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The antifungal activity of Aloe vera gel at 1–105 μl l−1 was tested on four common postharvest fruit pathogens: Penicillium digitatum, P. expansum, Botrytis cinerea, and Alternaria alternata. The natural gel suppressed both germination and mycelial growth with P. digitatum and A. alternata being the most sensitive species. Spore survival of P. digitatum, A. alternata, and B. cinerea was reduced by 15–20% at 1 μl l−1, but the gel was similarly effective against P. expansum only when the concentration exceeded 103 μl l−1. For the first two species, the suppressive effect of the gel increased with an increase in the concentration, culminating in 95% reduction in spore survival at 105 μl l−1. B. cinerea, however, responded with a partial germination recovery when the gel concentration was greater than 10 μl l−1. The inhibitory effect of the plant gel on colony growth was exhibited at 1 μl l−1, when a 67–69% reduction in radial growth was recorded for P. digitatum, A. alternata, and B. cinerea, and a 19% reduction for P. expansum after five days on potato dextrose agar (PDA) at 23 °C. The effect of the gel on disease development in P. Digitatum-inoculated grapefruit was expressed by both a delay in lesion development and a significant reduction in the incidence of infection following dipping in a concentration of plant gel of 103 μl l−1.

A hot water dip at 50°C for 2 min was more effective than 1 KGy of gamma radiation in reducing Botrytis cinerea and Rhizopus stolonifer decay in inoculated light-red tomatoes. The combined hot water and radiation treatment acted synergistically on fungal development resulting in 1.7% and 10.0% infection by B. cinerea and R. stolonifer, respectively, after 5 days at 23°C compared with 67% and 100% infection in the non-treated controls. Under natural infection conditions, hot water dip followed by irradiation at 0.5 KGy totally eliminated decay by Alternaria alternata during 8 days at 23°C. All treatments caused more rapid fruit softening, with 20% soft fruit in the combined treated fruit compared with zero soft fruit in the non-treated control.

Harvested ‘Galia’ melons (Cucumis melo L.) were dipped in hot water, wrapped in PVC stretch film and subjected to shelf-life trials. A dip time of 1–2 min in 55°C water was found to be the optimum anti-fungal treatment while a higher temperature or longer exposure time resulted in heat injury to the fruits. Wrapping dampened fruits before treatment, as a means of preventing reinfection of the fruit after heating, through exposure to the ambient air, resulted in heat injury due to the longer dip time required. Wrapping the fruits while still wet from the hot water treatment provided effective, antifungal protection for the melons for 9 days at 18°C without any retention of the excess water under the wrapping which would enhance decay development. This technique shortened the exposure time to possible reinfection to only a matter of seconds after heat treatment.

Ochratoxin content in sclerotia collected from grains of barley, wheat, and corn inoculated with Aspergillus ochraceus was significantly higher than that accumulated in sclerotia produced on synthetic medium (SM) (95.8, 47.3, 9.2 and 1.75 μg/g sclerotia, respectively). However, when sclerotia harvested from those grains were grown for 14 d on SM the amount of ochratoxin produced by the colonies formed was 3.4, 2.7 and 3.0 μg/plate, as compared with 5.2 μg/plate produced under the same growth conditions by colonies initiated from sclerotia which originated from the SM. Complete mortality of sclerotia from grains or SM occurred at a dose of 200 krad, but none of the levels tested (25, 50 or 100 krad) caused an increase in ochratoxin production. A marked reduction in sclerotial germination was recorded for sclerotia obtained from SM but not for those obtained from wheat grains after exposure to combined treatments of irradiation plus heat. Nevertheless, the combined treatment did not consistently result in significantly different quantities of ochratoxin produced.

Rhizopus stolonifer infection markedly stimulated ethylene and CO2 evolution from fruits of the two non-ripening tomato mutants, rin and nor, and caused the climacteric-like patterns of respiration typical of normal fruit. These changes were first detected 24 h after inoculation with maximum rates of ethylene production occurring on the second day after inoculation, while maximum respiratory rates, coinciding with total fruit rotting, occurred only on the fourth day. In uninfected mutant fruits, whether wounded or not, the rates of respiration and of ethylene evolution remained low and constant. Normal tomato fruits inoculated at the green fruit stage showed both an acceleration and an overall increase in the two physiological processes but, when inoculated in the postclimacteric red fruit, new climacteric peaks, with rates higher than those of the uninfected fruit followed fungal infection. The highest rates of ethylene production ocourred in the healthy tissues at the margin of the rot and little was produced by the rotted tissues containing actively growing fungus. Thus, ethylene appears to be a product of the host's metabolism, not of the fungurs.

