Field evidence of UK wild bird exposure to fludioxonil and extrapolation to other pesticides used as seed treatments

We determine the exposure of wild birds to pesticides via consumption of fludioxonil-treated winter wheat seeds following autumn drilling. We recorded the density of seeds left on the soil surface, bird density, and consumption of pesticide-treated seed by birds using camera traps. We calculated the dose ingested by each bird species in a single feeding bout and if they ate treated seeds exclusively for 1 day. We extrapolated this for an additional 19 pesticides commonly used as seed treatments, assuming equal consumption rates. All three fields contained grains on the soil surface (mean 7.14 seeds/m2 on sowing day). In total, 1,374 granivorous birds spanning 18 different species were observed in the fields, with 11 species filmed eating the seeds. Fludioxonil appears to pose a low risk to birds, with <1.14% of the LD50 potentially ingested by a bird for a daily maximum amount of seeds. Analysis of the further 19 pesticides commonly used as seed dressings suggests that the neonicotinoid insecticides imidacloprid, clothianidin, and thiamethoxam represent the highest risk for granivorous birds. For example, chaffinch (Fringilla coelebs) could consume 63% of LD50 of imidacloprid in a single feeding bout, and 370% in a day. Further investigation is clearly required to determine whether seeds treated with these other pesticides are consumed as readily as those treated with fludioxonil, as if so this is likely to cause significant harm.

​Effect of Seed Treatments and Storage Period on Seed Health Parameters of Pea (Pisum sativum L.) under Ambient Storage Conditions

Background: Pea (Pisum sativum L.) is an important leguminous crop utilized as vegetable and pulse, being an important source of proteins. Pea seeds harbour various mycoflora both in field and during storage, which plays important role in reducing seed viability, germination and vigour inflicting considerable losses in yield and quality. There is scarcely any recommendation available to maintain seed quality during storage of pea seeds, hence present study was carried out. Methods: Seeds of pea (cvs. Azad P. 1 and Arkel) were treated with Captan and Carbendazim 50%WP fungicides @ 2.0 g/Kg seed and stored under ambient conditions. The samples were drawn at three months interval to assess the effect of storage on seed quality parameters. The vigour index I, per cent germination and speed of germination of these seed samples were determined using ISTA rules. The detection of associated mycoflora in pea (Pisum sativum L.) seed samples was carried out by standard blotter method as recommended by International Seed Testing Association. Result: Total fourteen fungal species were found associated with different pea seed samples. Out of these, maximum incidence of Alternaria alternata (21.36%) followed by Aspergillus flavus (15.53%), A. fumigatus (14.56%), A. niger (11.60%) and Rhizopus stolonifer (9.71%), were recorded on untreated seed of pea cv. Azad P. 1, after 18 months of storage. The germination, speed of germination and vigour index of stored seed reduced with increase in storage period, whereas fungal incidence increased with the increasing storage period. Among the tested cultivars, germination in pea (cv. Arkel) remained above IMSCS even after 18 months of storage under ambient storage conditions. The maximum percent germination (99.0) was found in pea cv. Azad P. 1 seeds treated with Captan at 3 months of storage, whereas minimum percent germination (49.5) was found in untreated seed of pea cv. Azad P. 1 after 18 months of storage. The maximum speed of germination (23.88) was found in Captan treated seed of pea cv. Arkel at 0 month of storage and minimum speed of germination (3.52) was found in untreated seed of pea cv. Azad P. 1 at 18 months of storage. The maximum vigour index I (2339) was found in pea cv. Azad P. 1 (Captan treated seed) at 3 months of storage and minimum vigour index I (431) was found in untreated seed of pea cv. Azad P. 1 after 18 months of storage.

