Seaside petunia (Calibrachoa parviflora) is a mat-forming plant species that was recently reported in fall-seeded onion (Allium cepa) in the southwestern United States. To initiate development of herbicide recommendations for seaside petunia in onion, we conducted a study to determine seaside petunia susceptibility to commonly used herbicides for broadleaf weed control after onion emergence. Our study included herbicides applied at below-label rates, which provided insights on seaside petunia responses to reductions in the amount of herbicide available for plant absorption. For herbicides with preemergence activity, our growth chamber study indicated that soil applications of flumioxazin or oxyfluorfen (0.06 and 0.25 lb/acre, respectively) prevented seaside petunia seedling emergence when applied at 0.125×, 0.25×, 0.5×, and 1.0× the labeled rates for onion. Labeled rate treatments of dimethenamid-P (0.84 lb/acre) and S-metolachlor (0.64 lb/acre) inhibited seedling emergence similar to labeled rate treatments of flumioxazin and oxyfluorfen; however, below-label rate treatments of dimethenamid-P and S-metolachlor resulted in diminished control of seaside petunia compared with the labeled rate treatments. Following labeled rate applications of dimethyl tetrachloroterephthalate [DCPA (6 lb/acre)] and pendimethalin (0.71 lb/acre), more than 50% of seaside petunia seedlings emerged compared with the nontreated control. For herbicides with postemergence activity on weeds, our greenhouse study indicated that bromoxynil at 0.37 lb/acre, flumioxazin at 0.06 lb/acre, and oxyfluorfen at 0.25 lb/acre equally reduced growth of seaside petunia plants that were small at the time of spraying (stem length, 1–2 cm). Postemergence control of seaside petunia with oxyfluorfen and flumioxazin decreased as plant size at spraying increased; however, bromoxynil effects on seaside petunia remained high as stem length at spraying increased from 5 to 12 cm. Based on the results of this study, we conclude that promising herbicide programs for seaside petunia in onion include oxyfluorfen or flumioxazin for preemergence control and bromoxynil for postemergence control. These herbicides, alone and in combination, should be evaluated for seaside petunia control and onion phytotoxicity in future field trials.
Brian J. Schutte, Abdur Rashid, Israel Marquez, Erik A. Lehnhoff, and Leslie L. Beck
Sarah E. Dixon, Jerri L. Henry, Dean S. Volenberg, and Reid J. Smeda
The increasing adoption of dicamba-tolerant soybean (Glycine max) increases the potential exposure of wine grape (Vitis sp.) to dicamba, to which off-target injury may occur via particle drift or vapor drift. In Missouri, at one site in 2017 and at two sites in 2018, research of production vineyards focused on the effects of dicamba on hybrid ‘Vidal blanc’ grapevines. During flowering and early fruit set, bearing grapevines were exposed to low rates of dicamba delivered as a spray solution of 81 or 161 ppm or by vapor from treated soil. Grapevines were highly sensitive to dicamba, and visible symptoms extended throughout the growing season. The severity of dicamba injury (leaf cupping and feathering) was similar at two of three site-years, with greater injury related to particle drift than to vapor drift of dicamba. Early-season injury resulted in dicamba impacting the total soluble solids (TSS) content of grape berries and grape yield. At harvest during two site-years, yield reductions of up to 45% were associated with dicamba exposure at flowering. Across all site-years, no significant effects of dicamba drift were observed in the TSS content of berries during veraison in August, as measured by refractometer. However, the final TSS content of berries at harvest in September was reduced by 12% from dicamba as particle drift. At a minimum detection level of 10 ng⋅mL−1, high-performance liquid chromatography mass spectrometry identified dicamba at levels up to 33 ng⋅mL−1 in grape must over all site-years. Unexpectedly, this was up to 125 d after grapevine exposure despite low levels of visible dicamba symptomology.
