Overwintering of Sphaerotheca mors-uvae on black currant and gooseberry

The ability of Sphaerotheca mors-uvae to perennate as cleistocarps, and as mycelium in buds was examined during the winters of 1965-6, 1966-7 and 1967-8 in relation to its two principal hosts, gooseberry and black currant. Cleistocarps on black currant leaves were examined from August 1965 to April 1966 and from July 1966 to March 1967. In 1965 cleistocarps were first observed on the leaves on 5 August; in 1966 on 11 July. These continued to develop through August and September and by October approximately 70% contained well-defined ascospores. The ascospore content remained generally at this level until February 1966 and November 1966; then the numbers of cleistocarps with ascospores fell and by April 1966 and March 1967 few such cleistocarps remained. From 21 March 1966 and 15 February 1967, but not otherwise, discharge of ascospores from the overwintered cleistocarps was readily obtained in laboratory tests. The viability and infectivity of the ascospores was demonstrated by allowing them to discharge on to leaf discs of black currant in the laboratory and also on to leaf discs and plants in the field. Sporulating colonies of S. mors-uvae developed within 8 days. Cleistocarps from shoots of black currant were examined from 4 August 1966 to 9 March 1967, and from 27 July 1967 to 1 January 1968. They developed in a similar manner to those on black currant leaves and by September in both 1966 and 1967 over 60% contained ascospores. This level was not maintained; the number of cleistocarps with ascospores fell gradually and by 8 December 1966 and 1 January 1968 few remained. Only in one laboratory test (21 November 1967) were ascospores discharged from a sample of these cleistocarps. Cleistocarps from shoots of gooseberry were examined from July 1966 to March 1967, and from August 1967 to January 1968. The pattern of ascospore development and subsequent decline in number of cleistocarps with ascospores was similar to that observed for black currant shoots. No discharge of ascospores could be demonstrated in laboratory tests. Evidence that S. mors-uvae perennates in buds of gooseberry was obtained by dissecting buds and by inducing buds on surface-sterilized shoots to burst under conditions which precluded chance infection. Field observations also suggested that bud infection occurred on gooseberry. Similar experiments failed to demonstrate the fungus in buds of black currant, and there was no indication of bud infection of this host in the field.     

Transference of resistance to black-currant gall mite, Cecidophyopsis ribis, from gooseberry to black currant

Field and insectary tests confirmed that the black-currant gall mite (Cecidophyopsis ribis) is unable to survive on gooseberry and red currant. A dominant gene Ce, controlling resistance to the gall mite, has been transferred from gooseberry to black currant. Resistant, large-fruited, self-fertile black currants of commercial potential have been obtained in the third backcross. One accession of Ribes bracteosum and three of R. americanum proved field susceptible to the gall mite, but twenty-four accessions of other Ribes species remained free from galled buds for at least 3 years in an infection plot.     

Evaluation of a modified encapsulation-dehydration procedure incorporating sucrose pretreatments for the cryopreservation of <Emphasis Type="Italic">Ribes</Emphasis> germplasm

Summary A modified encapsulation-dehydration cryopreservation protocol based on the replacement of cold acclimation with high-sucrose pretreatment was assessed for the long-term storage of Ribes germplasm. Four steps in the procedure were examined for eight genotypes: (1) pregrowth of shoot tips in sucrose-supplemented solid growth medium for 1 wk; (2) pretreatment of alginate-encapsulated shoot tips in sucrose-supplemented liquid culture medium for 21 h; (3) evaporative desiccation of encapsulated-dehydrated shoot tips; and (4) exposure to liquid nitrogen (LN). Differential responses were observed for black currant and gooseberry genotypes. Recovery of growing shoots was high (72–100%) at all four steps for the five black currants tested. Evaporative desiccation slightly decreased viability for some black currants and in some cases LN exposure reduced regrowth. In contrast, three gooseberry species had poor recovery from the initial sucrose culture step (32–67%), indicating sensitivity to osmotic stress, which predisposed these genotypes to poor survival after LN exposure (12–26%). The effectiveness of the modified protocol for conserving a wider range of Ribes genotypes was further ascertained by screening 22 genotypes derived from nine Ribes species. The procedure was successful for 18 of the 22 genotypes in the gene bank in Scotland. Screening genotype responses at the time of storage demonstrated regrowth ≥60% for 15 genotypes, and only four genotypes had regrowth of 0–28%. Additional genotypes were also added to the USDA cryopreserved Ribes collection.     

