Closed canopy

The longest day has already passed and Dutch summer is well under way. Mr. Geluk’s potato plants are thriving. As you can see on the photos, which were taken at the beginning of July when the crop was around 60 days old, the foliage has grown substantially. As the yield of his crop is largely determined by sufficient photosynthesis, farmer Geluk is taking great care to obtain a closed canopy as rapidly as possible, making sure little of the light energy of the sun's rays is wasted by falling on bare soil.

A healthy, well-developed haulm not only ensures good photosynthesis, which in turn stimulates the production of dry matter inside the tubers, it also cuts short opportunity for weed growth.

Under Libyan conditions there is an extra incentive for the farmer to obtain a closed canopy quickly: this will protect his potatoes from the heat, especially later on in the growing season when climatic conditions can get really tough on the potato.

Selection: the good, the bad & the ugly

During this growing weather you will find Mr. Geluk in his field checking up every day on the wellbeing of his crop. To make his work in the field more effective, he uses a hydraulic potato selection cart, designed specifically to visually inspect his plants whilst driving between the rows.

Diseased plants pose a danger as viruses and bacterial diseases can spread easily to neighbouring plants. Any infected plants need to be removed as early as possible. Mr. Geluk also removes any plants that lag behind substantially in growth and those he suspects of varietal impurities. The plants he takes out are collected in the storage bin. The cart is equipped with two seats that are adjustable both in height and width, so two people can inspect simultaneously.

Early selection of virus infected plants is vital; by removing these early on, Mr. Geluk cuts short any possibility of aphids transferring the virus to healthy surrounding plants. Staying ahead of the aphids in this ‘race’ is key, and all the more important as young plants are more susceptible for virus infections than mature plants.

Field inspection by NAK

In Mid-June Mr. Geluk’s potato plants underwent their first field inspection by NAK, the Dutch General Inspection Service for agricultural seeds and seed potatoes. This inspection is the first of at least three field inspections that the NAK inspector will carry out each year on Mr. Geluk’s plot in the course of the growing season.

During his surveillance, the inspector not only checks the general appearance and development of the crop, he also watches for any symptoms of diseases, such as blackleg (Erwinia spp.), viruses and leaf roll, and he verifies the plants' trueness to type and varietal purity. This is the first step in the process that will lead to the final classification and certification of Mr. Geluk’s potatoes, necessary for export. After harvesting, NAK's quality control will continue with tests in the laboratory for viruses and bacterial diseases, as well as tuber inspection.

Upholding quality

Although the NAK resides under the Ministry of Agriculture, it is actually an independent foundation, set to (inter alia) closely monitor the quality of Dutch seed potatoes. It does so by making sure all seed potatoes comply with the existing laws and regulations. In this respect, it's worth mentioning that the Dutch seed potato standards are not only stricter than the EC-minimum standards, they also contain additional requirements. For example, Dutch farmers are bound to a maximum potato share in a crop rotation scheme to prevent soil diseases and pests.