Template-Type: ReDIF-Article 1.0 Author-Name: Antonín Dreiseitl Author-Workplace-Name: Agricultural Research Institute Kroměříž Ltd., Kroměříž, Czech Republic Author-Name: Daniel Jurečka Author-Workplace-Name: Agricultural Research Institute Kroměříž Ltd., Kroměříž, Czech Republic Title: Severity of powdery mildew on spring barley in the Czech Republicin 1971-2000 Abstract: Results of scoring the resistance to powdery mildew of 127 spring barley varieties that were gradually included in 923 official variety trials were analysed. The resistance of a variety was defined by the level of infection by the disease. Therefore, the data can be used to assess the disease severity. Several characteristics indicative of disease severity were considered, including the disease severity coefficient (= average infection of non-resistant varieties in trials with a high disease severity/the proportion of such trials). The value of the coefficient is inversely proportional to disease severity. According to the coefficient the highest powdery mildew severity occurred in 1988, 1972 and 1995, and during the period 1971-1975. This is confirmed by results of some other characteristics, while that of further characteristics point to 1985-1989 as the period with the highest disease severity. The lowest disease severity was found in 1982 and 1977 and for the period 1976-1980. High disease severity was found every year in 9-75% (on average in 33%) of the trials. The characteristics of disease severity as well as the effects of widely grown and susceptible varieties of winter barley on the increase in inoculum potential and, as a consequence, on faster adaptation of the pathogen to resistance of spring barley, especially that conditioned by gene Mla13, are discussed. Keywords: Hordeum vulgare, Blumeria graminis f.sp. hordei, powdery mildew, disease severity Journal: Plant Protection Science Pages: 39-51 Volume: 39 Issue: 2 Year: 2003 DOI: 10.17221/3825-PPS File-URL: http://pps.agriculturejournals.cz/doi/10.17221/3825-PPS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/pps-200302-0001.txt Handle: RePEc:caa:jnlpps:v:39:y:2003:i:2:id:3825-PPS Template-Type: ReDIF-Article 1.0 Author-Name: Jan Lukáš Author-Workplace-Name: Department of Stored-Product Pest Control, Research Institute of Crop Production, Prague-Ruzyně, Czech Republic Author-Name: Václav Stejskal Author-Workplace-Name: Department of Stored-Product Pest Control, Research Institute of Crop Production, Prague-Ruzyně, Czech Republic Title: Computer-based image analysis to estimate the area of a sticky trap occupied or contaminated by pests Abstract: Traps are tools frequently used to monitor and control pests. Therefore, it is important to study the prerequisites of their use. The instant active area of a trap (the instantly available area of a trap that is able to capture a pest) is a determinant of trap efficacy. However, to measure the instant active trap area is difficult. Therefore, we developed a technique of computer image analysis of digital photography to evaluate the instant active trap area, occupancy (area of insect bodies captured on the trap) and contamination (area of filth left by pests on the trap, such as wing-scales or faeces) of it. This study illustrates its use with two types of sticky traps applied to monitor the German cockroach, Blattella germanica, and the Mediterranean flour moth, Ephestia kuehniella. We found that moths decreased the capacity of the sticky surface more than cockroaches because of its contamination by wing-scales. The sticky trap area covered by wing-scales was nearly as large as the area occupied by moth bodies. Cockroaches contaminated the sticky surface by their faeces but the contaminated area was less than 2% of the area occupied by cockroach bodies. The results indicate that moths are heavy contaminators while cockroaches are weak contaminators of sticky traps. Keywords: monitoring, traps, digital image analysis, Ephestia kuehniella, Blattella germanica Journal: Plant Protection Science Pages: 52-60 Volume: 39 Issue: 2 Year: 2003 DOI: 10.17221/3826-PPS File-URL: http://pps.agriculturejournals.cz/doi/10.17221/3826-PPS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/pps-200302-0002.txt Handle: RePEc:caa:jnlpps:v:39:y:2003:i:2:id:3826-PPS Template-Type: ReDIF-Article 1.0 Author-Name: Vojtěch Jarošík Author-Workplace-Name: Department of Zoology, Charles University, Prague, Czech Republic Author-Name: Alois Honěk Author-Workplace-Name: Department of Zoology, Charles University, Prague, Czech Republic Author-Name: A. Tichopád Author-Workplace-Name: Department of Zoology, Charles University, Prague, Czech Republic Title: Comparison of field population growths of three cereal aphid species on winter wheat Abstract: Population growths of three aphid species colonising winter wheat stands, Metopolophium dirhodum, Rhopalosiphum padi and Sitobion avenae, were analysed by