Welcome to the Corteva Agriscience™
Forage Agronomy Update
These regular technical notes are a seasonal commentary to help those interested in improving grassland and forage productivity on dairy, beef, sheep and equestrian enterprises.
You can claim two CPD points for subscribing to this email update.
|
|
|
|
|
|
- Timing your dock control
- Using Envy to control buttercups and dandelions
- Key weeds to control in newly sown leys
- Planting maize after grass with LumiGEN Insecticide Bird Repellent treated seed
|
- Pioneer hybrid selection when sowing late
- Ask a question
- IASIS points
|
|
|
|
|
|
Perennial weeds emerge in pasture where there are gaps either caused by insect damage, grazing damage, poaching or where there has been poor establishment of grass species. Weeds will colonise any area of bare soil and the growth of perennial weeds is particularly quick where they are growing from existing root fragments or shoots.
Growth of docks will continue to be affected by the fluctuations in day and night temperatures. Coming out of winter, docks will typically appear purple and have thicker, waxy leaves and leaf area can be quite small. Both broad leaved dock and curled dock have deep tap roots (up to 1.5m in length). Translocated herbicides need perennial weeds to be actively growing to ensure that the chemical can get down to the roots of the weeds to achieve optimum control. Docks showing active growth will be a more vibrant green and less waxy. For optimal control wait until overnight frosts / cold nights have passed and sustained active growth has begun.
|
|
It is important to control docks because:
- They only have 60-65% of the feed value of grass and can affect silage fermentation, thus reducing overall quality.
- Docks compete with grass for light, space, water, and nutrients and thus reduces grass yields.
- They thrive in intensively used and highly fertilised grassland.
- Docks are generally unpalatable to livestock.
The ideal time to spray docks with an effective translocated product such as Doxstar® Pro, is when the plants are actively growing, the size of a dinner-plate (approx. 20cm across) and before they begin the flowering process. Apply Doxstar Pro at 2 litres/ha in at least 300 litres of water, or up to 400 litres of water if dock numbers are high or the grass sward is particularly dense. Water volume is very important to achieve good coverage of the weeds. It is tempting to reduce water rates, but this is likely to result in shorter term dock control.
Chickweed and dandelions are also controlled from an application of Doxstar Pro.
In cutting fields, ideally spray docks at least 28 days before cutting, this allows the spray to reach down to the roots to kill the plant and for the weed biomass to decay ahead of the silage cut, meaning that they won’t be taken into the clamp causing a reduction in silage quality. However, if grass is growing quickly and there is a need to cut sooner, spraying at least 21 days before cutting will still give good control of docks.
|
Using Envy to control buttercups and dandelions
|
Buttercups can become a significant problem in ageing pasture where sown species of grass are losing their vigour and where soil structure and drainage is poor. It might not be possible to re-seed these fields in the immediate future, so rejuvenation of the sward through removal of problem weeds such as buttercup can bring about significant improvements in grazing fields and in fields which are both grazed, and a silage cut taken.
Buttercups can be a skin irritant, causing contact dermatitis in livestock, and can also cause stomach irritation. As buttercup populations increase, grazing animals are less able to be selective in their grazing and the risk of these conditions increases. As with all perennial weeds, the best time to spray buttercups is before flowering in the spring.
Dandelion can also be a troublesome weed in some grassland fields and tends to colonise where grass has been over grazed and soil fertility is low. Although dandelions are palatable to stock, they are relatively unproductive in terms of nutrition and so can reduce the overall productivity of pasture if they are present. As with buttercups, best control is achieved with a pre-flowering treatment.
Use Envy® to control both buttercups and dandelions.
The advantages of using Envy:
- Envy is very safe to grass.
- Contains florasulam, enabling good control in cooler temperatures.
- It can give over 85% control of buttercups and dandelions.
- It has a short stock exclusion of just 7 days (allow 14 days where high populations of buttercup are present).
- Use in established grassland at 2.0 litres/ha in 200 to 400 litres of water per hectare.
|
|
The key weeds to control in newly sown leys
|
In newly sown leys, weeds can easily outcompete the seedling grasses if they are allowed to get too big. Now is a good time, once grasses have reached the 3-leaf stage, to check whether a herbicide spray is needed to remove any seedling annual weeds, such as chickweed and redshank, plus seedling perennials such as docks and thistles. Pastor® Trio and Envy are amongst the few products to have approval for weed control in newly sown leys, although it should be noted that neither are clover safe. For best results apply when weeds are small and actively growing.
