Abstract only

The privatization of land in Armenia has resulted in essential changes in the structure of agricultural production. The areas earlier occupied by vineyards, fruit and vegetable gardens, and fodder crops have dramatically reduced at the expense of areas sown to cereals. The latter are now cultivated in almost all the agricultural zones, under conditions of both irrigation and dryland. The problems of weed control under new conditions have acquired special importance. The abundance, specific composition and weed infestation level in different zones are different (Table). Presence of dicotyledonous weed stems at the rate of25 stems/m2 reduces yield in the cereals by 35% in average. Infestation of the fields at the level of 70 stems/m2 reduces yield of wheat and wild oat by 32%, while yield of barley is reduced by 56%. The most noxious and widespread weed in the croplands of Ararat valley sown to winter wheat is common reed. Common reed is presented by one species and 5 morphological forms or ecotypes. The density of reed is directly proportional to the yield losses. Thus, its density at the rate of 3 stems/m2, 5 stems/m2, 10 stems/m2, 15 stems/m2, and 25 stems/ m2, reduces the yield of wheat by 18%,26%, 63%, 78% and 93%, respectively. During vegetation, the reed up-takes a great amount of water from soil (one stem -3701) causing secondary salinization of the meliorated- cultivated soils, in which the deposition of subsoil water (highly mineralized) under Ararat valley conditions is rather high. Dicotyledonous weeds are controlled by the following herbicides: locally produced Fenagon ( 11/ ha) and Dialen-super (2 l/ha) from the Ukraine. As for monocotyledonous weeds, weed-killers are not being applied against them. However, we recom- mend using such weed-killers as Topic, Puma-super, Illoxan, Quartz-super, Prodifox, and Trialat. To achieve full control of the weeds in the areas of cereal crops in various regions of the republic, the following facts and recommendations should be taken into account. .Up to present, distribution areas of the weeds and the weed infestation extent have not been documented in Armenia. .Wild oats, bindweed and thistle weeds are better adapted to the environmental conditions, soil cultivation methods; therefore, their effective control by means of conventional agronomic methods is practically impossible. .Small-sized plots (0.5-3.0 ha) exclude the utilization of mechanical weed control measures, as well as chemical app]ications. .Scientific research in the development of non-chemical weed elimination techniques based on cultural and biological methods is not conducted due to the lack of the state financing. .The generally low level of farming creates conditions for unpredictable outbursts of infestation by weeds that are hard to kill and by the quarantine weeds, which leads to a significant reduction of yield. .The current situation in the agricultural sector asks for searching for new forms of cooperation between research institutions and farms in the plant protection area. .To conduct research in application of weed- killers and fertilizers combined with the use of irrigation water (herbigation), herbicides and fungicides. .To apply herbicides only after the specific composition of weeds, the weed contamination degree, the economic threshold of harmfulness and control feasibility have been determined. .For complete eradication of weeds in cereals (winter and spring) within different areas to provide for supplies of Topic, Quartz-super, Illoxan and Roundup. .To introduce on the meliorated soils of Ararat valley crop rotations with the application of herbicides, especially of Roundup to control common reed. Reed control should be carried out not only prior to soil melioration and but also in the course of it. Otherwise wide weed contamination would require many inputs for its eradication.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection