Pesticides are widely used in agricultural production to prevent or control pests, diseases, weeds, and other plant pathogens in an effort to reduce or eliminate yield losses and maintain high product quality. Although pesticides are developed through very strict regulation processes to function with reasonable certainty and minimal impact on human health and the environment, serious concerns have been raised about health risks resulting from occupational exposure and from residues in food and drinking water. Occupational exposure to pesticides often occurs in the case of agricultural workers in open fields and greenhouses, workers in the pesticide industry, and exterminators of house pests. Exposure of the general population to pesticides occurs primarily through eating food and drinking water contaminated with pesticide residues, whereas substantial exposure can also occur in or around the home. Regarding the adverse effects on the environment (water, soil and air contamination from leaching, runoff, and spray drift, as well as the detrimental effects on wildlife, fish, plants, and other non-target organisms), many of these effects depend on the toxicity of the pesticide, the measures taken during its application, the dosage applied, the adsorption on soil colloids, the weather conditions prevailing after application, and how long the pesticide persists in the environment. Therefore, the risk assessment of the impact of pesticides either on human health or on the environment is not an easy and particularly accurate process because of differences in the periods and levels of exposure, the types of pesticides used (regarding toxicity and persistence), and the environmental characteristics of the areas where pesticides are usually applied. Also, the number of the criteria used and the method of their implementation to assess the adverse effects of pesticides on human health could affect risk assessment and would possibly affect the characterization of the already approved pesticides and the approval of the new compounds in the near future. Thus, new tools or techniques with greater reliability than those already existing are needed to predict the potential hazards of pesticides and thus contribute to reduction of the adverse effects on human health and the environment. On the other hand, the implementation of alternative cropping systems that are less dependent on pesticides, the development of new pesticides with novel modes of action and improved safety profiles, and the improvement of the already used pesticide formulations towards safer formulations (e.g., microcapsule suspensions) could reduce the adverse effects of farming and particularly the toxic effects of pesticides. In addition, the use of appropriate and well-maintained spraying equipment along with taking all precautions that are required in all stages of pesticide handling could minimize human exposure to pesticides and their potential adverse effects on the environment.

https://www.mdpi.com/1660-4601/8/5/1402/pdf

Pesticide Exposure, Safety Issues, and Risk Assessment Indicators

Over the last decades, research efforts have been made at developing more effective technologies for the remediation of waters containing persistent organic pollutants. Among the various technologies, the so-called electrochemical advanced oxidation processes (EAOPs) have caused increasing interest. These technologies are based on the electrochemical generation of strong oxidants such as hydroxyl radicals ( OH). Here, we present an exhaustive review on the treatment of various synthetic and real wastewaters by five key EAOPs, i.e., anodic oxidation (AO), anodic oxidation with electrogenerated H 2 O 2 (AO-H 2 O 2 ), electro-Fenton (EF), photoelectro-Fenton (PEF) and solar photoelectro-Fenton (SPEF), alone and in combination with other methods like biological treatment, electrocoagulation, coagulation and membrane filtration processes. Fundamentals of each EAOP are also given.

Electrochemical advanced oxidation processes: A review on their application to synthetic and real wastewaters

