DNA extractions often contain impurities which limit the output of long-read sequencing technologies. Here a protocol is provided which removes impurities and size selects for longer fragments. To remove residual RNA and protein, an additional RNAse A and Proteinase K treatment is performed. A clean-up with chloroform: isoamyl alcohol (24:1) removes these proteins and other hydrophobic organics such as lipids. A low volume ethanol precipitation and wash is used to concentrate the DNA, hopefully also reducing polysaccharides. Finally, a Short Read Eliminator (SRE) kit by Circulomics is utilised for size selection, which also appears to clean the DNA. This has been trialled for the sorghum rot fungus Macrophomina phaseolina, providing highly promising results with an Oxford Nanopore MinION. One strain yielded 13.71 Gbases with an N50 of 21.75 kb, another strain yielded 9.72 Gbases with an N50 of 43.50 kb. Similar results are expected across many organisms, but have not been tested.