STUDIES ON GLOEOSPORIUM MUSARUM CKE. & MASSEE CAUSING STORAGE ROTS OF JAMAICAN BANANAS

A form of anthracnose, caused by Gloeosporium musarum Cke. & Massee, is responsible for appreciable wastage of Jamaican Lacatan bananas. Symptoms are often evident on immature fruit after 8–10 days storage in refrigerated ships' holds. On green fruit, lesions are characteristically lenticular, having a slightly sunken, dark centre and an orange-yellow border: they rapidly increase in size as the fruits approach maturity. The fungus readily infects small scratches on the skin and, in inoculation experiments, resulted in the development of lenticular lesions after 8–10 days storage at 55° F. Many observations suggest that naturally occurring infections often originate at small abrasions acquired during handling of fruit.
On the basis of histological findings, it is proposed to refer to lenticular lesions as 'non-latent anthracnose', thus distinguishing this form of infection from the 'latent' type described by earlier workers.
In several experiments the antifungal antibiotic nystatin, applied as a post-inoculation fruit-dip at concentrations of 200 and 400 p.p.m., effected good control of wound-infection by G. musarum. Percentage control was inversely related to the incubation period between inoculation and treatment, there being little or no control with periods exceeding about 30 hr.     

STUDIES ON GLOEOSPORIUM MUSARUM CKE. & MASSEE CAUSING STORAGE ROTS OF JAMAICAN BANANAS

Gloeosporium musarum Cke. & Massee is the most important fungus associated with finger-stalk rot of Jamaican Lacatan bananas, Fusarium spp. being of minor importance. Sodium salicylanilide (Shirlan WS), at concentrations of 0.5, 1.0 and 1.5%, provided approximately 30, 50 and 65% control, respectively, when inoculated fruit was dipped for 1 min. in the compound: severe phytotoxic effects were caused by all concentrations. When Shirlan WS treatment was followed by rinsing in water, there were no phytotoxic effects and approximately 15, 35 and 40% control of finger-stalk rot, respectively, was obtained. 1.0 and 1.5% Shirlan WS also effected good control of anthracnose ( G. musarum ), both with and without post-treatment washing.
Moderate to poor control of Gloeosporium rot was obtained when Shirlan WS/washing treatment was delayed for more than 24 hr. after inoculation. A 2 min. immersion period in Shirlan WS was more effective than shorter periods: a momentary dip was ineffective.
The antibiotic nystatin (200 and 400 p.p.m.) had no significant effect on the incidence of finger-stalk rot: also, the severity of main-stalk rot was not reduced appreciably.
Practical considerations arising from the possibility of commercial-scale treatment with Shirlan WS are discussed.     

Interaction of post harvest disease control treatments and gamma irradiation on mangoes

The effects of gamma irradiation and disease control treatments on disease severity and post harvest quality of several mango cultivars were investigated.
In mangoes cv. Kensington Pride, irradiation doses ranging from 300–1200 Gy reduced disease, but the level of control was not commercially acceptable. Hot benomyl immediately followed by irradiation provided effective control of anthracnose (Colletotrichum gloeosporioides) and stem end rot (Dothiorella dominicana) during short-term storage (15 days at 20°C). The effects of the two treatments were additive.
Satisfactory disease control was achieved during long term controlled atmosphere storage when mangoes were treated with hot benomyl followed by prochloraz and then irradiated. Effects of fungicide treatment and irradiation were additive. Fungicide, or irradiation treatments alone, were unsatisfactory.
Irradiation of cv. Kensington Pride at doses in excess of 600 Gy caused unacceptable surface damage (i.e. lenticel spotting, surface discolouration and retardation of degreening) which was particularly severe after long-term controlled atmosphere storage.
In a separate short-term storage trial, several other mango cultivars were assessed. Hot benomyl followed by prochloraz controlled anthracnose on all cultivars and stem end rot on some. Irradiation at 600 Gy contributed only minor improvements to disease control. The severity of surface damage that developed following irradiation and fungicide treatment varied with cultivars.     

