Amino Acid Synthesis Inhibitor Herbicide Injury
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Soil applied amino acid synthesis inhibitor herbicides labeled for soybean

imazaquin
Preplant incorporated or preemergence applications of imazaquin (Scepter®, Tri-Scept®, Squadron®) may cause some crop stunting and temporary yellowing of young leaves, resulting in uneven plant height. Internodes may be shortened. Root hairs and secondary roots may be sparse or exhibit a bottle-brush appearance, and the tap root may be damaged at the growing point. Adverse growing conditions which place the soybeans under stress or use of excessive rates will enhance injury. Stress conditions include heavy rains shortly after application, drought, high temperatures, root pathogens and nematodes. Prolonged injury symptoms may result in yield reductions.

Soil applied amino acid synthesis inhibitor herbicides not labeled for soybean

prosulfuron

prosulfuron

prosulfuron

prosulfuron

prosulfuron

chlorsulfuron
Prosulfuron (Exceed®, Peak®, Spirit®) and Chlorsulfuron (Glean®) carryover causes shortened internodes, small leaflets, and variations in plant height. Chlorosis may or may not be present on the leaves. Injury occurs more frequently on high pH soil. Yield reduction can range from none to severe.

Postemergence application of amino acid synthesis inhibitor herbicides labeled for soybean

thifensulfuron +
chlorimuron

thifensulfuron +
chlorimuron

imazethapyr

pith color

vein color
Thifensulfuron + chlorimuron (Synchrony®) can cause interveinal chlorosis and shortened internodes. Newly expanded leaves may exhibit crinkling and leaflet veins may be a darker green color. Adverse growing conditions that place soybean plants under stress or use of excessive rates will enhance injury. Stress conditions can include heavy rains shortly after application, drought, high temperatures, high pH soil, root pathogens and nematodes. Prolonged injury may result in yield reduction.

Imazethapyr (Pursuit®) postemergence may cause interveinal chlorosis. This damage is usually cosmetic and yield reductions are not likely.

Many ALS inhibitors cause injury that appears as a dark color in the pith of the stem. ALS inhibitors labeled for soybean can cause the veins on the backside of the leaf to change to a red or black color when applied at excessive rates or when applied to soybean under stress.

Tank contamination of drift of amino acid synthesis inhibitor herbicides not labeled for soybean

nicrosulfuron

nicrosulfuron

nicrosulfuron

prosulfuron

bensulfuron

primisulfuron

pyrithiobac

prosulfuron+
primisulfuron

prosulfuron+
primisulfuron
Nicosulfuron (Accent®), prosulfuron (Peak®) , bensulfuron (Londax®), primisulfuron (Beacon®), pyrithiobac (Staple®), prosulfuron + primisulfuron (Exceed® or Spirit®) postemergence on soybean via drift or spray tank contamination may cause chlorotic leaves, black/red veins on the back of the leaflets and dead terminal buds. Yield reduction is probable if the terminal growing point is damaged.


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