The relative movement and persistence in soil of chlorsulfuron, metsulfuron‐methyl and triasulfuron

Abstract

Summary. Adsorption and degradation rates of triasulfuron in 8 different soils were negatively correlated with soil pH and were generally lower in subsoils than in soils from the plough layer. The half‐life at 20°C varied from 33 days in a top soil at pH 5·8 to 120 days in a subsoil at pH 7·4. Adsorption distribution coefficients in these two soils were 0·55 and 0·19, respectively. Movement and persistence of residues of chlorsulfuron, triasulfuron and metsulfuron‐methyl were compared in a field experiment prepared in spring 1987. Triasulfuron was less mobile in the soil than the other two compounds. Residues of all three herbicides were largely confined to the upper 40–50 cm soil 148 days after application. With an initial dose of 32 g ha−1, residues in the surface soil layers were sufficient to affect growth of lettuce and sugar‐beet sown approximately one year after application. Laboratory adsorption and degradation data were used with appropriate weather data in a computer model of herbicide transport in soil. The model gave good predictions of total soil residues during the first five months following application, and also predicted successfully the maximum depth of penetration of the herbicides into the soil during this period. However, more herbicide was retained close to the soil surface than was predicted by the model. The model predicted extensive movement of the herbicides in the soil during winter but did not predict that residues sufficient to affect crop growth could be present in the upper 15–20 cm soil after one year.

Chemical control of branched broomrape in processing tomato using sulfonylureas in southern Italy

“…Indeed, when TS was sprayed over the crop and incorporated into the soil using sprinkler irrigation (TSFH) the parasite control was very similar to RS (93% reduction in o n l y broomrape spears), while when TS was applied by drip irrigation (TSDH) it was the lowest (40% reduction in P. ramosa spears). With this latter distribution method this herbicide seems to fail to ensure a full protection of the root apparatus, most likely as a result of its low soil mobility (Walker and Welch, 1989). As confirm of its low mobility, TS applied by drip herbigation caused a broomrape spears emergence about 30 cm from either side of the dripping line (Figure 4), creating only a strip free of broomrape along and in the center of the double row.…”

Best Management Practices for Silvicultural Chemicals and the Science Behind Them

“…Imazapyr is rarely detected at 50 cm, but is known to move below 30 cm in several soil types (Rahman et al, 1993). Similarly, the sulfonyl ureas (sulfometuron and metsulfuron) are known to move to 50 cm, but are not reported to move significantly below 70 cm (Walker andWelch, 1989, Lym andSwenson, 1991). In the process of movement through the soil profile, herbicides are acted upon by a variety of degradative and dilution processes.…”

A 10-year evaluation of plant growth regulator carryover in roadside test plots in Indiana

“…However, except for the 4-year trial reported by Dernoeden (1984), most evaluations in the same location have been based on one or more applications within a single season (Diesburg andChristians 1989, Walker andWelch 1989). While chlorsulfuron does appear to carry over from one season to the next (Walker and Welch 1989), this carryover appears to be insufficient to be detrimental to fescue or bluegrass at rates required for seasonal applications (e.g., 17.5 g/ha) in combination with mefluidide.…”