Long-term preservation of Neozygites tanajoae (Entomophthorales: Neozygitaceae) in cadavers of Mononychellus tanajoae (Acari: Tetranychidae)

To determine the effect of storage on fungal survival, mummified cadavers of the cassava green mite pathogen, Neozygites tanajoae were placed at different conditions of temperature and relative humidity. The best condition for long-term preservation was ?10°C. At this condition, the fungus retained viability for 10 years when the experiment was terminated, with a decrease in sporulation with time. Cadavers placed at 4°C and 5% RH sporulated for 2 years, while the fungus survived for only 7 days at 25°C and 50% RH.     

Effect of different eriophyid and tetranychid mango mite species on development,longevity, fecundity and predation of Typhlodromus mangiferus Zaher and El-Brolossy (Acari: Phytoseiidae)

Effects on development, longevity, fecundity and predation of the predatory phytoseiid mite Typhlodromus mangiferus Zaher and El-Brolossy were studied in the laboratory at different temperatures and relative humidities using four prey mite species: the motile stages of the eriophyid mango bud mite Aceria mangiferae Sayed, the eriophyid leaf coating and webbing mite Cisaberoptus kenyae Keifer, the eriophyid mango rust mite Metaculus mangiferae (Attiah) and nymphs of the tetranychid mango red mite Oligonychus mangiferus (Rahman and Sabra). The increase of different temperatures and decrease of relative humidities from 25°C and 60% to 30°C and 55% and 35°C and 50% shortened development and increased reproduction and prey consumption. The developmental durations were almost similar when the predator was fed on eriophyids compared to that on tetranychid. The maximum reproduction (2.70, 2.08, 1.97 and 1.66 eggs/ ♀ /day) was recorded at the highest temperature and the lowest relative humidity, while the minimum reproduction (1.7, 1.54, 1.53, and 1.06 eggs/ ♀ /day) was noted at the lowest temperature and highest relative humidity with all mango prey species. Life table parameters indicated that feeding of T. mangiferus on A. mangiferae led to the highest reproduction rate (rm = 0.204 and 0.139 females/female/day), while feeding on O. mangiferus gave the lowest reproduction rate (rm = 0.137 and 0.116) at 35°C and 50% relative humidity and 25°C and 60% relative humidity, respectively. T. mangiferus seems to be a voracious predator of both mango eriophyid and tetranychid mites. The adult female daily consumed about 127 A. mangiferae, 97 C. kenyae, 86 M. mangiferae, and 18 O. mangiferus at 35°C and 50% relative humidity, while it devoured only 99.81, 86, 81, and 15 individuals, respectively at 25°C and 60% relative humidity. The present study revealed that each injurious mite is thought to be profitable prey species to T. mangiferus as a facultative predator.     

Response of Callosobruchus maculatus (F.) to varying temperature and relative humidity under laboratory conditions

The effect of temperature and relative humidity were determined on the development of Callosobruchus maculatus (F.) on stored bean (Vigna unguiculata) seeds exposed to five temperatures (20, 25, 30, 35 and 40 °C) and six relative humidity levels (40, 50, 60, 70, 80 and 90%). Oviposition and total adult progeny responded in a curvilinear pattern to temperature and relative humidity while developmental period presented a linear response. Egg laying (117.33 ± 3.21) and adult emergence (35.00 ± 1.70) were least at 20 °C and 90% R.H. but those showed the optimal values at 30 °C and 70% R.H. The implication of these findings is that the growth attributes of C. maculatus relate with the weather variables studied in a curvilinear manner and thus quadratic equations generated could be used for the prediction of optimum temperature and relative humidity in a given area for the management of C. maculatus in stored beans.     

Breeding for resistance to American gooseberry mildew, Sphaerotheca mors-uvae, in the gooseberry (Ribes grossularia)

Strong resistance to American gooseberry mildew (Sphaerotheca mors-uvae) occurred in eight out of ten F₁ progenies from crosses of resistant North American Eugrossularia species with European gooseberry cultivars or seedlings. Bimodal segregations in four of these F₁'s and in one F₁ derived from the wild European Ribes grossularia uva-crispa suggested that each donor carried a major dominant resistance gene. Such a gene, Sph₁ was identified in a first backcross from R. oxyacanthoides. Accessions of R. oxyacanthoides, R. leptanthum and R. watsonianum proved the most promising donors of resistance to mildew and leaf spot (Pseudopeziza ribis).     