Rhuanito Soranz Ferrarezi and Tzu Wei Peng
Precision agriculture involves applying artificial intelligence, computers, sensors, and automation to improve crop field productivity while monitoring environmental conditions to conserve soil, water, and other natural resources focusing on agricultural sustainability. Despite many applications in agriculture, data monitoring and recording technologies have limited use due to the price. Low-cost open-source systems, like the ones available with the Internet of things (IoT) world, can potentially be developed as a universal-fit and cloud-connected technology for multiple applications. We designed and built a basic data collecting system using a commercial standalone embedded computer with Python programming language, serial data interface (SDI)-12/analog sensor adaptor, and digital sensors to monitor soil moisture and transmit the data remotely. SDI-12 is a standard communication protocol that transfers digital sensor measurements to a data recorder. We set up a pilot study that automatically collected and uploaded the data into the Internet to allow remote data transfer and access. The system performed reliably over 1 week with potting soil under field conditions without maintenance and successfully recorded data in real-time. The volumetric water content ranged from 0.03 to 0.23 m3·m−3, dielectric permittivity from 3.3 to 18.9 (unitless), EC from 0.0 to 0.3 dS·m−1, and soil temperature from 20.7 to 44.8 °C. All the data were successfully collected and uploaded to the cloud every 20 min, allowing users to remotely monitor the data using a free online application. However, heavy rainfall and high insolation could damage the system through excessive moisture or overheating, requiring a waterproof and heavy-duty protection case. The ThingSpeak channel allows customizing to suit a user’s specific requirements or adding more features for further development, such as automated irrigation, which can improve irrigation and fertilization efficiency by applying water and fertilizers at the right time based on sensor readings.
Lakshmy Gopinath, Dennis L. Martin, Justin Quetone Moss, Yanqi Wu, Shuhao Yu, and James R. Underwood
Suitable tensile strength is essential for sod harvest, transport, and installation. Thirty-nine bermudagrass (Cynodon sp.) entries were evaluated for sod handling quality (SHQ) and sod tensile strength (STS) during 2014–15. The SHQ (a discontinuous qualitative parameter) was evaluated using a 1 to 5 scale with 1 = complete pad separation during handling and 5 = no cracking or separation in the sod pad with excellent quality. The STS (a quantitative parameter) was determined using the force required to shear/separate the sod pad. Sod harvests were conducted at 14, 22, and 24 months after planting (MAP). The entry, harvest date, and their interaction affected STS and SHQ. Entries OKC 1302 and 12-TSB-1 had greater STS than ‘Patriot’ but less STS than ‘Latitude 36’, ‘Tifway’, ‘Astro’, and ‘TifGrand’. The seeded entry PST-R6T9S had the lowest STS and SHQ. The overall mean STS and SHQ were lowest at 22 MAP, which could be attributed to the slow recovery of the entries after Winter 2014. A strong positive correlation (r = 0.92) between STS and SHQ suggests that SHQ can be used as a rapid field method to estimate suitability for sod harvest. A predictive linear relationship between overall STS and overall SHQ (r 2 = 0.85) found predicted STS values of 8.5, 22.6, 36.8, and 51.0 kg⋅dm–2 for overall mean SHQ ratings of 2, 3, 4, and 5, respectively. The results of this work will help sod producers in cultivar selection and will aid breeders in making commercialization decisions.
Karen K. Schneck, Cheryl R. Boyer, and Chad T. Miller
Dahlia (Dahlia ×hybrida) is an important floriculture crop that has gained popularity in recent years. Greenhouse growers have recently reported a phenomenon known as “dahlia decline,” that can affect potted dahlias in greenhouse production. The crop exhibits graying foliage, root decline, and plant death, and the phenomenon has reportedly caused partial or total crop loss and has no known initiating factor. We hypothesized that plant exposure to supraoptimal root-zone temperatures (RZTs) during production may decrease dahlia root quality, especially above 40 °C and could initiate dahlia decline. Because there is a lack of understanding on how supraoptimal RZT may impact dahlia growth and development, experiments were conducted to evaluate the effects of supraoptimal RZTs on seven dahlia cultivars in Spring 2019 and 2020. Dahlias were grown for 4 to 5 weeks in the greenhouse and then root zones were exposed to ≈22 (control), 35, 40, 45, or 50 °C using a water bath. Root quality was rated before treatment and rated weekly after the hot water bath treatment, along with vegetative growth parameters for 4 weeks. In both years, significant decline in root ratings were observed. ‘XXL Veracruz’ and ‘XXL Sunset’ average root ratings decreased after a 45 and 50 °C treatments in year 2 and both cultivars demonstrated increased root rating averages by 3 weeks after treatment. Cultivars exhibited a significant increase in root rating in the final observations when compared with root ratings taken 1 week posttreatment even if the initial decline after treatment was not significant. Overall plant height was significantly impacted, resulting in shorter heights in both years for all cultivars as treatment temperatures increased to 50 °C in comparison with the control and 35 °C, and a few cultivars exhibited significantly shorter height at 40 and 45 °C. Ultimately, our research did not show typical plant responses that were consistent with reported dahlia decline, but we were better able to characterize dahlia response to supraoptimal RZT.
