Spring Cereal Weed Control

Once your crop is sown, spring cereal weed control is highly dependent on herbicides.  The key requirements for cost-effective herbicide programmes are listed below.
1. The type of weeds present-Correctly identifying the weeds present in your fields (field history can be very helpful here) and knowing the importance of these weeds are critical.  Some weeds are more competitive than others (see figure 1 below) and relatively small numbers of highly competitive weeds can cause large yield losses and cost you money. 

Figure 1: The Relative Competitiveness of Weeds in Spring Cereals
 

2. Weed size and population-Higher rates of herbicides are required for larger weeds and for dense weed populations.  There are significant opportunities to save money with reduced rates in fields with low levels of weeds and where the weeds are small.  Target the 3-5 leaf stage of the crop (opportunity to combine with an aphicide).  Waiting until the first fungicide timing (GS30-32) will cost more and may impact on yield.

3. Weather-Weather conditions when you spray obviously have an impact on the success of almost all spraying operations and spring cereal weed control is no exception.  What is also important is the weather in the 3-4 days immediately prior to spraying with active growth needed to ensure the weeds absorb the chemical (particularly important if reduced rates are being used).

4. Sprayer Setup-This can often be forgotten about but water volumes, boom height above the crop, forward speed, nozzles used, pressure and general sprayer condition play a very important part in achieving a good kill of weeds.

Key point: While product selection is important, there are a number of important other factors to consider to successfully control weeds in your spring cereal crops-the type of weeds present, weed size, weather conditions and sprayer setup.

5. Product Selection-The objective is to choose the herbicide product combination that will successfully kill the weeds, particularly the most important weeds, present in your fields for the lowest cost.  However, it is wise to build in some level of insurance with the product rates without increasing costs too much.

Your product selection will be limited by crop safety, crop growth stage and label restrictions.  There is a large array of suitable products for use in standard crops of spring wheat and barley.  Options are more limited for spring oats, triticale and crops undersown with grass and/or clover.

For standard spring cereal crops correct selection of a combination of a sulfonylurea (SU) mixed with an alternative chemistry product gives successful broadleaf weed control and acts well as an anti-resistance strategy. Dairygold recommends (SUs):
• Presite Max (68% Ally + 150% Harmony)-Do not apply to oats
• Cameo Max (100% Cameo + 38% Harmony)
• Biplay (83% Ally + 66% Cameo)
Dairygold recommends (alternative chemistry):
• Hi Load Mircam (hormone)
• Galaxy (Boxer, fluroxyper + Shield)
• Hurler/Reaper (straight fluroxyper)

Remember product restrictions when targeting Wild Oats e.g. never mix Wild Oat killers with hormones and allow the appropriate interval between application of separate Wild Oat and broadleaf herbicides i.e.
• Axial first-allow 7 days before applying the broadleaf herbicide
• Broadleaf herbicide first-allow 21 days before applying Axial.
 
Because of the importance of Wild Oats (rejection of premium crops, competitive nature of the weed etc.), in some fields it may pay you to prioritise wild oat control.  This can be done by combining Axial with the broad leaf herbicide. Note you can use Axial with SUs but the higher rate 0.3L/ha is required.  Galaxy or Hurler/Reaper are suitable mixer products in this situation.

Alternatively Wild Oats control can be carried out first, timed as early as GS 13-15 of the crop (combined with the aphicide) but it must be noted that all the Wild Oats need to be emerged for successful control and this may be later depending on local conditions. 

Key point: Given the importance of Wild Oats as a weed in spring cereals, you should prioritise its control.

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