Anthracnose, caused by the fungal pathogen Colletotrichum cereale Manns sensu lato Crouch, Clarke & Hillman, can be a damaging disease on many cool-season turfgrasses; however, it has not been reported as an aggressive pathogen on fine fescue species (Festuca spp.). Symptoms and signs associated with anthracnose disease were observed in fine fescues on the Rutgers University Plant Science Research and Extension Farm in Adelphia, NJ, in Jun 2014. The objectives of this study were to identify the causal agent, determine if the isolate of C. cereale (FF1A) obtained from symptomatic Chewings fescue (Festuca rubra L. ssp. commutata Gaudin) plants was pathogenic to Chewings fescue and hard fescue (F. brevipila Tracey) turfs, and whether cultivars and accessions collected from Europe varied in disease susceptibility. Pathogenicity of this fine fescue isolate was evaluated using four Chewings fescue and four hard fescue cultivars or accessions in a growth chamber. Disease symptoms were first observed at 5 days post-inoculation, and evaluations continued to 17 days post-inoculation. Infection was confirmed by morphological evaluations, re-isolation from symptomatic tissues, and real-time polymerase chain reaction (PCR). Three noncommercial accessions (two Chewings fescues and one hard fescue) were very susceptible to the fine fescue C. cereale FF1A isolate, whereas ‘Sword’ and ‘Beacon’ hard fescues exhibited low susceptibility. In addition, an isolate of C. cereale (HF217CS) from annual bluegrass [Poa annua L. f. reptans (Hausskn) T. Koyama] was included, and our data demonstrated that this isolate was also able to infect Chewings fescue and hard fescue. This study confirmed that C. cereale can be a damaging pathogen of fine fescues, and that breeding for resistance to anthracnose should be considered when developing new cultivars.
Shuxia Yin, Lisa A. Beirn, Trent M. Tate, Daniel L. Ward, Ruying Wang, William A. Meyer, and Bruce B. Clarke
Noel A. Madalla, Cornel Massawe, Mpoki Shimwela, Daud Mbongo, Grace Kindimba, Jerome Kubiriba, Ivan Arinaitwe, Kephas Nowakunda, Priver Namanya, Robooni Tumuhimbise, Asher W. Okurut, Adolf Saria, Munguatosha Ngomuo, Rony Swennen, Allan F. Brown, Michael Batte, Sebastien Carpentier, Inge Van den Bergh, Rhiannon Crichton, Pricilla Marimo, Eva Weltzien, and Rodomiro Ortiz
Shuangshuang Yi, Yi Liao, Mingzhong Huang, Zhiqun Zhang, Junhai Niu, Shunjiao Lu, and Junmei Yin
Moritz Knoche and Eckhard Grimm
Neck shrivel is a fruit disorder of european plum (Prunus domestica L.). We investigate whether an asymmetrical distribution of osmolytes might explain the observations of a turgid stylar end and a flaccid stem end, in a selection of 17 plum cultivars sourced from two sites. The osmotic potential (ΨΠ) of the juices expressed from stem or stylar end fruit samples decreased (became more negative) during development. The cell turgor (Ψ P ) slightly increased during development up to 352 ± 42 kPa at 78 days after full bloom (DAFB) in the stem end and up to 331 ± 51 kPa at 92 DAFB in the stylar end, and then decreased. At maturity, Ψ P averaged 22 ± 3 kPa in the stem end and 22 ± 4 kPa in the stylar end. These values are negligibly low compared with the very negative values of ΨΠ in the stylar end (−3188 ± 73 kPa) and stem end (−3060 ± 74 kPa). There was a transient gradient in ΨΠ between stylar end and stem end that almost disappeared by maturity. Marked differences in ΨΠ and its distribution were measured across 17 cultivars. In the majority (14), ΨΠ was more negative at the stylar end than at the stem end. A more negative ΨΠ in the stem was only detected in ‘Aprimira’, ‘Topfive’, and ‘Tophit’. Our results demonstrate that cell Ψ P is very low and is essentially independent of ΨΠ in developing european plums. In most cultivars, ΨΠ in the stylar end is more negative than in the stem end. The absence of an axial gradient in Ψ P and the small differences in ΨΠ between the stem and stylar end make both factors unlikely candidates for explaining neck shrivel.