William Reichert, Harna Patel, Christopher Mazzei, Chung-Heon Park, H. Rodolfo Juliani, and James E. Simon
Manoj Chhetri and Charles Fontanier
Objective methods of estimating green coverage using digital image analysis have been used increasingly by turfgrass scientists. The objective of our research was to evaluate the effectiveness of Canopeo, a relatively new smartphone application, for estimating green coverage of bermudagrass (Cynodon dactylon) emerging from winter dormancy, with or without colorants. A field study was conducted on a research ‘U3’ bermudagrass fairway in Stillwater, OK, during Spring 2019 and 2020. The experiment was conducted as a randomized complete block design with three colorant treatments: Endurant Fairway (FW), Endurant Perennial Ryegrass (PR), and an untreated control. Green coverage of the turfgrass canopy was determined weekly from mid-March to early May using a digital camera and ImageJ software, and a smartphone and the Canopeo application. Green coverage estimates from Canopeo correlated strongly (r = 0.91) with those from ImageJ when no colorants were applied. Correlation between Canopeo and ImageJ was diminished under plots treated with colorants. Canopeo is an effective tool for estimating green coverage of living turfgrasses, but additional calibration may be required for acceptable performance when evaluating greenness of colorant-treated turfgrasses.
Shannon Rauter, Youping Sun, and Melanie Stock
In response to the growing demand for specialty cut flowers, floral crops are increasingly produced in semiarid areas where soil salinity can impact crop timing, reduce stem length, and decrease yield. The goal of this study was to investigate the salinity sensitivity of ‘Carmel’ and ‘Galilee’ anemone (Anemone coronaria), and ‘Amandine’ and ‘LaBelle’ ranunculus (Ranunculus asiaticus) with respect to physiological characteristics and marketable yield. Nine plants were irrigated weekly for 8 weeks with a nutrient (control) solution with an electrical conductivity (EC) of 0.5 dS⋅m–1 or saline solutions prepared by adding sodium chloride and calcium chloride dihydrate to a nutrient solution to obtain an EC of 1.5, 2.5, 3.5, 4.5, or 5.5 dS⋅m–1. Yield was evaluated by dividing stems into marketable and cull grades based on length and bloom quality. At the end of the study, the visual quality of the plants was scored, and gas exchange data were collected using a portable photosynthesis system. Cultivars of each species responded similarly, and marketable yields were low across all treatments, with average marketable yields (mean ± sd) of 1.7 ± 0.6 stems/plant for anemone and 1.2 ± 0.1 stems/plant for ranunculus. Visual quality (0–5 scale, with 0 = dead and 5 = excellent) decreased from 3 to 1 for anemone and 3 to 2 for ranunculus as EC increased from 0.5 to 4.5 dS⋅m–1 and 0.5 to 5.5 dS⋅m–1, respectively. Anemone leaf greenness decreased by 48%, stomatal conductance (g S) decreased by 79%, transpiration (E) decreased by 75%, and net photosynthesis (Pn) decreased by 92% when irrigation solution EC increased from 0.5 to 4.5 dS⋅m–1. The ranunculus growth index decreased by 17%, leaf greenness decreased by 45%, and E decreased by 23% as irrigation solution EC increased from 0.5 to 5.5 dS⋅m–1. Both anemone and ranunculus can be considered sensitive to salinity, indicating the importance of careful soil management in cut flower production systems in semiarid areas that are at risk for elevated soil salinity.
