Out of the several virus diseases reported as infecting maize, only a few of these have been reported in the Asian countries. However, experience has shown that under certain conditions, nonidentified problems have been observed causing serious damage to maize plants, normally assuming these damage is caused by viruses. Based on the limited information available, the viral diseases reported affecting maize under natural conditions in the Asian region, are the maize mosaic (MMV), maize rough dwarf virus (MRDV), maize dwarf mosaic virus (MDMV), sugarcane mosaic virus (SCMV), brome mosaic virus (BMV), maize stripe virus (MStV), maize streak virus (MSV), maize vein enation (MVE), maize streak dwarf virus (MSDV), and barley yellow dwarf virus (BYDV). Identifications have been mostly based on symptom development on maize, thermal inactivation point, inoculation methods, and differential host range, but seldom done through electron microscopy or serology. It is suggested to study the correct distribution of the above, and probably other nonreported viral agents, determine the yield loss caused to maize production in the areas where present. A series of techniques for virus-diagnosis and identification are discussed for possible use. With the exception of Malaysia and Singapore, maize is an important crop in all other countries in the Asian region. Maize is mostly used as an energy source and staple food in most of these countries and as an animal feed in all countries. Regardless of the economic and social importance of this cereal, and mostly due to its wide adaptability and rusticity, it is grown in poor soil conditions suffering of several stresses, the good fertile soils being used to grow rice and other more economic crops. One of several stresses affecting maize production is caused by the presence of virus diseases. Viruses are the most misterious disease agents affecting both plants and animals, and hence the limited amount of studies and where there is the least information on their incidence and economic effects. This lack of information is more accute in the developing countries, where there is a lack of trained personnel and appropiate equipment, and mostly to the concept that when these viral diseases are present, nothing can be done to control them. The problem with such mentality , the incidence of these diseases continues to increase, especially under the present actively changing circumstances in agriculture when new germplasm is almost freely moving througout all environments, agronomic practices are changing, and there is a conspicuous expansion of area where maize is being grown due to an increased demand. These changes in technology are bringing along an increase in problems, specially insects and diseases, that were not previously considered problems of any significance. A similar situation is being detected and reported in other crops in other regions of the world. In this presentation, a summary of virus diseases reported in the Asian region is discussed, including the activities that the South American Regional Maize Program has initiated in this area of research at the request of the various national programs in the region. Our objective is to understand the distribution and importance of certain problems, including insects and diseases, previously known of no significance.

English

0208|AGRIS 0201|AL-Maize Program|R01PROCE

CIMMYT Staff Publications Collection