Spraying early in the life of a ley will ensure a clean start, allowing grass to establish quickly without competition from weeds. It is more economical and effective to treat weeds at this stage than wait for them to establish and treat when they are bigger. Both can be applied from 1st February and from the 3-leaf stage of the grass.
|
|
Where there is a wide range of weeds growing in a newly sown grazing ley, including seedling thistles and spring-germinating polygonums, treating with Pastor Trio at 1.0 litre/ha would be a better option as this has a broader spectrum of activity. Where docks are present in a newly sown ley, it is important to check to see if they are growing from seed or regenerating from dock root fragments which have carried over from the previous crop. If the latter, treating with Envy is a good option, as this can be sprayed onto a newly sown ley, which is intended for grazing or cutting, at a robust dose rate of 1.5 litres/ha.
Both Envy and Pastor Trio are very safe to grass but will kill clover. When compared with straight fluroxypyr, both products offer control of many more weed species and work far better if conditions are still cool.
If having clover in the mixture is important, spray out the weeds first and the clover can be stitched in as soon as three months after treatment with Envy or Pastor Trio.
|
Planting maize after grass with LumiGEN Insecticide Bird Repellent treated seed
|
When sowing maize following a crop of grass, the risk that the previous grass crop was infested with wireworms must be considered. Wireworms are the larvae of the click beetle. The larvae grow up to 25mm in length and are orangey/brown in colour with a narrow, segmented body, biting jaws and three pairs of short legs behind the head.
|
|
Wireworm on the base of a maize stem
Risk factors:
- Fields that have been in leys for four years or more.
- Fields in all arable (no-grass) rotations.
- Porous, well-drained loam soils.
- South facing fields are more inclined to be infected than north facing fields.
- Minimum tillage supports higher wireworm populations than conventional tillage.
Background
Wireworms are the larvae of three species of click beetles; Agriotes lineatus, A. obscurus and A. sputator. The life cycle is typically five years and it is the more mature larvae that cause the greatest crop damage. Symptoms will include non-emergence of seedling, stunted plants, holes at the base of the maize stem as well as yellow and twisted leaves. The wireworms are easily found by digging up the soil. Pioneer offer LumiGEN Insecticide Bird Repellent treatment on certain hybrids e.g. P7179 and P7326. Some protection against wireworm is provided by this seed treatment option.
|
Pioneer maize hybrid selection when sowing late
|
Delayed planting situations due to wet or cold weather invariably raises questions about how much yield is being lost.
Maize planting research generally shows an optimum planting window for maximum yield being between mid-April and early to mid-May after which yields decline. Surveying average yields in a large number of on-farm trials does not necessarily show the optimum planting date window but can give a sense of the rate of yield decline observed.
Such declines have been measured at around 75 – 100 Kg of silage dry matter per hectare per day. However, there are many other factors of course that can also affect yield and this decline can vary very substantially from one situation to another.
One way of ensuring a minimum yield loss in a late planting situation, especially in a maritime climate such as in the UK or Ireland, is to select an early flowering hybrid. This maximises the chance of a full grain fill period following flowering. In the Pioneer range two hybrids stand out for early flowering and they are P7179 and P7326. Both are extra early maturing hybrids due to this early flowering habit and provide a measure of confidence that full maturity can be reached even though planting may be delayed.
|
|
|
|
Q: Will Envy control all species of buttercups?
A: Yes, it controls meadow, creeping and bulbous buttercup.
Q: How long after removing docks, thistles and nettles can you stitch species to make a herbal ley such as clovers, sheep burnett, trefoil, lucerne etc.?
A: You need to wait 4 months after the use of Forefront T, which will give good control of all 3 of these weeds.
|
|
|
10 IASIS points will be awarded to those subscribing to the Forage Agronomy Update. Sign up to this e-newsletter to receive IASIS points.
|
|
|
|
|
|
|
Use plant protection products safely. Always read the label and product information before use. For further information including warning phrases and symbols refer to label. ®™ Trademarks Corteva Agriscience Limited and its affiliated companies. All other brand names are trademarks of other manufacturers for which proprietary rights may exist. All manufacturers tradenames and trademarks are duly acknowledged. © 2023 Corteva. Doxstar ® Pro contains fluroxypyr and triclopyr, Envy ® contains fluroxypyr and florasulam, Forefront® T contains aminopyralid and triclopyr, Pastor® Trio contains fluroxypyr, clopyralid and florasulam
|
|
|
|
|