The resistance to Oidium lycopersici conferred by ol-2 gene in tomato

The powdery mildew caused by Oidium lycopersici is one of the most destructive diseases in glass-house-grown tomato and is widespreading all over the world. A high level of resistance to O. lycopersici was found in an accession of Lycopersicon esculentum var. cerasiforme at the Department of Biology and Plant Pathology, University of Bari. The genetic analysis of F1, F2 and BC plants indicated that the resistance is conferred by a single recessive gene, designed as ol-2. Studies on the infection process of O. lycopersici on susceptible and ol-2 gene resistant tomatoes were carried out at 24 °C and 90 % relative humidity. Light microscope observations on conidia germination, formation of primary appressoria, elongation of hyphae and sporulation were made on artificially inoculated basal, intermediate and apical leaves. Inoculation was made by shaking mildewed tomato leaves over each test plant. Disease development were assessed by removing the fungal structure from the leaf surface with the ceroidin film technique and by direct observations of stained inoculated leaves. The rate of conidial germination and the appressoria formation was not affected by host genotype. Mycelia growth and sporulation on leaf surface of resistant plant was strongly restricted and influenced by the leaf age. The results indicated that the resistance in ol-2 tomato is postinfectional and is not associated with a hypersensitive response. This work was supported by the MURST and CNR (Paper no. 331)     

Effects of environmental factors on growth of lesions on field bean leaves infected by Botrytis fabae

Chocolate spot lesions increased in size only slowly when the relative humidity of the air was below 66%. Following a lag phase immediately after infection the rate of increase was linear and proportional to humidity between c. 70% and 100% r.h. Lesions on leaflets kept at 70% r.h. for 8 h and at 100% r.h. for 16 h/day increased in size at only 27% of the rate of those at continuous 100% r.h. The optimum temperature for lesion growth was between 15 and 22 °C, the minimum <4 °C and the maximum c. 30 °C. Humidity did not interact with temperature between 10 and 20 °C. Neither light intensity nor a film of water over the leaves affected lesion growth. These findings are discussed in relation to meteorological data and field observations. The possible mechanisms whereby humidity affects lesion growth did not appear to be related to CO₂ and O₂ concentrations nor to the overall water potential of the leaf. Preliminary evidence is presented for the production of phytotoxins within lesions.     

Sporulation,storage and infectivity of obligate aphid pathogen Pandora nouryi grown on novel granules of broomcorn millet and polymer gel

Aims: Producing granular cultures of obligate aphid pathogen Pandora nouryi for improved sporulation and storage. Methods and Results: Small millet–gel granules were made of the mixtures of 80–95% millet powder with 5–20% polymer gel (polyacrylamide, polyacrylate or acrylate‐acrylamide copolymer) and inoculated with mycelia at 30 mg biomass g^?1 dry granules plus 87·5% water, followed by static incubation at 20°C for 4–12 days. The fungus grew well on 12 preparations but best on that including 10% copolymer. An 8‐day culture of this preparation discharged maximally 58·5 × 10⁴ conidia mg^?1 granule at 100% RH and was capable of ejecting conidia at the nonsaturated regimes of 86–97% RH. During storage at 6°C, granular cultures with >85% water content had twofold longevity (120 days) and half‐decline period (34–36 days) of those stored at room temperature. The steadily high water content preserved the cultures better than that decreasing at 6°C. However, conidia from 70‐day‐stored granules were less infective to Myzus persicae nymphs than those from fresh ones based on their LC₅₀s. Conclusions: The millet–gel granules had higher sporulation capacity than reported Pandora cultures and a capability of spore discharge at nonsaturated humidity. Significance and Impact of the Study: The granular cultures are more useful for aphid control.     

