HAUSTORIUM 64 December 2013 1 HAUSTORIUM Parasitic Plants Newsletter

Determination of 23 populations of field dodder was conducted using light and scanning electron microscopy and subsequent molecular (PCR) methods in order to fully examine the biology and ecology of Cuscuta campestris and options for its control. The effects of different temperatures and rhizobacteria (PGPR) on germination of C. campestris seeds, as well as effects of different light treatments (red, far-red and blue light) on germination, growth, and height of attachment points of field dodder shoots on alfalfa stems were also investigated. We examined the effects of C. campestris on morphological (visualisation and fresh weight), anatomical (anatomy of leaf and stem of alfalfa; leaf and petiole of sugar beet) and physiological parameters (relative chlorophyll content, total carotenoids, nitrogen, phosphorus, potassium, organic and mineral matter and chlorophyll fluorescence) in alfalfa and sugar beet plants exposed and unexposed to herbicides (imazethapyr, glyphosate, propyzamide). The efficacy of imazethapyr, glyphosate, propyzamide and diquat in controlling field dodder in alfalfa crop was examined in field trials. After examining 23 populations of field dodder, two species of the genus Cuscuta were identified: Cuscuta campestris Yunk. and Cuscuta epithymum (L.) Nath. An optimal temperature for germination of C. campestris seeds was found to be 30 ̊C and treatment with red light (for 1h at daytime) produced the highest percentage of germinated seeds, while the highest percentage of seedlings attached to alfalfa stems at 4.65 cm height was found after treatment with far-red light (for 45 min at daytime). Also, the highest percentage of germinated field dodder seeds was recorded after treatment with the rhizobacterium Azotobacter chroococcum isolated from wheat rhizosphere. An analysis of our data showed that the highest values of most parameters (visualization and fresh weight; relative content of chlorophyll and total carotenoids, effective yield and intensity of fluorescence, variable fluorescence, variable/maximal fluorescence ratio; thickness of stem epidermis, thickness of cortex, thickness of central cylinder and stem diameter of alfalfa; thickness of upper and lower leaf epidermis, thickness of palisade and spongy mesophylls, thickness of mesophyll in alfalfa and sugar beet leaves; diameter of tracheids, petiole hydraulic conductance, xylem area, diameter of phloem cells and petiole phloem area of sugar beet) were found in noninfested alfalfa and sugar beet plants, then in infested plants treated with herbicides, and the lowest in plants infested by C. campestris but untreated with herbicides. C. campestris was found to affect and reduce nearly all parameters of stem, leaf and petiole anatomy of the host plants, in contrast to some physiological parameters. The infested alfalfa and sugar beet plants were found to have higher contents of nitrogen, phosphorus, potassium and organic matter, compared to non-infested plants. The highest efficacy in controlling field dodder in alfalfa field was demonstrated by diquat (product Reglon forte 3 l/ha), then by glyphosate (product Glifol 0.8 and 1 l/ha), while the other two tested herbicides (propyzamide – product Kerb WP-50 and imazethapyr – product Pivot 100 M) showed lower efficacy.