Crop Viruses and the Insects and Mites That Carry Them

Where plant virology began: Martinus Beijerinck isolated this virus in 1898, building on Dmitri Ivanovsky's earlier filtration experiments. Its extreme stability still makes it a model system, and it remains a pathogen of tobacco and greenhouse tomato.

Aphid transmitted and the most widely distributed viral disease of cereals. Its losses are often mistaken for poor soil or drought stress, which hides a cost estimated in billions of dollars a year.

Also called Sharka, an aphid transmitted virus first described in Bulgaria that deforms stone fruit. Eradication programs that destroy infected orchards have cost affected regions hundreds of millions of dollars, and it is on the EPPO A2 quarantine list.

Aphid transmitted, and its mid twentieth century epidemics in South America killed tens of millions of citrus trees on sour orange rootstock. That history drove the near universal move away from sour orange rootstock in commercial groves.

Aphid transmitted and considered the most economically important virus disease of banana. An infected plant never yields a usable bunch and is destroyed outright because there is no cure.

Aphid transmitted and nearly ended commercial papaya on Oahu by the 1990s. A papaya carrying a gene from the virus itself was approved in Hawaii in 1998, one of the first widely commercialized genetically engineered food crops.

Carried between peanut plants by the groundnut aphid across Sub-Saharan Africa. It infected eighty to ninety percent of plants in the Belgian Congo in 1939, and one Tanzanian study recorded sixty five percent affected within three weeks of detection.

Whitefly transmitted, and its spread has tracked that of the whitefly Bemisia tabaci from the Middle East to Africa, Asia and the Americas. Plants infected young may yield almost nothing, and it is regarded as the most damaging tomato virus worldwide.

A group of whitefly transmitted viruses in a crop that feeds several hundred million people in Africa. A pandemic of virulent recombinant strains from the late 1980s at times cut regional cassava production by more than half.

Caused by two viruses, first identified in Tanzania in 1936 and now found along the coast from Kenya to Mozambique. Root rot makes the tuber inedible, so research focuses on cultivars that do not develop the necrotic rot.

Leafhopper transmitted and native to Africa, where it is the most economically important virus disease of maize. Losses reached 100 percent in some outbreak years in susceptible varieties, which drove resistance breeding across the continent.

Spread by the wheat curl mite from volunteer wheat that carries both virus and mite into a new planting. Destroying volunteer wheat before the next crop is the main control on the US Great Plains.

Spread mainly by mealybugs and first found in Ghana in 1936. It has destroyed more than two hundred million cacao trees and accounts for about fifteen percent of world cocoa losses, so Ghana has run costly tree eradication programs.