You are somewhat correct. Official statistics on murders broken down by race and land ownership are difficult to find so it makes having a conversation on the topic difficult. The statistics that are available on white farm murders indicate that their murder rate is within the average for for rural/farm areas. Infact the murder rate of black men in rural areas is even higher then white farmers.

Here are additional sources if you or anyone else would like to know more on the topic;

https://africacheck.org/fact-checks/factsheets/factsheet-sta...

https://africacheck.org/fact-checks/reports/are-sa-whites-re...

https://africacheck.org/fact-checks/spotchecks/claims-about-...

https://africacheck.org/fact-checks/blog/analysis-why-calcul...