Yellow starthistle is one of the most important alien invasive weeds in the western United States. It has been targeted for biological control based on the assumption that its abundance is limited by natural enemies in its native region but not in the United States. The geographic center of diversity for yellow starthistle appears to be in Turkey. This region is being explored to discover potential biological control agents; however, there is no quantitative information regarding the population density or dynamics of the plant in this region. Such information could help determine which natural enemies help suppress the plant in its land of origin. We measured densities of yellow starthistle plants and seeds during 2 yr at three locations in central Turkey. Densities of mature plants were about 4% of those measured at sites in California. Densities of capitula and seeds produced were about 60 and 65%, respectively, of those measured in California. The greatest difference between the two regions appears to be the densities of mature plants, which indicates the importance of focusing research on natural enemies that reduce plant survival.

The species composition of thrips and abundance of three pestiferous thrips species, Frankliniella occidentalis (Pergande), Thrips tabaci Lindeman and Frankliniella intonsa (Trybom) (Thysan., Thripidae) on weed species during winter and spring time were studied in vegetable production and polycultured areas in the eastern Mediterranean region of Turkey in years 2002 and 2003. Of a total of 61 543 thrips extracted from 8933 samples collected, 77% were adults. F. occidentalis was collected from all of 49 weed species sampled and F. intonsa was detected on 18 plant species between May and June. T. tabaci was collected from 42 of a total of 49 weed species. Immature thrips were extracted from 42 of a total of 49 weed species. Four weed species of a total 35 weed species sampled between April and May in the sampling areas hosted 63% of larvae and approximately 50% of F. occidentalis collected. A total of 23 thrips species was recorded from weeds sampled in this study. F. occidentalis accounted for 83% of a total 47 640 adult thrips collected and followed by low rates of T. tabaci and F. intonsa (9 and 1%, respectively). Melanthrips spp. accounted for 3.54% of total numbers of adult thrips. Flower-inhabiting thrips species and T. tabaci were most abundant on weeds between April and May when the number of weed species in bloom was greatest, then decreased to low levels after May. Most pestiferous thrips on weeds species were collected from vegetable production areas. F. occidentalis was the predominant thrips comprising over 80% in most months in the vegetable grown area. In polycultured area, the composition of adult thrips shifted monthly. While Melanthrips was the more prevailing thrips by rates 53% in February and 81% in March, F. occidentalis was the predominant thrips with 60 to 62% in spring, respectively.

Yellow starthistle, Centaurea solstitialis (Asteraceae), is an important invasive alien weed in the western United States. Currently established biological control agents attack only the capitula (flowerheads), and are not effectively controlling the plant in much of its range. The geographic center of diversity for the plant appears to be in Turkey, but no agents have been introduced from this country. Ceratapion basicorne (Coleoptera: Apionidae) is common in Central Turkey, attacking 25-100% of yellow starthistle plants. In a field experiment, Ceratapion spp. attacked 90% of yellow starthistle plants and 88% of milk thistle plants (Silybum marianum) but not seven other plant species, including artichoke and safflower. We suspect that a different species of insect attacked milk thistle, but they emerged before the plants were sampled. Laboratory tests showed that C. basicorne does not oviposit in milk thistle. Ceratapion basicorne appears to be more host specific than was suggested by previous studies of a population in Italy (Clement et al. 1989. Ann. Entomol. Soc. Am. 82: 741-747). The insect is gregarious, and the number of larvae per plant was positively correlated to root diameter. The level of damage to individual plants was positively correlated to the proportion of plants attacked, indicating aggregation both among plants and within plants. Field data did not show any impact of the insect on plant size or number of capitula, but germination rate of seeds produced by infested plants was 15% lower than for uninfested plants at two of three sites studied.

