El polvillo de la hoja del trigo y su presencia en Chile.
1991
Parodi P Patricio C | Nebreda M Isabel M.
Leaf rust of wheat (Puccinia recondita Rob. ex Desm. f. sp. tritici) is a foliar disease found worldwide, considered by some authors as "the main pathogen of the world's most important crop". Its damages are expressed as a yield reduction mainly induced by a decrease in the number of kernels per spike. Its presence in Chile has been cyclic. In years of severe attacks susceptible cultivars have suffered yield reductions up to 30, 45 and 21%, according to different authors. It is estimated that average national losses are close to 5%. The last attack episode was recorded in 1986 at the extreme north of the wheat growing area, the fungus appearing severely but late in the season, fact that has reduced the yield damage level. Attack has continued the following years, excepting 1988, infections occurring earlier and more severely. In 1990 it was present as south as the IX Region. Several cultivars have shown to be susceptible to the fungus' new biotype, but there are others which are immune or resistant. Susceptible cultivars as long as they remain in the market must be treated with the appropiate fungicides, preventively before symptoms become apparent, and then curatively when the first pustules are visible. A methodology of early detection is suggested in order to recommend the date of the preventive fungicide application, based on satelite image of the wheat growing areas, and directed sampling of some areas with infrared aerial photographs, to determine the north to south movement of the pathogen. The simplest, most economic and efficient mean of controlling the pathogen is, however, genetic resistance, and the removal from the market of susceptible cultivars to reduce the sources of inoculum.
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