Cold storage of cut 'Sonia', 'Royalty', and 'Gold Rush' roses (Rosa hybrida L.) at reduced humidities (50% to 80% RH) significantly decreased the severity of Botrytis cinerea Pers. infections that developed from naturally occurring or experimentally applied inocula, compared to storage at saturated humidity. The disease reduction was attributed to the absence of free water on the petals. Wrapping the flowers in cellophane sleeves before reduced-humidity storage decreased water loss but also impaired disease control. No deleterious effects of reduced-humidity storage on poststorage fresh weight gain or visual quality were observed, whether the wrapped flowers are stored with or without vase solutions. Two biological control agen s, the yeast Exophiala jeanselmei and a Coryneform-type bacterium, controlled B. cinerea infections during storage at 2.5 degrees C when applied 0 to 48 hr after inoculation with the pathogen. The level of disease control achieved with the biological antagonists during storage was comparable to that achieved with the fungicide vinclozolin, but the biological antagonists did not control poststorage disease development as well.

Cold storage of cut 'Sonia', 'Royalty', and 'Gold Rush' roses (Rosa hybrida L.) at reduced humidities (50% to 80% RH) significantly decreased the severity of Botrytis cinerea Pers. infections that developed from naturally occurring or experimentally applied inocula, compared to storage at saturated humidity. The disease reduction was attributed to the absence of free water on the petals. Wrapping the flowers in cellophane sleeves before reduced-humidity storage decreased water loss but also impaired disease control. No deleterious effects of reduced-humidity storage on poststorage fresh weight gain or visual quality were observed, whether the wrapped flowers are stored with or without vase solutions. Two biological control agen s, the yeast Exophiala jeanselmei and a Coryneform-type bacterium, controlled B. cinerea infections during storage at 2.5 degrees C when applied 0 to 48 hr after inoculation with the pathogen. The level of disease control achieved with the biological antagonists during storage was comparable to that achieved with the fungicide vinclozolin, but the biological antagonists did not control poststorage disease development as well.

Taro, an important staple crop, is also subject to infestations and attacks by various disease-causing pathogens. Lowland taro is a crop grown similar to lowland rice, however, unlike rice, the most important edible portion harvested is the corm which grows underground making it susceptible to unfavorable growing conditions brought about by waterlogging. Under waterlogged conditions, physiological factors as well as biotic agents can cause damage or disease of the corms. There are several diseases that attack the taro plant but the most economically important in Hawaii and most parts of the Pacific and Asian areas where taro is grown, is the corm soft rot caused by several species of Pythium. Corm soft rot can cause as much as 50% to 100% losses in taro yields and the disease carries over to the harvested corms in storage or in transit. Control of the disease by chemical means is expensive and often ineffective. Farmers therefore have to resort to cultural management to keep the disease under control. The most important cultural methods of controlling corm soft rot are: (1) use of clean, disease-free planting materials; (2) proper handling and storage of planting materials; (3) maintenance and practice of good field sanitation; (4) draining, complete drying, aeration and fallowing of field between successive plantings of taro; (5) good irrigation or water management, allowing for ample fresh and cool water to flow through production field; (6) avoidance of stagnant, warm water in the field which favors disease outbreaks; (7) proper washing and cleaning of harvested corms to prevent post-harvest attack by the disease organisms, and (8) proper handling and storage of harvested corms.

A new post-harvest disease of mango (Mangiferae indica L.) has been recurrently observed in Bangalore. Fruits are infected during storage. The infection is also noticed on leaves throughout the year which probably acts as source of primary infection for fruits. The latent infection carried on mature fruits subsequently develops into post-harvest decay during storage. The pathogen was identified as Pestalotiopsis glandicola (Cast) Stey which is distinct from Pestalotiopsis mangifera (P. Hen) Stey.

