Crop diversity between 20 and 90 percent crop losses in the Congo. The FAO emergency relief and rehabilitation program is assisting vulnerable returnee populations in the African Great Lakes Region through mass propagation and distribution of CMD resistant or highly tolerant cassava. A well known occurrence of disease susceptibility in crops lacking diversity concerns the 'Gros Michel', a seedless banana that saw world marketing in the 1940s. As the market demand became high for this particular cultivar, growers and farmers began to use the Gros Michel banana almost exclusively. Genetically, these bananas are clones, and because of this lack of genetic diversity,
Crop circle alleged 'cattle mutilation' sites." (in reference to cattle mutilation). A study by Eltjo Haselhoff reported that the pulvini of wheat in 95% of the crop circles investigated were elongated in a pattern falling off with distance from the centre and that seeds from the bent-over plants grew much more slowly under controlled conditions. Furthermore, traces of crop circle patterns are sometimes found in the crop the following year, "suggesting long-term damage to the crop field consistent with Levengood's observations of stunted seed growth." In 2000, Colin Andrews, who had researched crop circles for 17 years, stated that while he believed