Defoliant Applications - Cotton

How to use TerrAvion imagery to help decide when to apply defoliant

With TerrAvion, you can use our imagery to help determine the best time to apply defoliants to your cotton crop.

Defoliants are generally applied when a cotton crop has reached sufficient maturity to remove the remaining leaves and open the bolls to prepare the crop for harvest. You can use TerrAvion’s NDVI imagery to help you determine the optimal time for a successful defoliant application.



A widely used method for defoliant application is based on the percentage of open bolls. The challenge to determining the optimal time for defoliant application, however, is that it is challenging to know the spatial extent of your field observations. In other words, you can tell what percentage of bolls are open in the area of the field that you have observed, but it is hard to know how these measures correspond with what’s happening across the whole field.



TerrAvion aerial imagery can help you make more informed defoliant decisions by showing you the relative maturity of various portions of your field and telling you the different areas to check before making a defoliant application decision.



Imagine that you are trying to decide whether or not to make a defoliant application to the field in the image above. You might drive around the field on the roads surrounding it, and hop out to make a few point inspections. After doing so, you might decide that the field is ready to defoliate as it appears from the portions of the field near the road. What the imagery shows you is that a large part of the field that is not easily accessible from the road is not ready for a defoliant application.



In fact, the histogram of the relative vigor in this field shows that almost 60% of the field is still growing rather vigorously and thus is not likely to respond well to a defoliant. Without the histogram, defoliants may have been harmful to the overall yield.

Had you applied defoliant at this time, you may well experience an ineffective application requiring you to re-apply defoliant or resulting in sub-optimal removal of leaves and opening of bolls. With the benefit of imagery, you would have avoided this ill-timed decision to apply defoliant and would have known to wait until the whole field was ready to defoliate.



This is how you can use TerrAvion imagery to help you determine the optimal time for a successful defoliant application. Please visit for more information.