Yes. If you use a pesticide product registered by the EPA in the production of organic agricultural plants, the WPS probably applies to you.
Check the pesticide product label in the DIRECTIONS FOR USE section. If you see a box labeled AGRICULTURAL USE REQUIREMENTS, the WPS applies where that pesticide product is used in agriculture, whether conventional or organic.
If you are using a pesticide product with labeling that refers to the WPS AND you are using it on an agricultural establishment directly related to the production of an agricultural plant, you must comply with the WPS. Otherwise, you will be in violation of federal law, as it is illegal to use a pesticide product in a manner inconsistent with its labeling.
Some protective requirements for workers and handlers (personal protective equipment, restricted-entry intervals, etc.) are clearly identified on the pesticide label. However, many of the requirements are not. They are still requirements because of this reference to the WPS (40 CFR 170) on the label.
If you are an agricultural employer, you must know your responsibilities under the WPS and provide WPS protections to your workers and handlers. You may qualify for the owner/immediate family exemption from certain WPS responsibilities.