From the info sheet (which probably recommends a week or two earlier than I normally do it!)
Spray ASULOX at or just before full frond extension (minimum 3 ‘pairs’ of ‘leaves’) and before senescence
• DO NOT apply during or immediately after drought periods or in conditions of high temperature and low
humidity.
• The use of the red feed nozzle for ‘Micron Ulva’ application is restricted to forestry use where bracken
suppression only is required.
• The fronds must not be damaged by livestock, frost or by cutting before treatment. Do not treat bracken affected
by late frosts (bronzed and stunted fronds).
• At least 6 weeks should elapse between applying ASULOX and sowing or planting any subsequent
crop.
• DO NOT cut the bracken or admit livestock for at least 14 days after spraying and preferably leave it undisturbed until late autumn. This is to allow adequate translocation of ASULOX within the bracken plant
Apply on a dry day. Bracken should be treated in full frond (all fronds fully expanded) but before yellowing (start of senescence)..
Normally this will be within the period from early July to late August (early August in Northern Britain).
Senescence begins with the fronds turning a darker green, becoming glossy and hard to the touch, with
subsequent bronzing.
• ASULOX may be applied in water with or without ‘Agral’, or ‘High Trees Non-Ionic Wetter’, or in mixture with
ADDER or ‘Actipron’. These additives increase the rate of uptake of ASULOX by the bracken fronds thereby
improving reliability under adverse climatic conditions.
• Herbicidal symptoms are virtually absent in the year of spraying but in the following season there is little or no
frond re-growth.
• Follow up treatments:
Owing to the nature of bracken growth and the difficulty of spraying sheltered or uneven terrain, 100% control is
rarely achieved. Any bracken surviving should be sprayed as soon as it recovers to full green frond. This may be
the year following the initial application but more likely the second year following initial application. If a
programme of follow-up sprays is undertaken the bracken-free period will be greatly extended.
I put some dishwashing liquid in with the spay as an additive.
You don't need to remove the dead bracken but if it is very thick I'd probably pull the bulk off when it is completely dead. The spray is the death of it (mostly). If it were me I'd reseed late the same Autum or the next spring to help keep the other weeds down.