In the frame of the TrichoNema (EU, Marie Curie) project, several Trichoderma species and isolates have been tested against plant-parasitic nematodes. The main targets are the root-knot nematodes Meloidogyne incognita and M. javanica, which are polyphagous sedentary-endoparasitic species, damaging worldwide. Biocontrol pot experiments are conducted mainly with T. hamatum-382 and a T. asperellum isolate, in nematode-inoculated sandy soil and potting-mixes, with vegetable and ornamental hosts, respectively. This report will focused on ornamental plants. Following screening of several hosts for their nematode sensitivity and growth enhancement by the fungi, Begonia and Impatiens have been chosen as the main model ornamental hosts. Trichoderma peat-wheat bran (fresh or dry) preparations were applied into the potting-mixes pre-planting, with or without pre-colonization of seedlings with the fungi. Trichoderma treatments reduced root galling and nematode reproduction, and plants growth was improved; treatments of seedlings usually enhanced the biocontrol activity. The Trichoderma preparations were applied also to soils naturally-infested with other polyphagous plant-parasitic nematodes: Pratylenchus penetrans (migratory endo-parasite), Rotylenchus robustus (ecto-parasite) and Paratylenchus projectus (ecto-parasite), planted with lettuce. Trichoderma treatments reduced the populations of the parasitic nematodes in soils from the pot experiments. Both Trichoderma species showed the ability to control several plant-parasitic nematodes. Fungal formulations are further tested with various application approaches, in order to define the most efficient methods for implementation of the biocontrol agents. Modes of action of these species are studied, aiming to improve their activity against plant-parasitic nematodes.

Fusarium oxysporum L sp. dianthi (Eo. dianthi), a fungus which causes wilt, and Meloidogyne javanica (M. javanica), the root knot nematode which inhibits growth, are two of the most destructive pathogens of carnation. Both pests are effectively controlled by methyl bromide (MB). We tested five soil disinfestation treatments for the control of these pathogens over two seasons in a naturally and uniformly infested field. The treatments were: soil steaming, metham-sodium (MES), dazomet, methyl bromide (NIB), and untreated control. Each treatment was tested with and without the nematicide 1,3,dichloropropene (Condor, Telone). Two carnation cultivars, 'Lior' (susceptible to both Fusarium and nematodes) and 'Galit', (moderately resistant to Fusarium and very susceptible to nematodes), were planted after fumigation. Condor alone reduced the Fusarium population in the soil by 25%, and reduced wilt incidence similarly. Steam, MES and MB, with or without Condor, each reduced the Fusarium propagule population to below the detection threshold down to 60 cm depth, and consequently, reduced wilt incidence in carnation plants to very low levels. Dazomet was the least effective treatment in reducing populations of Fusarium or of wilt incidence. Either steam or MES alone moderately reduced the growth inhibition or gall formation caused by nematodes, and their effects were similar to that of Condor. No growth inhibition was observed in plots treated with MB, with or without Condor, and gall formation was the lowest in these plots. The results indicate that steam or MES treatments can replace NIB for controlling Fusarium wilt but not for control of nematodes. MES or steam combined with Condor reduced growth inhibition similarly to MB, but MES was less effective in reducing gall formation than MB or steam treatments.

