Plant Protection Science, 2003 (vol. 39), issue 2
Severity of powdery mildew on spring barley in the Czech Republicin 1971-2000
Antonín Dreiseitl, Daniel Jurečka
Plant Protect. Sci., 2003, 39(2):39-51 | DOI: 10.17221/3825-PPS 
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...
Computer-based image analysis to estimate the area of a sticky trap occupied or contaminated by pests
Jan Lukáš, Václav Stejskal
Plant Protect. Sci., 2003, 39(2):52-60 | DOI: 10.17221/3826-PPS
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...
Comparison of field population growths of three cereal aphid species on winter wheat
Vojtěch Jarošík, Alois Honěk, A. Tichopád
Plant Protect. Sci., 2003, 39(2):61-64 | DOI: 10.17221/3827-PPS
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...
Broad Leaf Trees as Reservoirs for Phytoseiid Mites (Acari: Phytoseiidae)
Jan Kabíček
Plant Protect. Sci., 2003, 39(2):65-69 | DOI: 10.17221/3828-PPS
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...
Fungal leaf spot diseases of mango (Mangifera indica L.) in Southeastern Nigeria and biological control with Bacillus subtilis
Ralph N. Okigbo, Maria I. Osuinde
Plant Protect. Sci., 2003, 39(2):70-77 | DOI: 10.17221/3829-PPS
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...