Massimo Pugliese

Microbial enrichment of compost with biological control agents to enhance suppressiveness to four soil-borne diseases in greenhouse.

The aim of the present work was to study if the level and reproducibility of suppressive properties of compost can be increased upon enrichment with biological control agents. A compost made from green waste, organic urban waste and urban sludge was inoculated with commercial formulations of Trich oderma and non-pathogenic Fusarium. The compost showed to be suppressive against some soil-borne pathogens, except R. solani, while such activity was lost after sterilisation. The suppressive effect of enriched compost was assessed in greenhouse trials on cucumber, tomato, bean and basil. The addition of T. harzianum T-22 at 4 g l-1 dosage was able to increase suppressiveness against R. solani of a 40% compost and 60% peat mix and to increase biomass of bean compared to a peat inoculated control. The same enrichment did not reduce suppressiveness of compost against P. ultimum and P. nicotianae, so its addition might be considered a good strategy to increase compost suppressiveness. Disease suppressiveness of sterilised compost was restored by the addition of T. viride TV1 (> 4 gl-1) in P. ultimum /cucumber and in P. nicotianae/tomato. This study represents a further step toward the development of a substrate able to control a wide range of soil-borne pathogens and in the use of fortified composts for controlling plant diseases.

Selection of antagonists from compost to control soil-borne pathogens

One-hundred and one microorganisms have been selected and tested for their antagonistic activity towards soil-borne plant pathogens from a compost originated from urban organic and yard wastes. Among them, twenty eight microorganisms, tested under laboratory conditions on tomato seedlings growing on perlite medium in Petri plates, controlled tomato wilt caused by Fusarium oxysporum f. sp. radicis-lycopersici. In a second round of trials, they were assessed under greenhouse condition on three pathosystems: Fusarium oxysporum f.sp. basilici on basil, Phytophthora nicotianae on tomato and Rhizoctonia solani on bean. The Fusarium strain K5 showed a disease control of 69% and an increase in biomass production of basil of 32% compared to inoculated control. In the case of tomato/P. nicotianae, the bacteria strain B17 showed a disease control of 82% and an increase of 216% of biomass production of tomato. Two microorganisms, E19 and P11 controlled root and stem rot caused by R. solani on bean and increased the biomass of bean up to 163%. None of the microorganisms was able to control all the soil-borne pathogens. Three Fusarium (K7, K9 and K11) and two Trichoderma (E28 and E36) isolates showed the best results and were tested in a third round of trials mixed together and at different dosages. Two Fusarium isolates, K7 and K9, were able to control F. oxysporum f. sp. basilici and confirmed they could be used in the future as commercial antagonists.ZusammenfassungEinhundertundeins verschiedene Mikroorganismen wurden aus einem Kompost isoliert, der aus Haushalts- und Gartenabfällen stammte. Die Isolate wurden hinsichtlich ihrer antagonistischen Wirkung gegenüber bodenbürtigen Pflanzenpathogenen untersucht. Einundzwanzig dieser Isolate wirkten gegenüber der durch Fusarium oxysporum f. sp. radicis-lycopersici verursachten Tomatenwelke an Tomatensämlingen, die im Labor in Petrischalen auf Perlit-Medium angezogen wurden. Diese Isolate wurden dann in einer zweiten Versuchsrunde im Gewächshaus an den Pathosystemen Fusarium oxysporum f. sp. basilici an Basilikum, Phytophthora nicotianae an Tomaten und Rhizoctonia solani an Bohnen getestet. Der Fusarium-Stamm K5 reduzierte die Anzahl abgetöteter Basilikumpflanzen um 69% und erhöhte die Biomasse um 32% im Vergleich zur nicht mit diesem Stamm behandelten, mit F. oxysporum f. sp. basilici inokulierten Kontrolle. Der Bakterienstamm B17 verminderte die Zahl durch P. nicotianae abgetöteten Tomatenpflanzen um 82% und erhöhte die Biomasse der Pflanzen um 216%. Die Mikroorganismen E19 und P11 verminderten die Anzahl der durch R. solani, den Verursacher der Wurzel- und Stängelfäule der Bohne abgetöteten Pflanzen um 49 bzw. 42%; gleichzeitig wurde die Biomasse der Bohnenpflanzen um bis zu 163% erhöht. Keiner dieser Mikroorganismen wirkte gegenüber allen untersuchten bodenbürtigen Pathogenen antagonistisch. Drei Fusarium-(K7, K9 und K11) und zwei Trichoderma-Isolate (E28 und E36) zeigten die beste Wirkung und wurden in einer dritten Versuchsrunde kombiniert in verschiedenen Dosierungen getestet. Die beiden Fusarium-Isolate K7 und K9 waren in der Lage, F. oxysporum f. sp. basilici zu kontrollieren und besitzen daher das Potenzial, zukünftig kommerziell im Basilikumanbau eingesetzt zu werden.

