摘要:

SummaryThe aim of this study was to assess the effect and importance of the feeding of the pine top weevil (Pissodes piniphilus) on the germination ofEndocronartium pini(syn.Peridermium pini) in Scots pine (Pinus sylvestris), and thus to establish the possibility of theE. piniinfection via insect woundings. Germination tests were therefore carried out on current and previous year needle and phloem extracts. Elucidation of the importance of pathogen infection for the insect's feeding preference was also required; for this purpose feeding preference tests were carried out with healthy and infected pine branches using the pine top weevil as a test insect. Weevil feeding increased the germination ofE. piniaeciospores on pine extracts. Germination on previous year annual‐shoot extracts was lower than that on current year annual‐shoot extracts. The advance of the growing season increased this trend, but weevil feeding increased germination on extracts from older annual shoots to the levels found on extracts from current annual shoots. Spores germinated equally well on needle extracts and on phloem extracts. The weevils ate more often on infected branches than on healthy branches.E. piniinfections may occur via woundings on branches and weevil feeding may facilitate t

ISSN:0300-1237    

DOI:10.1111/j.1439-0329.1996.tb00843.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryTestsin vitroandin situshowed that both mycelial and conidial suspensions ofAcremonium mucronatumwere antagonistic forDiplodia mutila, a common pathogen on the apical twigs of decliningQuercus cerris, Quercus frainetto, Quercus pubescensandQuercus robur. Antagonism was greater with the mycelium than with the conidial suspensions, and was strongest at a test temperature of 20°C. The results suggest that pathogenicity ofD. mutilaon declining trees may be significantly reduced by the presence ofA. mucronatum

ISSN:0300-1237    

DOI:10.1111/j.1439-0329.1996.tb00844.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryOpen‐pollinated progenies from two trembling aspen (Populus tremuloides) families with a 30‐year field history of 91% (putatively susceptible, PS) and 45% (putatively resistant, PR) mortality, respectively, caused byHypoxylon mammatum, were grown in a greenhouse for 3 and 9 months. Seedlings were inoculated with two isolates ofH. mammatum, representing high and low aggressiveness, through a stem wound. Beginning 4 days after inoculation, host responses were examined on 312 seedlings per family for a period of 5 weeks on 3‐ and 9‐month‐old seedlings. Significant differences in host responses were observed between the two isolates, with the more aggressive isolate allowing less callus formation, causing more tissue necrosis and producing longer cankers than the less aggressive isolate on both aspen families. Between‐family difference was much greater than within‐family difference for tissue necrosis, callus formation and canker length for both seedling ages. When the 3‐month‐old seedlings were challenged withH. mammatum, the PR family showed greater tissue necrosis, longer cankers, and less callus formation than the PS family. However, when the more lignifìed 9‐month‐old seedlings of the same families were inoculated, the PR seedlings had much less tissue necrosis, shorter cankers, more callus formation and less seedling mortality than the PS family. The results indicate that artificial inoculation of seedlings in a greenhouse can differentiate two aspen families at the seedling stage, but their correlation to field performance is highly dependent upon the seedling age. Host responses of older seedlings may be a better indicato

ISSN:0300-1237    

DOI:10.1111/j.1439-0329.1996.tb00845.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryWithin the scope of a research project on the condition of roots of declining oaks (Quercus robur, Quercus petraea), samples of fine roots and surrounding soil, specimens of stripe cankers on the stem base, and samples of stream water were examined for the presence ofPhytophthoraspecies using both baiting methods and selective agar media. At 27 sites in Germany (Bavaria, Rheinland‐Pfalz, Schleswig‐Holstein), Switzerland, Hungary, Italy and Slovenia the following species were isolated (mainly from soil):Phytophthora citricola, Phytophthora cactorum,Phytophthora cambivora, Phytophthora gon‐apodyides, Phytophthora undulata, a species with affinity toPhytophthora drechsleri, and two additional species with close affinity to thePhytophthora cactorumgroup. Moreover,Pythiumgroup P,Pythium anandrum, Pythium chamaehyphon, and many otherPythiumspecies that have not yet been identified could be recovered. In a soil infestation test most isolates induced dieback of long root tips and necrotic lesions in the root cortex and at the root collar ofQuercus roburseedlings. AllPhytophthoraspecies tested andPythiumgroup P caused cortical necrosis after stem inoculation of youngQuercus roburtrees. It could be shownin vitrothatPhytophthora gonapodyidesandPythiumgroup P were able to produce a wilting toxin. Nitrogen input and climatic changes are discussed as predisposing factors for root damage observed in the

ISSN:0300-1237    

DOI:10.1111/j.1439-0329.1996.tb00846.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY

摘要:

SummaryPhellinus tremulaeis the most important decay fungus onPopulus tremuloides. In forest industries using aspen wood chips, two blue‐stain fungiOphiostoma crassivaginatumandOphiostoma piliferumcause considerable reduction in the value of the end product. Thirty‐eight homologues and analogues of 4‐phenyl‐3‐butenoic acid were studied againstP. tremulae, O. crassivaginatum, andO. piliferum. Varied inhibition of thein vitrogrowth of these fungi was observed at 1–1000 μg/ml. The wood‐chip colonization byP. tremulaewas not affected by the six most active compounds at 1 μg/ml, however, at 10 and 100 μg/ml the growth ofP. tremulaeon wood chips was totally arrested. 4‐Phenyl‐3‐butenoic acid and 4‐phenyl‐3‐butynoic acid prevented blue‐stain develo

ISSN:0300-1237    

DOI:10.1111/j.1439-0329.1996.tb00847.x

出版商:Blackwell Publishing Ltd    

年代:1996

数据来源: WILEY