For example, the liverwort Marchantia polymorpha produces gemmae which are small budlike structures that detach from the parent plant and serve as vegetative propagules. Algae are easily carried in water and so can be a serious problem where irrigation water is obtained from surface water sources, especially ponds. However, in the British Columbia study, none of the common cryptogamic pests were found in irrigation water or in samples of commercial growing media. For nurseries that do not sterilize theirs between crops, used containers are undoubtedly one of the major sources of entry. Therefore, growers must use cultural controls to prevent their establishment or at least minimize their growth.
Prevention is the first line of defense against cryptogams as it is with any nursery pest.
If obtained from surface water sources, irrigation water should be filtered to exclude algae. Chlorination has been shown to be effective against waterborne algae when done in conjunction with filtration. Used containers should be sanitized between crops with hot water, steam, or chemical sterilants. Bags of growing media should be kept covered to prevent contamination, especially when stored between crops. Nurseries mixing their own media may want to consider steam pasteurization, especially the organic components.