Verdelging van slakken en andere schadelijke dieben door eenden en kippen

European Journal of Plant Pathology -     

Ripening of Tomatoes

Experiments were carried out with aldrin, dieldrin, isodrin, endrin and DDT to ascertain whether, employed as insecticides, these compounds had any effect on cell division in onion root-tips. The doses used were equal to, or greatly in excess of, the recommended rates of application. By germinating onion seeds in direct contact with the insecticide under investigation, it has been shown that none of the compounds had any effects on germination or growth rate. High doses of aldrin, dieldrin or isodrin had a slight toxic effect on the resting cell, which, with aldrin, was also caused by the recrystallized compound. Aldrin and dieldrin had no effect on the dividing cell. Isodrin and endrin caused slight stickiness between chromatids in anaphase, which was insufficient to prevent the completion of division in the cell, and DDT caused a delay in the early stages of prophase and a shortening of chromosomes in metaphase.

Pot experiments, with high doses of each compound, showed that germination and growth rate were unaffected by any of the compounds. Resting cells were not affected and dividing cells were affected only by slight stickiness in anaphase, except with DDT, which also caused a slight delay in metaphase.

Attention has been drawn to the advantages of these compounds over gamma-BHC, chlordane and toxaphene as insecticides, from the point of view of causing less damage to the plant.     

Studies in Growth and Development in the Genus Fragaria I. Factors Affecting the Rate of Leaf Production in Royal Sovereign Strawberry

The Raspberry Cane Midge is principally important as a precursor of the fungal disease “ Midge Blight This disease may kill a substantial proportion of the canes of varieties such as Newburgh and Mailing Enterprise before they can bear fruit in the following spring (Pitcher and Webb, 1952) ; in addition, the yield of many of the surviving canes is reduced. Fortunately the midge is not a universal pest of raspberries ; in Britain its range is restricted to the south and the Midlands and several varieties, such as Norfolk Giant and Mailing Landmark, are highly resistant.     

The Pollination of Strawberries by Honey-Bees

Pollination of strawberries by honey-bees increased the percentage of flowers that set fruit, the weight of the berries, and the percentage of well-formed berries.