Effects of elevated CO2 and temperature on interactions of grapevine and powdery mildew: first results under phytotron conditions

This study reports the effect of increased CO2 and temperature on powdery mildew (Erysiphe necatrix) of grapevine evaluated under controlled conditions. Grapevine potted plants, belonging to the cv Moscato and Barbera, were grown in phytotrons under four different simulated climatic conditions: standard CO2 concentration for the area (450 ppm) with standard (ranging from 22 to 26°C) and elevated temperature (4°C higher than standard), elevated CO2 (800 ppm) with standard and elevated temperature. Physiological responses of grapevine and pathogen development were studied. Results showed an increase of the chlorophyll content with higher temperatures and CO2 concentration, to which consequently corresponded an higher fluorescence index. Disease incidence did not significantly vary between cultivars. In conclusion, an increase in CO2 did not affect powdery mildew incidence, probably due to the increased photosynthetic activity of plants under such conditions.ZusammenfassungDiese Untersuchung beschreibt den Einfluss von erhöhter Temperatur und erhöhtem CO2-Gehalt auf den Echten Mehltau der Weinrebe (Erysiphe necatrix) unter kontrollierten Bedingungen. Getopfte Weinreben der Sorten Moscato und Barbera wurden in Klimaschränken unter vier verschiedenen Simulationsbedingungen angezogen: die regionale Standard- CO2-Konzentration (450 ppm) mit entweder (1.) Standard- Temperatur zwischen 22 to 26°C oder (2.) um 4°C erhöhter Temperatur, oder erhöhter CO2-Konzentration (800 ppm) mit (3.) Standard- oder (4.) erhöhter Temperatur. Unter diesen Bedingungen wurden physiologische Reaktionen des Weins und die Entwicklung des Pathogens untersucht. Dr Chlorophyllgehalt der Weinblätter stieg mit zunehmender Temperatur und CO2-Konzentration, was mit einem höheren Fluoreszenzindex einherging. Die Befallsstärke zeigte keine signifikanten Sortenunterschiede. Aus den Ergebnissen kann gefolgert werden, dass erhöhte CO2-Gehalte die Befallsstärke des Echten Mehltaus der Weinrebe nicht erhöhen, was möglicherweise auf die erhöhte Photosyntheseaktivität der Pflanzen unter diesen Bedingungen zurückzuführen ist.

Effects of elevated CO2 and temperature on interactions of grapevine and powdery mildew: first results under phytotron conditions@@@Einfluss von erhöhtem CO2-Gehalt und Temperatur auf die Wirt-Pathogen-Beziehung von Weinreben und Echtem Mehltau: erste, im Klimaschrank gewonnene Ergebnisse

