TRADE AND MARKETING It’s not all Silver scurf that you see Picture of Silver scurf infection after cutting the tuber. disinfected. Once in storage, Black dot can no longer be controlled. It doesn’t really spread, but it becomes more visible. Contrary to Silver scurf, not only the tuber but the entire plant suffers the consequences of Black dot. So it’s important to take appropriate measures. Think of healthy soil, a good soil structure, sufficient organic matter. And avoid storing host plants, so no storage of potatoes or other carriers of the fungus. Black dot is also related to stress. If the plant is subject to stress, it can also be infected more easily, and die off quicker. In Great Britain, this is sometimes called ‘Early Dying’, where Black dot can be an important cause. The climate also plays an important role. A lot of research into Black dot has been carried out in Great Britain. In Southern England, 70 to 100 percent of soil contamination was found and only 20 to 30 percent in Scotland. Because of the different climatic conditions in the north, the growing and spreading chances for Black dot are smaller there. So, Black dot increases at high temperatures and in humid weather conditions. As there aren’t enough effective crop protection products against Black dot available on the market, it’s especially important to Picture of Black dot infection after cutting the tuber. avoid infection as much as possible and to limit infection with the measures mentioned in this article,’ Elemans emphasises. ● Leo Hanse ‘Diseases that are attributed to Silver scurf are often cases of Black dot’, points out Maries Elemans. Potato World 2015 • number 3 25 Pagina 24
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