You can use paraquat.

Paraquat is a kind of rapid inactivating herbicide, with poisoning effect and certain endosorption effect, it can be rapidly absorbed by the green tissues of plants and make them die. It has no effect on non-green tissues.

In the soil, it quickly combines with the soil and passivates, and is ineffective on plant roots and perennial underground stems and persistent roots.

Paraquat Scope of Application:

It can be used as an adjuvant in the late stage of defoliant use in machine harvested crops. Due to crop defoliant use in the harvest period close to the desired defoliation effect is not achieved, paraquat can be used as a rapid killing of crop green tissue, does not affect the short-term stacking and transportation of harvested fruit after mechanical harvesting.

Safety to crops: Paraquat is an inactivating herbicide, if it is not sprayed on the green stems and leaves of the crop, the liquid is only contaminated with brown lignified bark and branches, and it does not harm the crops and trees. Paraquat will lose its activity when it comes in contact with soil, and it is safe for crops when it is chemicalized 1-2 days before sowing.

Baidu Encyclopedia-Paraquat