Introduction
In the Netherlands, golf is increasing in popularity and the present golf courses are occupying 7300 hectares in total (Zibb: Portal voor ondernemers. Tips, tools en het laatste nieuws). Turf grasses are plants that are made very susceptible to infection by fungi because of their prerequisites. Especially the greens have high demands: The grass should be kept very short and has to form a smooth surface with as little unevenness as possible. Every time the grass is mowed, the plants are mechanically wounded and are therefore more easily penetrated by fungi. Throughout the year, turf grasses are dealing with a lot of different fungi, which all have a different ideal combination of factors to infect the grass.
Sclerotinioria homoeocarpa or Dollarspot and Microdochium nivale or Snow Mold are the most common fungi and cause severe infections of greens.
Dollarspot occurs from early spring till late autumn over the whole world. Many species of turf grasses are susceptible to these fungi. We this fungus infects the grass, small, circular, straw coloured spots occur. These can reach a width of 15 cm (Couch, 3th edition). The fungus can be spread by human, animals, wind and water and gets active when dew occurs on the edge of the grass. Wet leaves also favourable for the fungus. (Smiley et al, 3th edition).
Snow mold can occur in every month of the year and doesn’t exactly need a snow cover in order to be present. This fungus grows in cold and humid weather conditions. In autumn and winter, when the grass doesn’t grow as fast or not at all, it is extremely susceptible to snow mold (Smiley et al, 3th edition).
Many fungicides are used by golf keepers, but these are costly and often environmental damaging substances. Moreover, fungicides can only be used in restricted amounts in order to avoid that the fungi