‘Crimson Cabernet’ grape (Vitis vinifera) seeds showed physiological dormancy and germinated at ∼60% after 60 days of chilling stratification. Fresh seeds harvested after physiological maturity and sown without drying failed to germinate after 30 days when sown on agar. In agar-sown fresh seeds cut at the distal seed end or intact seeds treated with gibberellic acid (GA), the seeds germinated at ∼20% after 30 days. The highest germination percentages after 30 days were 63% to 83% in fresh, agar-sown seeds that were cut and treated with GA at 5000 mg⋅L–1 regardless of stratification time. Similar results were seen in seeds allowed to dry before sowing. Seeds cut and treated with GA at 5000 mg⋅L–1 germinated at 79% after 30 days. However, dry seeds sown on germination paper showed lower germination after cutting and GA treatment compared with agar-sown seeds. The highest germination percentages after 30 days in dry, cut seeds on germination paper treated with GA at 2000 and 5000 mg⋅L–1 were 33% and 55%, respectively, compared with agar-sown seeds, which germinated at 76% and 79%, with the same treatments. Results from this study provide a system that reduces the need for chilling stratification for grape seed germination by using partial seedcoat removal and GA treatment.
Bridget Bolt, Anna Baloh, Roberta Magnani, Marta Nosarzewski, Carlos Rodriguez López, and Robert Geneve
Kristine R. Buckland, Cynthia M. Ocamb, Ann L. Rasmussen, and Lloyd L. Nackley
Widespread outbreaks of tomato powdery mildew (Leveillula taurica and Oidium neolycopersici) are problematic in fresh market tomato (Solanum lycopersicum) crops in western Oregon, USA. In western Oregon, fresh market tomatoes are frequently grown in greenhouses or high tunnels where conditions can promote diseases such as powdery mildew. Heightened concerns about worker safety limit the pesticides available for use in enclosed systems. We studied the efficacy of ultraviolet-C (UV-C) light applications under high-tunnel conditions compared with a standard fungicide program. Plants treated with UV-C had zero incidence of powdery mildew on all sample dates in the first trial. In trial 2, disease incidence was lower on UV-C treated plants than both grower standard and nontreated control early in the study while disease severity remained lower in UV-C than nontreated control and similar to grower standard treatment. Additional research is needed to optimize UV-C treatment intervals to minimize negative effects on plant growth and maximize powdery mildew control.
Travis W. Shaddox, J. Bryan Unruh, Mark E. Johnson, Clark D. Brown, and Greg Stacey
Integrated pest management (IPM) is an important component of golf course maintenance and includes conventional chemical pesticide use as well as nonchemical cultural management practices. Determining how frequent pest management practices are used on golf courses is critical when developing educational and outreach programs. The objective of this study was to determine the frequency of pest management practices and pesticide mixing and storage facilities on US golf courses. A survey was sent to 14,033 operational US golf facilities with 10% responding. Reliance on all conventional chemical pesticides increased from 2015 to 2021. The reliance on biological control products declined to 14% and reliance on the nonpesticide practice of using plant growth regulators remained equivalent to 2015. The most common pest management practices included monitoring weather patterns and scouting for pests, with 93% of golf facilities reporting the use of both. The use of written IPM and pesticide application plans increased from 44% to 63% of golf facilities between 2015 and 2021, respectively. Generally, mixing and storage facilities remained unchanged from 2015 to 2021. US golf facilities continue to use nonchemical pest management practices, but reliance on chemical pesticides has increased.
Yue-E Xiao, Feng-Yang Yu, Cui-Mei Wang, and Wei Li
Timothy J. Hudelson, F. Mitchell Westmoreland, and Bruce Bugbee
Ethylene is an essential plant hormone at low concentrations. Concentrations in the field rarely exceed 5 nmol⋅mol−1 (0.005 ppm), but it can accumulate as a gas in closed, indoor environments. These elevated levels can reduce growth and yield. Temperature alters ethylene synthesis and has the potential to influence ethylene sensitivity of crop plants in sealed greenhouses and indoor environments. We studied ethylene sensitivity of tomatoes (Solanum lycopersicum L. cv. MicroTina) using a unique, 12-chamber system. Ethylene levels of 0, 20, and 40 nmol⋅mol−1 (parts per billion) were maintained throughout the life cycle, at an air temperature of 22 or 28 °C. Yield of red fruit was three times higher at 22 than at 28 °C. There was a steady decrease in yield with increasing ethylene concentration, but vegetative growth was reduced less than 10% in any treatment. The highest ethylene concentration reduced yield to 11% of the control at 22 °C and to 4% of the control at 28 °C; the intermediate ethylene level reduced yield to 51% of the control at 22 °C and 37% at 28 °C. Regardless of temperature, filtering of ethylene in indoor environments to below 20 nmol⋅mol−1 is necessary to achieve normal fruit set and yield in tomato.
Joseph B. Wood, Christopher S. Cramer, Robert Steiner, Richard Heerema, Brian J. Schutte, and Ivette Guzman
Bulb onion (Allium cepa L.) is an economically valuable vegetable crop in the United States. Onion production is threatened by onion thrips, which are the vector for Iris yellow spot virus, which is the causal agent of Iris yellow spot (IYS). New Mexico State University (NMSU) breeding lines 12-236, 12-238, 12-243, and 12-337 have exhibited fewer IYS disease symptoms in the field; however, little is known about the effects of the disease on the photosynthesis rate (Pn). We hypothesized that these NMSU breeding lines would have a higher Pn than IYS-susceptible cultivars Rumba and Stockton Early Yellow. To test this hypothesis, a field study was conducted for 3 years at NMSU, and Pn was measured five times throughout each season at 2-week intervals. During bulb development and maturation, which occurred at 10 and 12 weeks after transplanting, all NMSU breeding lines exhibited a higher Pn when compared with that of an IYS-susceptible cultivar. Pn was highest at the end of the vegetative growth stage and decreased as bulbs approached maturation for all cultivars. Additionally, a high Pn at 10 and 12 weeks after transplanting coincided with high bulb weight at harvest. NMSU breeding lines have increased Pn compared with that of IYS-susceptible cultivars and resulted in larger and more marketable bulbs. These results indicate that maintaining Pn may be related to reduced IYS symptom expression of onion.
S. Brooks Parrish, Renjuan Qian, Sandra B. Wilson, Gary W. Knox, and Zhanao Deng
Gulf vervain (Verbena xutha) is a herbaceous perennial native to the southern United States. The species produces attractive spike inflorescences that provide a source of food for many pollinators. Besides botanical classifications, pollen morphology and cytological traits of this species have not been documented until now. Gulf vervain was found to have 2n = 42 chromosomes, with the first report of 2C nuclear DNA content of 2.95 pg. Convex-triangular pollen grains averaged 37.18 μm in diameter, with 84% stainability after cotton blue staining to estimate pollen viability. This information brings light to the genetic makeup of gulf vervain and may aid in future breeding programs.