Fluorescein isothiocyanate (FITC)-conjugated lectins with different sugar specificities were found to be a useful aid for the study of the composition of yeast cell walls and of the organization of the polysaccharides in these walls. Using FITC-concanavalin A, mannan was shown to be located on the outer surface of Saccharomyces cerevisiae, S. bayanus, Candida mycoderma, and C. rugosa, as well as on Sporobolomyces roseus, but seemed to be overlayed by other components in the other yeasts examined. Schizosaccharomyces pombe, C. rugosa, and S. roseus reacted with both FITC-soybean agglutinin and FITC-peanut agglutinin, indicating the presence of galactose-containing polysaccharides on their surface. Rhodotorula glutinis readily combined with FITC-wheat germ agglutinin, indicating that chitin is present on its outer surface. In Sporobolomyces, however, a strong reaction with FITC-wheat germ agglutinin was observed only after the cells had been treated with KOH, indicating that the chitin is normally present in the interior. This was in contrast to the more homogeneous distribution of mannan and galactose in the walls of S. roseus.

A study on air-borne fungi was made in Eilat which is situated at the extreme south of Israel in an arid area surrounded by deserts. Petri dishes containing Sabouraud's medium were exposed daily, during 1959 under standard conditions, at two sites in Eilat and for comparison at Tel-Hashomer in the central part of the country. The total number of air-borne fungi and Actinomycetes collected was markedly lower at Eilat than at Tel-Hashomer, as well as at the other places in Israel recorded previously. This fact is apparently due to the particular ecological and meteorological conditions of Eilat. The most frequently found air-borne spores were of the same genera at Eilat and Tel-Hashomer. This may be due to the northeastern and northern winds blowing from the interior parts of the country toward Eilat. Cladosporium (Hormodendrum) constituted 27 to 32 per cent of the entire catches in Eilat. Alternaria constituted 15 to 20 per cent, Penicillium 14 to 20 per cent, Aspergillus 5 to 7 per cent, Stemphylium 4 to 6 per cent, Actinomycetes 1 per cent, and yeasts 1 per cent. Among the "miscellaneous," the most frequent were Helminthosporium, Epicoccum, Fusarium, Mucor, Rhizopus, Pullularia, Monilia, and Botrytis. A seasonal variation in the number of fungal spores in the air, characterized by marked decrease during January and February, was found at the three sites of exposure. Cladosporium, Alternaria, and Stemphylium were mainly responsible for the seasonal variation.

Gamma radiation of Penicillium digitatum Sacc. spores caused a dose-dependent lag in the polygalacturonase (PG) and cellulase activity of the fungus. A lag of 24 hr was obtained with a 50 krad dose and of five days with 150 krad. The delay in enzymatic synthesis generally corresponded with the delay in colonization of irradiated cultures. However, the production of these enzyme systems began before the end of the fungus' incubation period in citrus fruit. Inhibition of enzymatic synthesis of an irradiated spore population was found to be directly related to the number of conidia which remained viable after corresponding doses of gamma rays.

Direct effects of gamma rays on suspensions containing 105 spores/ml of the main fungi in Israel that cause the rot in stored melons, were tested by inoculating irradiated suspensions on Potato Dextrose Agar and into melon fruits. A 40 krad dose was lethal to Trichothecium roseum which was estremely sensitive. A 100 krad dose was lethal to Penicillium cyclopium, and P. viridicatum in vitro, while 150 krad was the lowest lethal dose tested in vivo. Lower doses (60 and 100 krad) caused some prolongation of the incubation period in melons stored at 17°C. The incubation period of Fusarium sp. inoculated into melons was 16–18 days for 100 krad doses, compared to ten days for controls. Its incubation was inhibited on melons by 200 krad for 24 days at 17°C, but there was a slow growth at 25°C in vitro between the 16th and 21st days. Alternaria tenuis was radiation resistance with 300 krad being sublethal both in vitro and in vivo.