THE ROTTING OF APPLES BY GLOEOSPORIUM PERENNANS ZELLER & CHILDS

The extent of rotting of commercially stored Cox's Orange Pippin apples by Gloeosporium species has been severe in recent years. G. perennans has been found to be mainly responsible.
Tree infections of this fungus have usually been found to be prevalent in the orchards on farms where storage losses of fruit have occurred, and conidia of G. perennans have been found on cankers at all seasons during the year. Winter as well as summer pruning cuts have been found to become infected. Detached leaves of Cox's Orange Pippin have been successfully inoculated with G. perennans in the laboratory and the fungus has also been found on dead detached leaves in the orchard after picking time. Considerable variations have been found in the susceptibility to rotting of samples of different varieties of apple and samples of Cox's Orange Pippin apples from different orchards. Periodic loading of fruit with spores after picking has shown that resistance declines with length of storage. Wide variation in the time at which rotting commences in commercially stored samples has been observed. A series of inoculations on picked and unpicked immature fruit has shown that the apple loses its resistance to attack on picking. Lenticels which are impermeable to gaseous exchange have been shown to be resistant to penetration by the fungus. Temperature affects the development of lenticel rotting by G. perennans , infection being most rapid at temperatures of about 20°. Rotting can occur at 0° C.     

Heat treatment of ripening apples: Differential effects on physiology and biochemistry

Apples ( Malus domestica Borkh.) were heated for 4 days at 38°C immediately after harvest and then placed at 20°C for 7–10 days. Protein synthesis, ethylene production and fruit softening were reversibly inhibited by the heat treatment. Fruit respiration, membrane permeability and chlorophyll degradation in the fruit peel were enhanced during the treatment. The heat-treated apples ripened normally but more slowly than untreated apple We hypothesize that heat treatment differentially affects processes which normally increase simultaneously during fruit ripening, by inhibiting those processes which require tie novo protein synthesis and enhancing those that do not.     

Storage of 'Gloster 69' apples in the preclimacteric state for up to 200 days after harvest

'Gloster 69' apples are unusual because they do not accumulate ethylene during storage at 2 kPa O₂ at 1.5–3.5°C with continuous ethylene removal. Their ethylene physiology and the extent of various ripening processes in storage were investigated. Ethylene production and l-aminocyclopropane-l-carboxylic acid (ACC) remained low for up to 200 days, and both increased on transfer of fruit to 15°C. The increase in ACC could be stimulated by ethylene treatment of apples after storage. In spite of this evidence that fruit remained preclimacteric, some softening and production of soluble pectin and volatile esters occurred at 3.5°C. These processes were suppressed at 1.5°C, but chlorophyll, starch, malate and sucrose losses and increases in glucose and fructose occurred at both temperatures.     

Remobilization of fructans in Phippsia algida during rapid inflorescence development

Plants of Phippsia algida (Sol.) R. Br. were cultivated in short days (SD; 8 h summer daylight) and in long days (LD; 8 h summer daylight + 16 h low irradiance extension of 5 μmol m⁻² s⁻¹) at 9, 15, and 21°C. In this plant, inflorescence primordia are initiated in both LD and SD, but LD are required for heading and inflorescence development (Heide, O.M.; Physiol. Plant. 85: 606–610. 1992). Total dry matter production was slightly increased by LD over SD at 9°C, while it was little affected by daylength at 15 and 21°C. Phippsia algida contained mainly fructans with a low degree of polymerization, largely of the kestose series. After 29 to 42 days (depending on the temperatature) of photoperiodic treatment, fructans constituted 15–20 percent of dry mass of SD-grown plants compared with only 2–3 percent of dry mass for LD-grown flowering plants. There was no difference due to photoperiod in levels of mono- and disaccharides. Shifting the SD-grown plants to LD conditions resulted in rapid inflorescence development, accompanied by a parallel rapid decrease in the fructan level, while the level of mono- and disaccharides remained constant. The results show that fructans are important as storage carbohydrates in the late snow-bed species P. algida that normally requires several growing seasons for completing its life cycle. Exhaustion of this storage pool during the extremely fast flower and fruit development constitutes an essential part of the plants adaption to a very short growing season.     

