Terbacil
Trade Names: Sinbar
Registration status: This herbicide is registered for use in tender fruit orchards. Use only on higher organic matter soils (more than 3%) and use lower rates on young trees.
When to suspect injury: Excessive rates on newly planted trees can cause injury. Do not use on soils with less than 3% organic matter for either new or established orchards. If you notice symptoms of interveinal chlorosis, followed by general chlorosis and finally total necrosis, look carefully at weeds in the treated area and check herbicide rates and the soil organic matter levels.
Herbicide Information: Knowing how the herbicide works will help to determine the likelihood of injury from either direct application or drift. Consider how the herbicide works in plants, behaves in soils and what symptoms are common in other plants.
Chemical Family: Uracil
Site of Action/WSSA Group: Inhibitors of photosynthesis at photosystem II, Site A/ Group 5
General Symptoms in Plants
- Foliar chlorosis, first interveinal, followed by total leaf chlorosis and eventually tissue death
- Inhibition of root and shoot growth
- More injury potential on low organic matter soils (less than 3%)
Symptoms in Fruit Trees
- As above, usually interveinal chlorosis followed by total chlorosis and leaf death
- Symptoms are worse if heavy rains follow application, and on low organic matter soils.
Uptake and Translocation
- Uptake is mostly through roots, although partially through foliage and stem
- Translocation is upward into leaves
Persistence
- Somewhat long residual, dependent on rate applied
- Half life in field: 120 days
- Stop applications of terbacil 2 to 3 years before removal of orchard
If you suspect herbicide injury, laboratory analyses of herbicide levels in plant tissue are necessary to confirm the presence of herbicides, although symptoms may be helpful in diagnosing which herbicides caused the problem.
Both damaged and healthy plant tissues should be analyzed, because comparison levels are not readily available for many herbicides. Contact your lab for instructions on which plant parts should be sampled, how to handle and ship the sample, and what costs are involved to ensure an accurate and timely diagnosis.
