Metribuzin Injury in Soybeans as Influenced by Application Timing and Cultivation¹

Abstract

Kansas growers wish to improve broadleaf weed control in soybeans [Glycine max (L.) Merr.] grown in sandy soils with high pH or low organic matter content. Metribuzin [4‐amino‐6‐tert‐butyl‐3‐(methylthio)‐as‐triazin‐5 (4H)‐one] applications would effectively control broadleaf weeds on such soils; however, crop injury risk would also be present. Thus, a field experiment was initiated to determne if a 3‐week interval between herbicide application and planting or cultivation after soybean emergence improved tolerance of soybeans grown on a soil with a high pH and low organic matter content. Metribuzin was applied at 0.6 or 1.1 kg/ha and incorporated prior to soybean planting in a Haynie very fine sandy loam (coarse‐silty, mixed, calcareous, mesic Typic Udifluvent) with pH of 7.9 and 0.7% organic matter content in 1978 and 1979. Visual injury of 4‐week‐old plants was less in 1978 but more in 1979 when metribuzin was applied 3 weeks before planting rather than immediately before planting. Injury in 7‐week‐old plants was not significantly affected by time of metribuzin applications in 1978 but was greater from applications immediately before planting compared to applications 3 weeks prior to planting in 1979. Injury differences were attributed to rainfall quantity and pattern. The meribuzin applications at 0.6 or 1.1 kg/ha 3 weeks prior to planting did not affect soybean yields either year even though the higher rate reduced plant stand and plant height. Yields were reduced only when metribuzin was applied at the higher rate immediately before planting. Cultivation at 3 and 7 weeks after soybean planting did not significantly affect soybean tolerance either year.

Integrated Weed Control Management in Soybeans (Glycine max) in Greece

“…The observed phytotoxicity of the applied herbicides, especially of metribuzin and imazaquin, may be attributed to the dose and soil pH. Other cultural conditions which could cause injury with these herbicides such as excessive rainfall during the first stage of soybean development did not occur, and the irrigation pattern was typical for this crop (5,9,17). The herbicide SAN 582H proved to be selective to soybean at a rate up to 1.5 kglha and the combination of pendimethalin plus linuron was selective at a rate of 1.5 plus 0.7 kglha.…”

“…The production environment for soybean in Greece includes its development on mineral soils, mainly of the type sandy loam, sandyclay loam, clay loam, and clay with organic matter 2 to 4% and alkaline pH. Dry conditions prevail since the net amount of rainfall after the subtraction of evaporation usually is less than 20 mm from planting date (middle of 1Received for publication Sept. 17,1993…”

Phytotoxic Response and Yield of Soybean (Glycine max) Varieties Treated with Sulfentrazone or Flumioxazin1

“…With metribuzin, differences among several varieties were shown to be the result of more rapid metabolism in the tolerant variety (Mangeot et al 1979). As with sulfentrazone and flumioxazin, the injury from metribuzin appeared to increase when an adequate rainfall event moved the herbicide into the root zone soon after planting (Moshier and Russ, 1981). Figure 2.…”

Soybean (Glycine max) Tolerance to Preemergence and Postemergence Herbicides

“…Even tolerant soybean varieties under excessive moisture commonly show varying degrees of metribuzin injury. Soybean susceptibility to metribuzin has been documented (1 , 10), and the degree of injury can be influenced by rainfall amount and distribution (2,7). Plants are able to recover; however, and yield typically is not reduced.…”