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Conditions affecting germination and growth of Fusarium mangiferae, causal agent of mango malformation disease, were studied in vitro. Both conidial germination and colony growth required temperatures >5°C and reached a peak at 28 and 25°C, respectively. A minimum 2-h wetness period was required for conidial germination, reaching a peak after 8 h of wetness. High incidence of fungal colonization in buds, predominantly the apical buds, was detected compared with inoculated leaves. The pathogen was detected in the roots of inoculated soil 19 weeks postinoculation but not in aboveground parts of the plants, and symptoms of the disease were not observed, either. Dry, malformed inflorescence debris serving as a source of inoculum caused significantly higher colonization (52 and 20%) of inoculated buds, compared with that (0%) of the untreated controls. Incidence of sampled leaf disks bearing propagules of F. mangiferae from an infected orchard peaked in June and July and decreased during the following months, whereas airborne infections on 1-month-old branches was the highest in May and June, corresponding with inoculum availability released from infected inflorescences. Colonization pattern, determined in naturally infected vegetative and woody branches, was significantly higher in node sections than in the internode sections. This study sheds light on infection dynamics, colonization patters, and the disease cycle of F. mangiferae in mango.

The effects of several spray and climate treatments on Leveillula taurica were tested under controlled and commercial greenhouse conditions either alone or combined with a climate treatment. Ampelomyces quisqualis AQ10 inhibited the germination of conidia on leaves, but not on glass. Trichoderma harzianum T39 inhibited germination on both surfaces. Neither the examined biological control agents (BCAs) nor the two tested mineral oils (AddQ and JMS Stylet-Oil) affected the viability of conidia. Sulphur drastically limited the germination and viability of L. taurica. In experiments at 15–25°C, AQ10 alone reduced hyphal leaf colonisation at 25°C. T. harzianum T39 significantly reduced leaf colonisation at all temperatures but significantly reduced disease only at 20–25°C. The oils significantly reduced leaf colonisation and sulphur reduced both leaf colonisation and disease at all temperatures. Results were confirmed in an experimental greenhouse. In a field experiment, azoxystrobin, polyoxin AL, neem extract, and T39 were effective; sulphur was superior to them. Under severe epidemic conditions the disease had a negative impact on yield; late fungicide treatments at spring-time were found unnecessary. Chemical sprays applied in alternation was compared with the ‘friendly’ spray regime (alternation of Heliosoufre, T. harzianum T39 + JMS Stylet oil, A. quisqualis AQ10+AddQ oil and Neemgard) in two climates i.e. (i.) day warm climate and (ii.) regular (cool) day climate regimes. In the warm climate, there was no significant difference in the performance of the ‘friendly’ spray regime and the chemical spray regime. However, in the cooler climate, the ‘friendly’ spray programme was not as effective as the chemical spray programme. It was concluded that a change in the greenhouse climate may affect the development of powdery mildew and, at the same time, promote the activity of BCAs and render a pathogen more vulnerable to these control agents, allowing for better disease suppression.

We review published and unpublished studies conducted in Israel with six acaropathogenic fungi, assayed in order to control the citrus rust mite, Phyllocoptruta oleivora (Ashmead) (CRM). Hirsutella thompsonii Fisher was introduced twice, killed 80–90% of the exposed mites, but due to its requirements for near-saturation humidities was deemed unsuitable for local outdoors conditions. Hirsutella kirchneri (Rostrup) Minter et al. and Hirsutella necatrix Minter et al. were also introduced and assayed against CRM and spider mites, but their efficacy was unsatisfactory. Three indigenous fungi found to be associated with mites, Meira geulakonigii, Meira argovae and Acaromyces ingoldii—all three recently described by Boekhout, Gerson, Scorzetti & Sztejnberg—were assayed against several mites. Meira geulakonigii killed 80–90% of several spider mites and of the CRM, and caused some mortality of Iphiseius degenerans (Berlese), one out of three phytoseiid predators assayed. Mortality was not due to parasitization; extracts from the media in which the fungi had developed caused considerable mite death, suggesting that it was a result of fungal toxins. Data from a field study indicated that spraying blastoconidia of M. geulakonigii on grapefruits infested by CRM significantly reduced pest-incurred damage from 23 to 13%. Applying qRT-PCR methodology indicated that M. geulakonigii was endophytic within sealed grapefruit flowers and in the flavedo of the fruits’ peel. Neither in the laboratory nor in the field was any evidence ever obtained that this fungus damaged the plants, leading us to hypothesize that M. geulakonigii serves as a “body guard” of grapefruits (and perhaps other plants as well). All three fungi suffered very little mortality after being exposed to various insecticides and acaricides that are in current local use (with the exception of sulfur). The ability of M. geulakonigii to reduce mite numbers without affecting the host plant, the minimal fungal effect on some predatory mites, its endophytic nature along with the apparent tolerance of M. geulakonigii to many insecticides and acaricides, suggest that this fungus could be suitable for integrated pest management (IPM) program.

