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