A large number of agronomic and horticultural crops are susceptible to injury and yield loss from drift-level exposures to synthetic auxin herbicides. A new generation of genetically modified crops including cotton (Gossypium hirsutum), field corn (Zea mays), soybean (Glycine max), and canola (Brassica napus) with resistance to dicamba and 2,4-D herbicides has been developed to address the problem of glyphosate-resistant weeds. In the few years since their commercial introduction, these technologies have been rapidly adopted. The objective of this study was to determine the potential effects of simulated, single drift events of 2,4-D and dicamba on pecan (Carya illinoinensis) trees. 2,4-D amine [3.8 lb/gal acid equivalent (a.e.)] or dicamba-Diglycolamine salt (4.0 lb/gal a.e.) were applied in 1.0%, 0.1%, and 0.01% by volume spray solutions to pecan trees in June 2013. In 2016 and 2017, 2,4-D choline (3.8 lb/gal a.e.) or dicamba-N,N-Bis-(3-aminopropyl) methylamine (5.0 lb/gal a.e.) were applied in 1.0%, 0.1%, and 0.01% by volume spray solutions to pecan trees in May. These results suggest that serious injury can occur to pecan trees receiving a drift application of 1.0% by volume dicamba or 2,4-D. This injury includes deformed foliage, dead foliage, dead limbs, and/or branches, and arrested nut development. There were no major differences in the response of pecan to either dicamba or 2,4-D at similar rates in this study. Pecan damage resulting from off-target movement of 2,4-D and dicamba at rates ≥1% by volume has the potential to cause significant injury. Yield was not negatively affected by any of the treatments, suggesting that pecan trees can compensate for the observed injury to some extent. The effect of treatments on percent kernel was variable.
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M. Lenny Wells, Eric P. Prostko and O. Wendell Carter
Jen A. Sembera, Tina M. Waliczek and Erica J. Meier
Wild taro (Colocasia esculenta) is identified as an invasive species in freshwater regions throughout the southeastern United States as well as Puerto Rico, Jamaica, and India, and thrives in freshwater swamps, streambanks, and riparian areas with rocky crevices that provide strong footholds. Management methods for the plant include using herbicides, mechanical cutting, manual removal, or a combination of methods with disposal into landfills. The purpose of this study was to evaluate the potential to manage wild taro waste using composting and to test the quality of the resulting compost. This study used ≈12 yard3 of wild taro mixed with food waste and regionally harvested wood chips to create ≈6 yard3 of cured compost. Oven propagule mortality tests determined wild taro propagules exposed to temperatures between 45 and 52 °C for a minimum of 3 days were killed. These temperatures were achieved during the active phase of the composting process. The final compost products created were of equal or higher quality to current compost standards. Therefore, this study determined composting and waste management industries can accept and incorporate wild taro as a feedstock to create a desirable compost product for application in the horticulture and agriculture fields rather than managing the species with herbicides and/or other disposal methods.
Julie H. Campbell and Benjamin L. Campbell
A survey of Connecticut consumers was used to investigate perceptions of various green industry retailers. Consumer perceptions of independent garden centers (IGC), home improvement centers (HIC), and mass merchandisers (MM) business practices and their perceived value were assessed. Analysis of variance and ordinary least squares regression models were used to analyze the data. Results indicated that customer service, knowledgeable staff, and high-quality plants are important factors when consumers are deciding where to shop. IGCs were ranked highest in perceived customer service, knowledgeable staff, and plant quality, followed by HICs. MMs were ranked lowest for the majority of measured business practices, with the most notable exception being price. Additionally, IGCs, HICs, and MMs are perceived differently across age cohorts.
S. Kaan Kurtural, Andrew E. Beebe, Johann Martínez-Lüscher, Shijian Zhuang, Karl T. Lund, Glenn McGourty and Larry J. Bettiga
A field study was conducted for three consecutive seasons in the hot climate of central California to assess the performance of ‘Merlot’ grapevine (Vitis vinifera) grafted onto ‘Freedom’ [Fresno 1613-59 × Dog Ridge 5 (27% V. vinifera hybrid)] during training system conversion to facilitate mechanization. The traditional head-trained and cane-pruned (CP) system was either retained or converted either to a bilateral cordon-trained, spur-pruned California sprawl training system (HP), or to a bilateral cordon-trained, mechanically box-pruned single high-wire sprawling system (SHMP). After the conversion, SHMP sustained greater yield with more clusters per vine and smaller berries without affecting the canopy microclimate. This was due to a higher number of nodes retained after dormant pruning. The SHMP canopies, compared with CP and HP; filled allotted canopy space earlier based on photosynthetically active radiation (PAR) transmitted through the canopies, populating the space allotted per vine, favoring higher production efficiency. There were no adverse effects of training systems on berry composition or flavonoid concentration, during or after conversion to mechanical management. However, experimental year effect was obvious on anthocyanin composition of ‘Merlot’ berries, increasing trihydroxylated (i.e., delphinidin-based) anthocyanins in the latter years of the experiment. Our results also provided evidence that earlier canopy growth coupled with sufficient reproductive compensating responses allowed for increased yields while reaching commercial maturity without a decline in anthocyanin content with the SHMP. Converting CP to SHMP reduced labor operations costs by 90%. Furthermore, the SHMP had greater gross revenue and resulted in greater net income per acre even when the conversion year was taken into account. Therefore, SHMP is recommended for growers within the hot climate of the central San Joaquin Valley as a means to maintain productivity of vineyards while not sacrificing berry composition at the farm gate.
