No abstract

A green grafting technique for indexing grapevines for viruses is described. It consists of joining actively growing stock and scion tissues with a slanting cut and then binding with a plastic or a rubber tie. The technique has some advantages over the more generally used dormant-chip-budding method, as it can be done for the greater part of the growing season, and very small stocks and scions can be grafted. It also provides a more rapid means of testing for GFLV than does chip-budding.

In the past twenty years there has been no noticeable decrease in the number of Helminthosporium infected oat and barley seed samples examined at the Official Seed Testing Station, Cambridge, and in the course of advisory practice. No reduction in the intensity of the seedling diseases caused by Helminthosporium has been noted during the first ten years under review. Formalin and copper carbonate were ineffective as seed disinfectants in reducing seedling mortality, and copper sulphate, although partially effective, had serious phytocidal effects and consequently cannot be recommended. Since the advent of the organo-mercury seed disinfectants a steady improvement in the control of these diseases has been noted, and field tests of such dressings have shown them to be eminently satisfactory. Barley straw infected with H. gramineum has been shown to be a source of secondary infection of barley seedlings.

A mulch of corn stover and barnyard manure has given excellent control of soil and water losses from corn after corn on a steeply sloping deep loess soil. During 9 years of measurement in Wisconsin, losses of soil and water from corn after corn with a mulch were less than from corn or oats without mulch in a corn‐oats‐hay rotation and were about equal to the losses from the meadow in the rotation. Corn yields averaged 3 bushels more from the corn after corn than from the corn in the 3‐year rotation.

The fungus Deuterophoma has been proved to be a pathogen of chrysanthemums in Victoria. It was isolated from a number of varieties in each of five Melbourne nurseries from which collections of chrysanthemum were made, and also from one variety growing in a Rutherglen home garden. In pathogenicity tests Deuterophoma was found to rapidly invade injured roots and move info the stems from which it could be readily re-isolated. Chrysanthemum infected with Deuterophoma do not show symptoms on the current season's growth. However, the fungus weakens the stools which may, die or regenerate slowly after being cut back in the autumn. Deuterophoma has been recorded previously only in Californian and in Illinois on chrysanthemums originating from California. In the nursery from which the fit isolates were obtained it was prevalent in chrysanthemums recent4 introduced from California. As it is impossible to detect Deuterophoma from visual observation of the current season's growth, the necessity of importing chrysanthemums from pathogen free sources is stressed. The use of pathogen free stocks coupled with soil sterilization and nursery hygiene is suggested as a means of control of Deuterophoma.