THE BIOLOGY OF CANADIAN WEEDS.: 58. Galinsoga parviflora and G. quadriradiata (= G. ciliata).

1983 ◽  
Vol 63 (3) ◽  
pp. 695-709 ◽  
Author(s):  
S. I. WARWICK ◽  
R. D. SWEET

A summary of biological information is provided on two species of Galinsoga — G. parviflora (small-flowered galinsoga) and G. quadriradiata (hairy galinsoga). Originating in Central America, both species are weeds of disturbed habitats and agricultural areas, occurring in most of the temperate and subtropical regions of the world. In recent years the galinsogas have become troublesome weeds of low-growing vegetable crops in northeastern North America. The two species serve as alternate hosts for many insects, viruses and nematodes which affect crop species. Both species possess several features which predispose them to weediness and contribute to a rapid buildup of populations after an initial infestation. These include lack of seed dormancy, lack of special requirements for germination, rapid seedling development, the ability to flower after a short period of vegetative growth, the production of flowers and fruits throughout the growing season, the production of several generations in a single growing season, self-compatibility and the production of large numbers of viable seeds under a wide range of environmental circumstances.Key words: Galinsoga parviflora, G. quadriradiata, biology

Agronomy ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1708
Author(s):  
Boyang Shi ◽  
Kunjithapatham Dhileepan ◽  
Steve Adkins

Parthenium weed (Parthenium hysterophorus L.) is an internationally important invasive weed native to the tropical and sub-tropical Americas, and invasive in more than 30 countries. This weed has serious adverse influences on rangeland and agricultural crop production, on human and animal health, and on the biodiversity of natural communities. Parthenium weed leaf litter can reduce seedling emergence and affect the early growth of a wide range of pasture and crop species. Soil collected from a heavily infested parthenium weed area was shown to reduce seedling emergence of a wide range of test plants (lettuce (Lactuca sativa L.), maize (Zea mays L.), curly windmill grass (Enteropogon acicularis L.), and liverseed grass (Urochloa panicoides P.Beauv.)) by between 20 to 40%; however, the soil had no effect on the subsequent growth of the surviving test plants. Soil amended with dried parthenium weed leaf litter reduced the emergence of test species by ca. 20 to 40%, but it had no effect on the growth of the surviving test plants. One week after emergence, the growth of all test species was stimulated by 9 to 86% in the leaf litter-amended soil with the increased growth matching the increased amounts leaf litter amended. In parthenium weed-infested landscapes, the substrate (soil) is affected by the plant during the growing season by the release of allelopathic chemicals. However, the plant’s litter can affect the community outside of the growing season, first through a residual allelopathic activity, but also by a fertilizing effect as litter breakdown occurs. This study demonstrates the significant ability of parthenium weed to affect plant communities throughout the year and, when considered over several years, this may lead to the creation of a complete monoculture of the weed.