Abby ShalekBriski, B. Wade Brorsen, Jon T. Biermacher, Charles T. Rohla and Will Chaney
Although irrigation is a common practice in pecan (Carya illinoinensis) orchards, the effects of different methods of irrigation on young tree growth, nut quality, and nutrient uptake have not been estimated. Five irrigation systems and one nonirrigated control system were established. Tree performance was characterized by change in trunk diameter, weight per nut, average kernel percentage, and total trunk diameter growth. Nutrient uptake was determined by foliar levels. The five irrigation systems were a microsprinkler with a 35-ft diameter, a microsprinkler with a 70-ft diameter, two subsurface driplines irrigating for 2 days/week alternating between water for 2 hours and no water for 2 hours, two subsurface driplines irrigating 1 day/week for 20 hours continuously (LI2), and four subsurface driplines irrigating for 10 hours continuously for 1 day/week (LI4). Irrigation systems affected foliar levels of potassium (K), boron (B), and manganese (Mn) levels. Irrigation system did not affect change in trunk diameter or kernel percentage. A spatial Durbin error model was estimated to use trunk diameter estimates from all trees in the orchard. This model found the trunk diameters of nonirrigated and LI4 system trees to be significantly less than those trees that were irrigated by the LI2 system. When observations were pooled over all years, LI4 trees had individual pecan nut weights that were significantly less than all other systems.
Yu-Wei Liu and Chen-Kang Huang
Hydroponic systems in plant factories can be categorized into recirculating or noncirculating systems. In this study, the effects of various commercially available circulation pumps, including a centrifugal magnetic drive pump, a regenerative self-priming pump, and a submersible pump, were experimentally explored. In addition, the effects of an ultraviolet sterilization system on the ion concentrations in nutrient solutions were examined. The concentrations of sodium, potassium, magnesium, calcium, nitrate, sulfate, and ferric (Fe3+) ions in the nutrient solution were measured. For all three types of pumps, the results indicated that there was no significant effect on the concentrations of ions in the nutrient solution. However, the concentration of Fe3+ ions decreased significantly after the nutrient solution was treated by a ultraviolet sterilization system for 48 hours. In addition, the effects of the three types of pumps on the growth of butterhead lettuce (Lactuca sativa) were examined. The temperature records during the pump circulation tests showed that the nutrient solution temperature of the regenerative self-priming pump increased by 15.5 °C (from 20.5 to 36 °C), which caused yellow seedling, scorching on the leaves, and browning of the roots. The ion concentration in the nutrient solutions and total fresh weight of butterhead lettuce did not show any noticeable difference between the centrifugal magnetic drive pump and the submersible pump. In this paper, we clarify the cause of the decreasing iron concentration and provide a guideline for selecting the pump for circulating hydroponic systems in plant factories.
Timothy Coolong, Andre Luiz Biscaia Ribeiro da Silva and Justin Shealey
High-value vegetable crops such as bell pepper (Capsicum annuum) are heavily fertilized by growers who seek to maximize yields. Field experiments were conducted in Spring 2016 and 2017 evaluating two liquid fertilizers with and without calcium (Ca), applied at three nitrogen (N) and potassium (K) levels in two varieties of bell pepper to determine whether current fertilizer recommendations were adequate and whether fertilizer source impacted fruit yield and quality. Plants were grown using plastic mulch and drip irrigation following standard production practices for the region. Two liquid fertilizer programs [7N–0P–5.8 (7–0–7) and 4N–0P–6.6K/9N–0P–0K–11Ca (4–0–8/CN9)] were applied twice weekly at three N rates (175, 200, and 225 lb/acre N). Yield, cull rate, and foliar nutrient concentrations were measured. In 2016, total marketable yields were greatest [910 boxes/acre (28 lb/box)] and blossom end rot (BER) incidence (14.4%) lowest in plants grown with the supplemental Ca (4–0–8/C9 fertilizer) at 175 lb/acre N. Cull rates increased in plants grown without supplemental Ca during the season (7–0–7 fertilizer), with BER incidence ranging from 22.9% to 27.2%. Yields ranged from 590 to 740 boxes/acre in plants grown without supplemental Ca in 2016. In 2017, yields ranged from 530 to 790 boxes/acre in plants grown with supplemental Ca at 200 and 175 lb/acre N, respectively. Culls due to BER were lower in 2017 than in 2016. In 2016, BER incidence was greater in ‘PSO9979325’ compared with ‘Antebellum’, despite no differences in total yield. Foliar nutrient levels were largely unaffected by fertilizer program; however, foliar N and K concentrations increased with the rate of N and K fertilization. The results of this study suggest that using liquid fertilizer program containing some Ca may benefit bell pepper growers in some, but not all, growing seasons.