regression method. The calculations were based on counts in 268 winter wheat plots at 3 or 7 day intervals over 10 (leaves) or 6 (ears) years. The population dynamics of a particular species differed widely between years. Density independent exponential growth of the population was most common, but its rate differed significantly between species, and for S. avenae also between populations on leaves and ears, on which the populations grew fastest. Field estimates of the intrinsic rate of increase derived from the exponential growths ranged between 0.010-0.026 in M. dirhodum, 0.0071-0.011 in R. padi, and between 0.00078-0.0061 and 0.0015-0.13 in S. avenae on leaves and ears, respectively. In the populations with the most vigorous population growth, S. avenae on ears and M. dirhodum on leaves, the rate of population increase significantly decreased with increasing aphid density. Keywords: Metopolophium dirhodum, Rhopalosiphum padi, Sitobion avenae, population dynamic, pest monitoring, winter wheat Journal: Plant Protection Science Pages: 61-64 Volume: 39 Issue: 2 Year: 2003 DOI: 10.17221/3827-PPS File-URL: http://pps.agriculturejournals.cz/doi/10.17221/3827-PPS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/pps-200302-0003.txt Handle: RePEc:caa:jnlpps:v:39:y:2003:i:2:id:3827-PPS Template-Type: ReDIF-Article 1.0 Author-Name: Jan Kabíček Author-Workplace-Name: Department of Plant Protection, Faculty of Agronomy, Czech University of Agriculture in Prague, Prague-Suchdol, Czech Republic Title: Broad Leaf Trees as Reservoirs for Phytoseiid Mites (Acari: Phytoseiidae) Abstract: The possibility that broad leaf trees can be reservoirs for phytoseiid mites was investigated by determining their occurrence and species diversity on common deciduous tree species. No phytoseiid mites were found on Betula pendula and Populus tremula. Altogether 280 specimens of phytoseiids belonging to six species (Neoseiulella ace-ri, N. tiliarum, Paraseiulus soleiger, Euseius finlandicus, Phytoseius severus, Typhlodromus rhenanus) were found on Acer platanoides, Fagus sylvatica, Quercus robur and Salix caprea. Ph. severus was the dominant phytoseiid species on S. caprea, while N. aceri was most abundant on A. platanoides. The greatest abundance and species diversity of phytoseiids were found on S. caprea that can thus constitute an excellent reservoir for some phytoseiid mites, particularly Phytoseius spp. Keywords: Phytoseiidae, Acari, broad leaf trees, species diversity of phytoseiid mites Journal: Plant Protection Science Pages: 65-69 Volume: 39 Issue: 2 Year: 2003 DOI: 10.17221/3828-PPS File-URL: http://pps.agriculturejournals.cz/doi/10.17221/3828-PPS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/pps-200302-0004.txt Handle: RePEc:caa:jnlpps:v:39:y:2003:i:2:id:3828-PPS Template-Type: ReDIF-Article 1.0 Author-Name: Ralph N. Okigbo Author-Workplace-Name: Department of Biological Sciences, Michael Okpara University of Agriculture, Umudike, Nigeria Author-Name: Maria I. Osuinde Author-Workplace-Name: Department of Biological Sciences, Michael Okpara University of Agriculture, Umudike, Nigeria Title: Fungal leaf spot diseases of mango (Mangifera indica L.) in Southeastern Nigeria and biological control with Bacillus subtilis Abstract: The incidence of fungal leaf spot diseases on mango (Mangifera indica) in Southeastern Nigeria and application of a biological control measure was investigated. The survey proved that the incidence of leaf spot diseases was greatest in Umuahia (72%) followed by Okigwe and Ojoto, with a peak at the beginning of the rainy season (February-March). Three pathogenic fungi, Pestalotiopsis mangiferae, Botryodiplodia theobromae and Macrophoma mangiferae, were isolated from leaf spots. Other fungi, Fusariella spp., which are well known saprophytes of dead plant materials, and the fungus Meliola sp., were also isolated from diseased leaves. Pathogenicity tests showed that P. mangiferae, B. theobromae and M. mangiferae were the causal agents of the fungal leaf spot diseases. Symptoms developed 5 weeks after inoculation of healthy leaves. Bacillus subtilis NCIB 3610, isolated from soil under a mango tree, inhibited P. mangiferae, B. theobromae and M. mangiferae by 57%, 61% and 58% respectively on agar plates. Also, in in vivo experiments the symptoms were considerably reduced in the field by the application of the antagonist. The importance of the biological control method for rural mango farmers is emphasised. Keywords: Pestalotiopsis mangiferae, Botryodiplodia theobromae, Macrophoma mangiferae, biological control, Bacillus subtilis Journal: Plant Protection Science Pages: 70-77 Volume: 39 Issue: 2 Year: 2003 DOI: 10.17221/3829-PPS File-URL: http://pps.agriculturejournals.cz/doi/10.17221/3829-PPS.html File-Format: text/html X-File-Ref: http://agriculturejournals.cz/RePEc/caa/references/pps-200302-0005.txt Handle: RePEc:caa:jnlpps:v:39:y:2003:i:2:id:3829-PPS