In response to concerns about the use of aminopyralid, we have compiled some questions to help you find the answers you are looking for.
For grassland farmers, these products offer the most effective weed control on the market today. Aminopyralid sprays work especially well on difficult to control weeds, such as thistles and docks as well as weeds that are potentially dangerous to livestock, such as ragwort.
These sprays deliver a level of control that frequently removes the need for follow-up treatment, so less herbicide is used overall. Forefront T, which contains aminopyralid, can only be used on grassland that is grazed by sheep and cattle only, and the manure produced by these animals must stay on the field. It is not to be used where horses graze. It is not to be used on grass intended for hay or silage.
If herbicide users follow the clearly stated recommendations on the label printed on each pack, there is very little chance that they will be found in manure in your garden.
Yes. In their review, CRD (previously PSD) indicate that the levels of residues found in affected crops do not have any implications for human health.
“Although aminopyralid is an effective weedkiller it is of low toxicity to mammals. Additionally the Chemicals Regulation Directorate (CRD) has assessed further information from the manufacturer that confirmed that using manure which may contain residues of aminopyralid in the ground used to grow vegetables does not have implications for human or animal health.
Even if the manure was derived from animals fed only grass, or silage made from grass treated with aminopyralid, and the plants took up all the aminopyralid present in that manure, the highest residues would not give rise to consumer health concerns and the vegetables should be safe to eat."
Sensitive plants include peas, beans and other legumes, carrots, potatoes, tomatoes, lettuces and spinach. Dahlia corms and a few species of rose are also affected.
Symptoms are expressed as cupping of leaves, stunting of plants, and curling of the growing point, giving it a fern-like appearance. See examples.
Yes, there are a number of other factors that may cause plant injury such as damping off, or insect or disease damage, trace elements and nutrient deficiency caused by weather conditions, soil and / or compost interactions, and you should check for these. You should also check the compost is appropriate for the intended use (i.e. mulch, potting compost, soil enrichment), follow compost recommendations regarding digging in and use rate.
Similar symptoms may also be observed if the compost or soil enricher contains an amount of green waste based upon grass clippings which have previously been treated with lawn care products.
If peas, beans, or potatoes (the most sensitive crops) are not affected, it is unlikely that aminopyralid is to blame.
Assuming that any affected manure or compost is worked in to the soil, and the ground is turned over, well cultivated and moist to ensure the breakdown of plant material in the manure/compost, then the ground will be safe to grow dahlia corms or vegetables the following year. If practicing a no-dig garden approach, then rake off and remove any residual manure or compost in the year prior to planting.
These symptoms may indicate aminopyralid residue in the manure. Signs of other kinds of damage will most likely indicate other issues such as damping off or bacteria-infected soil, etc.
Aminopyralid is broken down by soil micro-organisms, which live in damp, well-aerated soil. These conditions are best achieved by maintaining good soil conditions, and thoroughly incorporating the manure or compost into the soil. In dry soil conditions, breakdown may take longer, and you may need to consider watering.
Contact our technical hotline UKHotline@corteva.com for further advice.
Where it is possible to dig the soil, the best way to reduce the likelihood of a problem next season is to keep the land turned over to aerate the soil which encourages breakdown of the cellulose material in manure. As it breaks down aminopyralid is released into the soil and then broken down rapidly by naturally occurring micro-organisms.
Alternatively, around perennial plants such as roses and dhalias, rake away any visible signs of manure or mulch, then keep the soil around the plant in good condition to encourage microbial activity.
Dig in the compost or manure as much as possible, and maintain good soil conditions and you can then grow the following plants as appropriate to the season:
Brassicae e.g. broccoli, cabbage, cauliflower
Cucubits (e.g. courgettes, squash etc.)
Sensitivity or tolerance to any herbicide is dose‐dependent, so the list above is drawn up in the context of the likely amounts of aminopyralid found in manure that might be used in gardens or allotment.
We would advise that affected manure is not used where sensitive crops like potatoes, beans, lettuce and tomatoes are likely to be grown.
No. Until the aminopyralid is released from the cellulose and comes into contact with soil dwelling micro-organisms it will be stable. Breakdown will occur only after manure is incorporated into aerobic soil.
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