The commercial release of crops with engineered resistance to 2,4-D and dicamba will alter the spatial and temporal use of these herbicides. This, in turn, has elicited concerns about off-target injury to sensitive crops. In 2014 and 2015, studies were conducted in Tifton, GA, to describe how herbicide (2,4-D and dicamba), herbicide rate (1/75 and 1/250 field use), and application timing (20, 40, and 60 DAP) influence watermelon injury, vine development, yield, and the accumulation of herbicide residues in marketable fruit. In general, greater visual injury and reductions in vine growth, relative to the non-treated check, were observed when herbicide applications were made before watermelon plants had begun to flower. Although the main effects of herbicide and rate were less influential than the timing of applications with respect to plant development, the 1/75 rates were more injurious than the 1/250 rates; dicamba was more injurious than 2,4-D. In 2014, the 1/75 and 1/250 rates of each herbicide reduced marketable fruit numbers 13 to 20%, but only for the 20 DAP application. The 1/75 rate of each herbicide when applied at either 20 or 40 DAP reduced the number of fruit harvested per plot in 2015. Dicamba residues were detected in marketable fruit when the 1/75 rate in 2014 and 2015 and the 1/250 rate in 2015 was applied to plants at 40 or 60 DAP. Residues of 2,4-D were detected in 2015 when the 1/75 and 1/250 rates were applied at 60 DAP. Across both years, the maximum level of residue detected was 0.030 ppm. While early season injury may reduce watermelon yields, herbicide residue detection is more likely in marketable fruit when an off-target contact incident occurs closer to harvest.

Agronomic crops engineered with resistance to 2,4-D or dicamba have been commercialized and widely adopted throughout the United States. Due to this, increased use of these herbicides in time and space has increased damage to sensitive crops. From 2014 to 2016, cucumber and cantaloupe studies were conducted in Tifton, GA to demonstrate how auxinic herbicides (2,4-D or dicamba), herbicide rate (1/75 or 1/250 field use), and application timing (26, 16, and 7 d before harvest (DBH) of cucumber; 54, 31, and 18 DBH of cantaloupe) influenced crop injury, growth, yield, and herbicide residue accumulation in marketable fruit. Greater visual injury, reductions in vine growth, and yield loss were observed at higher rates when herbicides were applied during early-season vegetative growth compared to late-season with fruit development. Dicamba was more injurious in cucumber while cantaloupe responded similarly to both herbicides. For cucumber, total fruit number and relative weights were reduced (16 to 19%) when either herbicide was applied at the 1/75 rate 26 DBH. Cantaloupe fruit weight was also reduced 21 and 10% when either herbicide was applied at the 1/75 rate 54 or 31 DBH, respectively. Residue analysis noted applications closer to harvest were more likely to be detectable in fruit than earlier applications. In cucumber, dicamba was detected at both rates when applied 7 DBH, while in cantaloupe it was detected at both rates when applied 18 or 31 DBH in 2016 and at the 1/75 rate applied 18 or 31 DBH in 2014. Detectable amounts of 2,4-D were not observed in cucumber but were detected in cantaloupe when applied at either rate 18 or 31 DBH. While early season injury will more likely reduce cucumber or cantaloupe yields, the quantity of herbicide residue detected will be most influenced by the time interval between the off-target incident and sampling.

Effects on radish (Raphanus sativus L.) cv. ‘Cherry Belle’ of nitrogen dioxide (NO2), sulfur dioxide (SO2), and ozone (O3) alone and in combination at 0.2 or 0.4 ppm of each pollutant were studied. There was no difference in foliage or root weight of radish between exposure durations of 3 or 6 hours, and no significant interaction of hours with air pollutant and concentration. Ozone reduced root dry weight more at 0.4 ppm than at 0.2 ppm. Sulfur dioxide depressed the root/shoot ratio at both 0.2 and 0.4 ppm; however, when NO2 and SO2 were both present there was synergistic depression of the root/shoot ratio at 0.4 ppm. The average O3‐induced reduction in root weight of radish (1.75 g fresh and 101 mg dry, per plant) was additive in the presence of NO2 and SO2. The weight of the root was reduced even though the foliage was the direct receptor of the pollutant stress.

Cabbage, Brassica oleracea, var. Capitata L.; squash, Cucurbita pepo Alef.; and tendergreen, Brassica perviridis Bailey were grown at various water table depths in sheltered soil tanks on a fine sandy loam and a loam soil to evaluate the effects of high water table and soil type on growth and yield of these vegetable crops. Yields of the 3 species increased with water table depth to a depth of 76 to 102 cm. On both soil types the 15-cm water table depth caused considerable yield reduction and chlorosis for the 3 species. For maximum yields deeper water table depths were needed with loam than with sandy loam soil. Yield of cabbage was not significantly increased at water table depths greater than 30 cm in either soil. Squash yield was highest at water table depths of 61 to 76 cm in the fine sandy loam and 91 to 102 cm in the loam soil. Tendergreen yield was not significantly increased by water table depths greater than 61 cm in either soil.