Model experiments to establish behaviour of Yersinia enterocolitica O:9 strains in various types of fresh dry sausage

In model experiments different kinds of raw sausages were inoculated with liquid cultures of virulent-plasmid-carrying clinical Yersinia (Y.) enterocolitica (e.) strains of the O:9 serotype, doses being between 10⁴ and 10⁵ cfu g^-1. The sausage samples were stored at 3–5° and 13–16°C. During the first 10 d of storage the Y.e. plate count was detected with Desoxycholate-Citrate-Lactose-Sucrose Agar every day, later on in addition to it with phosphate buffer-enrichment and with enrichment according to Schiemann (1982) in intervals of several days' duration. The pH and a _w values, the contents of salt and water were detected. The multitude of complexly acting factors and substances prevents obviously the proliferation of Y.e. in fresh dry sausages. Decay dynamics of Y.e. were found to be considerably affected by storage temperature. Cold storage, basically, had a conservation effect and thus delayed the dying process of model strains. Yersinia enterocolitica -contaminated fresh dry sausage may cause potential danger to consumers, because of relatively extended survival periods of the pathogen. Therefore, manufacturers are expected to observe most stringent hygienic rules of Good Manufacturing Practice.     

Effect of short-term preservation of sea lamprey gametes on fertilisation rate and embryo survival

We assessed the effect of short-term (4.7–75.3 h) storage at low temperature (approximately 1 °C) on the viability of sea lamprey ( Petromyzon marinus L.) gametes. Hatching success decreased with storage time, but more than 20% eggs hatched even after 75.3 h of preservation. However, storage time drastically reduced the survival rate to the burrowing stage (i.e. the last prelarval stage), which decreased from 76% when the gametes were stored for 4.7 h to 0% after 75.3 h of storage.     

Changes during low-oxygen storage in the effects of ethylene on induction of ethylene synthesis and stimulation of respiration of 'Gloster 69' apples

The ability of ethylene to stimulate respiration and advance the onset of rapid ethylene production was investigated at different times during storage of 'Gloster 69' apples in 2 kPa O₂ at 1.5–3.5°C. Ethylene stimulated respiration in apples at 15°C immediately after harvest; maximal rates were recorded at 10–1000 μl I⁻¹ but attainment of these rates was delayed after low O₂ storage until day 3 of treatment at 15°C. The onset of rapid ethylene production at 15°C occurred later in non-ethylene-treated apples after storage than after harvest. Ethylene production was induced in some apples during ethylene treatment for 3 or 6 days; in others it was induced about 20 days after treatment, but a proportion of the fruit showed no induction in the 45-day duration of experiments. An ethylene treatment at 10 μl I⁻¹ led to a near maximal increase in the frequency of induction of ethylene production at all times. After storage apples were mainly induced during treatment or not induced, whereas after harvest induction after treatment was more frequent. The presence of 2000 μl l⁻¹ norbornadiene during ethylene treatment inhibited the stimulation of respiration and the induction of ethylene production; this inhibition was only partly reversed by ethylene at 1000 μl l⁻¹ the experiments suggest that receptors for ethylene were present at all stages but that response capacity changed during storage.     