Climatic factors influencing spore production in Alternaria brassicae and Alternaria brassicicola

Sporulation in A. brassicae and A. brassicicola on naturally-infected leaf discs of oilseed rape and cabbage required humidities equal to or higher than 91.5% and 87% r.h. respectively. The optimum temperatures for sporulation were 18–24°C for A. brassicae and 20–30°C for A. brassicicola at which temperatures both fungi produced spores in 12–14 h. Above 24°C sporulation in A. brassicae was inhibited. At sub-optimal temperatures sporulation times for A. brassicicola were significantly longer than for A. brassicae with the differences increasing with decrease in temperature. Interrupting a 16-h wet period at 20°C with a period of 2 h at 70% or 80% r.h. did not affect sporulation in either fungus but a dry interruption of 3–4 h inhibited sporulation in both. Exposure of both fungi to alternating wet (18 h at 100% r.h., 20°C) and dry periods (6 or 30 h at 5565% r.h., 20°C) did not affect the concentration of spores produced in each wet period. Sporulation times were not affected by either the host type of the age of the host tissue. White light (136 W/m²) inhibited sporulation in A. brassicae with the degree of inhibition increasing with increasing light intensity. The effect of light on sporulation in A. brassicicola was not tested.     

Interactions of Adult Stoneflies (Plecoptera) with Riparian Zones I. Effects of Air Temperature and Humidity on Longevity

The effects of constant air temperature and relative humidity on the longevity of three species of gripopterygid stonefly adults from New Zealand were investigated in laboratory experiments, and the results were compared to field measurements of air temperature and humidity obtained during summer. Greatest longevity for Zelandobius furcillatus, Zelandoperla decorata and Acroperla trivacuata was recorded in cool humid conditions (10°C, 100% humidity) for adults fed water and a 5% sucrose solution. Absence of feeding reduced survival by 37–73% at 17°C and 100% humidity. Survival decreased significantly with increasing constant air temperature (10, 17 and 25°C) and decreasing mean relative humidity (100, 81 and 15%). Males survived significantly longer than females in all temperature treatments for Z. furcillatus, but longevity was not influenced by gender in other species or in the humidity experiments. Interpolated LT 50 values over 96 h for female stoneflies in the temperature treatments averaged of 22–23°C. Field measurements at near-ground level and 1.5 m above the streambank during summer indicated that these air temperatures were exceeded for 25% of the time in a pasture catchment compared to &lt;0.1% of the time in a native forest catchment. These findings implicate air temperature as a factor potentially influencing the longevity of adult stoneflies, and suggest that maintenance of appropriate microclimate conditions should be a consideration in riparian management.     

Comparative longevity of Australian orchid (Orchidaceae) seeds under experimental and low temperature storage conditions

Seeds from ten terrestrial orchid species, nine from the south‐west Australian biodiversity hotspot (Caladenia arenicola, Caladenia flava, Caladenia huegelii, Diuris laxiflora, Microtis media ssp. media, Pterostylis recurva, Pterostylis sanguinea, Thelymitra crinita and Thelymitra macrophylla) and one from south‐east Australia (Diuris fragrantissima), were placed into experimental storage to assess their relative longevity and likely optimal conditions for long‐term conservation seed banking. Seeds from all species were desiccation tolerant, germinating after drying at 23% relative humidity (C. arenicola, C. huegelii, P. sanguinea and T. macrophylla) or 5% relative humidity (C. flava, D. laxiflora, M. media ssp. media, P. recurva and T. crinita) at 23 °C. From automatedly determined moisture adsorption and desorption isotherms at 23 °C, these equate to tolerance of drying to 0.03–0.06 g water g^?1 dry weight or 0.013–0.028 g water g^?1 dry weight, respectively. Results of storage experiments at a range of moisture contents and temperatures suggest conventional seed bank storage at ?18 °C after equilibration at c. 23% relative humidity (at 23 °C) may be suitable for most of the species, although there was higher germination of P. recurva seeds stored at ?80 °C and of M. media ssp. media seeds equilibrated at 75% relative humidity. However, there was considerable variation in germination of seeds sampled after different storage periods, making it difficult to identify optimal storage conditions definitively. Results of comparative longevity storage experiments at 60% relative humidity and 40 °C suggest seeds from these orchid species are short‐lived compared with non‐orchid species, and with Australian species in particular. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164 , 26–41.     

