Herbicides Growth Regulators
Symptoms are mainly observed on young, growing leaves and are characterized by the folding, bending or twisting of leaf blades. Stems and petioles become twisted and curled. Blisters develop on the leaf surface, giving them the appearance of 'strapping' or 'witches hands'. Due to the leaf deformation, the leaf veins appear to run parallel rather than netted. Leaf color changes from yellow to white and brown. No damage occurs to mature plant parts such as old leaves or developed bolls.
Symptoms usually appear within days after the application of herbicides belonging to a group of phenoxyacetic acids or synthetic auxins (group I). Cotton plants are extremely sensitive to 2,4-D or dicamba, which are used to control broadleaf weed species. Unsuitable timing, selection of the wrong formulation or simply adverse weather conditions can result in described symptoms on the cotton plants. The contamination can also be caused from neighboring fields. Stressed plants are more susceptible. The distribution of symptoms depends on the dosage and can range from a few nodes to the whole plant if rates are particularly high. It is important to understand that herbicides can damage crops even in small dosages.
There is no biological treatment available for this condition. Prevention and good farming practices are the keys to avoid that the harm happens in the first place. In the case of suspected overdosage, it could help to wash or rinse plants thoroughly.
Always consider an integrated approach with preventive measures and biological treatments, if available. Prevention and good farming practices are the keys to avoid that the harm happens in the first place. Before planning a herbicide spray, be sure that you know the type of weed you are dealing with (basically broadleaf weeds vs grasses) and select the best method. Carefully select the herbicide and follow dosage instructions as indicated on the label.