[show abstract][hide abstract] ABSTRACT: Level of susceptibility of Pseudoperonospora cubensis isolate from Ratkovo to metalaxyl in concentrations 50, 100, 200, 400 and 800 μg/ml was investigated. The trials were conducted on cotyledon and fully developed young leaves using cucumber cultivar Haroš. Reduced level of susceptibility was detected in metalaxyl concentrations of 50, 100 and 200 μg/ml because the intensity of sporulation in these treatments was on the same level as in control. Sporulation was also observed on developed leaves treated with metalaxyl in concentrations of 400 and 800 μg/ml.
[show abstract][hide abstract] ABSTRACT: During the year 2006, climatic conditions were favourable for the appearance of head blight in the majority of localities in which wheat was grown in our country. In the locality of Apatin, in certain plots, the amount of detected infection was up to 25 infected heads per m2. During the harvest, heads with distinct disease symptoms and sporulation of Fusarium graminearum fungi were gathered. Grains from the parts of heads with manifested disease symptoms were separated into separate samples, together with the grains above and below the infested head part. Apart from ocular evaluation, the percentage of grain infestation by Fusarium genus fungi was determined in all three sample categories, using wet chamber method. Deoxynivalenol (DON) was determined in the samples after extraction, using acetonitrile-water (84:16 v/v) solution. Quantitative amount of DON was determined using liquid chromatography with DAD detector at 220 nm. The content of DON in the samples was as follows: grains with manifested disease symptoms 353,4 ppm (μg/g), grains above the infested head part 0,225 ppm (μg/g), grains below the infested part 0,125 ppm (μg/g). The content of zearalenone in the samples was determined using thin layer chromatography method. This toxic agent was determined only in the samples taken from the head part in which disease symptoms were clearly manifested in the amount of 2,1 ppm (μg/g).
[show abstract][hide abstract] ABSTRACT: Sugar beet root rot appears regularly each year, but its intensity depends on agro ecological conditions. The predominant causers of root rot in Vojvodina are fungi from Fusarium genus and species Macrophomina phaseolina. Over the last couple of years, more intense occurrence of Rhizoctonia root rot has been observed. Rhizoctonia solani, the causal agent of root rot is present in sugar beet fields. During 2000-2005, on the territory of Vojvodina, the frequency of Rhizoctonia solani in phytopathological isolations from rotted sugar beet roots was between 0,0-18,2%. The intensity of the disease depends on localities, agro ecological conditions and genotypes. Symptoms of Rhizoctonia root rot were registered at some localities in all regions of Vojvodina: Srem, Banat and Bačka. The disease appearance is above all local. It occurs in small patches, on heavy, non-structured soil and on depressed wet parts of plots. Individual diseased plants can be found during July. Brown rot appears on sugar beet roots, with dried tissue on surface, which is present on the tail as well as on the middle part and the head of root. Tissues with described symptoms are deeper regarding the healthy part of root. On vertical root section, the necrotic changes are clearly visible comparing to tissue section without symptoms. The heavily infected tissue forms fissures on roots in most cases. Besides the above-mentioned symptoms on roots, the plant wilting and leaf handle necrosis as well as leaf dying are also observed. When rot spreads to the whole root head, plants quickly die.