2019 ◽  
pp. 5-10
Author(s):  
Y. Klechkovskiy ◽  
S. Glushkova ◽  
O. Palagina

Goal. To provide information about dangerous pests of vegetable crops — thrips. To describe the morphology and biology of the pest, the methods of spreading and harmfulness, provide information on the necessary phytosanitary measures to restrict its development and reduce the harmfulness, and to justify the need to use alternative biological methods to control the population of thrips in the conditions of the Southern steppe of Ukraine on an example of the most common of them — tobacco thrips (Thrips tabaci Lind.). Methods. Informational and analytical. The collection of information was carried out in accessible specialized literature and the Internet. Results. The information about sucking pests of vegetable crops - thrips is given.  Thrips are known for a long time, they belong to wide polyphages, that is they harm a wide range of cultural and wild plants  (from 100 to 400 spesies). On an example of the most common of them — tobacco thrips (Thrips tabaci Lind.) there is given information about the morphology and biology of the pest, the methods of its spreading and harmfulness, as well as the information on the necessary phytosanitary measures for restriction its development and reduction of the harm. This most widespread and dangerous polyphage, due to its close connection with plants, where its entire life cycle develops - from eggs to imago, has inhabited almost all greenhouses. In the natural conditions of the southern region of Ukraine, the tobacco thrips were found on large areas of vegetable crops with the seedling method of their cultivation, mainly cucumbers, tomatoes, onions, cabbage, watermelons, and the like. It harms bulbs in vegetable stores, which leads to a deterioration in the quality of garden plants and gardening material. The reaction of the plant to the damage by the trips is desensitization, which is manifested in growth retardation, distortion and loss of turgor of damaged leaves, which later become yellow and dries. Imago winter, mostly females, in greenhouses - in different slits, and in open ground - in the upper layer of soil at a depth of 7-10 cm, under plant remains or in the rootstock of perennials or weeds. At temperatures below 0 ° С and in the absence of snow cover, insects die. The pest spreads at all stages of development - eggs, larvae, imago - with planting material of vegetable crops (with plants or in soil), transport, containers, workers' tools, their clothes or footwear. This also occurs when collecting, packing and selling contaminated products. This is especially true for cabbage, with which the thrips can get to the greenhouse or indoor plants. In the conditions of the steppe and forest-steppe zones of Ukraine, the tobacco thrips can develop in open soil at temperatures over 10 ° C during the growing season from the second decade of May to the end of September, causing significant damage to vegetable crops. If this is the case, the pest can give 3-4 to 5-6 generations, depending on the weather conditions. In the population control of tobacco thrips, satisfactory results are received by systematic cultivation of plants with the following insecticides: Akketlik, Aktar, Phyitoverm, Karate Zeon, Confidor Maxi (with irrigation water) and others. It is obligatory to change preparations during the growing season. On the onion fields thrips is successfully reduced with insecticide of natural origin Spintor when using periodic spraying of plants. Because thrips are very resistant pests, therefore, in addition to insecticides, the use of predatory mites Amblyseius cucumeris, A. barken, A. derenerans, as well as predators of Orius laevigatus, O. magusaculus can be used to destroy them. Taking into account that nowadays the protection of vegetable crops takes the direction for the use of biological agents against pests - polyphages, special attention should be paid to the use of natural enemies of the tobacco thrips. Conclusions. In the natural conditions of the southern region of Ukraine, tobacco thrips were found on large areas of vegetable crops, therefore, there are all reasons for phytosanitary surveys of open-air vegetable crops to detect and eliminate this dangerous pest. Taking into account that nowadays the protection of vegetable crops takes the direction for the use of biological agents against pests - polyphages, special attention should be paid to the use of natural enemies of the tobacco thrips.


1983 ◽  
Vol 63 (4) ◽  
pp. 997-1014 ◽  
Author(s):  
S. I. WARWICK ◽  
L. D. BLACK

A review of biological information is provided for Sorghum halepense (L.) Pers., Johnson grass. A native of southern Eurasia to India, S. halepense occurs as a weed in most tropical and temperate areas of the world, and has recently become established in 10 counties in Southern Ontario. Listed as one of the world’s worst weeds, S. halepense infestations result in severe crop losses either from competition or alleleopathic effects and/or by serving as an alternative host for several crop pests. The species is, however, an important forage crop in the southeastern United States and other areas of the world. Johnson grass has several features which contribute to its success as a weed, including the production of extensively creeping rhizomes and large numbers of seeds, rhizomes which regenerate easily if cut into small pieces in cultivation procedures, self-compatibility, seed longevity, seed dormancy and vigorous growth under a wide range of environmental conditions. To date, one population of S. halepense from Brant County, Ontario is known to produce rhizomes which successfully overwinter in Canada. This population would appear to be distinct from the other Ontario populations and is characterized by smaller seeds and seedlings and lower rates of germination. A combination of repeated tillage, proper herbicides and crop rotation will give the best control of Johnson grass.Key words: Sorghum halepense, Johnson grass, biological review


2021 ◽  
Author(s):  
Andrew Cuthbertson

Abstract The exact origin of the MEAM1 species of Bemisia tabaci, and the reasons why it became such an important pest are still not fully known. MEAM1 was first identified in the mid 1980s when it invaded the southern states of North America. Vast numbers of whiteflies were found to be infesting winter vegetable crops and consequently caused an estimated $500 million loss to the 1991 winter harvest in California. Investigations led to the assumption that the B biotype had spread to the USA on ornamental plants that were being transported around the world. Species such as poinsettia and gerbera were highlighted as probable hosts. During the 1990s MEAM1 was reported on every continent. Biological traits of MEAM1 implied that it had evolved within intensive agricultural regions with exposure to pesticides and modern cultural practices. These included an ability to feed and develop on a wide range of plant and crop species, a high level of fecundity and a predisposition to develop resistance to a wide range of pesticides. MEAM1 is also an effective vector of many different plant viruses which, in conjunction with its high level of polyphagy, make it extremely problematic within agricultural regions where crops may be susceptible to viruses acquired from indigenous plants. Despite B. tabaci being a tropical/sub-tropical whitefly species, MEAM1 is often transported on plant species to temperate regions of the world. Within these cooler regions, MEAM1 can survive within a protected environment and could feasibly spread virus diseases to new locations. It is for this reason that B. tabaci and members of its species complex, including MEAM1, are on EPPO A2 Alert list.


