摘要:

In the field,Cryptodiaporthe salicellahas been found only onSalixsp., andFusarium lateritiumon nursery-grownPopulus trichocarpaTorrey and Gray. However, the pathogens for these diseases attackedP. trichocarpa,P. 'robusta',P. tremuloidesMichx., andSalixsp. when inoculations were made on cuttings which were allowed to dry gradually in a dormant condition. The development of the diseases in the field and in the laboratory was related to the moisture content of the host bark. Canker growth occurred only when the relative turgidity of the bark was below 80%. The possibility of employing similar methods of investigation for the discovery and evaluation of canker diseases of importance in disease-testing programs is discussed.

ISSN:0008-4026    

DOI:10.1139/b61-011

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

In cuttings from 1-year-old shoots ofPopulus trichocarpaTorrey and Gray andP. 'robusta', correlations were found to exist between the degree of vigor as expressed by the production of basal callus and the associated wound roots, and the relative turgidity of the bark at the time of harvest or planting. The ability to produce basal callus and wound roots decreased in cuttings with relative turgidities below the 80% level, and many were killed by the development of basal cankers caused byFusarium lateritiumNees andCytospora chrysosperma. (Pers.) Fr. Therefore, the bark moisture level in cuttings was indicative of their ability to produce basal callus and wound roots in addition to their vulnerability to these canker diseases caused by facultative parasites.In uniform-sized cuttings ofP. 'robusta' no relation was found between the production of morphological roots developing from root primordia, and the bark moisture level, or the percentage of plants which survived. Larger numbers of morphological roots developed on cuttings from the basal and, consequently, older parts of stems.The production of basal callus and wound roots inP. 'robusta' was found to be related to the total weight of cuttings of uniform size, which suggested that weight determinations in the field may provide useful guides into the general level of vigor of dormant nursery stock and stored material.

ISSN:0008-4026    

DOI:10.1139/b61-012

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

In this paper the modern concept of infection by species ofCintractiais briefly discussed. Three species are treated, two of which,C. elynaeSydow andC. kobresiaeMundkur, are redescribed, and the third is recognized as new,C. lindebergiaen. sp. The spore germination ofC. elynaeis described and illustrated. A short account of the host genusKobresiais given with special reference to the species attacked by the above smuts.

ISSN:0008-4026    

DOI:10.1139/b61-013

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

An intensive study was made of the morphology, cultural characters, and infection capabilities of 18 isolates ofVerticillium. These were in part isolated from differentVerticilliumhosts occurring in the Niagara Peninsula and the balance were obtained as named stock cultures from different herbaria. In terms of their pathogenicity to strawberries, resistant and susceptible tomatoes, and eggplants, the isolates comprised a number of races whose virulence ranged from lethal to very mildly pathogenic. Under the experimental conditions, current-year runner plants of strawberries proved to be virtually immune from infection, in contrast to normal overwintered plants. The symptoms on the strawberry are variable and diagnosis should be confirmed by isolation of the pathogen, for which a technique was evolved. Morphologically the isolates varied considerably and in culture the color ranged from white through gradually deepening gray to black. At the extremes the differences were conspicuous but were so intergrading in the group as a whole that the isolates are regarded as belonging to one variable species which, because of priority, must be calledVerticillium albo-atrumR. and B.

ISSN:0008-4026    

DOI:10.1139/b61-014

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Flood fallow and silting were the only practices that consistently reduced incidence of banana wilt induced byF. oxysporumf.cubense(E. F. S.) Snyd. and Hans. The efficiency of flood fallow was greatly increased by interflood plowing, and in most locations by postflood fungicide drenches. Even these treatments, however, did not insure economic control in some areas. It was necessary, therefore, to select areas where soil factors tended to retard rapid disease development. Also, the absence of the banana host for a number of years previous to flood fallow appeared to influence treatment success.

ISSN:0008-4026    

DOI:10.1139/b61-015

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

The events following fertilization up to the maturation of the seed inAdhatoda vasicahave been described. The first two transverse divisions accompanying the division of the primary endosperm nucleus partition the embryo sac into (1) a micropylar chamber, (2) a chalazal chamber, and (3) a central endosperm chamber. The first two develop into binucleate haustorial structures, while the bulk of the endosperm is derived from the products of the central endosperm chamber. An unusual case of a micropylar haustorium containing four hypertrophied nuclei and four small nuclei has been observed. The central endosperm chamber is partly cellular and bears a tubular free nuclear basal apparatus. The latter, however, ultimately becomes cellular. The embryo development is of the Solanad type. The mature seed has only two layers of thin-walled endosperm cells and a wavy testa representing the persistent epidermis of the integument. The rest of the integument is consumed by the endosperm. The uneven surface of the testa results from unequal development of the integumentary parenchyma and not due to either unequal radial stretching of the epidermis or irregular growth of the endosperm as inAndrographis serpyllifolia.

ISSN:0008-4026    

DOI:10.1139/b61-016

出版商:NRC Research Press    

年代:1961

数据来源: NRC

摘要:

Nine species representing five genera of the Sclerotiniaceae were found to be self-fertile. These are as follows:Ciboria acericolasp. nov.,C. acerinaWhetz. & Buchw.,C. amentacea(Balb. ex Fr.) Fckl.,C. betulicolasp. nov.,C. caucus(Rebent. ex Fr.) Fckl.,Ciborinia erythronii(Whetz.) Whetz.,Rutstroemia paludosa(Cash & Davidson) comb. nov.,Septotinia podophyllinaWhetz., andVerpatinia calthicolaWhetz. Two new species and one new combination are proposed and validating Latin diagnoses are provided forCiboria acerina, the genusSeptotinia, andS. podophyllina.

ISSN:0008-4026    

DOI:10.1139/b61-017

出版商:NRC Research Press    

年代:1961

数据来源: NRC