Weed infestation dynamics in observation fields in Vidzeme region 1997-2000
2001
Vanaga, I. (Latvian State Centre of Plant Protection, Riga (Latvia))
The change from large scale agriculture to private small scale farming has resulted in a severe lack of plant protection means. Fields of Latvia have become more weedy for last four years. This fact shows the necessity for a change in the strategy of weed control. The effect of inexpensive and wide-spread herbicides 2.4-D and MCPA is insignificant in weed control. From 1994 Latvian State Centre of Plant Protection has been studying the occurance of weed species in the Central part of Latvia (Vidzeme), to make use schedules of necessary herbicides. The research was carried out jointly with the Latvia University of Agriculture. During the research carried out from 1997 to 2000, 60 weed species were established, but in all the crop sowings 10 species were predominant. The number of Elymus repens, Myosotis arvensis and Viola arvensis has increased during last four years. In Vidzeme region, from 1997 to 2000, it was stated that soil infestation of weed seeds varies from 4.5 to 11.1 thousand seeds per square metre on the average. Perennial dicot-weeds have shown the lowest variation coefficient, compaered with other weed groups.
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