Mango malformation, caused by the fungus Fusarium mangiferae, is one of the major diseases of this crop occurring worldwide. This study was conducted to investigate aspects of the epidemiology, survival and spread of the pathogen in general and specifically in seedlings, the majority of which are cultivated in infected orchards in Egypt. Survival of conidia of a representative isolate (506/2) declined very rapidly in soil under summer conditions (1·6 weeks for 50% population decline), but significantly less in controlled and winter conditions (17·9 and 15·0 weeks, respectively, for 50% population decline). Likewise, inoculum survival in naturally infected panicles on the soil surface declined faster than in those buried at 30-cm depths. Natural infections were evaluated on fruits and seeds in a heavily infected and a healthy orchard. In infected trees, the skins of all sampled fruits within a 2-m radius of infected panicles were infected, but the pathogen was not detected in the seeds, seed coats or flesh. The pathogen was not detected in any parts of fruits from a healthy orchard. Vegetatively malformed mango seedlings, growing under infected trees bearing infected panicles, were sampled in two locations in Egypt to determine whether infection in seedlings was systemic (evenly distributed within plant tissue) or whether the pathogen originated from malformed panicles. According to PCR-specific primer amplification, the pathogen was detected in 97% of seedling apical meristems, declining gradually to 5% colonization in roots. It was concluded that inoculum of the pathogen originates from infected panicles and affects seedlings from the meristem, with infections descending to lower stem sections and roots. Minor infections of roots may occur from inoculum originating from infected panicles, but the pathogen is not seedborne.

The Basidiomycotine fungi Meira geulakonigii, Meira argovae and Acaromyces ingoldii were assayed in the laboratory against five species of herbivorous mites: Phyllocoptruta oleivora (Eriophyidae), Panonychus citri, Eutetranychus orientalis, Tetranychus urticae and Tetranychus cinnabarinus (all four Tetranychidae). All fungi caused significantly high mortality rates (as compared to controls) after 14 days, some after 1 week. Phyllocoptruta oleivora was the most susceptible, showing >80% mortality even after 1 week. In a field trial, grapefruits sprayed either once a month or once a season with M. geulakonigii had significantly fewer P. oleivora and less damage than unsprayed fruit. These results suggest that M. geulakonigii may protect grapefruits against the injurious P. oleivora.

Scytalidium wilt, caused by Scytalidium lignicola, has become prevalent on ‚Star Ruby’ grapefruit in orchards in the Jordan Valley, an area with a warm climate in the north of Israel. It occurs in the summer in certain years, soon after extreme hot and dry weather conditions have prevailed for several consecutive days, but not in other years with regular summer temperatures. The effect of temperature conditions before and after inoculation with S. lignicola on disease development on ‚Star Ruby’ was studied in greenhouse chambers with three day/night temperature regimes: ‚Very Hot’ (47 °C/34 °C); ‚Hot’ (36 °C/28 °C); and ‚Moderate’ (30 °C/20 °C). Among the pre-inoculation regimes, ‚Very Hot’ was most conducive to infection, whereas the ‚Hot’ regime sustained canker development only when followed by a ‚Very Hot’ post-inoculation regime. The moderate pre-inoculation conditions appeared to have a negligible, if any, effect on canker development, even with a ‚Very Hot’ post-inoculation regime. Wilt developed in infected saplings if they were exposed to the ‚Very Hot’ temperature regime either pre- or post-inoculation, but did not develop under the cooler conditions. Saplings of ‚Star Ruby’ exposed to a ‚Very Hot’ regime developed heat-stress symptoms, similar to those observed on ‚Star Ruby’ in the Jordan Valley. Under a constant ‚Very Hot’ regime, both canker expansion and subsequent foliar wilt developed on ‚Flame’, but not on ‚Marsh Seedless’ or ‚Rio Red’ grapefruit. The study confirmed an hypothesis that predisposition induced by extremely hot temperature is a prerequisite for infection of susceptible hosts by S. lignicola.

