IITA plant virologist James Legg asks:
Cassava mosaic virus disease & Cassava brown streak virus disease constrain production throughout East & Central Africa, but do the effects get worse if farmers keep recycling planting material?
Yes, right?
Well, it’s more complicated than that. Spoiler alert:
1. Degeneration is most clear in resistant varieties as it happens slowly
2. Virus-free planting material gives greater yield gains than extreme resistance
3. BUT, virus-free material has no value for highly susceptible varieties
But read how they got there.