Abstract only

Modern strategy of protection of agricultural plants, including winter wheat, from various pests is based on selection of methods according to their biological and economical efficiency and environmental safety. That's why the integrated system of plant protection is widely applied. This system includes various practices, aiming at decrease of pest populations, such as land treatment, biological and breeding methods as well as chemical treatments, based on the economic thresholds of damage. Approaches in pest control differ depending on species and populations of pests, so the most thorough sanitary monitoring of crops is essential. Investigation of the condition of crops in Kartli and Gare Kakheti has shown the contamination by over 80 weed pest species, some of them being resistant to 2,4-D. The dominant species among them are: Convolvulus arvensis (frequency of occurrence 81%), Galium tricorne (54%), Galium aparine L. (51%), Cirsium arvense L. (48%), Sinapis arvensis L. (3~%), Agropyrum repens L. (20%), Avena ludoviciana Dur (38%). The following plant families prevail among the weeds: Compositae, Leguminosae, Cruciterae, Polygoniaceae, Gramineae, while other families are represented by single species. The study of crops has proven wide spreading (7-21 %) of common bunt of wheat caused by Tilletia caries (DC) Tul. The disease shows itself at the stage of heading, where under the intact membrane of the grains the mass of black spores can be found. The spores, falling on the surface of the seed, penetrate and the plant becomes the latent carrier of infection. Another representative of smuts often found in wheat crops is Ustillago tritici (Pers) Sens, though with the comparatively low rate of spreading (3-5%). Fusarial wilt caused by Fusarium gra- minearum Schuabe was also detected with the severity rate varying within 5-7%. The disease damages root base and spikes of wheat. Root rot caused by Ophiobolus graminis Sacc was also identified. Disease shows itself on the plant roots and the first intemode initially in the form of yellow spots and causes gradual darkening of the roots and stem collar. Root rot may be caused by various pathogens, such as: Gibeleina cerealis Pass, Cereospotella hernotriohoides Foron, Aspecgillus niger Link. Gray spots appearing on leaves are the signs of Septoria tritici Rob et Desm. Wide spreading of Erysiphe graminis DC was observed at weedy plots and neglected crops. At strong expansion of this disease plant leaves are covered by the white blotch. Wide spreading of pest insect representatives, such as Segmentoptera -ground beetle Zabrus tenebrioides goeze, Lema melanopus L, Hemoptera -big aphid Sitelion avenae F, Hemiptera- pentatomid Eurygaster integriceps Net, Lepidoptera -winter moth Apamea sordida (BKA) was noted. Significant expansion of the infections detected at the surface or inside the grains and also in soil induced us to contemplate seed treatment. Tests ascertained that themost effective is the semi- damp treatment with the chemicals of triazole group (Dividend, Raxil, and Vincit at the rates of 2 kg /t). In cases of strong infection of cereal crops with powdery mildew application of fungicide Tilt was prescribed. The best means of prevention of powdery mildew are the weed control and observation of the optimal dates and established rates of seeding. Lintur at the rates of 180g/ha proved to be the most efficient and environment friendly (as per Ecotox rating) from the tested herbicides. This herbicide is effective also against the 2,4-D resistant weeds. Soil pests were controlled by the treatment of soil with the granulated insecticides in cases when their populations exceeded established economic thresholds of damage. Choice of pest controlling techniques was based on their economic feasibility and Ecotox environmental rating.

English

0409|AGRIS 0401|AL-Wheat Program

Juan Carlos Mendieta

CIMMYT Publications Collection