No abstract

This study was conducted using seeds in Petri dish containing agar medium in order to determine acetyl-CoA carboxylase (ACCase) herbicides resistance (R) in Avena sterilis that was grown in wheat fields at Adana province, Turkey. Seeds were collected from one large suspected field, where clodinafop-propargyl (Aryloxyphenoxypropionate "FOPs") and pinoxaden (Phenylpyrazoline "DEN") have been applied for many years. Susceptible (S) population was collected from the road side on the same region. Agar media of concentration 14 g/L was prepared and it was melted in microwave. Then the amount of 20 mL agar media was added into each Petri dish. Five seeds were placed on agar mediums containing discriminating dose of clodinafop and pinoxaden. Petri dishes were placed in growth incubator operating at 10 °C. After 15 d, both radicle and hypocotyl length were measured. The percentage of germinated seed and dose-response curves were determined. At these different concentration levels, there were more than 50% of R and less than 40% of S seed germinated for pinoxaden. However, for clodinafop, more than 60% of R and less than 50% of S seeds were germinated. At higher concentration levels, the populations of resistant and susceptible were not germinated for both herbicides. The resistance value of R population was then compared with that of the S biotype. From the resistance index (RI), the population was more resistant to pinoxaden (7.43 for radicle and 2.47 for hypocotyl) than the clodinafop-propagyl (1.39 for radicle and 3.77 for hypocotyl). The method provided a simple, quick and cost effective way to identify ACCase herbicides resistance in most grass weeds.

Broomrapes (Orobanche spp.) which belong to the family Orobanchaceae are obligate parasitic flowering plants. The main center of distribution is the Mediterranean basin, where large areas are heavily infested. Yield losses due to Orobanche range from 5 to 100% depending on the region and the crop. Orobanche species infesting crops in the eastern Mediterranean region of Turkey are: O. aegyptiaca, O. ramosa and O. crenata. O. aegyptiaca / O. ramosa were present in 27.72% of the tomato greenhouses and 80% of the tomato fields, O. crenata and O. aegyptiaca / O. ramosa were present in 57.89% of the faba bean fields and 75.

Acroptilon repens is an invasive weed in North America but also causes problems in disturbed habitats in its native range in Asia. In order to test the effect of simulated biological control and soil disturbance on established A. repens patches and the competing vegetation, two levels of shoot clipping as well as soil tillage were imposed on A. repens patches in an undisturbed meadow and at two fallowland sites in the native range of the weed. At the meadow site, 2 years of partial clipping of shoots and of soil tillage had no influence on A. repens performance, while soil tillage significantly reduced the above‐ground biomass of the competing vegetation. At the fallowland sites, which had been continuously cultivated for several years prior to the experiment, A. repens shoot density, biomass and number of seed heads were significantly higher in the undisturbed control than in the tillage plots. The total number of seed heads per unit area increased with shoot density up to 200 shoots m−2. These results indicate that A. repens has considerable regrowth capacities that allow established patches to tolerate substantial losses of above‐ground biomass and that the competitive ability of A. repens is favoured both when soil disturbance is imposed on previously undisturbed sites, as well as when repeated soil disturbance is abandoned. The only promising nonchemical herbicide‐based approach to reduce the competitive ability and seed output of A. repens appears to be a long‐term management that enhances the interspecific plant competition by reducing soil disturbance and selectively damaging A. repens.

Harmful insect species were investigated in soybean and sunflower seed samples mixed with weed seeds and stored for a short time in the open field in the Çukurova Region (Türkiye) including Adana, Mersin and Osmaniye Provinces in 2020. A total of 8 harmful insect species were found in the samples of stored soybean and sunflower seeds. Seeds of 12 weed species were detected in both soybean and sunflower seed samples. The red flour beetle, Tribolium castaneum (Herbsts, 1797) (Coleoptera: Tenebrionidae) was the major pest insect in both sunflower and soybean seeds. A few species of the rice weevil, Sitophilus oryzae (L. 1763) (Coleoptera: Curculionidae), which are the primary pest of stored cereals, were recorded under outdoor conditions. No insect feeding damage was observed on the seeds of both crops and also on the seeds of the weeds. Finally, the seeds of soybean and sunflower crops which were harvested and kept outside the warehouses, for a short time, were attacked by some stored pest insects particularly Tribolium spp. This issue may create a problem, in the case that harvested crops with insects are moved into the warehouse,which has suitable temperature and moisture for the pest insects to develop and multiply.