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Spraying Around Trees


Notes on the use of Roundup Pro Biactive around Trees
 
   
 
When planning new woodland, hedging or tree planting it is vital to remove pernicious and invasive weeds before planting to give the trees the best possible start.  Roundup Pro Biactive/Roundup ProBiactive450 can play an important role in creating and maintaining trees by removing weed competition, thus allowing maximum use of water, light and soil nutrients. There is no residual effect in the soil, so the treatment will not affect the trees through their roots and planting can start 7 days after spraying.  Trials show spraying pre-planting improves both tree survival and subsequent growth.

Roundup combines unrivalled weed control with the best environmental and operator safety profile.
 
Once planted further directed sprays will be necessary to maintain a weed free area around the trees. A circle of 1.5m in diameter is optimum to remove competition for moisture, light and nutrients and should be carried out as necessary - usually between April and September. Apply the higher perennial dose rate for a mixture of perennial and annual weeds.
 
Dose Rates
 
 
Spraying
Weedwiper
Perennial and annual weeds
Annual weeds only
Roundup Pro Biactive
5l/ha
3l/ha
1 part Roundup to 2 parts water
Roundup ProBiactive450
4l/ha
2.4l/ha
1 part Roundup to 2.75 parts water

For knapsack rates see application information
 
General Guidance on Spraying Around Trees
  • There is no danger to the trees from the product via the soil as it is not residual and has virtually no leaching potential, being tightly bound to the soil particles and quickly broken down to harmless components.
  • Mature trees, which have brown bark will not absorb glyphosate, but avoid any wounded areas on trunks as entry direct to the cambium can result in damage.
  • Any green area can absorb the product and potentially cause damage, so care should be taken around low hanging branches that leaves are not sprayed. Using a guard or hood over the nozzle of the sprayer should minimise accidental damage.
  • An alternative method is to use a Hand-held Weedwiper, taking care not to let the rope wick touch any part of the tree.
  • As drop size is important in minimising drift into the foliage, care should be taken that the correct nozzles are chosen to produce nothing finer than a medium spray (BCPC definition) or CDA drops of 200-300 microns and that the correct pressure for the application equipment is adhered to. Low pressure or low drift nozzles are recommended.
  • Tree shelters fitted around young trees helps provide protection against vermin and adverse weather conditions. Where trees are fitted with solid shelters there is no need to use a spray guard or direct the spray away from the tree, but spiral shelters or those with holes do not provide sufficient protection and should be treated as if they had no shelter.
  • Care should also be taken with species like Prunus, which have a tendency  to produce  suckers.  Uptake through side shoots and suckers can also cause damage to the mother tree. This is most likely to occur during late summer/ autumn when the sap flow is towards the mother plant. Suckers can either be avoided or cut down before spraying commences. Lime trees tend not to sucker in the true sense, but do produce a fringe of basal shoots from the base of the bowl. These basal shoots should be avoided with directed applications as some uptake to the mother tree will occur. (Any damage is likely to be small if sprayed in the spring and is usually outgrown within the year.)
  • Operators who carry a pair of secateurs in their pocket can soon snip off any branches or suckers which are inadvertently sprayed!
Timing 
 
Early spring application
 
Perennial weeds grow from root reserves, with sugars rising in spring. Glyphosate uptake is therefore not as efficient as late summer or autumn treatments when the sugars are flowing down to the roots for winter storage.  

When planning weed control programmes this factor needs to be taken into consideration. Where early spring treatments are carried out, then a second application for complete control of perennial weeds may be necessary in the summer.
 
Winter application - Technical Tips
  • Cold weather, moist leaves with dew in mornings, light frosts, slower growth - NO problem.
  • Catchy day, only have a dry morning - NO problem.
  • Couch, perennial grasses, perennial broad-leaves, annuals - NO problem.
  • Rainfast in 2-3 hours on annual grasses, 3 hours on couch.
  • Rainfast in 4-6 hours on other weeds.
  • More reliable than other glyphosate formulations in tough autumn/ winter conditions.
  • Spray on a frost in morning as long as leaves will dry later. Frost is only a problem if it continues for days and causes the weeds to stop growing and become flaccid.
  • Spray on the dew/mist in the morning so long as the day will stay dry. (Do not spray in the evening as increasing dew leads to run-off).  Use medium -coarse spray to avoid driftable fines.
  • Plants often take months to develop full symptoms in cold conditions, but death is certain if above guidelines are followed.
Weed growth stages
  • The best time to kill perennial broad-leaved weeds is around flowering.
  • Perennial grasses like couch should have 4-5 actively growing leaves, each with 10-15cm of new growth.
  • Annual grasses and broad-leaved weeds need to have at least 5cm of leaf growth or two expanded true leaves before they will take up the herbicide.
  • Poorer uptake also occurs during the rapid stem extension phase as the flowering stem is extending and should also be avoided if possible.