MARITIEMA
Seed preparation
Seeds are best kept in a mechanically cooled storage area at 3-4 degrees until 1-2 weeks before planting. Then, 1 to 2 weeks before planting, warm air is used to slightly pre-sprout the seeds so that their eyes are just open. However, it is inadvisable to pre-sprout or disturb the seeds too much as this may result in uneven emergence. Only the top-sprouts may be removed.
Planting
Good soil structure and a sufficiently high soil temperature are very important if uniform emergence is to be achieved. Planting depth is the same as for Bintje. The optimum number of seeds per hectare depends on their size, with the following guidelines given for ware potatoes:
Sizes 35/50 plant spacing approx. 33-35 cm (approx. 2,100 kg/ha)
Maritiema potatoes take slightly longer to emerge than the Bintje variety and are sometimes less uniform.
Crop protection and fertilisation
Weeds can be prevented by spraying with a soil herbicide before potatoes emerge; in this case the manufacturer’s instructions can be followed. For nitrogen fertilisation, it is advisable to use 30 kg N (pure) more than the recommended dosage for Bintje. As for potassium fertilisation, a minimum K level of 22 should be aimed for. If the K level is lower it would be wise to carry out corrective fertilisation in the autumn. Then in the spring either a dosage of 150 kg (heavy soil) – 180 kg (light soil) pure potassium chloride can be applied or an over-fertilisation dosage of a combination of Nitrate and Potassium (eg. 400 kg Multi KMg 13-0-26), which is just as effective. This variety needs to be fertilised with lots of potassium! Maritiema’s foliage is fairly susceptible to Phytophtora infection (slightly more susceptible than Bintje), but its tubers have proved to be less susceptible than Bintje. Maritiema does not produce berries, it is highly resistant to Am Ro1 and Ro4 (A) and resistant to Am Pa2 (D) but is vulnerable to wart disease fysio 1
& 2.
Harvest and storage
Due to its thin skin and high cell tension, Maritiema is slightly more susceptible than Bintje to internal damage during harvest. The skins should therefore be adequately hardened during harvesting. The optimum temperature for storage during the wound healing period is approx. 14 degrees. The temperature should then be gradually reduced to around 7 degrees (particularly if the product is to be supplied for processing into chips, so that a good frying colour is maintained). Maritiema keeps well and is not very prone to sprouting during storage, so sprout inhibitors (CIPC-IPC) can be used more sparingly than with Bintje. They should, however, be applied just as frequently. It is advisable to use only gaseous treatments (CIPC) as both liquid and powder sprout inhibitors can cause defects if applied during the storage process.
