A study of five viral soybean diseases in Argentina puts soybean mosaic virus at the top of the country's hit list. Here's a rundown of the type of damage done by the five diseases:

* Soybean mosaic virus can be found all over Argentina, causing yield losses of up to 33% when early infection occurs. The disease mottles seeds and is seed-transmitted.

* Alfalfa mosaic virus has reduced yield by up to 10% within a broad producing area of the country. It causes generalized chlorotic symptoms and foliar malformation, besides reducing plant growth. At least 11 weed species, which may act as virus reservoirs, have been detected. The research also concluded that alfalfa can be an alternate host for the virus in parts of the country.

* Peanut mottle virus, found only in the province of Cordoba, has been detected in soybean fields near infected peanut growing areas. Early infection reduces growth and causes fewer, smaller and malformed pods and seeds. Yield loss hasn't been higher than 10%.

* Tobacco streak virus reduces growth and causes severe bud necrosis. Early infection could cause seed mottling of up to 70% and total yield loss. The good news: It's seldom detected and then in just parts of the country.

* The geminivirus is widely spread in northwestern Argentina. It stunts growth and causes intense mosaic and chlorotic mottling, blistering and leaf malformation. It can reduce pod numbers by up to 40%, seed weight by 46% and seed number by 42%. The virus is not seed-transmitted.

(I.G. Laguna, P. Rodriguez Pardina, et al, INTA-Instituto de Fitopatologia y Fisiologia Vegetal, Cordoba, Argentina and Estacion Experimental Agroindustrial "Obispo Columbres," Tucuman, Argentina)