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Herbicide treatments can damage beet if applied when the crop is under stress or wax protection on the leaves is inadequate. Adverse weather, pest damage and nutrient deficiency can all interact with herbicide applications but herbicide choice can bring the flexibility to work around such stresses.

Weather has a big influence on crop stress and herbicide safety:

  • Hot weather (above 21°C) reduces the selectivity of all herbicides so during very hot periods, spraying in the evening or the early morning is a better option than spraying in the heat of the day
  • High light intensity also reduces the selectivity of herbicides
  • Frosts not only stress plants but also affect wax layers. There is a risk of severe damage and yield loss when herbicides are applied during or immediately after frost, particularly if it is the first one after a warm period
  • Fluctuating temperatures are likely to cause crop damage if night and day temperatures fluctuate by around 18°C or more. Also, if it has been hot for a few days (low 20sC day and night) and temperature then drops to 10°C or less (usually at night) crops can be at risk
  • Windy / cool conditions can increase wax layers on beet leaves and reduce herbicide damage, but unfortunately have the same effect on weeds, so can reduce activity unless a selective herbicide with good foliar penetration is used such as Betanal maxxPro. On light soils strong winds move abrasive sandy particles and damage leaf surfaces resulting in an increased risk of herbicide damage
  • Hail can also damage crop foliage and reduce herbicide selectivity


Betanal maxxPro’s advanced oil dispersion (OD) formulation widens the spraying window for weed control enabling the application of robust, broad-spectrum treatments to weeds at the early true leaves stage.

As a result, Betanal maxxPro adds the flexibility to select spray days with optimum conditions for herbicide activity to avoid the risk of crop damage.


Leaf damage caused by pests such as leaf miner reduces herbicides’ selectivity by allowing more to penetrate the foliage. Having lost the seed treatments control will be more difficult. The only authorised foliar spray for leaf miner control is Hallmark Zeon (lambda cyhalothrin) but this is likely to have a negative impact on beneficials.

Nutrient deficiency and soil acidity can reduce the crop’s tolerance of herbicides. Beet showing manganese deficiency symptoms are especially prone to herbicide damage and on manganese deficient soils (e.g. fen peats), manganese treatment should be included in the spray programme as routine.

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