occurrence especially in the last experimental year. This could be due to creation of a new microbial balance in the soil. Fusarium spp. in the soil could influence plant infestation during the next time period and a moderately strong relationship (43%) was found. The amount of Fusarium isolated from the roots, root collars and nodes of winter wheat showed the importance of these pathogens. The seed treatment with the biological or the chemical preparation caused a decrease in plant infestation. No differences were observed between variety susceptibility.
Integrated management of Anthracnose (Colletotrichum gloeoesporioides (Penzig) Penzig & Sacc,), a disease of increasing importance of onion in the Philippines
R.T. Alberto1, M.V. Duca2 and S.A. Miller3
1Professor 1, Department of Pest Management, College of Agriculture, Central Luzon State University, Science City of Munoz, 3120 Philippines; 2Research Specialist, Crop Protection Division, Philippine Rice Research Institute, Maligaya, Science City of Munoz, Nueva Ecija, Philippines; 3 Associate Professor, Department of Plant Pathology, College of Agriculture and Environmental Science, OARDC, Ohio State University, Wooster, OH, USA.
A field study was conducted at PhilRice Central Experiment Station in Maligaya, Science City of Muñoz, Nueva Ecija, Philippines to develop integrated management strategies against anthracnose of onion. Different combinations of disease management and cultural practices showed that wider spacing (18 x 20cm) of onion seedlings with low nitrogen (60kg/ha) application and Mancozeb application at 7 days interval significantly reduced the incidence, severity and AUDPC of anthracnose of onion. However, the yield did not differ significantly with the other treatments except with the treatment with no Mancozeb, standard spacing and low nitrogen.
Biological activities of 3-O-methylfunicone, a secondary metabolite of Penicillium pinophilum
Rosario Nicoletti1, Elisabetta Buommino2, Mario De Stefano3, and Maria A. Tufano2
1Tobacco Experiment Institute, Scafati, Italy, 84018, 2Department of Experimental Medicine, Section of Microbiology, The Second University of Naples, Napoli, Italy, 80100, 3Department of Environmental Sciences, The Second University of Naples, Caserta, Italy, 81100.
3-O-Methylfunicone (OMF) is a recently characterized secondary metabolite extracted by liquid cultures of the soil fungus Penicillium pinophilum. Its chemical structure is founded on a -pyrone ring connected to a resorcylide nucleus through a ketone function. Such a molecular framework is common to a family of closely related secondary metabolites produced by a few species belonging to the P. funiculosum group (Penicillium subgenus Biverticillium), and by the related species Talaromyces flavus (anamorph P. vermiculatum); the latter is a well known antagonist of soil-borne plant pathogenic fungi. More recently P. pinophilum has been also described as an ecological antagonist of Rhizoctonia solani, and its antagonistic behaviour has been reported in relation to the production of OMF. Actually mycotoxin production does occur in dual cultures prepared with isolates of both species. In vitro assays showed that the OMF is able to inhibit growth of R. solani hyphae at a concentration of 0.1 mg/ml; it also inhibits other plant pathogenic and dermatophytic fungi at the same concentration. Electron microscopy showed that the toxin induces plasmolysis and disorganization of the cell structure on R. solani hyphae. In vitro assays have been also carried out on several human tumour cell-lines, and potent cytostatic properties have resulted. In fact the metabolite is responsible of cell growth arrest associated to evident morphological changes and modifications in the organization of tubulin fibres. Expression of genes involved in the cell cycle, which is arrested in the G1 phase, is also affected; moreover induction of apoptosis has been demonstrated. The metastatic process may also be inhibited since cell motility is reduced substantially. The capacity of the compound to affect cell cycle and to modulate apoptosis is indicative of a potential for the development of a new agent for cancer chemotherapy.
Biological activity of the Qo Inhibitor fungicides trifloxystrobin and pyraclostrobin against Cercospora beticola
D. A. Karadimosa, G. S. Karaoglanidisb, and K. Tzavella–Klonaric
a Hellenic Sugar Industry S.A., Sugar Factory of Larissa, Plant Protection Department, 41110, Larissa, Greece
b Hellenic Sugar Industry S.A., Sugar Factory of Platy, Plant Protection Department, 59032, Platy Imathias, Greece
c School of Agriculture, Plant Pathology Laboratory, Aristotelian University of Thessaloniki POB 269, 54006, Thessaloniki, Greece
The effect of trifloxystrobin and pyraclostrobin on spore germination of Cercospora beticola, were determined in vitro. In addition, the protective, curative, translaminar and post-symptom activity against the pathogen was determined on sugar beet plants in growth chambers with difenoconazole and chlorothalonil as standard fungicide treatments. Both pyraclostrobin and trifloxystrobin were highly active causing complete inhibition of spore germination at concentrations of 0.01 and 0.1 μg ml-1, respectively. Both fungicides were protective against C. beticola when applied 96h and 24h before inoculation of plants. Both fungicides, applied at 20 μg ml-1 , were superior to difenoconazole applied at 10 μg ml-1 and to chlorothalonil applied at 100 μg ml-1. Effective control was obtained when strobilurin fungicides were applied 24h after inoculation, but were less effective at 96h after inoculation. Pyraclostrobin at 20 μg ml-1 applied 96h after inoculation, was more effective than difenoconazole while control with trifloxystrobin at 20 μg ml-1 applied 96h after inoculation was similar to that obtained with difenoconazole. Chlorothalonil showed little activity against C. beticola in curative treatments.