Epidemiology and prediction of brown leaf rust of mulberry caused by Peridiopsora mori

Brown leaf rust (BLR) caused by Peridiopsora mori is one of the major foliar diseases of mulberry (Morus sp.) in the subtropical hills of eastern India. The disease appeared in first week of August and continued up to September with maximum severity in second and third week of September. The disease symptoms appeared at atmospheric temperature (27.00–20.07°C), relative humidity (92.14–82.43%), rainfall (11.20 cm) and rainy days (7) of the preceding week. Disease severity (>50 PDI) was observed at temperature (26.29–19.29°C), relative humidity (94.14–80.14%), rainfall (4.12 cm) and number of rainy days (2–3 days). Apparent rate of infection was found high at temperature (27.00–19.83°C), relative humidity (94.67–85.00%), rainfall (4.6 cm) and rainy days (2) of the preceding week. The correlation coefficient between disease severity and average meteorological factors of the preceding 7 days revealed that BLR disease severity showed significant negative correlation with minimum temperature. It was also revealed that contribution of maximum and minimum temperature 42.23% and 35.21%, maximum and minimum relative humidity (RH) 11.23% and 10.69% and rainfall and number of rainy days 0.11% and 0.50%, respectively towards development of BLR disease severity. Multiple regression analysis revealed that average of maximum and minimum temperatures and minimum RH of preceding 7 days were found to maximally influence BLR disease severity.     

Fertility of the polyembryonic parasite Copidosoma koehleri, effect of humidities on life length and relative abundance as compared with that of Apanteles subandinus in potato tuber moth

Males and females of Copidosoma koehleri were kept separately in desiccators producing relative humidities of 20, 40 and 70% at 24 and 28°C and found to be very susceptible to low relative humidity. They lived less than 1 day at 20%, about 2 and 4 days at 40% and about six times longer than these respectively at 70% r.h. When kept at 26°C and 70% r.h. females of C. koehleri parasitised 98.8 hosts. The number of parasites that emerged from a male brood was 21.2 and from a female brood 33.2. Mated females produced 3026 progeny and unmated 2289. The sex ratio of broods produced by mated females was 1:1 and the female percentage among progeny was 59. It is known that C. koehleri is rare at the beginning of the potato-growing season and becomes the predominant parasite later on. It is known also that in potato crops when the plants are small at the beginning of the season the air within the crop is less humid but as the canopy of foliage develops, relative humidity rises and becomes higher than at 1.2 m above ground. It is suggested that relative humidity in the potato crop is the major factor affecting the relative abundance of C. koehleri and Apanteles subandinus in South Africa.     

Prediction of cotton leaf curl virus disease and its management through resistant germplasm and bio-products

Cotton leaf curl virus disease reduces the cotton yield significantly every year and is transmitted by Bemisia tabaci. The study was designed to evaluate 15 varieties/lines against the disease. Multiple regression analysis was performed based on a-biotic environmental variables (maximum air temperature, minimum air temperature, relative humidity and rainfall) to predict disease incidence and its vector (Bemisia tabaci). Two bio-products were evaluated against the whitefly population to control the disease. Out of 15 cotton varieties/lines, no one was found highly resistant against the disease. Five varieties/lines (BT BT-980, BT-457, KIRAN, BT-666 and SLH-BT-6) exhibited moderately resistant response. Maximum air temperature (34–35.5 °C), minimum temperature (25.75–26.25 °C), relative humidity (64.14–66%), rainfall (1–2 mm) and wind speed (5.50–5.75 Kmh^?1) favoured the disease development. Maximum whitefly population was favoured by maximum air temperature from 34–35.5 °C, 25.8–26.2 °C minimum air temperature, 64.14–66% relative humidity, 1–2 mm from rainfall and 5.50–5.75 Kmh^?1 wind speed. Datura stramonium was found more effective as compared to Aviara (Homoeopathic) but not from the positive control (Acetamiprid).     

Isolation and Characterization of a Temperature-sensitive Sporulation Mutant of Bacillus subtilis

Temperature-sensitive sporulation mutants were isolated spontaneously from Bacillus subtilis 168 TT by a sequential transfer method. A representative mutant strain, ts32, was characterized in detail. The mutant grew normally at 30°C and 42°C, but did not sporulate at 42°C. Electron microscopic observation and physiological analysis showed that the mutant was blocked at stage 0-1 of sporulation. Genetic analysis suggested that the mutation was located at the spo0B locus on the B. subtilis chromosome. Temperature-shift experiments clearly showed that the spo0B gene product functions only at the beginning of sporulation.     