Lingling Zhang, Kunlin Wu, Guohua Ma, Lin Li, Lin Fang, Ming Kang, and Songjun Zeng
Yule Miao, Zhiqiang Wang, Junren Meng, Wenfang Zeng, Lei Pan, Guochao Cui, and Liang Niu
Nelly Guerra, Steven A. Fennimore, Mark C. Siemens, and Rachael E. Goodhue
Steam injected into the soil, raising soil temperatures to >70 °C for 15 to 20 minutes, will control weed seed and soilborne pathogens. The effect of this reduction in the weed seedbank viability results in weed control in the treated zone that can persist for several weeks or months. The effect of steam pasteurization of soil on weed seeds produces results similar to a preemergence herbicide. In our study, steam was applied to the soil to control weed seed and propagules of Sclerotinia minor and Pythium spp. Replicated field trials in carrot, lettuce, and spinach were conducted using two types of band steam applicators in 2020 and 2021. Data collected were soil temperatures after steam application, weed control, hand weeding times, diseased plant counts, pathogen populations in the soil, and crop yields. Post-steam soil temperature intervals >70 °C in the top 10 cm of the soil ranged from 67 to 176 minutes. Steam reduced weed densities by 64% to 100% and lowered hand weeding times by 23% to 91%. The reduction of S. minor sclerotia propagules after steaming was 69% to 95% compared with the no steam control. The percentage of lettuce plants infected with lettuce drop was reduced by 60% to 70% and the reduction of Pythium spp. propagules in the soil was reduced by 50% to 100% compared with the no steam control, respectively. Lettuce head diameters in steamed soils were 10% to 24% larger compared with the no steam control. Carrots grown in the steam-treated soil had a 10% greater root diameter than the no steam control. Steam increased lettuce yields in two of three trials 22% to 28% compared with the no steam control. Gross revenues for the steam-treated lettuce were $3231/ha higher than in the no steam control. The data suggest that band steam is a viable soil pest control treatment for vegetable crops.
Fei He, Tatiana Borisova, Kevin Athearn, Robert Hochmuth, and Charles Barrett
State and federal policies in the United States focus on agricultural best management practices (BMP)—such as improving nutrient management—to address water quality issues. BMP development is a challenging process as a new BMP may also affect farm profitability. This article explores the economic feasibility of nitrogen (N) management programs, including nitrogen application rates (N rates), given alternative scenarios for current nitrogen use and producer risk perceptions of carrot production in Florida. In this study, eight alternative N rates are ranked to find the economically optimal BMP. Carrot profitability is determined based on carrot yields per hectare, input costs, and carrot sale prices, using data from a 2-year carrot production experiment. The analysis applied stochastic simulation to account for the uncertain factors by using Simetar Add-In for Excel. We found that 224 kg·ha−1 N fertilizer rate is the most preferred by the producers among the eight rates considered. According to Florida’s agricultural water policy, BMP recommendations should balance water quality improvements and agricultural productivity. We consider the potential reduction of nitrogen fertilizer rate BMP from 224 kg·ha−1 to 168 kg·ha−1 and show that the effect of such reduction depends on producers’ current fertilizer application rates and their risk aversion levels. For example, reducing the N fertilizer rate from 336 kg·ha−1 to 168 kg·ha−1 decreases mean net returns by only 2% ($49/ha). In contrast, reducing the nitrogen fertilizer rate from 224 kg·ha−1 to 168 kg·ha−1 reduces the mean net returns by $151/ha, with an almost 10% reduction in the certainty equivalent of the net returns (for extremely risk-averse producers). Overall, if most producers in the region are very or extremely risk-averse, and if most of them operate close to the optimal level of fertilizer use, then setting the more restrictive BMP of 168 kg·ha−1 N can be perceived as undermining their economic profitability and require significant cost-share incentives to ensure targeted 100% adoption of BMP recommendations.
Tai-Yin Chen and Chin-Mu Chen
Satoru Motoki, Kazuki Okada, Shumpei Imai, Takumi Taguchi, and Akira Kanno
Asparagus (Asparagus officinalis L.) is a dioecious perennial plant. Male plants have a higher yield than female plants; therefore, all-male cultivars are more commonly produced. In contrast, female plants have a higher spear weight than that of male plants. To increase profitability, selective cultivation of only female plants would increase the yield of asparagus with a thick spear, which has a higher unit price. However, the effects of cultivar and cropping type on the growth and yield of male and female asparagus plants have rarely been examined. This study compared the growth and yield of female and male plants of three cultivars grown under various cropping types: a rootstock planting forcing culture; a long-term harvest production system in an open field; and a semi-forcing culture. As a measurement of growth, the rootstock weight was significantly higher for female plants compared with that of male plants with the rootstock planting forcing culture. Regarding yield measurements, the spear weight and yield were not significantly different with the rootstock planting forcing culture. However, with the long-term harvest production system in the open field and semi-forcing cultures, the weight and yield of female plants were equivalent to or significantly higher than those of male plants, regardless of the cultivar, except during some harvest periods. These results indicated that the selective production of female plants may be advantageous in terms of growing heavier spears with a higher unit price in a long-term harvest production system in the open field and semi-forcing cultures in Japan. Additionally, the development of a simple and low-cost method for sex identification would be beneficial.