2020 ◽  
Vol 13 (2) ◽  
pp. 062-067
Author(s):  
Gulchehra Kulmuminovna Khalmuminova ◽  
Shukhrat Ganievich Kamilov ◽  
Olga Antonovna Verushkina ◽  
Mutabar Kushakovna Khujanazarova

In the article the tasks have been set on the inventory of the species composition of fungi of the genus Alternaria Nees ex Walroth - pathogen of various Alternaria diseases of vegetable crops in Uzbekistan. More than 200 isolates were collected and about 150 monosporous pure cultures were obtained from them. According to preliminary data, they belong to 15 species of the genus Alternaria and have been isolated from the 12 most important crop species. It was found that a more accurate identification of species requires the study of a wide range of morphological and biochemical traits. The article discusses the issue of infection of vegetable seeds in Uzbekistan. The composition of micromycetes living on seeds of vegetable and green crops was revealed. In total, 21 species were recorded, of which 9 species includes to Alternaria genus.


2021 ◽  
Vol 314 ◽  
pp. 01004
Author(s):  
Samira El Aouidi ◽  
Ayoub Benmhammed ◽  
Azzouz Benkdad ◽  
Nezha Mejjad ◽  
Edit Toth-Bodrogi ◽  
...  

The present study examines the radionuclides (40K, 226Ra and 210Pb) concentrations in soil and plants collected from El Jadida agricultural area. The transfer factors of radionuclides from the soil to different components of the plants (stems, roots, leaves, and fruits) was also determined and assessed. The plants include various vegetable crops, including pumpkin, zucchini, beans, fennel, potato, sunflower, broccoli, onion, carrot, cabbage, tomato, and mallow from three different locations. A wide-range HPGe gamma-ray spectrometer is used for radionuclide activity measurement. The radionuclides activities of soil samples display a wide range of variability from one location to another. The concentrations of 226Ra vary between 18 ± 1 Bq.Kg-1 and 80 ± 4 Bq.Kg-1, the concentrations of 210Pb range from 49.7 ± 4.4 Bq.Kg-1 to 269 ± 16 Bq.Kg-1, and the 40K values fluctuate between 94,1 ± 6,5 and 286,1 ± 15,3 Bq.Kg-1. The study showed that the transfer factor for K-40 is more significant than Pb-210 and Ra-226, mainly related to the use of fertilizers rich in potassium in the agricultural areas, leading to its concentrations increase.


2013 ◽  
Vol 16 (1) ◽  
pp. 59-67

<p>The Soil Science Institute of Thessaloniki produces new digitized Soil Maps that provide a useful electronic database for the spatial representation of the soil variation within a region, based on in situ soil sampling, laboratory analyses, GIS techniques and plant nutrition mathematical models, coupled with the local land cadastre. The novelty of these studies is that local agronomists have immediate access to a wide range of soil information by clicking on a field parcel shown in this digital interface and, therefore, can suggest an appropriate treatment (e.g. liming, manure incorporation, desalination, application of proper type and quantity of fertilizer) depending on the field conditions and cultivated crops. A specific case study is presented in the current work with regards to the construction of the digitized Soil Map of the regional unit of Kastoria. The potential of this map can easily be realized by the fact that the mapping of the physicochemical properties of the soils in this region provided delineation zones for differential fertilization management. An experiment was also conducted using remote sensing techniques for the enhancement of the fertilization advisory software database, which is a component of the digitized map, and the optimization of nitrogen management in agricultural areas.</p>


2021 ◽  
Vol 13 (16) ◽  
pp. 3069
Author(s):  
Yadong Liu ◽  
Junhwan Kim ◽  
David H. Fleisher ◽  
Kwang Soo Kim

