In vitro test of antagonistic activity of culture filtrates from Trichoderma harzianum Rifai and Trichoderma pseudo-koningii Rifai strains against post-harvest pathogens of some fruits were investigated. The undiluted culture filtrates of the two Trichoderma species completely inhibited germination of conidia/spores of all the rot pathogens, but 50% dilution showed varying degree of inhibition of spore germination. T. pseudo-koningii culture filtrate had a rather moderate to strong inhibitory effect on mycelia of the pathogenic fungi. The highest per cent inhibition of 45.6% of mycelial growth was recorded for Aspergillus niger Tiegh.
A survey was conducted in February of 2004 on the outbreak of stem rot and wilt disease of pepper at the Kitabawa/Danzakara and Ajiwa irrigation sites in Northern Nigeria. Laboratory investigations revealed that it was elicited by Phytophthora capsici Leon. The disease caused severe loss in yield and USD 1 700.00 to USD 3 200.00 loss in revenue/ha. The disease was probably further aggravated by the presence of Fusarium sp. as well as ecto- and endoparasitic nematodes. Reasons for outbreak were elucidated and solutions proffered.
The purpose of the present work was to estimate the effectiveness of grapefruit extract and Pythium oligandrum in protection of common bean, runner bean and pea from soil-borne pathogenic fungi. The investigated preparations were used for seed dressing and spraying plants at the beginning of anthesis. The results pointed out that the applied products considerably improved emergence, healthiness and yielding of the examined plant species. Besides, Biosept 33 SL showed a better effect than Polyversum. Independently on the species, the fewest plants, with the greatest proportion of infected ones and the smallest yield of seeds were obtained from the untreated control. Alternaria alternata, Fusarium spp., Pythium irregulare, Rhizoctonia solani and Sclerotinia sclerotiorum were frequently isolated from infected roots and stem bases as well as from seeds of bean and pea. Fusarium oxysporum tuned out to be dominant. The proportion of the above listed fungi in the treatments with Biosept 33 SL or Polyversum was smaller than in the control. At the same time, the role of those fungi in infecting the plants of common bean, runner bean and pea treated with Biosept 33 SL was only a little smaller than after using Polyversum.
Plants under attack of herbivores can emit increased amounts of volatile compounds from their leaves. Similarly, mechanically-injured plants can emit volatile chemicals that differ both quantitatively and qualitatively from undamaged plants. In this experiment, mechanical injury increased the release of the secondary metabolites linalool (3,7-dimethyl-1,6-octadien-3-ol) and linalool oxide (5-ethenyltetrahydro-2-furanmethanol) by wheat plants. The amounts released varied significantly with injury type and the period of time after injury. The time interval for the volatile collection within the photophase also influenced the amount collected for each day. The increased emission of these compounds, as a result of injury, may be explained as a defense mechanism against wounding. The role of these plant volatiles can be further investigated in the context of plant response to mechanical injury, within the broader context of all types of injury.
Observations on the development of the horse chestnut leafminer on red horse chestnut (Aesculus x carnea H.) were carried out in Wrocław, Lower Silesia, Poland, in 2001–2003. Three generations of the pest were recorded to lay eggs on the red horse chestnut leaves. Although females of each generation deposited eggs abundantly, the hatching larvae died after a short period of feeding in the plant’s leaves and the species did not complete its development on this tree. Mostly L1 and L2 larvae were found inside the leaf mines. The observed leaf damage was, therefore, negligible.
The research on impact of Cleonus piger Scop. (Coleoptera; Curculionidae) feeding and the occurrence of other pest insects on milk thistle plants grown in monoculture and crop rotation after cereals, with two different seeding dates was carried out in the years 2003–2005. The infestation and density of C. piger larvae in roots of plants grown in monoculture increased with subsequent developmental phases and subsequent years of the experiment. Feeding resulted in the decrease in crop yield by 40% compared to the crop rotation treatment. In crop rotation stands, the infestation of milk thistle roots by C. piger larvae was 4–5 times lower at the final phase than in monoculture. Postponing seeding by three weeks led to the decrease of infestation and density of C. piger larvae, but the crop yield was lower than that from the earlyseeded stands. No other phytophagous species of economic importance were found.
