at a concentration of 800 ppm showing lack of dominance in the apical meristem. The greatest number of shoots occurred when plants were treated with 800 ppm twice, whereas one application of 800 or 1600 ppm often, but not always, resulted in more shoots compared with mechanically pinched plants. Interestingly, the increased number of shoots from treated plants was often more than double the number compared with mechanical pinching, but those additional shoots failed to develop, which resulted in only one or two additional inflorescences. Production time was found to be a tradeoff because most dikegulac sodium-treated plants experienced an increased number of days to first color, visible bud, and/or anthesis. These results demonstrate that height control, whether to encourage stem elongation or halt apical dominance, is cultivar-specific, and that although both the method and concentration may be determined uniformly on some cultivars, the timing of application is crucial because of potential delays in floral development.

Recently, some commercial apple growers have been adopting hedging as an alternative or supplement to hand-pruning. With increasing labor costs across the United States, alternatives to hand-pruning and current training systems are being considered. One management strategy involves transitioning tall spindle trees to a narrow tree wall and simplifying labor-intensive activities of apple production, such as pruning, harvesting, and fruit thinning. The objective is to form the orchard system into a “fruiting wall” that makes fruit more visible and accessible, thus facilitating harvesting. Four management practices (tall spindle; narrow tree wall with manual pruning; narrow tree wall with dormant and summer hedging; and narrow tree wall with dormant hedging, summer hedging, and root pruning) were used to convert 12-year-old ‘Brak Fuji’ apple trees from the tall spindle training system to a narrow tree wall. Photosynthetically active radiation (PAR) and ultraviolet light levels within the canopies were improved by summer hedging, but they were still low for all treatments. Light within the canopy was improved most when root pruning was included. Specific leaf weight was not significantly impacted by hedging or root pruning. Detailed spur sampling showed that treatments had no effect on vegetative or reproductive growth on 2- to 3-year-old wood. Although dormant plus summer hedging alone did not affect shoot length, the combination of hedging and root pruning caused a significant reduction in terminal shoot length. Red fruit color was only improved with dormant hedging plus summer hedging plus root pruning. Compared with dormant plus summer hedging, dormant plus summer hedging plus root pruning improved fruit set and yield, but it reduced fruit size. Without root pruning, hedging had little effect on light, specific leaf weight, flower initiation, fruit set, and fruit quality. Conversion to narrow tree walls by manual pruning resulted in more poorly colored fruit and less highly colored fruit compared with maintaining the trees as tall spindles with manual pruning.

Florida has a long association with citrus (Citrus sp.) production. However, the citrus industry in Florida has been devastated by Huanglongbing (HLB) or citrus greening disease (Candidatus Liberibacter asiaticus). HLB affects the citrus tree phloem and eventually causes tree death. Cover crops, or noncash crops, have traditionally been used in row crop production to improve soil organic matter, for nitrogen fixing, and for weed control. Citrus growers may benefit from adopting cover crops because healthier soils could improve yields and fruit quality of citrus trees. However, growers are uncertain about the costs and benefits associated with cover crop investments. The objective of our study was to analyze whether cover crops represent an economically feasible option for Florida citrus growers. We calculated the break-even prices for ‘Valencia’ and non-‘Valencia’ oranges (Citrus sinensis) in terms of price per box (equivalent to 90 lb of oranges in Florida) and price per pound solids per box (amount of soluble solids per box of oranges) by considering additional costs and short-term savings from using cover crops across various yield and quality scenarios based on the past 10 years of data. Considering the short-term savings from adopting cover crops, the per-acre cost of production increased by $107.3/acre or by 5.73% and constituted 5.42% of the total production cost during the first year of adoption. After the 2018–19 peak, the yield and quality for both ‘Valencia’ and non-‘Valencia’ oranges have decreased steadily. Adopting cover crops in the current yield–quality scenario will not be profitable for either ‘Valencia’ or non-‘Valencia’ oranges. However, for ‘Valencia’ oranges, at the median yield and quality levels of 193.5 boxes/acre and 6.08 lb solids/box, respectively, cover crop adoption would be profitable because the break-even price of $2.25/lb solids would be comparable to the market prices of the past 5 years.

Demand for butterfly milkweed (Asclepias tuberosa L.) has increased in recent years. However, seed production practices are not well-defined. We partnered with a wildflower seed producer to investigate the effects of weed barrier cloth, plot shading, mature follicle harvest timing, and dry–cold stratification on seed production and germination. Weed cloth had no impact on seed production. However, shading decreased the number of seeds produced by 1.2- to 9.6-fold. Seeds harvested in July and August showed 2.9- and 2.3-fold improvements in total germination and more uniform and rapid germination compared with September-collected seeds. Conversely, seeds exposed to dry–cold stratification displayed a 3.0-fold reduction in the germination rate compared with nonstratified seeds. Our results indicate that the production system significantly impacts seed production and quality of A. tuberosa. Seed producers can use weed barrier cloth to facilitate seed collection from shattering follicles and suppress weeds without a considerable loss of seed production. However, plants should not be grown under conditions of additional shade. Furthermore, high-quality A. tuberosa seeds can be collected earlier in the year, but they should not be subjected to dry–cold stratification.

Chinese cymbidiums are important flowering ornamental plants. Traditional propagation via seed or division cannot satisfy growers’ demand for commercialization of new cultivars, and in vitro propagation has a low micropropagation efficiency due to the browning of rhizomes. In this study, rhizomes of Cymbidium ‘14-16-13’ and ‘14-16-5’ were cultured on half-strength Murashige and Skoog (MS) medium supplemented with 6-benzyl aminopurine (BAP), NAA (α-napthaleneacetic acid), or BAP with NAA under either the dark or light. The degree of browning was read, and rhizome proliferation or sprouting (sprout numbers) was evaluated. Results showed that there was significant difference in browning grade of rhizomes between ‘14-16-13’ and ‘14-16-5’ regardless of dark and light culture. Dark culture induced rhizome proliferation but failed to induce sprouts. Light culture slightly elevated the degree of browning but induced sprouting. Among the growth regulators evaluated, BAP was more effective for sprout induction. As rhizome browning appeared to be inevitable in micropropagation of the cymbidiums, a compromise between browning and sprout production could be a realistic approach. Our study showed that rhizomes cultured on half-strength MS medium supplemented with 1.5 mg·L⁻¹ BAP were able to produce more than 16 sprouts per vessel even though browning occurred in the rhizomes. Thus, culturing rhizomes in this medium could be a practical solution for in vitro propagation of Chinese cymbidiums.