Statistical study of Pine tree's infestation to Rhyacionia buoliana Den and schiff in Guilan province.

More advantage of pine woods in different industries , fast growth of them and privation of importance and commerical species of pine in the natural forests of Iran , cased which the number of them planted in reforestation programs . Pine trees (Pinus sp.) are important exotic species which planted in a wide areas of the forest regions in north of Iran . Rhyacionia buoliana is the most important pests which damaged on pine trees specially young seedling in Guilan province , and decreesed their quality. This study was carried out in 20 regions of Guilan reforestation ( 12 regions in the west , 2 regions in the center and 6 regions in the east of Guilan ) , which planted with 5 species (Pinus taeda , Pinus sylvestris , Pinus pinaster , Pinus nigra and Pinus ponderosa) and then 30 trees in each region selected by systematic random sampling , and assessmented . In this research , condition of trunk , curvature in body and countenance of crown as are important quality factors of silviculture charactristics in the forest species , investigated for this sample species . condition of trunk in 3 position (unbranched , two branched and multi branched) , curvature in body in 5 position (uncurvature , curvature in 1/3 first o trunk , curvature in 1/2 first o trunk , curvature in 1/3 upper o tree and multi curvature) and countenance of crown in 4 group (safe , umbellate , crown desiccated and broomy) separate and classified and then all of this charactristics assessmented by using of K² test . Results showed that , from 5 species (P. taeda , P. sylvestris , P. nigra , P. pinaster and P. ponderosa) which planted in different regions of Guilan , P. taeda (%88) and P. ponderosa (%0) demonstrated the most and the least infesting to this pest . This compared showed that the species of P. nigra , P. sylvestris and P. pinaster in respect of infestation , were in degree of second , third and fourth respectively . Based on the results obtained , all of above factors connected with infesting and there are significant different between connected were different in the species . Infested trees from species of P. pinaster , P. nigra , P. taeda and P. sylvestris had %100 , %76 , %50 and %50 curvature in body respectively . Countenance of crown in %80 of 3 species (P. nigra , P. taeda and P. sylvestris) , %100 of P. pinaster was umbellate . Trunk position specified that more than %50 of infested trees from above species had charactristics .