Tomato production is a common and important agricultural activity in Nicaragua. During the last decades tomato producers have suffered great yield losses due to Begomoviruses (family Geminiviridae). The genome of Begomoviruses generally consists of two circular ssDNA components, DNA-A and DNA-B. Tomato yellow leaf curl virus (TYLCV) is an example of a Begomovirus with only one component. An approach to manage the virus epidemics has been to breed a cultivar with Begomovirus resistance genes, which have been transferred from wild tomato.

Every year Begomovirus infections cause severe constraints to the tomato production in Nicaragua. Extensive yield losses are followed by large economical losses, both for the country and the single farmer. During recent years the use of Begomovirus resistant or tolerant tomato cultivars has increased in Nicaragua as an effort to improve yields. Still, Begomovirus infection is a large threat to the tomato production. Therefore, ongoing work in Nicaragua is focusing on finding new, better, Begomovirus tolerant or resistant tomato cultivars.

Cassava (Manihot esculenta Crantz) is a root crop that plays an important role in many households in Africa. It is sometimes called ?Africa´s food insurance?. The advantages with the crop are that cassava is drought-resistant and it can grow in a semi-dry land. It is a perennial crop and does not require much labor.