Pre-emergence herbicidal activity and persistence of 2,4-di-tertbutylphenol in relation to soil types

Although 2,4-di-tert-butylphenol (2,4-DTBP) has demonstrated strong phytotoxic effect on various weedy plants in previous findings, research on its pre-emergence herbicidal activity in the soil is still scanty. The aim of this study was to investigate the effects of two soil types on pre-emergence herbicidal activity and persistence of 2,4-DTBP. The bioassay was carried out in a growth chamber where goosegrass [Eleusine indica (L.) Gaertn.] seeds were sown in different rates of 2,4-DTBP in two soil series under sterilized and non-sterilized soil conditions. Bioassays of each treatment were conducted in four replicates and arranged in completely randomized design. 2,4-DTBP exhibited potent pre-emergence activity as a root inhibitor where it completely inhibited (100% inhibition) of the root growth of E. indica in sandy loam soil at an application rate of 6.14 kg ai/ha. 2,4-DTBP was rapidly detoxified in silt loam soil as a result of high microbial activity where it completely lost its phytotoxicity by giving 100% emergence within 10 weeks even it was applied at an application as high as 20.4 kg ai/ha. However, 2,4-DTBP remained highly phytotoxic in sandy loam soil where it reduced the root and shoot growth by 47 and 36%, respectively, throughout 10 weeks duration of the investigation. The presence of microbes in non-sterilized soil further suggest that soil microbes may modify the chemical structure of the 2,4-DTBP, which in turn decreased its toxicity. The high level of pre-emergence herbicidal activity in conjunction with its biodegradation in silt loam soil imply that 2,4-DTBP may have potential for development as a natural-soil applied herbicide