SEED POTATO DEHAULMING METHODS

Dehaulming, in potato production refers to the act of detaching the vegetative part of the potato plant, found above the ground, from the root tubers. Dehaulming is one of the pre-harvest practices which are aimed at hardening the skin of the tubers and therefore reduce injuries during post-harvest handling.
Despite of its benefits and depending on the method of dehaulming used, the practice can contribute to the spread of virus diseases such as potato leaf roll virus and potato virus Y (PVY)
There are three methods of dehaulming, namely:
• Haulms cutting
• Haulms pulling
• Paraquat spray
Haulms cutting is a dehaulming method whereby a sharp object such as a panga is used to cut off the vegetative part. This method of dehaulming may lead to spread of viruses from an infected plant to a healthy plant through the cutting objects which carry infected plant sap.
Haulms pulling is a method of detaching the foliage from the root tubers by pulling them using hands. One hand is used in pulling the foliage while another hand holds the base of the foliage to prevent tubers from coming out. It is the safest method of dehaulming although it could be time consuming in seed potato production.
Paraquat spray is a chemical method of doing away with foliage. Once sprayed the chemical is absorbed into the plant system where it interferes with the physiological processes of the plant eventually leading to its death. One drawback of the paraquat spray as a method of dehaulming is the fact that since the process is systematic (must first be absorbed into the plant tissues before action), it takes longer compared to the other methods.

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