<b>The susceptibility of various watermelon (</b><b><i>Citrullus lanatus</i></b><b>) accessions to 2,4-D drift</b>

Due to the widespread application of 2,4-D in controlling the broadleaf weed species in southern cereal crop production systems of Iran, a risk of non-target drift threatens the watermelon crops in these regions. A 3-yr field experiment (2019-2021) was conducted to evaluate the susceptibility of sixteen Iranian watermelon accessions to the use of three 2,4-D drift doses. The WA-H712 was the least sensitive accession to 2,4-D doses of 3.7, 11.2, and 112.1 g ae ha-1 with the lowest herbicide injury of 15, 10, and 5%, respectively, when observed at 8 wk after treatment. Only the plants of accession WA-H712 tolerated the herbicide damage and produced economic yield after the application of 2,4-D at the drift dose of 112.1 g ae ha-1. The lower doses of 3.7 and 11.2 g ae ha-1 reduced the yield of this accession by only 10 and 20%, respectively, compared with untreated control. Therefore, based on these results, watermelon accession WA-H712 could be grown in areas prone to drift doses of 2,4-D. This accession can also serve as a genetic resource in conventional or modern breeding programs to introduce 2,4-D-tolerant cultivars of watermelon.</p