Powdery mildew of strawberry is caused by the obligate pathogenic fungus Sphaerotheca macularis f. sp. fragariae. The disease affects the leaves, flowers and fruit of this crop. This study examined the effects of different environmental factors on disease cycle components (germination, conidiation and survival) in strawberry to determine which conditions limit the progress of the disease. The optimal environmental conditions for conidial germination and conidial germ tube length ranged between 15 and 25 °C with relative humidity (RH) higher than 75%, but less than 98%. High light intensity reduced germination and hyphal growth. The viability of conidia on infected leaves was examined at temperatures ranging from 15 to 35 °C at 80–85% RH. Conidia survival declined over time, but a certain percentage of conidia remained active after 5 months incubation. The rate of conidial germination was significantly higher on young leaves than on older leaves. This observation was consistent across all four tested cultivars. Conidiation at 70–75% RH was similar to that at 80–85%, but greater than that at ≥95% RH. The shortest time from inoculation to appearance of the first disease symptoms was 4 days, at 20 and 30 °C with RH above 75%. In growth chambers, temperatures of 10 and 30 °C, RH above 95%, radiation of 7000 lux and the use of a more tolerant cultivar were all detrimental to disease development. In general, the environmental conditions required for germination and dispersal of powdery mildew are conducive to disease progress under strawberry production conditions in Israel. Furthermore, viability and survival of the pathogen during and between seasons appears to be dependent on asexual inoculum production.

Two biocontrol preparations were tested for their ability to control Sphaerotheca fusca and Botrytis cinerea on greenhouse cucumber. Trichoderma harzianum T39 (TRICHODEX) spray reduced powdery mildew severity by up to 97% but its efficacy declined to 18–55% control as the epidemic progressed. Unlike on young leaves, on older leaves the control of powdery mildew by T. harzianum T39 was poor. Ampelomyces quisqualis (AQ10) was very effective against powdery mildew, achieving up to 98% of control. Its effectiveness declined with the progress of the epidemic but unlike the other biocontrol agent it retained significant control capability on older leaves. Two aliphatic petroleum distillate oil products improved the efficacy of both biocontrol agents. The co-application of T. harzianum T39 and A. quisqualis AQ10 was tested on cucumber plants infected with powdery mildew followed by fruit gray mold infection. It resulted in no improvement of the control of powdery mildew, and in an improvement of gray mold control, the latter probably because of the use of additive oil (ADDQ) along with the second biocontrol preparation. There was no significant interference between the biocontrol agents in the co-application treatment as compared with the application of each agent alone; the level of population of T. harzianum T39 remained similar and the parasitism of S. fusca by A. quisqualis was not nullified. The application of T. harzianum T39 to soil instead of spraying it resulted in 75–90% lower powdery mildew coverage on the leaves. It was concluded that the mode of action of T. harzianum T39 in powdery mildew control is induced resistance, not mycoparasitism or antibiotic action.

Two antifungal terpenoids, 6-isopropyltropolone β-glucoside and 5-(3-hydroxy-3-methyl- trans -1-butenyl)-6-isopropyl-tropolone β-glucoside, named by us cupressotropolone A and B, respectively, were isolated from the bark of Italian cypress, in response to infection by the fungus Diplodia pinea f. sp. cupressi . These tropolone glucosides inhibited in vitro germination of spores of Diplodia pinea f. sp. cupressi, Seiridium cardinale, Alternaria alternata and Verticillium dahliae .

