Control of Volunteer Cotton Using Post-Emergent Herbicides in the Texas Rio Grande Valley

The Lower Rio Grande Valley (LRGV) is the last zone that still has significant breeding populations of boll weevil(Anthonomus grandis). The LRGV is the only area in the entire US that has a sub-tropical growing season. Volunteer cotton can grow all year without the threat of freezing in most years. This creates a huge problem with a successful eradication effort. The issues that Tamaulipas, Mexico have had also put into question the future of the LRGV boll weevil eradication efforts.

The multiple crops that are grown in the LRGV pose a unique challenge for controlling volunteer cotton. Controlling volunteer cotton in crops such as corn, onions, sugarcane, and sorghum can be challenging. Volunteers in these subsequent crops provide breeding areas for the boll weevil if left uncontrolled. This requires more insecticide applications and costs the producer a considerable amount of funds. These funds can come from the application of herbicides, insecticides, or hostable fees that are enforced when these crops contain volunteer cotton.

Much work has been done on controlling volunteer cotton on barren land, but not on current growing crops and very minimal research has been done in the LRGV. 2,4-D has been used as the most common control for volunteer cotton, but with the introduction of 2,4-D tolerant cotton varieties this could produce more issues with control. This research is focused on finding post-emergent herbicides from multiple modes of action and mixtures to help control volunteer cotton in the LRGV in actively growing crops.