Exposure to pesticides and the associated human health effects

Rice ( Oryza sativa L.) is a principal source of food for more than half of the world population, especially in South and Southeast Asia and Latin America. Elsewhere, it represents a high‐value commodity crop. Change in the method of crop establishment from traditional manual transplanting of seedlings to direct‐seeding has occurred in many Asian countries in the last two decades in response to rising production costs, especially for labor and water. Direct‐seeding of rice (DSR) may involve sowing pregerminated seed onto a puddled soil surface (wet‐seeding) or into shallow standing water (water‐seeding), or dry seed into a prepared seedbed (dry‐seeding). In Europe, Australia, and the United States, direct‐seeding is highly mechanized. The risk of crop yield loss due to competition from weeds by all seeding methods is higher than for transplanted rice because of the absence of the size differential between the crop and weeds and the suppressive effect of standing water on weed growth at crop establishment. Of 1800 species reported as weeds of rice, those of the Cyperaceae and Poaceae are predominant. The adoption of direct‐seeding has resulted in a change in the relative abundance of weed species in rice crops. In particular, Echinochloa spp., Ischaemum rugosum, Cyperus difformis , and Fimbristylis miliacea are widely adapted to conditions of DSR. Species exhibit variability in germination and establishment response to the water regime postsowing, which is a major factor in interspecifically selecting constituents of the weed flora. The relatively rapid emergence of “weedy” (red) rice, rice phenotypically similar to cultivars but exhibiting undesirable agronomic traits, has been observed in several Asian countries practicing DSR, and this poses a severe threat to the sustainability of the production system. Stale seedbeds, tillage practices for land leveling, choice of competitive rice cultivars, mechanical weeders, herbicides, and associated water management are component technologies essential to the control of weeds in DSR. Herbicides in particular are an important tool of weed management, but hand weeding is either partially or extensively practiced in countries of Asia, Africa, and Latin America. Though yet to be globally commercialized, transgenic rice varieties engineered for herbicide resistance are a potential means of weed control. The release of herbicide‐resistant rice for red rice control in the United States has indicated the need to critically examine mitigation methods for the control of gene flow. Integrating preventive and interventional methods of weed control remains essential in managing weed communities in DSR, both to prohibit the evolution of herbicide resistance and to maximize the relative contributions of individual components where herbicides are not widely used. There remains a need to further develop understanding of the mechanisms and dynamics of rice weed competition and of the community dynamics of weed populations in DSR to underpin sustainable weed management practices.

Weed Management in Direct‐Seeded Rice

Intercropping, the agricultural practice of cultivating two or more crops in the same space at the same time, is an old and commonly used cropping practice which aims to match efficiently crop demands to the available growth resources and labor. The most common advantage of intercropping is the production of greater yield on a given piece of land by making more efficient use of the available growth resources using a mixture of crops of different rooting ability, canopy structure, height, and nutrient requirements based on the complementary utilization of growth resources by the component crops. Moreover, intercropping improves soil fertility through biological nitrogen fixation with the use of legumes, increases soil conservation through greater ground cover than sole cropping, and provides better lodging resistance for crops susceptible to lodging than when grown in monoculture. Intercrops often reduce pest incidence and improve forage quality by increasing crude protein yield of forage. Intercropping provides insurance against crop failure or against unstable market prices for a given commodity, especially in areas subject to extreme weather conditions such as frost, drought, and flood. Thus, it offers greater financial stability than sole cropping, which makes the system particularly suitable for labor-intensive small farms. Besides, intercropping allows lower inputs through reduced fertilizer and pesticide requirements, thus minimizing environmental impacts of agriculture. However, intercropping has some disadvantages such as the selection of the appropriate crop species and the appropriate sowing densities, including extra work in preparing and planting the seed mixture and also extra work during crop management practices, including harvest. The selection of an appropriate intercropping system for each case is quite complex as the success of intercropping systems depend much on the interactions between the component species, the available management practices, and the environmental conditions. Plant breeding can contribute determinedly to increase of productivity of intercropping systems by investigating and exploiting the genetic variability to intercrop adaptation. This paper provides an overall view and evaluation of annual intercropping, summarizing its main advantages supported by a number of key examples from the literature which point out its great value in the context of sustainable agriculture.

/pdf/annual-intercrops-an-alternative-pathway-for-sustainable-fh12loak0h.pdf

Annual intercrops: an alternative pathway for sustainable agriculture.