Fahed A. Al-Mana, Abdullah M. Algahtani, Yaser H. Dewir, Majed A. Alotaibi, Mohammed A. Al-Yafrsi, and Khalid M. Elhindi
Freshwater resources are being rapidly depleted because of the increased demand resulting from exponential world population growth and the effects of climate change, especially in arid and semiarid regions (e.g., Saudi Arabia). The present study aimed to examine the changes in growth and inflorescence production of snapdragon (Antirrhinum majus L.) plants in response to irrigation with saline or magnetized water, in addition to application of inorganic and/or organic soil amendments. Three different water types—tap water, magnetized saline water, and nonmagnetized saline water—were used to irrigate A. majus plants with or without soil amendments consisting of ferrous sulfate (Fe2SO4) and/or peatmoss. Irrigation with magnetized saline water adversely affected vegetative growth, inflorescence production, mineral contents, and survival rates of A. majus plants as compared with irrigation with tap water or magnetized saline water. Nevertheless, compared with unmagnetized saline water treatment, magnetizing nonmagnetized saline water before irrigation significantly improved water characteristics and plant growth and survival. Moreover, the addition of inorganic or organic soil amendments enhanced the growth of A. majus plants regardless of irrigation water type. Interestingly, the combination of irrigating with magnetized saline water and soil amendments (Fe2SO4 and peatmoss) significantly enhanced the growth of A. majus plants to a level that was comparable to that of control plants irrigated with tap water without soil amendments. Magnetization improved water quality and increased plants’ ability to absorb water and nutrients from soil solution. The utilization of magnetized saline water for irrigating food and forage crops either alone or in combination with soil amendments has potential benefits that warrant further research.
Ricardo Goenaga, Brian Irish, and Angel Marrero
Banana (Musa acuminata AAA) is the most exported fruit worldwide and represents a major source of revenue for Central American and South American countries as well as the Caribbean region, among others. Black leaf streak disease (BLSD) or black sigatoka, caused by Pseudocercospora fijiensis (formerly Mycosphaerella fijiensis), is responsible for significant losses to this crop due to the high susceptibility of the most economically important cultivars. BLSD does not immediately kill banana plants, but it causes severe leaf necrosis that results in reduced photosynthetic area, thereby adversely impacting bunch weight and fruit production. Without cultural and chemical control, yields can be reduced by 20% to 80%, depending on severity. This study evaluated ‘FHIA-17’, a BLSD-resistant synthetic hybrid (AAAA), against ‘Grand Nain’, a standard commercial cultivar with no BLSD tolerance, at two locations in Puerto Rico on Ultisol (Corozal site) and Oxisol (Isabela site) soils where BLSD was not managed. Significantly lower bunch yield (45,990 kg·ha−1) and significantly fewer fruit (220,671 fruit/ha) were obtained at Corozal than at Isabela (53,755 kg·ha−1; 380,241 fruit/ha). Lower production at Corozal was the result of higher severity of BLSD at this location than at Isabela and to soil factors interfering with optimum nutrient uptake. Average fruit production of ‘FHIA-17’ was significantly higher than that of ‘Grand Nain’ at both locations, with bunch yields of 68,105 and 72, 634 kg·ha−1 at Corozal and Isabela, respectively. Fruit of the third-upper hand was significantly longer for ‘FHIA-17’ at Corozal but not different at Isabela; however, ‘FHIA-17’ fruit in this hand were of significantly greater diameter. Fruit in the last hand of ‘FHIA-17’ were significantly longer than in ‘Grand Nain’ at Corozal, but of significantly greater diameter at both locations. At both locations, the mean fruit weight was significantly higher in ‘FHIA-17’ than in ‘Grand Nain’. The number of functional leaves present at flowering and at harvest was significantly higher in ‘FHIA-17’ than in ‘Grand Nain’ at both locations, indicating more availability of photosynthetic area in ‘FHIA-17’ during the fruit-filling period. The harvest cycle of ‘FHIA-17’ was significantly longer than for ‘Grand Nain’. It took 315 and 204 more days in Corozal and Isabela, respectively, to harvest three cycles (mother crop and two ratoon crops) of ‘FHIA-17’ than for ‘Grand Nain’. No significant differences were found for starch and soluble sugars in green unripe or fully mature fruit among cultivars. In this long-term study, ‘FHIA-17’ showed to have good production and resistance against BLSD and is a viable alternative to current commercial cultivars. Its relative advantage of reduced production costs by not needing fungicide applications should be weighed against its longer harvest cycle to produce a fruit bunch.