Early start pays for pea sprays
Early start pays for pea sprays
PEA yields can be boosted by up to 45% by getting herbicide strategy right, according to the PGRO. For most growers that means getting herbicides on early, says weed specialist Cathy Knott.
Pre-emergence products should be used where high populations of broad-leaved weeds are expected, and on lighter soils with fine seedbeds. But on organic soils or where cleavers are expected to be a problem, control should be left to a post-emergence timing.
Pre-emergence treatment should also be avoided on late sown crops as cultivation will remove much of the weed burden and no herbicide may be necessary, she adds. However, where a graminicide will be needed, a pre-emergence broad-leaved herbicide can buy time later on.
"Graminicides tend to strip the wax off the leaves, so crops have to be left for 14 days before another herbicide can be used. By then the broad-leaved weeds could be getting big and difficult to control," she explains.
Which pre-emergence product to use will depend on the soil type and weed spectrum anticipated. Reflex T (fomesafen + terbutryn) or Bullet (cyanazine + pendimethalin) should be used where volunteer oilseed rape is a problem, with Reflex T being the cheaper option on lighter soils as rates can be lowered.
"Bullet has a 5 litre/ha rate whatever, and it cant be used on sand or organic soils." However, Bullet is the best bet where knotgrass is a problem.
Reflex T should be used for fools parsley and black-bindweed, and also takes out poppies. Opogard (terbuthylazine + terbutryn) may be a cheaper option for the latter, but again is not recommended on the light sandy soils.
For all the pre-emergence products to work soil moisture is essential. If it is dry, or where cleavers are expected, growers should wait and use a post-emergence product instead, says Ms Knott.
With approval from first to third node, newly launched (Arable Feb 25) Impuls (bentazone + pendimethalin) has the earliest post emergence timing. Controlling cleavers, volunteer oilseed rape and most other broad-leaved weeds it could provide a one-hit answer for some growers, she acknowledges. However, it is not approved on soils with over 10% organic matter.
Half-rate Pulsar plus Fortrol (bentazone + MCPB plus cyanazine) is approved from second to fourth node and will take out volunteer oilseed rape. But to tackle cleavers a full-rate mix is required, which is only approved from third node. *
PEAWEEDCONTROL
• Best results from early applications.
• Pre-emergence where possible.
• Early post-em for cleavers or if very dry.
• Third node still earliest option on organic soils.
Precision timing is vital for pea herbicides, says PGROs Cathy Knott.