Abstract only

Wheat is one of the main crops cultivated in Armenia. However, as a result of the impact of some diseases, particularly, common bunt and powdery mildew, the expected yield and grain quality are reduced to a great extent. Measures for pre-sowing seed treatment and spraying of fields by fungicides are carried out to control these diseases. Until recently, the chemicals such as grano- zan, TMTD and vitatiuram have been applied in the republic to control common bunt. However, these fungicides were not distinguished by high effec- tiveness. Furthermore, these chemicals have been removed from the official list of the registered chemical agents allowed for the use in agriculture. In this connection, a necessity of testing new fungicides has arisen. For this purpose and for the first time in the republic the chemical agents 3%-emulsion concen- trate (EC) of Divident and 6%-EC Raxil to control common bunt and 25% EC-Horizon and Folikur to control powdery mildew have been tested. The tests were carried out under conditions of Ararat val1ey and the upland area 1997-2000. Seeds of winter wheat Armyanka-60 were treated by Divident (2 l/t) and Raxil (0.41/t), as well as 80%- EC of TMTD, which served as a check. Fungicide- untreated check plots were also included in the test. Number of spikes infected by common bunt was estimated based on 1000 plants taken in 10 places (100 spikes each). The summarized data concerning effective- ness of chemical preparations against common bunt for all the period of studies are given in table below. From the table data it is evident that in case of high natural infection of spikes in the check (20.2%), the variant of treating the seeds by Raxil is found to have the highest biological effectiveness. The effect of Dividend way lowers then that of Raxil. Similar results were obtained in the tests carried out in other areas of the republic, where the biological efficiency of Raxil exceeded that of Divident and TMTD by 2-3% and by 8-10% respectively In parallel, tests of the new fungicides to control powdery mildew of wheat were also conducted. Folikur and Horizon were tested at the rate of ll/ha, 25% with Bayleton powder applications (1 kg/ha) being the check. Untreated plots were also used as checks. Spraying by the above-listed fun- gicides at the tillering stage showed the following results: Folikur- 78.8%, Horizon -77.4%, and Bay- leton being the most effective (82.3%). On the basis of the data of the long-term testing of new fungicides against common bunt and powdery mildew, it may be concluded: 1) with a significantly low rate (0.41/t), Raxil is differentiated by high biological activity and is the most promising chemical agent to control common bunt in wheat. 2) Folikur and Horizon being little inferior to Raxil by biological activity can, nevertheless, be included in the list of fungicides applicable against powdery mildew of wheat.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection