Effect of fungicide application on Wheat Head Blight, occurrence of Fusarium spp. and mycotoxin production.

The aim of the study was to determine if azoxystrobin and metconazole used for the control of wheat FHB at half, full, and quarter more the recommended dose rate may affect in differentiated way on the occurrence of Fusarium spp. and their ability to mycotoxin production in harvested grain, in wheat ears artificially inoculated with two DON-producing isolates of F. culmorum. Macroscopic evaluation showed high incidence of fusariosis. Plant health in the plots where the heads were artificially inoculated and fungicide was not applied was similar to the protected ones. Only increasing the dose metconazole resulted in a stronger reduction of fusariosis. The advantageous effect of azoxystrobin was not observed. Mycological analysis of harvested grain showed the presence of a number of F. culmorum, but from samples sprayed with metconazole it was isolated in smaller quantities. Also F. avenaceum, F. graminearum, F. poae and F. tricinctum were isolated. Molecular analysis showed the presence of F. culmorum in all samples of harvested grain. Also genes from Tri cluster were identified, involved in the synthesis of type-A and type-B trichothecenes - especially DON and 3Ac-DON. Chromatography revealed the presence of small quantities of mycotoxins. In all samples DON and 3Ac-DON were predominant. In general, F. culmorum isolate, which caused weaker symptoms of FHB and was less numerously isolated from grain that the other one, produced smaller amounts of mycotoxins. Samples protected with azoxystrobin contain the largest quantities of DON. Effect of different doses of fungicides on the number of mycotoxins was not clearly established..

Development of Sclerotinia sclerotiorum (Lib.) de Bary on stored carrot treated with Pythium oligandrum Drechsler determined by qPCR assay

Sclerotinia scletoriorum (Lib.) de Bary is a serious pathogen of carrots that can cause up to 50% losses of stored roots. Fungicides were found not to be completely effective for its control and due to residues they are not permitted for the use in storage. Biological control agents such as Pythium oligandrum may be a chance. The aim of research was to determine the level of carrot infection with S. sclerotiorum during few-month storage with qPCR and the potential control ability of this pathogen by Polyversum WP containing oospores of P. oligandrum. We analyzed carrot roots in combinations treated with Polyversum WP on the field, fumigated with biopreparation before storage and untreated control. S. sclerotiorum developed on carrots treated and untreated with Polyversum WP. During the storage, pathogen was isolated from 44.4% samples and P. oligandrum from 53.8% ones, respectively in the range from 0.0001 to 130 200.0; pg and from 0.004 to 0.3440 pg per sample. The number of roots with S. sclerotiorum and degree of their infection increased with prolonged storage. Analyses suggest that Polyversum WP may potentially limit the growth of S. sclerotiorum

Health status of Swedish whitebeam (Sorbus intermedia L.) in selected regions of the Tatra National Park

Swedish whitebeam (Sorbus intermedia (Ehrh.) Pers.) is a species with a very limited range. It occurs only in southern Scandinavia and along the Baltic coast, without the Gulf of Finland. Its southernmost natural localities are situated in northern Poland. They are few in number, grouped in two regions: near Kołobrzeg and the Gulf of Gdańsk. Currently, only three of them survive: vicinity of Sarbinowo as well as Kępa Redłowska and Przylądek Rożewski. In the Podtatrze region, S. intermedia has long been planted along roads, on green areas, in gardens and parks, among others in Zakopane. In the Tatras it did not appear, so it is a foreign species for this region. Currently, in the Tatra National Park there are several hundred fruiting specimens of this species growing. Most of them are part of a forty−year−old stand planted on the back of the Grzybowiec ridge. The aim of this research was to recognise the health status of S. intermedia. Phytopathological research was conducted in 2018 in the Tatra National Park. Leaves that were subject to analysis were decontaminated in 1% surfactant solution of sodium hypochlorite. Their fragments of about 0.5 cm were placed on Petri plates with PDA (Potato Dextrose Agar). The growing fungal colonies were consequently re−planted onto PDA slants for further culturing and taxonomic identification. The pathogens were identified basing on morphological features and with molecular tools. All S. intermedia in the Tatra National Park showed disease symptoms. Infected S. intermedia leaves were colonized by A. alternata, which fraction amounted to over 40%. The following dominant was B. exigua with over 30% share. F. avenaceum (close to 10%) and E. nigrum and D. macrostoma were also found. The S. intermedia population growing in the Tatra National Park is characterized by a poor condition, which may in the future affect the population of this plant in the Tatra Mts