Occurrence of Phytophthora macrochlamydospora in New South Wales and its pathogenicity to some legume species
Herbarium material of a Phytophthora species recorded on soybeans in New South Wales during 1985 was re-examined and identified as P. macrochlamydospora Irwin. A range of soybean cultivars and some legumes that occur naturally on the north coast region of New South Wales were tested for their reaction to artificial inoculation with P. macrochlamydospora. On soybeans, variable reactions were recorded indicating resistance in some cultivars. A number of the legumes were susceptible to infection. P. macrochlamydospora appears to be endemic on the north coast of New South Wales but has not been recorded from other areas of New South Wales.
Arkoola nigra gen. et sp.nov. (Venturiaceae) causing black leaf blight of soybean in Australia.
Arkoola nigra gen. et sp.nov. (Venturiaceae) is described, causing black leaf blight of soybean in New South Wales. It forms a superficial black mycelial web on infected plants and penetrates the host from large appressoria, causing severe spotting and blighting of leaves, stems and pods. Ascocarps develop on dead fallen leaves and on detached leaves inoculated in culture. They are black, setose and contain large cylindrical bitunicate asci with pale greenish two-celled ascospores and abundant pseudoparaphyses. The connexion between ascosporic and mycelial states has been proved by pure culture studies, and plant inoculations reproduce the disease symptoms. It is transmitted to a limited extent with seed. A range of native legumes were infected in artificial inoculation tests. The relationship of A. nigra to other genera of Venturiaceae, its possible origin, host range and associated matters are discussed.
Increasing pulp yield in kraft cooking of softwoods by high initial effective alkali concentration (HIEAC) during impregnation leading to decreasing secondary peeling of cellulose
Abstract Pulp yield can be improved by a more homogeneous delignification of the chips, achieved by improved impregnation prior to the cooking stage. Complete and efficient impregnation is obtained by increasing the diffusion rate by means of an impregnation liquor with a high initial effective alkali concentration (HIEAC). In the present study, the effect of HIEAC in the impregnation was evaluated and compared to a reference impregnation procedure and a prolonged impregnation. After the various impregnation scenarios, the alkali concentration was always adjusted to the same level in the beginning of the cooking stage. Impregnation with a HIEAC resulted in yield improvements by 1–1.5% units, due to a higher cellulose yield and possibly also to higher yield of glucomannan. The HIEAC with an even alkali distribution within the chips prior to the cooking stage resulted in a more uniform delignification carbohydrate degradation. Yield increase obtained by uniform delignification is due to both decreased shives content as well as less secondary peeling.