During 2010–2012, we monitored flight activity of male and female stem weevils (Ceutorhynchus napi, C. pallidactylus) using yellow water traps, the effectiveness of various application dates for the insecticide thiacloprid (72 g active ingredient/ha), and the influence on yield. The first occurrence of beetles in traps was recorded after soil temperature at 5 cm reached 8°C in all experimental years. In all years, males of C. pallidactylus dominated in the traps and the times of beetles’ first occurrence. The most effective applications of thiacloprid at the stated rate were 14 days (2010), 6 days (2011), and 1 day (2012) after peak flight. Females with eggs appeared in bowls in 2010 and 2012 at first flight, while in 2011 no females were recorded. After the most effective applications, yields increased significantly in 2010 (+5% vs. the control) and in 2011 (+4%), and insignificantly in 2012 (+2%).

Five pseudoguaianolide sesquiterpenes (neoambrosin, damsinic acid, damsin, ambrosin, and hymenin) isolated from the aerial parts of Ambrosia maritima were tested for their antibacterial activity against two plant pathogenic bacteria, Agrobacterium tumefaciens and Erwinia carotovora. The tested compounds exhibited variable degree of antibacterial activity against both tested bacteria as minimum inhibitory concentrations (MIC) ranged 90–520 mg/l. Neoambrosin showed the highest antibacterial activity among the tested sesquiterpenes with MIC values of 150 and 90 mg/l against A. tumefaciens and E. carotovora, respectively. On the contrary, hymenin was the least effective compound with MIC values of 520 and 310 mg/l against A. tumefaciens and E. carotovora, respectively. Neoambrosin, damsinic acid, and damsin caused significant reduction in sulfhydryl group content with the former being the most effective. The tested sesquiterpenes significantly inhibited polygalacturonase and pectin-lyase activities of A. tumefaciens and E. carotovora except for hymenin which caused a significant activation of E. carotovora enzymes.  

We identified sources of Rice yellow mottle virus (RYMV) resistance in rice cultivars. Eight cultivars together with susceptible and resistant controls were evaluated under screenhouse conditions as inoculated and uninoculated treatment in completely randomised design with three replications. Seedlings were inoculated with the virus by sap transmission at two weeks after sowing. Disease incidence and severity (scale 1–9: 1–3 = green leaves with sparse dots or streaks, 9 = yellow or orange leaves and some plant dead), yield, and agronomic traits were recorded. Data analyses included Area Under the Disease Progress Curve (AUDPC), independent t-test, and Analysis of Variance. According to differences in most measured traits control cultivars FARO 29 and Gigante were proved to be the most susceptible and partially tolerant ones, respectively. Cvs FARO 12, FARO 17, FARO 37, and FARO 52 were classified as partially tolerant. Uninoculated control plants performed better than the inoculated for all the yield and agronomic parameters. Reduction in plant height (6%) and number of tillers per plant (4.8%), increased days to heading (3 days), and reduction in paddy yield (6.5%) was lowest in cv. Gigante. Paddy yield per plant of the RYMV-inoculated was the highest in cv. Gigante (2.4 g). The rice cultivars which combined RYMV-resistance with high-yield could be utilised in rice breeding programmes in order to enhance food security.

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Bromus tectorum is a highly invasive annual grass. The fungal pathogen Pyrenophora semeniperda can kill a large fraction of B. tectorum seeds. Outcomes in this pathosystem are often determined by the speed of seed germination. In this paper we extend previous efforts to describe the pathosystem by characterising secondary dormancy acquisition of B. tectorum. In the laboratory approximately 80% of seeds incubated at –1.0 MPa became dormant. In the field, seeds were placed in the seed bank in late autumn, retrieved monthly and dormancy status determined. The field study confirmed the laboratory results; ungerminated seeds became increasingly dormant. Our data suggest that secondary dormancy is much more likely to occur at xeric sites.

In semi-arid regions of the United States, Pyrenophora semeniperda kills seeds of the winter annual Bromus tectorum. We report on pathosystem outcomes under manipulated water potential and temperature environments commonly observed within semi-arid environments for dormant and non-dormant seeds. We propose a range of outcomes for infected seeds. During summer, seeds remain dormant and are killed across a range of water potentials. During autumn, seeds survive by rapidly germinating or are killed if radicle emergence is delayed by intermittent hydration. In winter/spring, secondarily dormant seeds can be killed by the fungus. The only likely scenarios where seeds escape death include absence of infection (autumn, spring, or following autumn, germination) or infection in autumn when seeds germinate rapidly.

The biochemical properties of proteases from the digestive system of the fig tree skeletonizer moth, Choreutis nemorana, were determined. Gut extracts of C. nemorana larvae were analysed using different specific peptide substrates and proteinase inhibitors. The optimal pH and temperature for proteolytic activities using azocasein as substrate were obtained as pH 11 and 45°C, respectively. In the case of N-benzoyl-l-arg-p-nitroanilide as substrate, the enzyme showed the maximum tryptic activity at pH 11. The kinetic parameters of trypsin-like proteases indicated that the K<sub>m</sub> and V<sub>max</sub> values of trypsin in the gut of C. nemorana were 0.157 ± 0.006mM and 0.188 ± 0.005 µmol/min/mgprotein. Using specific proteolytic inhibitors, the inhibitors including phenyl methane sulfonyl fluoride, N-p-tosyl-l-lys chloromethyl ketone and ethylene diamine tetraacetic acid showed the greatest inhibitory effect on total proteolytic activity. These results indicated that serine proteinases accounted for the major proteases in the gut of C. nemorana. Inhibition assays and zymogram analysis showed that only small amounts of cysteine proteases are present in the digestive system of C. nemorana.

Fifty genotypes of cauliflovwer (Brassica oleracea var. botrytis) were evaluated for resistance to clubroot disease (Plasmodiophora brassicae Wor.) under controlled conditions in a plant growth chamber. The cultivars with the highest resistance were Brilant, Agora, and Bora, while the most susceptible were the cultivars White Top, White Fox, and Octavian. The variation in disease index is probably due to different pathogenicity rates of clubroot pathotypes and genetic heterogeneity of European cauliflower cultivars. The obtained results will be tested in an infested and non-infested field.  

In the growing seasons from 2003 to 2008, 547 isolates of Phytophthora infestans from five regions in the Czech Republic were collected and examined for their sensitivity to the active ingredients (metalaxyl, dimethomorph and propamocarb-HCl) of frequently used fungicides. The response of the isolates to each of these substances was examined using the in vitro amended-agar method; in 352 of these isolates, the sensitivity to metalaxyl was also assessed by the floating leaf-disc assay. The majority of the isolates were sensitive (89.8%) to metalaxyl. Resistant isolates were found only in two of the sample years (2003 and 2008); they represented 58% of the samples in 2003 and only 29% in 2008. Four isolates from 2004 were found to be intermediate for their level of resistance. All the isolates that were tested were sensitive to dimethomorph and propamocarb-HCl; these particular substances completely suppressed mycelial growth at 1 µg a.i. per ml.