S OF PRESENTATIONS AT T H E 22ND C O N G R E S S O F T H E I S R A E L I P H Y T O P A T H O L O G I C A L S O C I E T Y February 12-13, 2001 ARO, The Volcani Center, Bet Dagan, Israel Opening Lecture The Contribution of Epidemiological Research to Plant Disease Management D. Shtienberg Dept. of Plant Pathology, ARO, The Volcani Center, Bet Dagan 50250, Israel [e-mail: danish@ netvision.net.il ] Epidemiological research deals with the three components of the disease triangle: the host, the pathogen and the environment. One important goal of epidemiological research is to develop means for rational and cost-effective disease management. In some pathosystems it is possible to identify one (or a few) distinctive factors that govern(s) the occurrence of disease outbreaks. Manipulation of this factor may enable us to prevent the development of an epidemic. However, in most systems the situation is more complicated and many factors, and their interactions, govern the intensity of epidemics. In the 1970s, models based on past (measured) weather and decision rules were used for development of management tools. With the progress in computer science in the 1980s, models that simulated the development of the host and the pathogen were developed. However, simulation models were found inadequate for decision-making. Epidemiological knowledge is currently formulated as relatively simple, hence precise, decision models. These decision models are the frameworks I?y which epidemiological knowledge is transferred to the decision-maker. Nevertheless, the models would not necessarily be suitable in dissimilar environments. (L) A: PHYSIOLOGY AND RESISTANCE Endo-l,4-fl-Giucanase Activity in Isolates ofAlternaria alternata in Relation to Their Virulence in Apple Fruit M. Reuveni, 1 N. Shegalov, 1 D. Shegalov, 1 D. Eshel, 2 Ruth Ben-Arie 3 and D. Prusky 2 1Golan Research Institute, Qazrin 12900 [e-mail: mreuveni@research.haifa.ac.il]; 2Dept. of Postharvest Science, ARO, The Volcani Center, Bet Dagan 50250; and 3Fruit Storage Research Laboratory, Qiryat Shemona 10200, Israel The fungus Alternaria alternata is one of the principal causal agents of moldy core rot of different strains of "Delicious' apples. Disease symptoms generally become apparent after cold storage of the fruit, even though the apple core becomes infected in the orchard. Suitable temperature and humidity conditions in the orchard are evidently conducive to inoculation, but the mode and phenology of infection are not yet clearly understood. Artificial inoculation with fungal spores, of fruits at different stages of development, indicated that the initial blossom (10-30%) and full bloom stages were the most susceptible to infection. Of the 150 A. alternata isolates collected in three orchards in the Golan Heights and Galilee region, three strains with different levels of virulence were chosen for further study. The degree of virulence was based on the level of disease that developed on postharvestinoculated fruit. Inoculation of flowers with strains showing low and high virulence resulted in 30% L = lecture sessions; P = poster (market place) sessions. Phytoparasitica 29:3, 2001 243 and 56% disease incidence, respectively, in harvested fruit. In an attempt to clarify the mode of fungal infection of the fruit, the ability of the three strains to produce two hydrolytic enzymes, endo1,4-/3-glucanase (EG) and polygalacturonase (PG), when grown on apple cell walls, was examined. Thus it was tound that EG production of the virulent strain was twice and six times higher than that of the strains with intermediate and low levels of virulence, respectively. The level of PG production was 2.3 times higher in the highly virulent than in the least virulent strain. Activity gels following electrophoresis of protein extracts from the three strains indicated quantitative, but no qualitative, differences between the strains. A purified EG preparation caused disease symptom development on sensitive apple fruit skin, similar to symptom development following wound inoculation. Disease development in apple fruit following infection with A. ahernata may possibly be related to the ability of the fungus to produce EG and PG enzymes in the core and surrounding fruit tissue. (L) Cotton-Associated Vegetative Compatibility Groups of VerticiUium dahliae in Israel and Their Pathogenicity Nadia Korolev, 1,* J. Katan 2 and Talma Katan 1 1Dept. of Plant Pathology, ARO, The Volcani Center, Bet Dagan 50250 [*e-mail: vpptlg@agri.gov.il]; and 2Dept. of Plant Pathology and Microbiology, The Hebrew Universi~. of Jerusalem, Facul~. of Agricuhural, Food and Environmental Quali~. Sciences, Rehovot 76100, Israel A collection of 351 Verticillium dahliae isolates from cotton, recovered between 1992 and 2000 at 20 sites in Israel, was tested for vegetative compatibility using nitrate-nonutilizing (nit) mutants. Three cotton-associated vegetative compatibility groups (VCGs) were found and identified as VCG1 (34 isolates), VCG2B (218 isolates), and VCG4B (98 isolates). VCG2A was represented by one isolate only, although it was frequently recovered from non-cotton hosts. Three cotton pathotypes were defined among 40 isolates tested, using G. hirsutum cv. 'Acala SJ2' as differential. VCGI isolates induced severe leaf symptoms, stunting and defoliation, and were defined as the previously described cotton-defoliating (D) pathotype; VCG2B isolates also caused severe foliar symptoms, stunting and often death but no-to-partial defoliation, and were defined as cotton-defoliating-like (DL) pathotype; most of the VCG4B isolates induced weak-to-moderate symptoms on cotton and were similar to the previously described cotton-non-defoliating (ND) pathotype. Representatives of each VCG-associated pathotype were tested for their pathogenicity to a range of plant species. The D and DL pathotypes differ in their aggressiveness (D >DL), but the order of hosts (from highly susceptible to resistant) was the same: okra (commercial cultivar), cotton (Acala S J2), watermelon ('Crimson Sweet'), safflower (PI 251264), sunflower (2053), eggplant ('Black Beauty'), tomato ('Rehovot 13'). The ND pathotype formed another sequence differing from the DL pathotype with respect to cotton tolerance and eggplant susceptibility. Tomato was resistant to all tested cotton isolates and pathotypes. (P) Fusarium verticillioides: The Causal Agent of Corn Blight in Israel? A. Sharon, 1'* L. Oren, 1 S. Ezrati 1 and D. Cohen 2 1 Dept. of Plant Sciences, Tel-Aviv Universi~., Tel Aviv 69978 [*e-mail: amirsh @ tauex, tau. ac. il]; and 2Northern R&D, Qiryat Shemona 10200, Israel Corn rots are the most severe diseases of sweet corn in Israel. The incidence of stalk rot and the associated plant blight has increased in recent years, rendering some areas in northern Israel unsuitable for corn. Fusarium verticillioides is known as the causal agent of corn rots, but although previous findings demonstrated that the fungus can be lound in the soil, seeds and plants, it is unclear if this pathogen is indeed the primary cause of plant blight. In the current study we characterized the disease using E verticiUioides-transgenic strains that express the reporter genes green fluorescent

New nematode control measures are required due to the likely removal of effective nematicides from the market because of increasing concerns of possible effects on human health and the environment. Biological control, organic and inorganic soil amendments, naturally occurring nematicides, induced resistance, interruption of host recognition and transgenic plants will be a part of integrated management of plant-parasitic nematodes in the near future. The paper reports work carried out in Israel on these topics. (C) 2000 Society of Chemical Industry.

