Kanankaalin levinneisyydestä ja torjunnasta

The writer describes at first the botanical qualities of the wintercress, Barbaraea arcuata (Opitz) Rchb. as well as its noxiousness and utility to the agriculture. The spreading of the wintercress in Finland is exposed in the table 1. It shows that the frequency of its spreading in the different parts of the country is relatively low and equal. Locally there is though exceedingly great differences in the frequency of its appearence. During the years 1945—1947 the writer was making tests in Tuusula to effect the control of wintercress. The results of these tests are exposed in the tables 2, 3 and 4, and are showing, that the possibilities of wintercress control by using calcium cyanamide and hormone products are limited, but not quite unimportant. The hormone products used both as sprays and as dusts are efficient in preventing the qrowth of wintercress on the grasslands. Their use is though to be taken into consideration so far it is economically profitable and only on cloverless meadows, because clover do not endure hormone application. The effect of calcium cyanamide (100—150 kg/ha) on wintercress is insufficient. Though it prevents partly the development of the plantvines and reduces the seeding. The best results were obtained by using of a very early distributing time the wintercress being at the rosette stage. The use of greater amounts of calcium cyanamide (200—250 kg/ha) with greater effect on the wintercress might appropriate on old weedless grasslands, where the vegetation for the most part consists of timothy or other fieldgrasses