Why You Will Benefit From Boron Application This Season

Jess Sampson

Jun 02, 2022

In a wet season it is really important to keep an eye on our crops' nutrition program. Many of the micronutrients our crops require can be easily leached in wet years. This can result in stunted crops, lower yields or lower protein and oil percentages in crops. 


Boron is a micronutrient that plants require for healthy cell wall production, it plays an important part in healthy pollination & fruit/seed development. Boron is also instrumental in the translocation of sugars and carbohydrates within the plant. 

Along with other micronutrients such as zinc, copper and manganese, it is important to be proactive when applying Boron. Unfortunately, once a deficiency is noticeable, yield has already been affected. For best results it is recommended to apply a small amount, often. 

Some indications of Boron deficiency in crops include:

  • Yellowing and death of growing points (Chlorosis)

  • Thickening and cracking of stems (Distortion)

  • Root development anomalies

  • Dropping of buds

  • Discoloration and the crinkling of leaves.

As Boron is stored in soil organic matter, its availability will fluctuate according to microbial activity. Boron becomes available as organic matter decomposes. As a result, it can be easily leached, particularly during a wet season. 

Calcium, potassium, and nitrogen concentrations in both the soil and plant can affect boron availability and plant function, the calcium:boron (Ca:B) ratio relationship being the most important. Therefore, soils high in calcium will require more boron than soils low in calcium. 

As Boron requirements are low it is best to check your crop requirements. Doing a soil test or tissue test is the best way to find out how much Boron is readily available. Higher rates of Boron may be required in heavy clay soils, or soils that have a higher water pH/calcium content. 

Boron toxicity is a greater risk on low calcium-content soils. Some symptoms of Boron Toxicity may include:

  • Leaf tip yellowing

  • Leaf necrosis and drop - beginning in the leaf tip

  • Brown & stunted root tips

It is best to apply foliar B either in the early morning or evening, when the evaporation rate is low. This will maximise the length of time that the leaves will remain damp, allowing the plant to absorb the most Boron. 

OmniBor is compatible with a wide range of agricultural herbicides and pesticides. Check the Compatibility Guide as a reference. Always do a small jar test before preparing a full tank mix.


Rate L/ha


Water L


1 - 2

Mid - late tillering

50 - 80



1 - 2

10 - 14 days before flowering

50 - 80


1 - 2.5

Prior to flowering

50 - 80


1 - 2

Spring flush 



0.5 - 2

Flower clusters visible

200 - 800


1 - 2

10 - 14 days before flowering

50 - 80


1 - 2

10 - 14 days before flowering

50 - 80

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Jess Sampson

Jun 02, 2022