Black genocide

To label family planning and legal abortion programs "genocide" is male rhetoric, for male ears. It falls flat to female listeners, and to thoughtful male ones. Women know, and so do many men, that two or three children who are wanted, prepared for, reared amid love and stability, and educated to the limit of their ability will mean more for the future of the black and brown races from which they come than any number of neglected, hungry, ill-housed and ill-clothed youngsters. Black genocide or a black extinction scenario usually takes the form of a genocide conspiracy in which whites (and sometimes Jews as well) are covertly killing off the black population en masse. This often takes the form of tainted food or medical supplies intended to spread disease or induce sterility among the black population, à la the Tuskegee syphilis experiment.

The Post-Bellum South and urban areas
Many of the elements of these conspiracy theories can be found among the more extremist black charismatic preachers of the South and urban North of the United States after that country's Civil War. One of the most popular was F.S. Cherry of the Black Hebrew Israelite sect. Cherry laid out a sort of prototypical version of Afrocentrism as well as introducing aspects of anti-Semitism and apocalyptic visions of a race war (which he prophesied would occur in the year 2000) into extremist black ideology.

AIDS conspiracy theories and denialism
AIDS denialism and related conspiracies are probably one of the most popular components of the "black genocide" theory. The disproportionate effect that AIDS has had on the black population has led to conspiracy theories that the disease was introduced by the CIA or some other infamous organization in an attempt to kill off blacks. This conspiracy theory has had severe effects in Africa. There, it often cross-pollinates with Big Pharma-related conspiracy theories. The most infamous case of this was South Africa's Thabo Mbeki's denial of the HIV/AIDS connection, which led to over 300,000 preventable deaths.

Sterility
Inducing sterility in black men is another common theme. One of the more well-known incidents of this idea gaining popular traction was the "Tropical Fantasy scare" of the early 1990s. Rumors and fliers were passed around claiming that the soft drink Tropical Fantasy contained a secret ingredient that would cause sterility in blacks and that the beverage was actually bottled by the Ku Klux Klan.

Abortion
Abortion as an alleged tool of black genocide is a conspiracy theory generally specific to anti-abortion activists (as well as some black supremacist and black nationalist groups, including the Nation of Islam). This one works backward from the data showing that black women are more likely to have abortions than white women. Therefore, abortion is secretly a eugenics plan to eliminate the black population, no matter if the black population has progressively increased!

This probably has something to do with the fact that Planned Parenthood's founder Margaret Sanger endorsed eugenics (as did many American intellectuals at the time, including some African-Americans), although she insisted that it be voluntary and not based on race (something omitted by most critics). In any case, the group as it currently exists certainly no longer endorses these beliefs.

Anti-Semitism
Black supremacists such as Louis Farrakhan of the Nation of Islam and the New Black Panther Party throw anti-Semitic conspiracies into the stew as well. This often involves ripping off ideas from older sects such as the Black Hebrew Israelites as well as recycling ideas popular among neo-Nazis and shoehorning Jews into the historical narrative as the "real" perpetrators behind instances of oppression of blacks, such as the idea that the Jews masterminded the slave trade.

Real conspiracies
While the historical oppression of blacks has been at the heart of these conspiracy theories, three incidents of real conspiracies in particular in the US seem to drive many of them.

The first is the aforementioned Tuskegee experiment. There was a cure for syphilis at the time; malaria. The body responds to malaria by increasing the temperature to levels which kill syphilis, at which point quinine was administered to the victim patient to kill the malaria. Even the weaker strain of malaria used for this is still quite deadly and could have permanent long term effects, so this brutal cure was not available for the extremely young, the elderly, or people suffering from the advanced effects of a debilitating disease such as syphilis. As many African Americans are resistant to malaria, this cure isn't available, so it did make a lot of "ends justify the means" sense to see if it was possible to detect syphilis sooner or another cure developed. Hundreds of black men were unwittingly recruited into a secretive study of syphilis in return for free (albeit limited) health care and food. They were already infected with syphilis but not told this, while being assured that the "treatment" would cure or prevent a made-up ailment the examiners diagnosed them with. However, a much safer cure, penicillin, was discovered and made any purpose for the study absolutely moot, but the patients were not informed; failing to do so was really not much better than murder. Nearly all of the men went on to die horrific deaths as their conditions worsened, but not before infecting others, including their spouses and children.

The second was the discovery of an FBI program that infiltrated civil rights groups such as the NAACP, among others. While it would make sense for the FBI to investigate any large organization, especially ones that had been receiving funding from the Russians and in the groups that COINTELPRO often went beyond observing and into the actual realm of criminal activity, ranging from assaults and burglary to actual murder.

The third was the forced sterilization of Black people. Surprisingly, this went on all the way until 1974, with 60,000 victims in total. Technically, every racial group was at risk, including White people, but unsurprisingly given the article you decided to read, it happened far more often to Black people. Sexism played a huge role, too; far more women were sterilized than men. If you think it couldn't get worse, well, being a rape victim was one of the reasons you could be sterilized.

Slavery
Millions of black people died as a result of slavery; however, unlike the Nazi Holocaust, where the slave labor was incidental to the main goal (killing people), here the main goal was the slave labor and killing people was incidental. There were also quite notable differences in survivability of enslavement from time to time and place to place. During the last 50 to 60 years of slavery in the US, there was no legal importation of slaves to the US and thus the "supply" had to be "self-sustaining", hence too big a dieoff rate was not desirable. Meanwhile, in other eras and places. a slave who survived the passage and the first two years of slavery was actually among the "lucky" minority, as most didn't.

Real genocide

 * Black African people were subject to genocide by white people during the Herero and Nama genocide in German South-West Africa.