Inoculum availability and conidial dispersal patterns of Fusarium mangiferae, causal agent of mango malformation disease, were studied during 2006 and 2007 in an experimental orchard. The spatial pattern of primary infections in a heavily infected commercial mango orchard corresponded with a typical dispersal pattern caused by airborne propagules. Malformed inflorescences were first observed in mid-March, gradually increased, reaching a peak in May, and declined to negligible levels in August. The sporulation capacity of the malformed inflorescences was evaluated during three consecutive months. Significantly higher numbers of conidia per gram of malformed inflorescence were detected in May and June than in April. Annual conidial dissemination patterns were evaluated by active and passive trapping of conidia. A peak in trapped airborne conidia was detected in May and June for both years. The daily pattern of conidial dispersal was not associated with a specifically discernable time of day, and an exponential correlation was determined between mean relative humidity (RH) and mean number of trapped conidia. Higher numbers of conidia were trapped when RH values were low (

The potential of the biological control fungus Penicillium oxalicum to suppress wilt caused by Fusarium oxysporum f. sp. melonis and F. oxysporum f. sp. niveum on melon and watermelon, respectively, was tested under different growth conditions. The area under disease progress curve of F. oxysporum f. sp. melonis infected melon plants was significantly reduced in growth chamber and field experiments. In glasshouse experiments, it was necessary to apply P. oxalicum and dazomet in order to reduce Fusarium wilt severity in melons caused by F. oxysporum f. sp. melonis. For watermelons, we found that P. oxalicum alone reduced the area under the disease progress curve by 58% in the growth chamber experiments and 54% in the glasshouse experiments. From these results, we suggested that P. oxalicum may be effective for the management of Fusarium wilt in melon and watermelon plants. © 2009 Elsevier Inc. All rights reserved.

The effect of pruning of side-branches of the lower part of cypress trees ( Cupressus sempervirens L.), a management practice in recreation forests in Israel, on development of cankering diseases caused by Seiridium cardinale (Wagener) Sutton & Gibson and Diplodia pinea (Desm.) Kickx, Petrak & Sydow f. sp. cupressi Solel, Madar, Kimchi & Golan, was studied. Pruning of trunk side-branches enhanced both incidence and severity of natural infection of the trunks by either of these pathogens. The effect of an asphalt wound dressing paste on severity of Diplodia cankering varied depending on the season of pruning. In winter and spring, disease severity ranks were significantly lower in trees treated with paste than in untreated ones, whereas in summer or autumn, application of paste did not affect the disease ranking. The effect of trunk pruning on the response of the crown to artificial inoculation was studied in relation to season. Spring pruning resulted in smaller Diplodia cankers on the stem, but not on branches, whereas summer pruning did not affect canker development in the succeeding autumn inoculation. Expansion of Seiridium cankers in pruned trees was hindered both in spring — on stem inoculations — and in autumn — on branches.

Sweet pepper-Leveillula taurica microclimate relations were studied under controlled conditions and in commercial greenhouses. Conidial germination occurred at 10 to 37 degrees C and was optimal at 20 degrees C. Conidial viability declined as temperatures increased to 40 degrees C for 6 h. Leaf colonization was optimal at 15 to 25 degrees C. Severe leaf infections occurred at 15 to 20 degrees C and conidiation was suppressed at 20 to 25 degrees C. Highest germination rates were observed at 75 to 85% relative humidity (RH). Severity of leaf coverage by symptoms was high for plants which were subjected to longer periods of temperatures between 10 to 15 degrees C and daytime RH between 85 to 95%, and positively correlated with nighttime RH. Disease severity was negatively correlated with lengthy periods of temperatures >25 degrees C, day and night average temperatures, and average daytime RH. Conversely, leaf shedding was relatively high under conditions characterized by long periods of temperatures >20 degrees C and

The effects of pre- and post-planting soil solarization on white root rot of apple caused by Rosellinia necatrix were examined in two naturally infested orchards. The pathogen was eradicated in solarized soil to a depth of 30 cm. Partial or complete destruction of the pathogen was obtained in solarized-shaded (partially shaded by the tree canopy) plots. No reinfestation of solarized and solarized-shaded soil was observed 2 years after treatment. No death of replanted apple trees occurred in the solarized plots up to 2 years after solarization, whereas 60% of trees died in untreated plots. No disease developed during the third year after solarization in an existing apple orchard, but a low rate of disease recurred in the fourth year. In contrast, mortality in diseased trees in the absence of solarization reached 100%, 4 years after treatment. Two previously solarized soils, out of seven tested, caused reduced growth of the pathogen, indicating induction of soil suppressiveness by solarization.