The attractiveness of uncultivated (weedy) and cultivated strips (planted with a mixture of flowering plants) and the adjacent sugar beet crop to Carabidae was studied in 1999–2000 at the Experimental Research Station near Wrocław, Poland. Obtained results showed that greater plant abundance and their diversity on weedy strips had a positive effect on the number of carabid beetles. Also more carabid species were identified in uncultivated strips than in strips of mixture of Phacelia tanacetifolia, Coriandrum sativum and Sinapis alba. The lowest number of species was trapped in sugarbeet crop and bare soil. The most numerous species in all treatments were Pseudoophonus rufipes, Anchomenus dorsalis (Pont.), Poecilus cupres and the species of the Bembidion genera.
The aim of the study was to investigate the effect of some different environmental conditions prevailing during the development and ripening of Echinochloa crus-galli diaspores on their germination. Some seeds were tested in the autumn the same year, whereas others were divided into two groups: dispersed seedsand seeds within the inflorescence. Then the seeds of both groups were buried. After eight-month stratification in the soil, the diaspores were tested under the same conditions as the samples examined in the autumn. The seeds tested in the spring germinated faster than those tested in the autumn. Also the germination capacity of barnyard grass caryopses examined in the summer was almost twofold higher than the germination capacity of those examined in the autumn. Both autumn and spring tests revealed that the harvest time affected germination. The seeds obtained in the second half of August and at the beginning of September (in the middle of the growing season) were characterized by a higher germination capacity than the caryopses collected at the beginning and the end of the reproduction period. The results show that the germination capacity and rate were not influenced by the place of origin, habitat conditions and accompanying plants. It was found in spring tests that germination depended on the kind of dissemination unit stored in the soil. After eight-month soil stratification, dispersed caryopses germinated by approx. 20% better than those stored with a part of the inflorescence.
Measurements of spectral reflectance from potato plants were carried out in the years 2000 and 2001 using the field radiometer CE 313 of Cimel Electronique Company. Field experiments permitted to perceive differences in the reflectance of electromagnetic radiation from potato plant cultivars Bekas and Mila as well as differences between the plants treated with fungicides providing the protection against Phytophthora infestans and the untreated plants. A differentiation of the values of vegetative indices between potato cultivars resulted from the unequal development rate of the cultivars and from their different susceptibility to Phytophthora infestans. The assessment of potato plants infection by the studied pathogen using spectral measurements agreed with the results of field inspection.
Fusarium avenaceum, F. oxysporum, Alternaria alternata, Botrytis cinerea, Rhizoctonia solani, Mucor sp., Aspergillus niger, Penicillium spp. were the most often isolated species from fiber seeds. The antagonistic action of Trichoderma lignorum T 13–82 in relation to seed contaminants was evaluated. The use of Trichodermin-BL, based on that antagonist, applied as pre-sowing seed treatment and on growing plants decrease diseases incidence. The application of Trichodermin-BL improved a set of biometrical and physiological parameters during crop vegetation, increased the yield and raised flax fiber quality.
From Hedera helix and Epipremnum aureum showing necrosis of shoot base spread upwards and on leaves Phytophthora tropicalil was isolated. The species was obtained from ⅞of Hedera and ¾ of Epipremnum diseased shoot and root parts. Additionally, Botrytis cinerea, Fusarium avenaceum and Rhizoctonia solani was recovered from some of affected plants. The chosen 2 isolates colonised petioles and leaf blades of both host plants. P. tropicalis caused necrosis of leaves of 11 tested cultivars of H. helix and 13 other pot plant species and seedlings of tomato. The fastest spread of necrosis was observed on leaves of Peperomia magnoliaefolia, Pelargonium zonale and Phalaenopsis x hybridum. The development of disease was observed at temperatures ranged from 10 to 32.5°C with optimum 30°C.