| dc.description.abstract | Finesse and Atrazine herbicides are often used by producers as a pre-emergence control method for annual weeds. Across the state of Oklahoma, there are varying levels of soil pH that generally follow a geographical trend. In this study, we attempted to simulate the pH's possibly found in Oklahoma to get a grasp on how these residual herbicides interact with a range of pH soils and the plants growing in them. We conducted a 28-day trial to test effectiveness of these herbicides at different pH levels on sensitive crops. We are looking for a crop response from the pH levels and the activity of the herbicides therein. The pH was chemically altered to attain batches of soil at levels of 4, 5, 6, and 8. In each pH treatment, soybean, wheat, and cotton. Finesse was sprayed at a rate of 0.4 oz/acre and Atrazine was sprayed at a rate of 2 qts/acre. The pots were watered every other day or as needed for duration of the trial. Pictures were taken periodically to note significant events, at 21 days post-planting, and 28 days post-planting. Crop injury reports were also taken at 21 days and 28 days. At the end of the trial we took biomass weights. Nothing germinated in pH 4. Results showed crop injury and biomass were lower in pH 5 in all three crops. However, in soybean pH 6 & 8, data showed increased injury from atrazine. In wheat there was significant injury from atrazine, but surprisingly, also injury from finesse. This was shown by both the injury reports and the biomass data. Cotton showed in pH 5, initial injury and recovery after a week, but this is because of judging injury off the non-treated plants. pH of 5 soil caused the cotton plants to have equal injury. At pH 8 we see a reduction in injury from pH 6. We expected the injury to be higher in pH 8 due to the herbicide being more available in the soil in higher pH's. This leaves the question open to why this happened. Perhaps, in higher pH soils, herbicide activity is reduced initially, but residual is extended. Overall, we learned that pH does have an effect on how residual herbicides interact with plants and it varies in different crops. Further studies need to be conducted to investigate the extent of these effects. With more research we can better predict how long herbicide residuals stick around in Oklahoma's wide range of pH soils and how these also affect the weeds we are managing. | |