Disease forecasting model for newly emerging bacterial seed and boll rot of cotton disease and its vector (Dysdercus cingulatus)

Bacterial seed and boll rot disease is a newly emerging threat to the cotton growers. Disease prediction model was devised to predict the disease progression impacted by the vector (Dysdercus cingulatus) and environmental variables (maximum air temperature, minimum air temperature, relative humidity and rainfall) on four varieties to minimise its losses and disease management cost. Impact of a-biotic environmental variables (maximum and minimum air temperature, relative humidity and rainfall) was assessed on bacterial seed and rot of cotton disease and its vector (D. cingulatus) on FH-941, FH-942, MNH-886 and FH-114 cotton varieties. Maximum red cotton bug population was assessed at 29–31 °C maximum temperature and at 15–17 °C minimum temperature. Disease severity was noticed maximum when maximum and minimum temperature was measured at 28–29 °C and 13–14.5 °C, respectively. Vector population was maximum when relative humidity and rainfall were 63–66% and 1.50–2.5 mm, respectively. Relative humidity at 66–68% and 0.5–1.5 mm rainfall favoured disease development. With increase in number of bugs, increase in disease severity was noted, maximum disease severity 45–48% noticed when 7–8 bugs were recorded. Red cotton bug (Dysdercus cingulatus) population prediction model was devised based on a-biotic factors (maximum and minimum air temperature, relative humidity and rainfall) on four cotton varieties. Disease forecasting model was developed based on biotic (D. cingulatus) and a-biotic factors. A close resemblance between observed and the predicted red cotton bugs and disease severity was seen.     

The biology of Peronospora viciae on pea: laboratory experiments on the effects of temperature, relative humidity and light on the production, germination and infectivity of sporangia

Germination of Peronospora viciae sporangia washed off infected leaves varied from 20% to 60%. Sporangia shaken off in the dry state gave 11–19% germination. Most sporangia lost viability within 3 days after being shed, though a few survived at least 5 days. Infected leaves could produce sporangia up to 6 weeks after infection, and sporulating lesions carried viable sporangia for 3 weeks. Sporangia germinated over the range 1–24 °C, with an optimum between 4 and 8 °C. Light and no effct. The temperature limits for infection were the same as for germination, but with an optimum between 12 and 20 °C. A minimum leaf-wetness period of 4h was required, and was independent of temperature over the range 4–24 °C. Maximum infectivity occurred after 6h leaf wetness at temperatures between 8 and 20 °C. Infection occurred equally in continuous light or in darkness. After an incubation period of 6–10 days sporangia were produced on infected leaves at temperatures between 4 and 24 °C, with an optimum of 12–20 °C. Exposure to temperatures of 20–24 °C for 10 days reduced subsequent sporulation. Sporangia produced at suboptimal temperatures were larger, and at 20 °C. smaller, than those produce at 12–16 °C. Viability was also reduced. No sporangia were produced in continuous light, or at relative humidities below 91%. For maximum sporulaiton an r.h. of 100% was required, following a lower r.h. during incubation. Oospores wre commonly formed in sporulating lesions, and also where conditons limited or prevented sporulation. The results are discussed briefly in relaiton to disease development under field conditions.     

Study on the factors affecting storage of edible aroids

The effects of temperature (15 °C, 25 °C, 30°C and 24–29°C), relative humidity (45%, 85% and 86–98%) and harvest maturity on the storage behaviour of cormels of the edible aroid species Colocasia esculenta and Xanthosoma sagittifolium were studied. The changes monitored were respiration rates, weight losses, incidence of decay and sprouting. Post-harvest losses that occurred during storage were influenced by the storage conditions, the state of maturity at harvest and the morphological characteristics of the cormels. When stored under high temperature and humidity more sprouting and decay occurred with C. esculenta cormels than with X. sagittifolium cormels. Less sprouting and decay occurred with Colocasia cormels at high temperature and low humidity than at high temperature and high humidity but higher weight losses were recorded. Wound pathogens were the major cause of post-harvest deterioration in Colocasia cormels and the causal pathogen of cormel decay was Sclerotium rolfsii. Under conditions of low temperature (15 °C) and high humidity (85%), cormels of both C. esculenta and X. sagittifolium were successfully stored for periods of 5–6 weeks. Similar storage periods were also possible under tropical ambient conditions with the Xanthosoma cultivars used in these experiments. Under the same storage conditions up to 60% decay occurred in the Colocasia cormels indicating the need for post-harvest fungicide treatment.