Carlo Filippi

Controlling of fusarium wilt in carnation with bark compost

Abstract Poplar bark compost has been tested for its ability to control fusarium wilt caused by the phytopathogenic fungus Fusarium oxysporum f.sp. dianthi on carnation plants. Compost was obtained through composting poplar bark previously inoculated with specific bacteria, following procedures to increase the antagonistic effect of such a substrate against Fusarium oxysporum f.sp. dianthi. Poplar bark compost was added to a soil naturally heavily infested by Fusarium oxysporum f. sp. dianthi (3000 units g−1) and previously cultivated with carnations. Experimental tests were carried out in both greenhouse and open field. A visual inspection to evaluate mortality of carnation plants was performed every 15 days. In greenhouse experiments protection against fusarium wilt was higher than 40% in compost-amended soil when compared to the control until the 60th day of the carnation cultural cycle. On the other hand, no significative difference was found among different treatments in open field experiments.

Interaction between gfp-tagged Pseudomonas tolaasii P12 and Pleurotus eryngii

Pseudomonas sp., (formerly reported as strain P12) which produces brown blotch disease symptoms on Pleurotus eryngii, has been identified as P. tolaasii based on its biochemical, physiological properties and 16S rDNA sequence analysis. This pathogen is able to infect basidiocarps when surface-inoculated on mushroom casing soil. However, infected basidiocarps develop the brown blotch disease symptoms when the pathogen concentration in the fruiting body tissues is higher than 10(4) cfu/g d.w. Using gfp-tagged cells and confocal laser scanning microscopy, it was possible to show that the pathogen has the ability to tightly attach to the hyphae of Pleurotus eryngii.

Effects of the antimycotic molecule Iturin A2, secreted by Bacillus subtilis strain M51, on arbuscular mycorrhizal fungi.

A new system, devised for the study of early stages of arbuscular mycorrhizal infection, was used to test the effect of the biological control agent Iturin A2, secreted by the strain M51 of Bacillus subtilis, on the development of arbuscular mycorrhizal fungi. The saprophytic growth of the fungus Glomus mosseae was inhibited by Iturin A2 concentrations higher than 100 micrograms/g of sand; whereas, in the presence of the tomato host plant, both, pre-infection events and intraradical growth were not negatively influenced by the antifungal compound; furthermore, the development of arbuscular mycorrhizal symbiosis was not impeded by the biocontrol agent in field conditions, while Fusarium oxysporum f. sp. lycopersici infection was hindered.

The role of telluric microflora in the control of Fusarium wilt in carnations grown in soils with bark compost

Abstract The role of microbial flora in the ability shown by poplar bark compost to combat the carnation phytopathogen Fusarium oxysporum f.sp. dianthi was investigated. Compost was divided into two parts, one sterilized and the other not, and was added to two different types of soil naturally infested with Fusarium oxysporum f. sp. dianthi . Experiments were carried out in greenhouse benches. At 15-day intervals the main microbial groups present in the soil were analysed and visual inspections were carried out to evaluate the mortality of the plants. Protection against Fusarium oxysporum f. sp. dianthi due to the compost added was found in both soil types, and the protection was more marked in the case of sterile compost. This difference in protection is due to a different growth rate of the soil zymogeneous fraction, a consequence of the different amounts of easily assimilable organic matter contained in the two types of compost.

Effect of soil temperature on infective capacity of Fusarium oxysporum f. sp. dianthi in presence of poplar bark compost

Summary The effect of soil temperature on infective ability of Fusarium oxysporum f. sp. dianthi against carnation plants cultivated in a soil amended with poplar bark compost has been investigated. The compost has been divided in two parts: one sterilized and the other one not sterilized. Subsequently, those two kinds of compost have been added to the same soil on three greenhouse benches. The experimentation has been carried out by maintaining the soil of each bench at a different temperature, namely 16, 23, 30°C. Temperature and humidity of ambient-air in the greenhouse have been maintained everywhere at the same values. Variations of most important soil microbial groups have been analyzed and visual readings of plant mortality have been taken on 15 days intervals. It has been shown that soil temperature has no appreciable effect on Fusarium pathogenicity. On the contrary, a less incidence of the disease has been observed in amended soils (both with sterilized and not sterilized compost), with respect to control soils. This occurrence has been more evident in soil amended with sterile compost, at increasing temperatures. Likely, nutrients added by compost has caused a response of zymogenic soil-microflora, which is responsible of the protection against disease. Consequently, the soil temperature influenced the incidence of the disease, simple by acting as a selective factor controlling the growing of microbial soil population.

Protective Effect of Soil Microbial Response Due to Organic Substance Addition in Radical Phytopaties

Summary Authors have investigated the effect of soil microflora against phytopathies caused by Fusarium oxysporum f. sp. dianthi on carnation plants. Two naturally infected soils were amended with composts containing idrosoluble elements with various concentrations. A relations has been found between readily assimilable elements added and growth of microbic populations: but is has been concluded that protection is not directly due to microbial growth. It has been noted finally, that plants, when protected, always exhibited a stress state, possibly due to lack of nitrogen.

Sensitivity to uv treatment and nuclear size of mycoplasma-like organism infected Humicola sp

The infection of MLO in a soil microfungus (Humicola sp.) originates different types of non-lethal parasitism. Differences have been found in the U.V. sensitivity and nuclear characters according to the type of MLO-microfungus interrelationship.

A relation between nitrogen deficiency and protective effect against tracheofusariosis (Fusarium oxysporum f. sp. dianthi) in carnation plants

Summary A relation between nitrogen deficiency and protective effect against tracheofusariosis, caused by Fusarium oxysporum f. sp. dianthi, is hypothized in carnations plants, when grown in a naturally infested soil amended with a poplar bark compost. Protective effects induced in the plants by fertilizations with fertilizers containing nitrogen have been studied and it has been observed that, by the above mentioned treatments, the infective destructive phase rate at the interia of plants decreased, but also that the final infection degree remained unchanged. In this sense, it has been therefore hypothized that the same treatments have induced in plants a sort of “tolerance” against pathogenic microorganisms.