Seasonal forecasts of crop yield are important components for agricultural policy decisions and farmer planning. A wide range of input data are often needed to forecast crop yield in a region where sophisticated approaches such as machine learning and process-based models are used. This requires considerable effort for data preparation in addition to identifying data sources. Here, we propose a simpler approach called the Analogy Based Crop-yield (ABC) forecast scheme to make timely and accurate prediction of regional crop yield using a minimum set of inputs. In the ABC method, a growing season from a prior long-term period, e.g., 10 years, is first identified as analogous to the current season by the use of a similarity index based on the time series leaf area index (LAI) patterns. Crop yield in the given growing season is then forecasted using the weighted yield average reported in the analogous seasons for the area of interest. The ABC approach was used to predict corn and soybean yields in the Midwestern U.S. at the county level for the period of 2017–2019. The MOD15A2H, which is a satellite data product for LAI, was used to compile inputs. The mean absolute percentage error (MAPE) of crop yield forecasts was <10% for corn and soybean in each growing season when the time series of LAI from the day of year 89 to 209 was used as inputs to the ABC approach. The prediction error for the ABC approach was comparable to results from a deep neural network model that relied on soil and weather data as well as satellite data in a previous study. These results indicate that the ABC approach allowed for crop yield forecast with a lead-time of at least two months before harvest. In particular, the ABC scheme would be useful for regions where crop yield forecasts are limited by availability of reliable environmental data.


Plants ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 885
Author(s):  
Pooja Tripathi ◽  
Sangita Subedi ◽  
Abdul Latif Khan ◽  
Yong-Suk Chung ◽  
Yoonha Kim

Roots play an essential function in the plant life cycle, as they utilize water and essential nutrients to promote growth and plant productivity. In particular, root morphology characteristics (such as length, diameter, hairs, and lateral growth) and the architecture of the root system (spatial configuration in soil, shape, and structure) are the key elements that ensure growth and a fine-tuned response to stressful conditions. Silicon (Si) is a ubiquitous element in soil, and it can affect a wide range of physiological processes occurring in the rhizosphere of various crop species. Studies have shown that Si significantly and positively enhances root morphological traits, including root length in rice, soybean, barley, sorghum, mustard, alfalfa, ginseng, and wheat. The analysis of these morphological traits using conventional methods is particularly challenging. Currently, image analysis methods based on advanced machine learning technologies allowed researchers to screen numerous samples at the same time considering multiple features, and to investigate root functions after the application of Si. These methods include root scanning, endoscopy, two-dimensional, and three-dimensional imaging, which can measure Si uptake, translocation and root morphological traits. Small variations in root morphology and architecture can reveal different positive impacts of Si on the root system of crops, with or without exposure to stressful environmental conditions. This review comprehensively illustrates the influences of Si on root morphology and root architecture in various crop species. Furthermore, it includes recommendations in regard to advanced methods and strategies to be employed to maintain sustainable plant growth rates and crop production in the currently predicted global climate change scenarios.


Weed Science ◽  
2020 ◽  
pp. 1-10
Author(s):  
Muhammad Javaid Akhter ◽  
Per Kudsk ◽  
Solvejg Kopp Mathiassen ◽  
Bo Melander

Abstract Field experiments were conducted in the growing seasons of 2017 to 2018 and 2018 to 2019 to evaluate the competitive effects of rattail fescue [Vulpia myuros (L.) C.C. Gmel.] in winter wheat (Triticum aestivum L.) and to assess whether delayed crop sowing and increased crop density influence the emergence, competitiveness, and fecundity of V. myuros. Cumulative emergence showed the potential of V. myuros to emerge rapidly and under a wide range of climatic conditions with no effect of crop density and variable effects of sowing time between the two experiments. Grain yield and yield components were negatively affected by increasing V. myuros density. The relationship between grain yield and V. myuros density was not influenced by sowing time or by crop density, but crop–weed competition was strongly influenced by growing conditions. Due to very different weather conditions, grain yield reductions were lower in the growing season of 2017 to 2018 than in 2018 to 2019, with maximum grain yield losses of 22% and 50% in the two growing seasons, respectively. The yield components, number of crop ears per square meter, and 1,000-kernel weight were affected almost equally, reflecting that V. myuros’s competition with winter wheat occurred both early and late in the growing season. Seed production of V. myuros was suppressed by delaying sowing and increasing crop density. The impacts of delayed sowing and increasing crop density on seed production of V. myuros highlight the potential of these cultural weed control tactics in the long-term management programs of this species.


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