Sequential and combined spray of herbicides to tomato field on weed reduction, fruit parameters and carryover residues

Tomatoes are in great demand worldwide and consumed due to their nutritional and sensory qualities. Weed infestation poses a great challenge in tomato production, prompting growers to employ two to three herbicides in combinations and sequences for comprehensive control. Consequently, this study was undertaken to investigate the effects of glyphosate, pendimethalin, and metribuzin when applied individually or in sequential combinations in tomato fields. The herbicides significantly reduced the weed density and dry biomass and enhanced the weed control efficiency (WCE) compared to control. A tank mix spray of pendimethalin and metribuzin following glyphosate gave significantly higher WCE (80–91%) and fruit yield (88.47 t/ha). The tomato quality parameters were unaffected by the herbicides. The terminal residues in fruits were found below the safe limit of 0.1 mg/kg for glyphosate and 0.01 mg/kg for pendimethalin and metribuzin. Moreover, there was no evidence of residual carryover toxicity from the applied herbicides, as confirmed by the plant bioassay and instrumental techniques. However, continuous spraying of herbicides repeatedly in succession and in combination necessitates long-term monitoring to assess the potential development of herbicide-resistant weeds, the bio-magnification of residues in soil, their transfer to tomato fruits and the impact on the food chain.