Chemical and Microbiological Changes during Storage of Vacuum Packed Sliced Bacon

Summary: The micro-ecology of block cured, sliced, vacuum packed bacon has been studied during storage at 20 and 30°; high salt (8–12% NaCl, based on the aqueous phase) and low salt (5–7% NaCl) bacon were used. The dominant flora of all samples during the first 9 days' storage comprised catalase positive cocci. They persisted in the high salt bacon but, under lower salt conditions, group D streptococci and motile lactic acid bacteria became dominant.
Of the chemical changes studied, proteolysis, lipolysis and reduction of nitrate and nitrite were due largely to coagulase negative subgroup II staphylococci. Micrococci which predominated at 20° were capable of reducing nitrate to nitrite but of only slightly increasing free amino or fatty acids.
Inoculation of low count bacon with subgroup II staphylococci confirmed that this group was responsible for putrefaction in low salt bacon stored at temperatures above 20°. Similarly micrococci which tend to delay spoilage did not contribute much to the off odours and it was thought that the heterofermentative catalase negative organisms could contribute to typical sour spoilage.     

Sensitivity of wild and genetic sexing strain Ceratitis capitata to high-temperature disinfestation of Valencia oranges

Abstract:  The purpose of this research was to investigate post-harvest heat treatment of Valencia oranges as an effective disinfestation protocol (fast, no fruit damage) for the Mediterranean fruit fly Ceratitis capitata (Wiedemann). Forced high-temperature air was applied under the following conditions: (a) exposure to air temperature of 56°C, for fast increase of temperature in the interior of the fruit, (b) reduction in air temperature to 47°C when the fruit centre reached 47°C and (c) maintenance of fruits in the chamber for another 30 min. Relative humidity in the treatment chamber was kept between 50% and 65% during treatment. Forced air at 47°C applied for 30 min on eggs before hatch or late third instar larvae (the most heat-tolerant stages) resulted in complete kill. Egg and larval sensitivity to high temperature differed between a wild strain and a laboratory genetic-sexing strain based on white pupa mutation. In this strain males emerge from brown pupae and females from white pupae. In particular, mature eggs from the wild strain were significantly more temperature resistant than eggs from the laboratory strain. Exposure of Valencia oranges of a diameter of 7–7.5 cm to 56°C forced air for about 86 and 99 min was required to increase temperature to 47°C at 1.5 cm depth and the fruit centre respectively. Treated oranges showed no substantial peel or interior deterioration, or change in colour and taste when kept at 25°C and 50–60% RH for a period of up to 1 month following treatment. Treatment in 1% O₂ atmosphere, produced by flushing of CO₂ into the treatment chamber, resulted in about 1°C reduction in killing temperature and faster increase in temperature inside the fruit to a lethal level.     

Factors affecting the activity of alatae of the aphids Myzus persicae (Sulzer) and Brevicoryne brassicae (L.)

Apparatus was designed for testing the frequency of flights of aphids under different conditions of temperature, relative humidity, light and pressure. Young aphids (1–4 days after metamorphosis) flew more often and showed less individual variability than older ones; with all ages activity increased for the first few hours under experimental conditions. Starving increased activity for the first 1–2 hr. Aphids used in experiments on a second day flew less frequently than controls which had remained on the plant the first day. Alate B. brassicae were more active than M. persicae : both species showed alternating periods of activity and quiescence.
At light intensities between 100 and 1000 f.c. there was little difference in flight frequency, but below 100 f.c. activity declined rapidly and apparently ceased with darkness.
Changes in relative humidity temporarily affected flight frequency, a change to a higher humidity retarding, a change to a lower increasing it. After adjusting to the change aphids flew readily at all humidities tested between 50 and 100% with temperatures below 80° F. (26.7°C.). The combination of high humidity and high temperature (90°F. = 32·2°C.) sometimes inhibited flight.
Changes of pressure often increased activity temporarily and flight frequency was greater under fluctuating pressure than under constant pressure.
It is concluded that changes in microclimate in crops are adequate to influence frequency of flight of aphids and consequently the spread of virus diseases.     