Field experiments were conducted to study the effect of three rye (Secale cereale L.) populations, six triticale (×Triticosecale Wittm.) cultivars, and two barley (Hordeum vulgare L.) cultivars, used as cover crops, on the emergence and growth of barnyardgrass [Echinochloa crus-galli (L.) P. Beauv.], bristly foxtail [Setaria verticillata (L.) P. Beauv.], and corn (Zea mays L.). Moreover, bioassay studies were conducted to assess allelopathic potential of the winter cereal extracts on both weed species and corn. All winter cereal extracts reduced barnyardgrass and bristly foxtail seed germination and growth, but none of them had any effect on corn. Bristly foxtail was affected more by all extracts than barnyardgrass, and growth of both weed species was reduced more by the extract of barley cultivar Athinaida. In field, 4 wk after corn planting, barnyardgrass and bristly foxtail emergence was reduced by 27 to 80% and 0 to 67%, respectively, in winter cereal mulched plots compared with that in winter cereal mulch-free plots. On the contrary, corn emergence was not affected by any cover crop mulch. At harvest, corn grain yield increased by 45% in no herbicide treated barley cultivar Athinaida mulched subplots as compared with that in respective mulch-free subplots. This corn yield in no herbicide treated Athinaida mulched subplots was similar with that obtained in respective herbicide-treated subplots. The results of this study suggest that some winter cereals such as barley cultivar Athinaida could be used as cover crop for annual grass weed suppression in corn and consequently to minimize herbicide applications.

Allelopathic Potential of Winter Cereals and Their Cover Crop Mulch Effect on Grass Weed Suppression and Corn Development

Field experiments were carried out in northern Greece during 1994, 1995, and 1996 to study the effect of nitrogen fertilization on competition between sterile oat and wheat, barley, and triticale. Dry weight of all crops was not affected until early March by sterile oats (110 plants m−2), but wheat and triticale dry weight were significantly reduced by sterile oats competition after that time. Grain yield of both wheat and triticale was equally reduced by 61% due to the presence of sterile oats, whereas the reduction for barley grain yield was 9%. Nitrogen fertilization (150 kg N ha−1) slightly increased yield of all crops grown without weed competition compared to the control (0 kg N), whereas the same treatment increased sterile oats dry weight as well as its competitive ability against wheat and triticale. Split application of nitrogen (50 kg N ha−1 before planting and 100 kg N ha−1 in early March) caused a slightly higher increase in sterile oats dry weight compared to the control or one appl...

Influence of nitrogen on competition between winter cereals and sterile oat

Effects of aromatic plants incorporated as green manure on weed and maize development.

Summary: Resume: Zusammenfassung
Bioassay procedures, based on the root growth of maize (Zea mays L.), sunflower (Helianthus annuus L.), lentil (Lens esculenta M.) and sugar-beet (Beta vulgaris L.) were used to study the phytotoxicity and persistence of the herbicides chlorsulfuron, tribenuron-methyl, triasulfuron, and metsulfuron-methyl as affected by concentration and soil type. All bioassays indicated that phytotoxicity of all herbicides was not affected by soil texture but was increased with increasing herbicide concentration and soil pH. Chlorsulfuron and metsulfuron-methyl showed the highest phytotoxicity, and tribenuron-methyl the lowest; triasulfuron indicated intermediate phy-toxicity. Sugar-beet was found to be the most sensitive crop to all four herbicides, while maize and sunflower were the least; lentil showed intermediate sensitivity. The relationship between phytotoxicity and herbicide concentration was best described by a quadratic equation. Concerning field persistence, the results indicated that persistence and leaching of all herbicides in all soils increased with increasing rate of application, except for tribenuron-methyl in the sandy clay loam soil where they were very low. Sunflower, lentil and sugar-beet sown 8 months after herbicide application in the sandy loam soil were not affected by tribenuron-methyl, but were injured by all the other herbicide treatments. These three crops and sunflower sown at the same time in the sandy clay loam and silty clay loam soils, respectively, were not affected by any treatment while lentil and sugar-beet were injured by chlorsulfuron in the silty clay loam soil only.