Abdullah Ibrahim, Hesham Abdel-Razzak, Mahmoud Wahb-Allah, Mekhled Alenazi, Abdullah Alsadon and Yaser Hassan Dewir
The present study reports on the effect of humic and salicylic acids on the growth, yield, and fruit quality of three red sweet pepper (Capsicum annuum) cultivars: Barbero, Ferrari, and Imperio. The plants were grown in a greenhouse and the leaves were treated with humic or salicylic acids at 0, 0.5, 1.0, and 1.5 g·L−1 at 20, 40, and 60 days after transplanting. Foliar application of humic or salicylic acids significantly increased vegetative growth, fruit yield, and quality of the three cultivars as compared with the control plants. However, salicylic acid treatment proved more effective than humic acid treatment. Red sweet pepper plants of all three cultivars sprayed with 1.5 g·L−1 salicylic acid showed the greatest vegetative growth; fruit yield components, such as fruit number, diameter, and fresh and dry weights; and fruit quality traits, such as vitamin C content, total soluble solid content, titratable acidity, and total sugar content, than the plants in all other treatments. There were significant differences (P ≤ 0.05) among cultivars in response to humic and salicylic acid foliar application; ‘Ferrari’ showed significantly higher yield and productivity than ‘Barbero’ or ‘Imperio’. ‘Ferrari’ plants sprayed with 1.5 g·L−1 salicylic acid showed the highest fruit weight (202.41 g) and flesh thickness (68 mm), both of which are preferred by consumers, and therefore, have increased market value. This treatment also increased total yield by 27.7% (16.03 t·ha−1), 15.9% (12.38 t·ha−1), and 17.9% (11.88 t·ha−1) in ‘Barbero’, ‘Ferrari’, and ‘Imperio’, respectively. Therefore, salicylic acid foliar application is recommended for enhancing fruit yield and quality of greenhouse-grown red sweet pepper.
Haijun Zhu and Eric T. Stafne
Paclobutrazol (PBZ) was applied to 6-year-old pecan (Carya illinoinensis) trees as a basal trunk drench (0, 30, 90, and 150 mg·cm−2 trunk cross-sectional area) in Dec. 2012. Terminal shoot growth was retarded for 1 year after a single application of PBZ. The total number of current season shoots showed a significant increase with 30- and 90-mg·cm−2 PBZ treatments. After PBZ application at 30, 60, and 90 mg·cm−2, the percentage of very short shoots (<5 cm) was 32.3%, 36.3%, and 32.3%, respectively, compared with 22.4% on control trees; the percentage of short shoots (5–15 cm) increased to 36.0%, 38.1%, and 43.5%, respectively. The percent of long shoots (>30 cm) was decreased to 7.4%, 5.1%, and 7.6%, respectively, after PBZ application, compared with 18.7% with control. Shoots varying from 5 to 30 cm in length accounted for at least 63.3% of all pistillate inflorescences the following spring.
Le Luo, Yichi Zhang, Yingnan Wang, Tangren Cheng, Huitang Pan, Jia Wang and Qixiang Zhang
Gesnariad (Primulina yungfuensis) is a popular houseplant species, native to southwest China. However, stunting frequently occurs as a result of limited knowledge about the growth requirements of this plant. Understanding water and fertilizer requirements of gesnariad are important for effective large-scale greenhouse cultivation. Using a response surface methodology (RSM) based on a rotatable central composite design (RCCD; half implementation), a pot experiment was performed in a natural-light greenhouse from June to Sept. 2014. The study assessed the interaction between irrigation volume (W) and nitrogen (N), phosphorus (P), and potassium (K) fertilizer rates on plant height, crown diameter, number of leaves, single leaf area, and fresh weight. Results showed that W had a significant positive effect on plant height, crown diameter, single leaf area, and fresh weight. Furthermore, P fertilization resulted in increased leaf number. Combined P and K fertilization reduced individual leaf area, whereas combined N and P fertilization reduced fresh weight. By analyzing the multiobjective decision-making model, we found that a combination of 100.2 mL water, 3.6 mmol·L−1 N, 0.10 mmol·L−1 P, and 1.2 mmol·L−1 K could be used to achieve optimum growth of gesnariad.