The persistent and proliferating growth habit of alligatorweed makes this weed difficult to control in crops. Therefore, its integrated control by employing pre- and post-emergence herbicides along with cultural weed control methods may be required for its long-term sustained management in sunflower crop. Two-years field investigation was therefore conducted to compare the efficacy of different weed management strategies (plastic sheet mulch, pre-emergence application (PEA) of S-metolachlor, PEA of S-metolachlor + alligatorweed mulch 40 days after sowing (DAS), PEA of S-metolachlor + directed post-emergence application (DPOEA) of glufosinate 20 DAS, single and dual DPOEA of glufosinate with or without adjuvants (alkyl ether sulphate / ammonium sulphate) for controlling alligatorweed in autumn planted sunflower. All weed management treatments reduced alligatorweed growth, its nutrients’ uptake and thus enhanced sunflower growth and yield. Plastic sheet mulch gave 100% control of alligatorweed. However, among herbicide treatments, PEA of S-metolachlor + DPOEA of glufosinate caused the highest reductions in alligatorweed density (95%), its dry biomass (98%), its macronutrients’ (up to 98%) and micronutrients’ (up to 99%) uptakes over weedy check. Maximum sunflower achene yield increase was recorded with plastic sheet mulch (124%) followed by PEA of S-metolachlor + DPOEA of glufosinate (84%). The economic analysis revealed that PEA of S-metolachlor + DPOEA of glufosinate 20 DAS gained the higher net benefit (US$138 and US$157) as well as benefit-cost ratio (6.87 and 6.36) during years 2015 and 2016, respectively. Therefore, in terms of better alligatorweed control, sunflower yield and cost-effectiveness, PEA of S-metolachlor + DPOEA of glufosinate 20 DAS could be considered the best option recommended for sunflower growers.

Broomrape (Orobanche cumana Wallr.) causes severe yield losses in sunflower (Helianthus annuus L.). The emergence and rapid spread of highly virulent races of the parasite have been observed. The dominant Or7 (HaOr7) gene is used in breeding to control the widely spread broomrape race G. The question of the dominance degree in conditions of severe infection of different genotypes remains open. Twelve sunflower genotypes with different allelic state of the gene Or7 were used. The plant resistance was assessed in a climatic chamber at optimal conditions for sunflower and broomrape growth. Molecular marker system was applied to confirm the allelic state of Or7 gene. Resistant homozygous Or7Or7, heterozygous Or7or7 and susceptible homozygous or7or7 genotypes shown infection rate of broomrape at 1.81, 6.58 and 19.00 tubercles per plant accordingly. Partial dominance degree of h/d = -0.44 and the dose effect of a dominant Or7 allele were obvious. For the first time a change of dominance was noted in a cross combination in which the broomrape resistance trait was completely recessive. Development of a homozygous hybrid for Or7 gene can solve the problem of low broomrape resistance of heterozygous high yield hybrids in breeding programs.

As it is known, sunflower is a very important oil crop that is generally used in Turkey and the world. To compensate of Turkish vegetable oil need, with increasing population day by day, it needs to increase the sunflower yield. To increase sunflower seed yield and production as well as the quality, the planted cultivars should have the resistant genes for better adaptation capability to bad environmental conditions as well as new better specifications for higher yielding. Sunflower wild species growing in very hard environments are the main resources for these purposes. There are many conducted studies to give proper information to sunflower breeders until now for classifying wild species. In addition to classical phylogenetic, it is so important that searching of relationships and specifications of sunflower wild species utilizing from molecular phylogenetic studies given more appropriate and reasonable information. In this study, molecular phylogenetic analysis was performed by using 14 SSR markers that are high polymorphic in sunflower to define of the phylogenetic relationship among wild sunflower species with using 52 different species in Helianthus genus. PCR products obtained as a result of SSR analysis were measured with a capillary electrophoresis. The frequencies of the obtained alleles were analyzed using GenAlex 6.5 and PIC values were analyzed using CERVUS programs. A total of 134 different alleles were obtained for 8 SSR loci. Remained 4 SSRs were monomorphic and 2 of them did not produce scorable products. The most polymorphic SSR was ORS662 marker with 19 alleles. The least allele (10) was seen in ORS331 marker. The average number of alleles per locus was calculated as 16. Then, the UPGMA dendrogram was created based on similarity matrices. According to the dendrogram, it was observed that the closest species to cultivated sunflower (H. annuus) was H. eggertii. The similarity index between the two species was calculated as 0.589. After H. eggerti, the most similar species were H. pauciflorus, H. praecox and H. decapetalus, respectively. With this study, 8 markers that could distinguish the similarities among sunflower species were determined and the results were obtained about the proximity of the species to each other.

The moderate genetic diversity of cultivated sunflower, along with a changing environment, make sunflowers subject to the attack of many pests and diseases, with great economic impact. In Argentina, fungi and oomycetes produce four of the most challenging diseases: Sunflower Verticillium Wilt, Phomopsis Stem Canker, Sclerotinia Head Rot and Sunflower Downy Mildew. Efficient crop management to reduce the impact of pathogens requires resistant hybrids, recommendations for agricultural practices, and epidemiological monitoring to aid decision-making. However, each pathosystem has its own caveats. The integration of genotypic and phenotypic knowledge of sunflower breeding resources with the characterization of pathogens is critical to effectively assisting breeders in improving plant resistance and reducing yield losses. Below, we provide an overview of the latest scientific knowledge on each pathosystem and the strategies being pursued for breeding disease-resistant hybrids.