TRADE AND MARKETING breeders? that is caused by small organisms that are somewhere between a virus and a bacterium. Scientists and research workers speak of phytoplasma infestations. There are several types that may affect different plants, including the potato. In plants, they cause a stronger tendency for numerous thin stems, hair roots and small tubers. Because of the symptoms above ground – the many stems – we know the phytoplasm infestations in the Netherlands under the name of Potato stolbur phytoplasm. The disease is still rare in potatoes here, but this is different in Southeast Europe. The infection would not be so bad if it only limited itself to extra stems and tuber initiation. However, the flesh of the tuber is effected as well. According to Meyer, the tubers turn rubbery and the sugar content is very low. Furthermore, the infected tubers are known to have problems with sprouting. This may be fine for storing consumption potatoes, but it is disastrous for propagation. In response to the disease, Interseed Potatoes has developed varieties that are resistant to the infection. ‘Stolbur is a disease that is slowly advancing towards Northern Europe. If it should come to the point where the summer temperatures reach the same high levels and the disease makes its appearance here as well, then we are prepared with an effective weapon. A well-known Interseed Potatoes variety that already has that resistance is the Atlantic. During a tour of the seed boxes, Meyer shows that several products crossed with the Atlantic are included in the APF Holland variety range. seems to have been just as dry as last summer. Nevertheless, I believe that the climates in some parts of the world are slowly changing. That’s what we are noticing ourselves right now in Southeast Europe. We have been running a breeding programme in Romania for many years now. Last year, the mercury ran up to 40 degrees Celsius every day for a long period in that country. That’s very extreme.’ Periods with very high temperatures have been quite common in Southeast Europe lately, is Meyer’s experience. That brings with it specific cultivation problems such as water stress and various heat-loving diseases. A disease that thrives at such high temperatures is Stolbur, which is an infection ‘Good does not always have to be new’ Climate change? No, this is not yet a main topic in Medemblik, as can be heard at Agroplant. Jan van der Lee Sr. and Jr. clearly work with other terms and themes in their breeding and business activities. For example, a variety that is transported to distant dry destiPotato World 2010 • number 3 15 Pagina 14
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