温度和气体成分对冬枣果实贮藏期间品质的影响

主要探讨冬枣(Ziziphus jujuba Mill.cv Dongzao)在-1℃的动态气调(CA-Ⅰ,70%O2 0%CO2处理7天,然后转入5%O2 0%CO2中)、普通气调(CA-Ⅱ,5%O2 0%CO2;CA-Ⅲ,10%O2 0%CO2)及普通冷藏和常温(25℃)等条件下,果实发病率、色素、可溶性固形物、可滴定酸、乙醇和乙酸乙酯含量等的变化.结果表明:与普通冷藏相比,气调贮藏能减缓果实的腐烂,抑制色素的分解和减少果肉中乙醇、乙酸乙酯的含量.动态高氧处理能有效地保持果实的颜色,抑制色素降解及果皮褐变.CA-Ⅲ(10%O2 0%CO2)能有效地减少果肉乙醇的含量而CA-Ⅱ(5%O2 0%CO2)能有效地减少果肉乙酸乙酯的含量.气调贮藏的果实可滴定酸及可溶性固形物含量与其他处理的果实没有明显的差异.     

The control of postharvest decay in table grapes using acetaldehyde vapours

Grapes ( Vitis vinifera L. cv. 'Sultanina') harvested at the end of the 1985–1988 seasons, received postharvest application of acetaldehyde (AA) vapours for 24–40 h. Treatment with AA vapour at 20 °C or 0 °C reduced significantly the decay caused by several fungi: Botrytis cinerea, Rhizopus stolonifer, Aspergillus niger and Alternaria alternata . In grapes treated with 0.5% AA for 24 h, no R. stolonifer was found after 8 days of storage at 20 °C. Treatment with 0.25% AA vapour for 40 h of grapes cv. 'Perlette' inoculated with R. stolonifer reduced the decay by 89%.     

Induction of Enzymes and Phenolic Compounds Related to the Natural Defence Response of Netted Melon Fruit by a Bio-elicitor

Fungal disease in netted melon fruit is an important factor affecting their postharvest quality and therefore an important cause of large economic losses around the world. Among the alternatives to control fungal diseases, the induction of the natural defence response (NDR) in fruits is promising. The objective of this study was to induce the NDR in netted melon treated with a bio-elicitor formulated from Fusarium oxysporum growth in a potato dextrose agar enriched with netted melon skin. Netted melon fruits (cv 'Primo') were not treated (C), untreated and inoculated with F. oxysporum (IN), treated with a bio-elicitor (FES), or treated with the bio-elicitor and inoculated (FES + IN). After treatments, fruits were stored for 8 days at 20°C with 90–92% relative humidity. Melon was sampled every 2 days at 20°C to evaluate the development of Fusarium rot symptoms as disease index percentage (DI), changes in phenolic compounds, changes in phenylalanine ammonia-lyase (PAL) activity, chitinase activity (ChA) and β-1,3-glucanase activity (GA). It was found that DI in netted melon fruit was significantly reduced in the FES + IN as compared with the IN treatment. FES + IN and FES treatments showed the highest increase of phenolic acids. Higher levels of PAL activity were observed in the treatments IN, FES, and FES + IN with respect to C, after 4 days of storage. A large increase in ChA activity was observed in the treatments IN, FES and FES + IN after 6 days of storage. No differences in GA activity were found among FES, FES + IN and C treatments throughout storage. IN treatment showed the highest increase in GA activity after 4 days of storage. It is concluded that the bio-elicitor activates the NDR as measured by the increase in phenolic acids synthesis, PAL and ChA enzymes activity, in a similar way as the infection by the living pathogen.     

Study of pectin esterase and changes in pectin methylation during normal and abnormal peach ripening

