Synergistic mechanism and environmental behavior of tank-mix adjuvants to topramezone and atrazine.

An effective way to reduce herbicide quantity is to use adjuvants in order to optimize the amount of herbicide and improve its control efficiency. In order to screen for efficient herbicide tank-mix adjuvants, improve the control of weeds in maize fields, reduce the amount of effective ingredients, and improve the adsorption and digestion behavior of herbicides in soil, this study evaluated the synergistic effects and soil behavior of four types of tank-mix adjuvants combined with herbicides. Different types of adjuvants can enhance herbicide production. Surface tension was significantly reduced by 13% after the pesticide solution was applied with AgroSpred™ Prime. The contact angle with the foliar surface was significantly reduced and solution wettability improved using Atp Lus 245-LQ-(TH). The permeability of topramezone and atrazine in leaves of Amaranthus retroflexus L. and Digitaria sanguinalis (L.) Scop. was increased by 22-96% after adding either tank-mix adjuvant. The solution drying time and maximum retention on leaves were not affected by the tank-mix adjuvants. Ethyl and methylated vegetable oils can reduce the adsorption of topramezone in the soil, thus reducing its half-life in soil. The tank-mix adjuvants had no significant effect on soil dissipation or adsorption of atrazine. AgroSpred™ Prime and Atp Lus 245-LQ-(TH) have the best synergistic effect on topramezone and atrazine in the control of A. retroflexus L. and D. sanguinalis (L.) Scop. in maize fields.

Natural Occurrence of Mycotoxins in Maize in North China.

Mycotoxins seriously threaten the quality of maize seriously around the world. A total of 426 samples of maize kernel from northeast and northwest China were analyzed in this study. Ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was performed to analyze the mycotoxin contamination of maize samples. The results showed that it was contaminated by mycotoxins in maize. The average contamination levels of fumonisins, deoxynivalenol, aflatoxins, zearalenone, ochratoxin A, T-2 and HT-2 were 937, 431, 22, 27, 2 and 12 µg/kg, respectively. Concentration of mycotoxins in some samples exceeded their limit, but most were still at safe levels. The contamination level of FBs and DON were most significative. The proportion of mycotoxins exceeding the maximum limit standard was in the following order: 8.0%, 8.0%, 7.0%, 1.6%, 1.4% and 0.0%. The contamination of mycotoxins in maize varies from region to region.

Natural occurrence of fumonisins B1 and B2 in maize from eight provinces of China in 2014.

A total of 249 maize kernel samples from 8 maize-producing provinces of China were collected after the harvest season in 2014. All samples were analysed using high-performance liquid chromatography. The incidences of FBs (FB1 + FB2) from Guizhou, Hebei, Inner Mongolia, Shanxi, Chongqing, Liaoning, Heilongjiang, and Henan provinces were 71.4%, 73.8%, 28.0%, 52.6%, 85.0%, 87.5%, 38.1%, and 100.0%, respectively. The average concentration of FBs was 817 µg kg-1 and the concentrations ranged from <6 to 15,252 µg kg-1. Among the 249 maize kernel samples, 28 samples exhibited higher levels as set by the Food and Drug Administration (2000 µg kg-1), whereas 12 samples exhibited higher levels as set by the European Commission (4000 µg kg-1). The average exposure to FBs (0.12 µg kg-1 body weight/day) is within the provisional maximum tolerable daily intake of 2.0 µg kg-1 body weight as set by the Joint FAO/WHO Expert Committee on Food Additives.

Fusarium species identification and fumonisin production in maize kernels from Shandong Province, China, from 2012 to 2014.

A total of 225 maize kernel samples were collected from Shandong Province in China from 2012 to 2014 and analysed for contamination with Fusarium spp. and fumonisins (FBs) using molecular methods and high-performance liquid chromatography with fluorescence detection. The results showed that the average incidences of Fusarium spp. in 2012, 2013 and 2014 were 23.3%, 37.1% and 36.5%, respectively, Fusarium verticillioides being the predominant species. In 2012, the average contamination level of FBs was 3071 ng g(-1), which was higher than that in 2014 (2913 ng g(-1)) and 2013 (2072 ng g(-1)). Of all samples, 13% and 19% had FB contamination levels higher than 2000 and 4000 ng g(-1), which are the maximum limits as set by the Food and Drug Administration of the United States and the European Commission, respectively. Therefore, efforts should be taken to minimise the potential risk of FBs to the health of humans and animals.

Natural incidence of Fusarium species and fumonisins B1 and B2 associated with maize kernels from nine provinces in China in 2012.