Nematode control methods without using nematicides have been studied. Biological control by nematode antagonists, use of soil amendments to build up antagonistic microorganisms and release toxic compounds to nematodes, detection of naturally occurring nematicides in plants, interruption of nematode's host-recognition process and study of nematode collagen genes are described here.

A fungal parasite was isolated from black - coloured egg masses of Meloidogyne javanica on tomato roots . The fungus did not sporulate on any of the culture media tested or in the egg mass . Hyphal characteristics suggest that it is similar to the hyphomycete genus Scytalidium. Hyphae of the Scytalidium- like fungus (CBS 645 . 97 and IMI 368886) proliferated in the gelatinous matrix of the egg mass and penetrated the eggshell via a penetration peg . Parasitism of the egg mass greatly lowered the hatch rate of M. javanica juveniles in vitro. Application of the fungus to soil did not inhibit juvenile penetration into tomato roots . However , the nematode population in soil treated with the fungus was lower than in non - treated soil after one nematode generation . The exact identification of the Scytalidium like fungus , technology for mass production and its application in the field for control of root - knot nematodes requires further investigation .

Pasteuria penetrans spore adhesion to Meloidogyne javanica second-stage juveniles (J2) was examined following several different pretreatments of the latter. The detergents sodium dodecyl sulfate and Triton X-100, the carbohydrates fucose and alpha-methyl-D-mannoside, and the lectins concanavalin A and wheat germ agglutinin reduced spore attachment. Spores exposed to M. javanica surface coat (SC) extract exhibited decreased adherence to the J2 surface. Second-stage juveniles that had been treated with antibodies recognizing a 250-kDa antigen of J2 SC extract had fewer spores attached to their surfaces, as compared to nontreated J2, except in the head region. This inhibition pattern was similar to that of antibody-labelling on M. javanica J2 as observed by electron microscopy. It is suggested that several SC components, such as carbohydrate residues, carbohydrate-recognition domains, and a 250-kDa antigen, are involved in P. penetrans spore attachment to the surface of M. javanica.

A gradient of reduced effectiveness of solarization toward the edge of the plastic mulch is known as a ‘border effect’, corresponding with decreasing soil temperatures from the middle toward the edge of the mulched area. The cyst nematode Heterodera avenae , of wheat was completely controlled by solarization at 90 cm or more inward from the edge of the mulched plots. A gradient of decreasing effectiveness of nematode control in the mulched plot, toward the edge of the mulch, was observed. There was a similar gradient with height of wheat planted after solarization, and in the incidence of pod wart disease of peanuts caused by Streptomyces spp., planted as a second crop after soil disinfestation. Disease reduction was correlated with a decrease in population of streptomycetes. A similar, but less pronounced, border effect was observed when solarization was combined with methyl bromide or formalin at reduced dosages.

Cereal cyst nematodes were found in varying population densities in the majority of wheat fields surveyed in Israel. The dominant species was Heterodera avenae (Ha), while H. latipons (Hl) occurred mainly in the more arid (southern) areas. The phenology and life cycle of the two species was basically similar: both species completed a single generation per year, life-stage development being closely related to climate and plant development. The two species differed in their etiology; whereas Ha attacked the root tip region inducing typical branching and swelling of roots with ensuing adherence of soil particles, juveniles of Hl penetrated at sites along roots more distant from the apex and, therefore, did not produce clearly visible root symptoms in the early seedling stage. In field conditions, the presence of Hl could be recognized only when cysts appeared on the roots. Moreover, the growth inhibition caused by Ha was more severe than that due to Hl.All local wheat cultivars tested were found to be excellent hosts for both Ha and Hl, as were all tested cultivars of barley and Phalaris sp.; oat cultivars were extremely poor hosts of Ha, but good hosts of Hl. Seven Ha populations showed the predominance of two pathotypes: Ha21, in the northern and the coastal regions, and Ha41 in the southern areas. Soil temperature affected both Heterodera' species hatching and damage to roots: at 6-degrees-C, life-stage development took 4 months, and it shortened as temperature increased up to 18-degrees-C, when it took only 40 days. At 24-degrees-C, juveniles failed to penetrate the roots. The effects on plant growth of early vs later sowing in dry and wet soils were recorded and are discussed.