Gas-priming as a novel simple method of seed treatment with ethylene, hydrogen cyanide or nitric oxide

The gases used: ethylene (C2H4), hydrogen cyanide (HCN) and nitric oxide (NO) showed a high activity as inductors of germination in primary dormant or non-dormant seeds exposed to stress or suboptimal temperatures. So far, research on the role of ethylene, hydrogen cyanide and nitric oxide has involved these gases during seed germination. This work describes gas-priming as a novel method for treating air dry seeds of the genus Amaranthus serving as a model. Effects of C2H4, HCN or NO applied to dry seeds were similar to those obtained when the gases were used during seed germination for an identical period of time. Application of the gases to air dry seeds presents a new opportunity to study the role of those gases in germination of dormant and non-dormant seeds and to constrain effects of the gases from time 0. The prolonged treatment time for dry seeds (24 h) is convenient because if the treatment is started in the morning, there is sufficient time the next day for further experiments to begin, e.g. germination test in water or in solutions of other compounds. Moreover, it is important that the gas-treated seeds can be stored or transported prior to use. The gas-priming method allows to prepare treated seed samples which can be used in experiments either immediately or after storage in open air or in a closed container. Gas-priming with C2H4, HCN and NO is a simple and useful treatment of air-dried seeds, which opens up new useful possibilities for basic research on the role of those gases in releasing dormancy and seed germination of various plant species. In addition, the method may prove very useful in horticulture and agriculture in improving germination of gas-sensitive seeds.

Effect of Ozone on Inactivation of Purified Pepper Mild Mottle Virus and Contaminated Pepper Seed

Pepper mild mottle virus (PMMoV) is a major viral pathogen of pepper (Capsicum spp.). PMMoV is readily mechanically transmitted and is seed transmissible. Trisodium phosphate (TSP) treatment is commonly used to reduce the level of viable PMMoV in contaminated seed. Ozone is efficacious in disinfecting fungal-contaminated seed and disrupting bacterial and viral pathogens on various substrates. The purpose of this study was to evaluate efficacy of ozone and chemical treatment on PMMoV viability. Treated pepper seed infectivity was evaluated via bioassay with Nicotiana benthamiana. Symptoms of PMMoV infection were not observed in bioassays of TSP-treated seed. Sufficient viable PMMoV remained on ozone-treated seed to cause infection, which was confirmed by ELISA. Neither treatment affected seed germination. Ozone treatment of purified PMMoV was assessed to determine the extent, if any, of PMMoV inactivation by ozone. At the low PMMoV concentration (0.01 mg/ml), 14-h ozone exposure eliminated infectivity as determined by N. benthamiana bioassays with ELISA confirmations. At the higher PMMoV concentration (0.1 mg/ml), ozone treatment was insufficient to prevent infection. Ozone inactivation of purified PMMoV was quantified via bioassay using the local lesion host N. glutinosa and quantitative real-time PCR. Ozone exposure reduced lesion counts and PMMoV concentration, and PMMoV degradation increased with exposure time. Although PMMoV infection was eliminated at the low PMMoV concentration, bioassays using naturally infected seed and purified PMMoV preparations at relatively higher concentrations demonstrated that ozone is not efficacious as a standard treatment to sufficiently reduce levels of infective PMMoV in contaminated pepper seed. [Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Seed treatment of canola (Brassica napus) with the endomycorrhizal fungus Piriformospora indica does not reduce clubroot

A Basidiomycete endomycorrhizal fungus, Piriformospora indica, colonizes and promotes the growth of canola and other Brassica crops, and can reduce diseases of other crops. Clubroot is an important disease of Bbrassica crops caused by the obligate, soil-borne pathogen Plasmodiophora brassicae. The effect of P. indica on clubroot severity in canola was assessed in replicated growth room studies. Seed was treated with P. indica using a proprietary process. Microscopic observation confirmed that canola roots grown from treated seed were colonized by P. indica. However, P. indica did not consistently reduce clubroot severity and did not promote the growth of canola.

Sowing Uncertainty: What We Do and Don’t Know about the Planting of Pesticide-Treated Seed

ABSTRACT Farmers, regulators, and researchers rely on pesticide use data to assess the effects of pesticides on crop yield, farm economics, off-target organisms, and human health. The publicly available pesticide use data in the United States do not currently account for pesticides applied as seed treatments. We find that seed treatment use has increased in major field crops over the last several decades but that there is a high degree of uncertainty about the extent of acreage planted with treated seeds, the amount of regional variability, and the use of certain active ingredients. One reason for this uncertainty is that farmers are less likely to know what pesticides are on their seed than they are about what pesticides are applied conventionally to their crops. This lack of information affects the quality and availability of seed treatment data and also farmers’ ability to tailor pesticide use to production and environmental goals.