Fusarium species, which can produce mycotoxins, are the predominant pathogens causing maize ear rot, a disease that results in severe economic losses and serves as a potential health risk for humans and animals. A survey was conducted in 2012 to investigate the contamination of maize by Fusarium species and fumonisins B1 and B2. A total of 250 maize samples were randomly collected from nine provinces (Hebei, Shanxi, Inner Mongolia, Yunnan, Sichuan, Guizhou, Heilongjiang, Liaoning and Ningxia) in China. Fusarium species were isolated and identified using morphological (electron microscope) and molecular methods (polymerase chain reaction (PCR) and sequencing). Fumonisins B1 and B2 were analysed using high-performance liquid chromatography with fluorescence detection (HPLC-FLD) with OPA (2-Mercaptoethanol, o-phthaldialdehyde) post-column derivatisation. A total of 2321 Fusarium isolates (20.7%) were obtained from all the samples. These isolates included nine Fusarium species, namely, F. graminearum, F. verticillioides, F. subglutinans, F. proliferatum, F. temperatum, F. oxysporum, F. equiseti, F. meridionale and F. chlamydosporum. The incidence of occurrence of Fusarium species in Guizhou was the highest, while in Inner Mongolia it was the lowest. F. verticillioides was the dominant species of maize ear rot in Liaoning, Sichuan, Hebei and Ningxia. F. graminearum was the dominant species in Yunnan, Guizhou and Shanxi. F. subglutinans was the dominant species in Heilongjiang. F. verticillioides and F. graminearum percentages were the same in Inner Mongolia. The incidence of fumonisins in Liaoning was high (up to 81.0%) and in Heilongjiang low (up to 10.3%). Except Shanxi, more than 50% of maize samples from other provinces were contaminated with fumonisins, with concentrations less than 500 ng g(-1). About 33% of maize samples from Yunnan were contaminated with high levels of fumonisins, and average of fumonisin levels were 5191 ng g(-1). Fusarium species causing maize ear rot in different areas in China were highly diverse and such areas with exposure to high levels of fumonisin contamination have a potential health risk for human and animals.

Fumonisins B1 and B2 in maize harvested in Hebei province, China, during 2011-2013.

A total of 125 maize kernel samples were collected from Hebei province in China during 2011-2013 and were analysed for incidence and contamination levels of fumonisins (FB1 + FB2) by HPLC with fluorescence detection. The incidence of FBs for all samples was 46.4%. The mean contamination level of FBs for the samples collected in 2013 was 706 µg kg⁻¹, which was higher than the levels in 2012 (429 µg kg⁻¹) and 2011 (250 µg kg⁻¹). All samples, except five, exhibited total FB levels below 4000 µg kg⁻¹, which is the maximum limit as set by the European Commission. The probable daily intakes of FBs (0.04 in 2011; 0.07 in 2012; 0.12 in 2013, expressed as µg kg⁻¹ body weight/day) were all within the provisional maximum tolerable daily intake of 2.0 µg kg⁻¹ of body weight/day as set by the Joint FAO/WHO Expert Committee on Food Additives. Nevertheless, monitoring is needed to prevent and control the potential risk of FB exposure to the consumers.

Natural occurrence of fumonisins B1 and B2 in corn in four provinces of China.

Fumonisin B1 (FB1) and fumonisin B2 (FB2) are the most abundant fumonisins (FBs) occurring worldwide in maize, infected mainly by Fusarium verticillioides and F. proliferatum. A total of 307 corn kernel samples were collected from 45 districts of Gansu, Shandong, Ningxia and the Inner Mongolia provinces of the north and northwest China. The samples were analysed for FB1 and FB2 by high-performance liquid chromatography. The FBs (FB1+ FB2) incidence rate in samples from Gansu, Shandong, Ningxia and Inner Mongolia were 31.5%, 81.1%, 46.2% and 53.6%, respectively. Average FBs concentration was 703 µg/kg and the concentrations ranged from ≤11 to 13,110 µg kg(-1). Results were compared with the European Commission (EC) regulation for FB1+ FB2 in unprocessed maize for human consumption of 4 mg kg(-1). Contamination in 17 samples was higher than these levels. More than 80% of the samples from Liaocheng county, which is located in the Shandong province, were contaminated with FBs, with a mean total FB concentration of 2496 µg/kg. The result was significantly different from that of the Inner Mongolia (1399 µg/kg), Ningxia (373 µg/kg) and Gansu (175 µg/kg). Average exposure to FBs (0.12 µg/kg body weight/day) is within the provisional maximum tolerable daily intake of 2.0 mg/kg of body weight set by the Joint Food and Agriculture Organization and World Health Organization Expert Committee on Food Additives.