This study reports the effect of increased CO2 and temperature on powdery mildew (Erysiphe necatrix) of grapevine evaluated under controlled conditions. Grapevine potted plants, belonging to the cv Moscato and Barbera, were grown in phytotrons under four different simulated climatic conditions: standard CO2 concentration for the area (450 ppm) with standard (ranging from 22 to 26°C) and elevated temperature (4°C higher than standard), elevated CO2 (800 ppm) with standard and elevated temperature. Physiological responses of grapevine and pathogen development were studied. Results showed an increase of the chlorophyll content with higher temperatures and CO2 concentration, to which consequently corresponded an higher fluorescence index. Disease incidence did not significantly vary between cultivars. In conclusion, an increase in CO2 did not affect powdery mildew incidence, probably due to the increased photosynthetic activity of plants under such conditions.ZusammenfassungDiese Untersuchung beschreibt den Einfluss von erhöhter Temperatur und erhöhtem CO2-Gehalt auf den Echten Mehltau der Weinrebe (Erysiphe necatrix) unter kontrollierten Bedingungen. Getopfte Weinreben der Sorten Moscato und Barbera wurden in Klimaschränken unter vier verschiedenen Simulationsbedingungen angezogen: die regionale Standard-CO2-Konzentration (450 ppm) mit entweder (1.) Standard-Temperatur zwischen 22 to 26°C oder (2.) um 4°C erhöhter Temperatur, oder erhöhter CO2-Konzentration (800 ppm) mit (3.) Standardoder (4.) erhöhter Temperatur. Unter diesen Bedingungen wurden physiologische Reaktionen des Weins und die Entwicklung des Pathogens untersucht. Dr Chlorophyllgehalt der Weinblätter stieg mit zunehmender Temperatur und CO2-Konzentration, was mit einem höheren Fluoreszenzindex einherging. Die Befallsstärke zeigte keine signifikanten Sortenunterschiede. Aus den Ergebnissen kann gefolgert werden, dass erhöhte CO2-Gehalte die Befallsstärke des Echten Mehltaus der Weinrebe nicht erhöhen, was möglicherweise auf die erhöhte Photosyntheseaktivität der Pflanzen unter diesen Bedingungen zurückzuführen ist.

Quantification of Aspergillus fumigatus and enteric bacteria in European compost and biochar

ABSTRACT Although most potential human pathogens (PHPs) can be inactivated during composting, the risk that such substrates represent for human health remains largely unknown due to the shortage of information on presence and abundance of PHPs in finished composts. This study focused on the assessment of Salmonella spp., Listeria monocytogenes, Shiga toxin-producing Escherichia coli (STEC), and the opportunistic fungal pathogen Aspergillus fumigatus in different compost commodities. A total of fifteen European composts, made from different waste types and processes, were evaluated for the occurrence of the selected PHPs using molecular and traditional techniques. The analyses were extended to five biochar because of their growing application in agriculture, horticulture, floriculture, and private gardening. Enteric bacteria were detected by molecular methods in eight out of fifteen composts; however, viable propagules were confirmed for L. monocytogenes only in two composts, and for STEC in three more composts. No bacterial pathogens were found in biochar. Living A. fumigatus was present in eleven composts and two biochars. None of the eighteen isolates contained single nucleotide polymorphisms (SNPs) relevant for resistance to azole fungicides. The role of compost and biochar as a source of PHPs in the environment and the risk for human health is discussed.

Organic Amendments and Soil Suppressiveness: Results with Vegetable and Ornamental Crops

Organic amendments are an important tool for the management of diseases of vegetable and ornamental crops. They include manure, crop and food residues, compost and organic fertilisers. Their use can help to control soilborne pathogens in vegetable and ornamental crops, especially when applied in conjunction with other management practices and considering a system approach. Composts and Brassica pellets are considered those more promising. The use of Brassica species as green manure is considered a type of biofumigation that involves the release of volatile and toxic compounds. Compost involves different modes of actions, mainly correlated to its microbial community and the presence of biological control agents. Organic amendments can be successfully integrated with other control strategies, like soil solarisation and grafting on resistant rootstocks, to control soilborne pathogens affecting vegetable crops in field conditions. Another possibility is their application mixed in potting soils, which is of particular interest for ornamental crops.

Evaluation of the efficacy of insecticidal coatings based on teflutrin and chlorpyrifos against Rhynchophorus ferrugineus

BACKGROUND The date palm (Phoenix dactylifera L.), an important economic resource for many nations worldwide, has recently been threatened by the presence of different insect pests, like the red palm weevil (RPW) Rhynchophorus ferrugineus. RESULTS Two products, a glue (polyvinyl acetate) and an oil (raw linseed oil) were used as coatings and applied together with a repellent and two insecticides (teflutrin and chlorpyrifos) at different dosages on two species of palm (P. dactylifera and P. canariensis). Phytotoxic effects of the treatments were evaluated in a greenhouse on 260 potted palms (130 P. dactylifera and 130 P. canariensis) and no negative effects were observed. Afterwards, a trial lasting 400 days was carried out in a nursery located in Sicily (south Italy), treating 572 potted palm trees (286 P. dactylifera and 286 P. canariensis) with an average diameter at the base of 18-20 cm. After 400 days, 48% of the untreated palms were infested, while only 3% of date palms and 7% of Canary palms treated with insecticide at lower dosages were infested. CONCLUSIONS The application of an insecticide-based coating is a good strategy to control and prevent the red palm weevil infestation, in particular on date palms.

