Diagnosing contact herbicide damage in field peas

This includes contact herbicides from a range of chemical groups that require uniform spray coverage to be fully effective.

Sprayed plants rapidly become pale
Rapid bleaching and death where the spray lands
Plants rapidly wither and die
Group L Bipyridyls Group G Aryl triazalinone
Chemical name Example trade name Chemical name Example trade name
Diquat Reglone Carfentrazone Affinity, Hammer
Paraquat Gramoxone Group G Pyrimadindione
Diquat+paraquat Spray Seed

Butafenacil

Knockdown component of Logran B-Power

Group C Nitrile Group G Diphenyl ethers
Bromoxynil Buctril 200 Oxyfluorfen Goal

Symptoms appear within hours (Group L), or one or two days (Group G) of application.

 

What to look for

    Paddock

  • Widespread plant bleaching and limpness
  • Wind drift damage is worst on paddock edges. Temperature inversion drift occurs in low lying areas.

    Plant

  • The pattern of damage reflects spray coverage and may be worse on one side of the plant. Plants die or recover with fresh new growth appearing.
  • Numerous pale necrotic spots sometimes with a brown edge or streaks on the leaves,stems and tendrils.
  • More serious damage includes leaf wilting, marginal leaf burn and death of sprayed parts.
  • Severely damaged plants shrivel up within four days of application

What else could it be

Condition Similarities Differences
Diagnosing group F herbicide damage in field peas Pale leaf blotches and streaks on sprayed leaves. Plants recover.
Diagnosing glyphosate damage in field peas Chlorosis and death. Damage appears more slowly and begins with young growth interveinal chlorosis.
Diagnosing group C herbicide damage in field peas Chlorosis and death. Damage appears much more slowly, and starts in older growth.

Where does it occur?

Spraying herbicide
Spraying herbicide
  • Serious damage is generally caused by direct spraying. Contact herbicide spots may be caused by spray drift, but plants will generally recover.
  • Group G damage symptoms are greater when spraying occurs under humid, high temperature, high moisture, dewy and high sunlight conditions. Plant symptoms will also be greater where adjuvants such as oils are used. There has been no reported yield loss associated with these symptoms.
  • Bipyridl herbicides have some movement within a plant if sprayed at night, and consequently cause more damage than when sprayed in daylight

Further information

Where to go for expert help

John Moore
+61 (0)8 9892 8476
Page last updated: Wednesday, 13 May 2015 - 1:44pm