The method of isolation of epidermis of tomato and cucurnber leaves for microscopic investigation of pathogenic fungus development

There has been described a new, easy method of isolation and staining of epidermis from leaves and cotyledon of healthy cucumber and infected one with the fungus <em>Pseudoperonospora cubensis</em> Berk and Curt and from tomato leaves infected with the fungus <em>Oidiurn licopersicum</em> Cook and Massee. The epidermis was taken of with the use of transparent Scotch from the leaves and stained with toluidyne blue. This method is helpful in distinguising the differences in a structure of epidermis of healthy and infected leaves and in estimating the following: stage of development of the fungus on epidermis, number and size of haustorium in epidermis cells, number of spores of a fungus on the certain surface of the host leaf. This method is valuable because it enables to protect the material for a long time, which is very important during testing a big number of plants. Key words: leaf epidermis, method of isoIation, cucumber, tomato, pathogenic fungus.

A Mycoherbicide Integrated with Fungicides in Rice,Oryza sativa

Field experiments were conducted to determine the effect of selected rice pesticides on the mycoherbicideColletotrichum gloeosporioides(Penz.) Sacc. f. sp.aeschynomene(designated as C.g.a.) for northern jointvetch control in dry-seeded rice. Sequential treatments of pencycuron at 0.56 kg ai/ha, SN-84364 at 0.40 kg ai/ha applied 7 and 14 days after C.g.a., or pencycuron sprayed sequentially after a tank mixture of C.g.a. plus actifluorfen did not reduce infectivity of C.g.a. Also, propiconazol at 0.60 kg ai/ha or pencycuron applied 7 days before and after C.g.a. did not reduce fungus development on northern jointvetch. Sequential treatments of benomyl at 0.56 kg ai/ha or propiconazol applied 7 and 14 days after C.g.a. reduced pathogen activity on northern jointvetch.

Fomesannosus stump colonization and fungus development in the California mixed-conifer type

The pattern and rate of colonization of ponderosa pine (Pinusponderosa Laws.) stumps and stump roots by Fomes annosus (Fr.) Karsten were determined by sampling inoculated stumps periodically. Colonization occurred in the sapwood and wood–bark interface. Downward growth was fastest in the wood–bark interface and large stump roots were completely colonized in less than 1.5 years. Comparisons were made among colonization patterns and rates in ponderosa pine, sugar pine (P. lambertiana Dougl.), and Douglas–fir (Pseudotsugamenziesii (Mirb.) Franco) stumps.Conidiophores were observed only during the early periods of bark loosening and were produced in 'tubes' and beetle galleries of inoculated and non-inoculated stumps. Mycelial plaques formed during the later stages of bark loosening in both inoculated and non-inoculated stumps. Basidiocarps developed on inoculated stumps within 1.5 years and on older non-inoculated stumps.

Inoculation and Development of Eutypella Canker of Maple

Possible ways by which infection with Eutypellaparasitica can occur on sugar and red maple were investigated using various artificial infection courts and different inocula. Close to 50% of wound-inoculated sugar maple trunks became infected, using either mycelium or ascospore inoculum. Red maple was much less susceptible to infection than sugar maple, as only 6% of the tests were positive. Fifteen to 25% of sugar maple branches, 0.25 to 0.5 in. (0.6 to 1.2 cm) in diameter, inoculated with ascospore suspension, became infected when they had received one of the following wounds: knife cut, bruised bark, or incomplete breakage of the branch. No infection occurred when inoculations were attempted at axils of nonwounded 1- to 2-year-old twigs. On many successful trunk inoculations, a slight swelling of the stem and the characteristic mycelial fans of the fungus under the bark were observed 2 years after inoculation. Where rapid extension of the canker occurred, the initial advance of the fungus was in the bark tissue and subsequently in the underlying cambium and xylem. This fungus development corresponds to that observed in naturally infected trees.