Herbicide Residue Drift Injury - Canola Council of Canada

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8 Herbicide Residue Soil Characteristics Interactions between soil factors are complex and may either slow the rate of herbicide breakdown or increase the availability of any remaining herbicide residue to the crop. Organic Matter and Soil Texture As organic matter decreases, microbial degradation of the herbicide decreases, increasing potential carryover. Soils with low clay content have decreased adsorption of residual herbicides, thereby increasing potential carryover. Therefore, potential for injury on subsequent canola crops increases as organic matter decreases, and clay content decreases (except where soluble herbicides are leached by lots of rainfall). pH Soil pH affects herbicide decomposition and availability to the subsequent canola crop (Table 1). Climate Drought Under drought conditions, microbial and hydrolytic breakdown of herbicides is decreased and adsorption of herbicide to soil particles is increased. The influence of drought on soil may override any previously favourable pH or organic matter conditions. Temperature When microbial decomposition is an important mechanism (e.g. imidazolinones), decomposition is reduced by cool soil temperatures.
Table 1: Soil factors that effect the degradation of some residual herbicides. Group Name Group No. Herbicides Mechanism of Degradtion Rate of Degradation is slowed when: Imidazolinone 2 Imazethapyr Imazamox Imazamethabenz Microbial Soil pH < 7.0 Drought Sulfonylurea 2 Metsulfuron Ethametsulfuron Chemical Hydrolysis Soil pH < 7.0 Drought 2 Sulfosulfuron Hydrolysis Microbial Soil organic matter < 4% Soil pH > 7.0, Drought Sulfonylamino carbonyltriazolinone 2 Flucarbazone Microbial Low soil organic matter Soil pH > 7.0, Drought Triazolopyrimidine Sulfonanalide 2 Florasulam Microbial Low soil temperature Dinitroanilines 3 Trifluralin Ethafluralin Microbial Drought Pyridinecarboxylic Acid Protoporphyrinogen Oxidaze Inhibitors 4 Clopyralid Microbial 14 Sulfentrazone Microbial Drought Low organic matter Drought High soil pH, Low CEC Source: Factors Affecting Herbicide Residue: Impact of a Dry Year. Eric Johnson, M.Sc., P.Ag., Agriculture and Agri-Food Canada, Scott Research Farm, Scott, SK. 2006 Recognizing Herbicide Residue and Drift Injury in Canola 9
Page 1 and 2: Recognizing Herbicide Residue Drift
Page 3 and 4: Foliar Herbicide Injury Introductio
Page 5 and 6: Recropping Restrictions for Residua
Page 7: Herbicide Clearfield Canola Non-Cle
Page 11 and 12: Carryover can have considerable fie
Page 13 and 14: In this case, cupping was caused by
Page 15 and 16: These plants also exhibit symptoms
Page 17 and 18: An unaffected (left) and severely a
Page 19 and 20: An unaffected plant (left) and one
Page 21 and 22: Severe Symptoms At the 3-leaf stage
Page 23 and 24: Severe Symptoms Leaf purpling and c
Page 25 and 26: Severe Symptoms The combination of
Page 27 and 28: Recognizing Herbicide Residue and D
Page 29 and 30: Symptoms observed at this stage are
Page 31 and 32: Chemical Family Active Ingredient F
Page 33 and 34: Conclusion Herbicide carryover can
Page 35 and 36: Recognizing Herbicide Residue and D
Page 37 and 38: OBJECTIVES AND METHODS This section
Page 41 and 42: Sulfosulfuron symptoms: 2% of an 11
Page 49 and 50: Imazethapyr and Imazamox symptoms:
Page 51 and 52: Imazethapyr and Imazamox symptoms:
Page 55 and 56: 2,4-D Ester 600 symptoms: 5% of a 2
Page 57 and 58: 2,4-D Ester 600 symptoms: 10% of a
Page 59 and 60:
Effects of Foliar-Applied Group 6 H
Page 61 and 62:
Effects of Foliar-Applied Group 9 G
Page 63 and 64:
Effects of Foliar-Applied Group 14
Page 66:
Canola Council of Canada 400 -167 L
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Herbicide Residue Drift Injury - Canola Council of Canada

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