Effects of Drip Fertigation Management on Nutrient Losses and Pear Production at Chongming Dongtan in Yangtze River Estuary, China

Drip fertigation was applied to evaluate the effects on nutrient losses and crop production in a pear orchard at Chongming Dongtan in Yangtze River Estuary in 2006 and 2007, compared to conventional irrigation and fertilization practices. Based on runoff paddocks and leaching pipes construction, the volumes of runoff and leaching water, and the corresponding concentrations of nitrogen and phosphorus were measured and estimated. The results indicated that, under the experimental conditions, N and P losses through runoff and leaching occurred mainly in the period of rain season from June to October, and leaching was the dominating pathways for N loss while runoff was the main pathways for P loss. Compared with the conventional irrigation and fertilization system, under the consistency of crop yields, the drip fertigation system could decrease the total amounts of nitrogen and phosphorus losses through runoff and leaching by 36.4% and 16.5%, and reduce the total amounts of nitrogen and phosphorus consumptions of chemical fertilizer application by 73.4% and 61.1%, respectively.

Molecular characterization and sensitivity to demethylation inhibitor fungicides of Aspergillus fumigatus from orange-based compost

Aspergillus fumigatus, the causal agent of human aspergilloses, is known to be non-pathogenic in plants. It is present as saprophyte in different types of organic matter and develops rapidly during the high-temperature phase of the composting process. Aspergilloses are treated with demethylation inhibitor (DMI) fungicides and resistant isolates have been recently reported. The present study aims to estimate the abundance, genetic diversity and DMI sensitivity of A. fumigatus during the composting process of orange fruits. Composting of orange fruits resulted in a 100-fold increase in A. fumigatus frequency already after 1 week, demonstrating that the degradation of orange fruits favoured the growth of A. fumigatus in compost. Most of A. fumigatus isolates belonged to mating type 2, including those initially isolated from the orange peel, whereas mating type 1 evolved towards the end of the composting process. None of the A. fumigatus isolates expressed simultaneously both mating types. The 52 investigated isolates exhibited moderate SSR polymorphisms by formation of one major (47 isolates) and one minor cluster (5 isolates). The latter included mating type 1 isolates from the last sampling and the DMI-resistant reference strains. Only few isolates showed cyp51A polymorphisms but were sensitive to DMIs as all the other isolates. None of the A. fumigatus isolates owned any of the mutations associated with DMI resistance. This study documents a high reproduction rate of A. fumigatus during the composting process of orange fruits, requesting specific safety precautions in compost handling. Furthermore, azole residue concentrations in orange-based compost were not sufficient to select A. fumigatus resistant genotypes.

Microbiological Features Associated with the Suppression of Fusarium Wilt of Lettuce Studied by Applying a Single Selected Compost

ABSTRACT The effect of compost suppressiveness towards Fusarium oxysporum f. sp. lactucae has been studied using a combined approach. Bioassays have been carried out in controlled conditions to obtain standardization of the environment in order to minimize the disturbances and variability of the soil microbial communities. Compost addition has demonstrated significant efficacy in controlling the disease. The microbial activities and the bacterial and fungal concentrations have been quantified and correlated in a principal component analysis in order to clarify the correlation between the original variables. The samples were clearly distinguished between the substrates in which the plants were grown and the rhizosphere samples. Denaturing Gradient Gel Electrophoresis (DGGE) has been used to track the microbial communities throughout the bioassays. The approach has shown to be useful in detecting both bacterial and fungal species that preferentially associate with the roots of seedlings. Detected microorganisms assumed to be involved in compost-mediated suppression had a high probability of being vital because they were not detected in the substrate where the plants were grown at the start of the experiment.