Phytotoxicite et persistance du chlorsulfuron, du metsulfuron-methyl, du triasulfuron et du tribenuron-methyl dans trois sols

Des essais biologiques bases sur la croissance rac-inaire du mais (Zea mays L.), du tournesol (Helianthus annuus L.), de la lentille (Lens esculenta M.) et de la betterave a sucre (Beta vulgaris L.), ont ete utilises pour etudier la phytotoxicite et la persistance du chlorsulfuron, du metsul-furon methyl, du triasulfuron et du tribenuron methyl en fonction de leur concentration et du type de sol. Tous les essais ont montre que la phytotoxicite de tous ces herbicides n'etait pas affectee par la texture du sol, mais augmentait avec leur concentration et le pH du sol. Le chlorsulfuron et le metsulfuron methyl etaient les plus phytotoxiques, le tribenuron methyl le moins, alors que la phytotoxicite du triasulfuron etait intermediare. Une equation du second degre fournissait la meilleure description de la relation entre la concentration d'herbicide et sa phytotoxicite. La persistance au champ et le lessivage de tous les herbicides dans tous les sols augmen-taient avec la dose de traitement, a l'exception du tribenuron methyl dans le limon sablo-argileux, cas ou ces phenomenes etaient peu importants. Le tournesol, la lentille et la betterave a sucre semes huit mois apres le traitement dans le limon fin argileux n'etaient pas affectes par le tribenuron methyl, alors qu'ils 1'etaient par les autres herbicides. Ces trois cultures et le tournesol semes en meme temps, respectivement dans le limon sablo-argileux et le limon fin argileux, n'etaient affectees par aucun traitement alors que la lentille et la betterave e sucre etaient touchees par le chlorsulfuron seulement dans le limon fin argileux.

Phytotoxlzita undPersistenz von Chlorsulfuron, Metsulfuron-methyl, Triasulfuron und Tribenuron-methyl in 3 Boden

Mit Biotests des Wurzelwachstums von Mais (Zea mays L.), Sonnenblume (Helianthus annuus L.), Linse (Lens culinaris M.) und Zuckerrube (Beta vulgaris L.) wurden die Phytotoxizitat und Persistenz der Herbizide Chlorsulfuron, Tribenuron-methyl, Triasulfuron und Metsulfuron-methyl nach Dosierung und Bodenart untersucht. Alle Tests ergaben, das die Bodentextur die Phytotoxizitat aller Herbizide nicht beeinfluste, jedoch steigende Dosis und pH-Wert des Bodens. Chlorsulfuron und Metsulfuron-methyl waren am meisten phytotoxisch, Tribenuron-methyl am wenigsten, Triasulfuron mittel. Die Zuckerrube war gegenuber allen Herbiziden am meisten empfindlich, Mais und Sonnenblume am wenigsten, Linse mittel. Die Beziehung zwischen Phytotoxizitat und Herbizidkonzentration folgt am besten einer quadratischen Gleichung. Die Persistenz und Auswaschung aller Herbizide nahmen mit dem Aufwand zu, auser bei Tribenuron-methyl in einem sandig-tonigen Lehmboden, wo beides niedrig war. Bei der Sonnenblume, der Linse und der Zuckerrube zeigten sich bei Aussaat 8 Monate nach der Herbizidanwendung in einem sandigen Lehm keine Schaden von Tribenuron-methyl, wohl aber von der anderen Herbiziden. Bei Aussaat der Testpflanzen in sandig-tonigem Lehm oder schluffig-tonigem Lehm wurden bei allen Herbiziden keine phytotoxischen Wirkungen gefunden, auser bei Linse und Zuckerrube und Chlorsulfuron nur in dem schluffig-tonigen Lehm.

Ilias G. Eleftherohorinos

Papers

Pesticide Exposure, Safety Issues, and Risk Assessment Indicators

Allelopathic Potential of Winter Cereals and Their Cover Crop Mulch Effect on Grass Weed Suppression and Corn Development

Influence of nitrogen on competition between winter cereals and sterile oat

Effects of aromatic plants incorporated as green manure on weed and maize development.

Phytotoxicity and persistence of chlorsulfuron, metsulfuron‐methyl, triasulfuron and tribenuron‐methyl in three soils