wiping out an entire crop. In fact, it is so prolific that in 1957 Congress allocated money in an attempt to eradicate witchweed. Because of Striga, the Animal and Plant Health Inspection Service (APHIS) of the U.S. Department of Agriculture established a research station and control methods. Through infestation mapping, quarantine, and control activities such as contaminated seed destruction, the acreage parasitized by witchweed has been reduced 99% since its discovery in the United States. APHIS has even offered cash rewards those who identify and report the weed, and encourages landowners to check their own acreage. Parasitizing important economic plants, witchweed is one of the most destructive pathogens in Africa. In fact, witchweed affects 40% of Africa's arable savanna region, resulting in up to $13 billion lost every year. Striga affects 40 million hectares (98,842,153 acres) of crops in sub-Saharan Africa alone. The witchweed infestation is so bad in parts of Africa, some farmers must relocate every few years. The majority of crops in Africa are grown by subsistence farmers who cannot afford expensive witchweed controls, who therefore suffer much as a result of this pathogen. Species Common crop parasites Striga asiatica has a very wide geographic distribution, from Africa through southern and eastern Asia to Australia. Since the 1950s, it is also known from the United States. This introduction, likely a result of human activity, resulted in an infestation of corn (maize) across many counties in North and South Carolina. The United States Department of Agriculture and state agencies imposed a quarantine on this area to control its spread - a process that was apparently successful. Striga gesnerioides, cowpea witchweed, as its name implies, is a parasite of cowpea (Vigna unguiculata), which is not a grass, but a member of the legume family (Fabaceae or Leguminosae). This species was also accidentally introduced into Florida in the United States, where it was found parasitizing Indigofera hirsuta (hairy indigo, another legume). Striga hermonthica (purple witchweed) is also a parasite that affects grasses, particularly sorghum and pearl millet in sub-Saharan Africa (Senegal to Ethiopia, Democratic Republic of Congo and Tanzania, Angola, Namibia). Species list The following are listed as "Accepted" on The Plant List. Striga aequinoctialis West Africa Striga angolensis Angola Striga angustifolia East Africa, Asia, Indonesia Striga asiatica (Asiatic witchweed) Africa, Arabian peninsula, India, Burma, China, Indonesia, the Philippines, Malaysia, New Guinea, Australia (introduced?), USA (introduced) Striga aspera Africa Striga baumannii