Attention must now be given to those fields which were not sprayed prior to first cut. Grassland herbicides use growth function to kill weeds, therefore peak growth periods should be used for herbicide application. There must be sufficient growth to allow herbicides to be effective and vegetative growth is the key time to apply, as the chemical then gets drawn down into the roots. Herbicides are less successful once plants have progressed to the reproductive stage and have thrown a stem or began to seed. Once weeds are beyond the ideal growth stage for spraying, they should be mowed or topped and allowed to regrow again, and a herbicide applied to the fresh young growth.
To optimise efficacy of any herbicide, recommended water volumes should be observed, even when it means more time spent spraying. It is important to note ragwort plants in their second year are now coming close to flower and should be sprayed immediately as flowering ragwort is poorly controlled. The routine herbicide treatments for this weed are full rate MCPA or 2, 4-D, and they are most active on growing rosettes with reduced activity as the stem starts to extend. They are not clover safe. You can use a mixture of both these products as Nufarm Lupo which allows an increased dose herbicide compared with either alone, with a consequent activity benefit. Forefront is also very effective on ragwort. Stock must be kept off until the weeds have rotted away, which can take up to six weeks.
Buttercups are now ready for treatment. Best results are achieved if sprayed before flowering. ENVY is very effective on both buttercup and dandelions. Envy contains florasulam and fluroxypyr. Together they deliver excellent control of weeds found in pastures which typically get over grazed, receive minimal nitrogen or have poorly competing grass species present. Envy has no manure management restriction and has a short seven-day stock withdrawal period so animals can return quickly. Envy is very safe to grass and won’t hold back its growth. Buttercups are best controlled when they are still green and leafy and before the main flowering period. You will still get control during flowering but for the best effect treat now. Product choice depends very much on which other weeds are being targeted. Where clover is important SPRUCE may be applied to control buttercup.
Where broad –leaved weed control has yet to be completed and the crop has passed the latest timing for Sencorex a reduced rate of Sencorex tank-mixed with Titus will provide a wider weed spectrum of weed control than Titus used alone and can be used on emerged crops up to 25cm high where the label allows .Scutch, other grasses or volunteer cereals are not controlled by the Titus/Sencorex mix. Where these weeds become a problem in coming weeks the graminicide Falcon can be used. Falcon can cause transient yellowing and is therefore not approved for use on seed crops.
As canopies close, the soil surface will tend to remain damper, encouraging slugs onto the soil surface. Timing is critical for effective control, just before the crop meets across the rows. Take advantage of any rainfall by applying pellets just afterwards, as this will bring slugs up onto the soil surface. Potato varieties particularly susceptible to slug damage include Maris Piper, Desiree and Kerrs Pinks.
Blight fungicides move through the plant in three different ways contact, translaminar and systemic. Dithane, Shirlan and Tizca are all contact fungicides. These Products protect only the outer surface of the leaf onto which they are deposited.Translaminar products such as Curzate M, Invader and Ranman Top move into the leaf and redistribute throughout the leaf tissue as it increases in size whilst systemic products such as Zorvec and Infinito move in through the leaf surface and upwards into the new growth protecting this from infection also. Products that have zoospore activity are the most effective 1st spray, applied at the rosette stage prior to rapid haulm growth. Shirlan or Tizca will control any zoospores that may be in the soil and provide good protection of the new plant. During the main canopy development phase with the considerable amount of new growth it is essential the product being used is fully systemic to properly protect the new leaves being put on between applications. Later planted crops are higher risk as they produce more new growth between applications than earlier drilled crops, at a time when the level of inoculum in the air is progressively increasing. The way the blight product is applied is as important as the product choice. Make sure nozzle type used is correct to ensure sprayer pressure; droplet size and water applied is as directed on the label. Inspect and calibrate nozzles regularly to maintain performance. Never use any blight product at reduced rates. Do not spray when the leaves are wet as this will significantly increase the likelihood of runoff.