Peach fruit ( Prunus persica cv. Hermosa) were allowed to ripen immediately after harvest or after 30 days of 0°C storage. The fruits lost 75–80% of their firmness after 5 days at 20°C. During ripening after harvest there was a loss of both uronic acid and methyl groups from the cell wall. Cell wall labelling with JIM 7, a monoclonal antibody which recognized pectins with a high degree of methylation, was lower in ripe fruits than in freshly harvested fruits. However, ripe fruit cell walls did not cross-react with JIM 5, which recognizes pectins with low methylation. During storage, de-methylation occurred and in fruit ripened after storage there was little further change in pectin methylation or pectin content in the cell walls. The labelling of stored or stored plus ripened cell walls with JIM 7 was similar, but the cell walls of fruit ripened after storage showed some low cross-reactivity with JIM 5. The in vitro activity and mRNA abundance of pectin esterase (EC 3.1.1.11) was not correlated with the amount of de-esterification as measured chemically or by immuno-labelling in the cell walls. Eighty percent of the fruits which ripened after storage developed a woolly texture. It is suggested that woolliness is due to de-esterification of pectins, not accompanied by depolymerization, which leads to the formation of a gel-like structure in the cell wall.     

Effect of time and temperature on toxicity of insecticides to insects

The effects of a change in temperature (15–28° C.) on the toxicity of dilute suspensions of DDT to larvae of Aédes aegypti L., as assessed by a photomigration method, depended on the stage of the test during which the temperature was changed. Increase in temperature during exposure to DDT (0.02 p.p.m. for about 1 hr.) increased the toxic action. When larvae were left in the suspensions for the duration of the test (3 hr.-4 days), increase in temperature throughout the test decreased the toxic action of a very low concentration of DDT (0.002 p.p.m.), but had no effect with higher concentrations (0.1–0.2 p.p.m.). Toxic action was greater in larvae held at a low temperature than in larvae held at a high temperature after treatment (0.025 p.p.m. for 3 hr.). Such toxic action was reversible: a change from high to low temperature increased paralysis, and larvae, paralysed at a low temperature, recovered when the temperature was raised.     

Changes in the ovaries of olive flies (Dacus oleae (Gmelin)) during the summer, and their relationship to temperature, humidity and fruit availability

Abstract. 1. Examination of the ovaries of female olive flies ( Dacus oleae ) from wild populations on Corfu during the summer months of 1975 indicated that all were non-gravid for a period of several weeks during June and July and the terminal follicles were resorbed.
2. Experiments in outdoor cages indicated that olive fruits could stimulate ovarian development during the summer months.
3. Experiments in constant temperature cabinets indicated that high temperatures (i. e. 26–29°C) in conjunction with a low humidity (45 ± 5°%) inhibited ovarian maturation.
4. Whereas the presence of olive fruits offset the effects of temperature and humidity on ovarian development at 26°C in all flies, at 29°C very few were able to mature their ovaries.
5. It is suggested that it is the interaction of temperature, humidity and access to fruit which determine when ovarian maturation ceases and recommences during the summer months.     

Cloning of cDNAs encoding cell-wall hydrolases from pear (Pyrus communis) fruit and their involvement in fruit softening and development of melting texture

'La France' pear ( Pyrus communis L.) fruit stored at 1°C for 1 month (short-term storage) before transfer to 20°C softened and developed a melting texture during ripening, whereas fruit stored for 5 months (long-term storage) before transfer to 20°C softened but did not develop a melting texture. To clarify the mechanisms involved in fruit softening and textural changes, the cDNAs encoding cell-wall hydrolases were isolated by RT-PCR, and their expression and localization were investigated in 'La France' pears. Genes encoding three polygalacturonases (PG; EC 3.2.1.15), four pectin methylesterases (PME; EC 3.1.1.11), one α -arabinofuranosidase (ARF; EC 3.2.1.55), three β -galactosidases (GAL; EC 3.2.1.23), and two endo-1,4- β - d -glucanases (Cel; EC 3.2.1.4) were isolated. Among these 13 isolated genes, PcPG1 was the only gene for which the mRNA expression levels increased in both the short- and long-term stored fruits. This suggested that PcPG1 is involved in fruit softening rather than in the development of the melting texture. In contrast, the expression levels of PcPG3 , PcPME1 , PcPME2 , PcPME3 , PcGAL1 , PcGAL2 , and PcCel2 increased during ripening only in the short-term stored fruit. These genes might thus be involved in the development of the melting texture.