The effects of gamma irradiation and temperature of incubation on accumulation of the phytoalexin scoparone were investigated in citrus inoculated with the fungus Phytophthora citrophthora. In all the tested citrus species, scoparone concentration in the branches was higher and lesion length was shorter when the incubation temperature after inoculation with P. citrophthora was 28 rather than 20 C. The temperature effect was pronounced, especially in inoculated branches of rough lemon, which after 4 days at 28 C had a scoparone concentration of 290 μg/g fresh weight, compared with 42 μg/g fresh weight at 20 C. The comparable lesion length in this species was 5.2 mm at 28 C compared with 11.0 mm at 20 C [...]

(...) The lengths on seedlings of resistant species were 2.8 mm for Citrus macrophylla and 3.2 mm for Poncirus trifoliata; lengths on moderately-resistant species were 5.0 mm for C. aurantium and 5.2 mm for P. trifoliata × C. sinensis; lengths on susceptible species were 11.0 mm for both C. jambhiri and C. sinensis. Thirty-two hybrids (P. trifoliata × «poorman orange») were tested using this method. Of these, 14 hybrids were resistant, eight were moderately resistant, and 10 were susceptible

Different isolates ofTrichoderma harzianum andTrichoderma hamatum were isolated from naturally infected roots ofRosellinia necatrix. T. harzianum andT. hamatum isolates overgrew cultures ofR. necatrix placed simultaneously in petri dishes. Relative levels ofR. necatrix population were assessed by the avocado leaf colonization method.T. harzianum isolate T-8, significantly reducedR. necatrix colonization of avocado leaves in comparison to other isolates in artificially and naturally infested soils.R. necatrix inoculum decreased steadily over 4 and 6 week periods in artificially inoculated soil and naturally infested soil respectively when isolate T-8 was applied, to a point where noR. necatrix could be recovered. Disease incidence of almond seedlings was significantly reduced when isolate T-8 was added to naturally infested En-Zurim soil.

Multiplication of bacteria on beetroot leaves was reduced when dilute aqueous solutions of chloramphenicol or streptomycin, but not penicillin, were placed as droplets on the leaves. There was also a change in the composition of the bacterial flora. Streptomycin and penicillin at higher concentrations inhibited germination of B. cinerea spores in vitro. After removal of droplets containing antibiotics from leaves and addition of fresh B. cinerea spores in vitro there was improved germination with chloramphenicol and streptomycin, but germination remained poor with penicillin. Satisfactory germination of B. cinerea spores on beetroot leaves occurred only in the presence of 50 μ/ml streptomycin. Application of streptomycin to beetroot leaves caused increased leakage of amino acids, and to a lesser extent, of carbohydrates. A reduction in amounts of streptomycin and penicillin, but not of chloramphenicol, in droplets on beetroot leaves was recorded after 24 h.

Rosellinia necatrix, the cause of white root rot in fruit trees, was efficiently controlled in an infested avocado orchard soil, by applying methyl bromide by deep injection (up to 90 cm) of cold gas and by surface application of hot gas, at a dosage (for heavy soil) of 1500 kg/ha and 1000 kg/ha, respectively. Efficiency of control was evaluated: 1) by testing pieces of naturally diseased avocado roots buried in the soil before treatment at different depths up to 100 cm; 2) by planting avocado and almonds in the treated field and in soil samples; 3) by burying avocado leaves in the soil samples. All the evaluaton tests showed that both treatments of methyl bromide were effective in controlling R. necatrix completely up to the depth of 100 cm, immediately and 9 months after treatment.

6,7-Dimethoxycoumarin was isolated from the bark of citrus trunks, branches and fruit peels following inoculation with the fungus Phytophthora citrophthora . The compound inhibited growth in vitro of Phytophthora citrophthora, Verticillium dahliae, Penicillium digitatum, P. italicum, Colletotrichum gloeosporioides, Diplodia natalensis and Hendersonula toruloidea.

In macrophylla, sour orange, and rough lemon, concentrations of scoparone were two- to fourfold greater in inoculated branches treated with 300 μg of fosetyl-Al or 125 μg of phosphorous acid (H 3 PO 3 ) per milliliter than in inoculated, untreated branches. Lesion length in these three species decreased more rapidly than in niva after treatments with 0-300 μg of fosetyl-Al or 0-125 μg of H 3 PO 3 per milliliter, whereas lesion length in niva decreased sharply only with treatments of more than 500 μg of fosetyl-Al or 200 μg of H 3 PO 3 per milliliter