Ultrastructure of Calli Cells of Poplar Exposed to Toxin Produced by Dothiorella gregaria Study on Use of Two Kinds of Cultivating Techniques to Control Poplar Canker A STUDY ON THE EFFECTS OF DOTHJORELLA GREGARlA CANKER ON THE GROWTH AND VOLUME OF YOUNG POPLAR TREES Genetic Variation and Initial Selection of Clones from Hybrid between Populus deltoides Marsh.×P.cathayana Rehd. A PRELIMINARY STUDY ON THE RELATION OF THE CHEMICAL COMPOSITIONS IN THE BARK OF POPLAR TO DOTHIORELLA GREGARIA SACC.——Ⅰ. THE RELATION OF THE MACRONUTRIENTS TO D. GREGARIA SACC. Study on the Disease Resistance of New Poplar Cultivars to Trunk Cancer, Dothiorella gregaria, and Leaf Black Spot, Marssonina brunnea Study on the Control Index of Dothiorella gregaria Canker of Poplar STUDY ON THE ANTAGONISM OF TRICHODERMA SPECIES ON CANKER PATHOGEN FUNGI OF POPULAR MECHANISM OF VESICULAR ARBUSCULAR MYCORRHIZAL FUNGI ENHANCED RESISTANCE OF POPLAR TO CANKER THE STUDY ON GROWING LOSS ASSESSMENT OF YOUNG POPLAR CAUSED BY DOTHIORELLA GREGARIA STUDY ON THE CONTROL OF POPLAR CANKER DISEASE CAUSED BY DOTHIORELLA GREG ARIA A STUDY ON THE LATENT INFECTION OF POPLAR CANKER