The susceptibility of different carrot lines and cultivars to soft rot was assessed by comparing four methods of inoculation, four pathogen concentrations and five strains of Erwinia carotovora. There were differences between strains with most severe damage by Erwinia carotovora pv carotovora SR 394 and Erwinia carotovora pv atroseptica SR 159. Between methods compared inoculation on root slices with soaked paper disc produced the most consistent response. The severity of disease damage was proportional to bacterial suspension concentration. Postharvest storage of roots in cold room (4 degrees C) for 12 weeks had no effect upon severity of bacterial soft rot. Also only small differences were observed connected with postharvest root cutting. Intact and cut roots had a similar disease response during storage but the tip portion of root was slightly more susceptible to soft rot than was the crown portion. The difference between carrot lines and cultivars tested suggested that by using a proposed method for screening it would be possible to select carrots with reduced susceptibility to soft rot for breeding

The susceptibility of different carrot lines and cultivars to soft rot was assessed by comparing 5 methods of inoculation, 4 pathogen concentrations and 4 strains of Erwinia carotovora. There were differences between strains with most severe damage by Erwinia carotovora pv carotovora SR 394 and Erwinia carotovora pv atroseptica SR 159. Between methods, inoculation on root slices with soaked paper disc produced the most consistent response. The severity of disease damage was proportional to bacterial suspension concentration. Postharvest storage of roots in cold room (4 degrees C) for 12 weeks had no effect upon severity of bacterial soft rot. Also only small differences were observed connected with postharvest root cutting. Intact and cut roots had a similar disease response during storage, but the tip portion of the root was slightly more susceptible to soft rot than was the crown portion. The differences between carrot lines and cultivars tested suggested that by using a proposed method for screening, it would be possible to select carrots with reduced susceptibility to soft rot for breeding.

Two new rapid methods that use monoclonal antibodies to detect aflatoxins in groundnuts were tested. The Quantitox is an enzyme immunoassay using microtitre wells and the Aflatest is based on monoclonal antibodies adsorbed onto an affinity column. It was confirmed that aflatoxin contamination occurs preharvest and that storage under low-moisture conditions prevents any further toxin development. There were differences in susceptibility of the locally bred cultivars to aflatoxin development. The Aflatest procedure was useful to rapidly screen groundnut samples for aflatoxin contamination, but there were problems with the Quantitox method. Aflatoxin contamination occurred in the field prior to harvest and was not aggravated by storage conditions at Cleveland Depot during 1987. There was a 19.23 per cent incidence of aflatoxin contamination in the samples taken in early 1987, but it was not related to the farm management system (communal, small-scale commercial, and large-scale commercial) or any particular pest or disease

A long term field experiment to compare 4 methods of fallowing for annual winter cereal production on a Darling Downs Vertisol was started in 1968 on the Hermitage Research Station near Warwick, Queensland. Fallowing systems being investigated are (i) tined tillage with stubble burnt (TcSb); (ii) tined tillage with stubble retained (TcSr); (iii) zero tillage with stubble burnt (TzSb); and (iv) zero tillage with stubble retained (TzSr); each at 3 rates of nitrogen (N) fertiliser application. This paper reports the effect of these treatments on fallow water accumulation, fallow N mineralisation, crop growth and yield, for the period 1968-79. Average values for available soil water in the 0-150 cm zone at sowing were 195 mm for TcSb, 212 mm for TcSr, 225 mm for TzSb and 252 mm for TzSr, and for storage efficiency (percentage of fallow rainfall stored) were 18, 20, 25 and 27% respectively. The relatively greater water storage efficiency of Tz treatments occurred mainly in fallow seasons when initial storage was low. Nitrogen mineralisation during fallows averaged 61 kg/ha and was depressed in some years by Sr. Carryover of available N in excess of crop requirements was shown at the higher rate of N fertilisation. Grain yields averaged over 12 crops were similar for the 4 fallowing systems. The lack of grain yield response to the improved water storage under TzSr was probably caused by yellow spot disease (Pyrenophora tritici-repentis) and root lesion nematode (Pratylenchus thornei), which were most prevalent under this treatment in wheat crops. Poor early growth of barley under TzSr limited its water use and grain yield potential, however, the cause of the poor early growth of barley is not known. A reduction in grain yield of 232 kg/ha associated with Sr was overcome with the addition of 23 kg N/ha as urea.

Researches were carried out, in individual seeds belonging to 13 genotypes, on the two major groups of storage protein: gliadins and glutenins. The analysis were performed, through starch gel electrophoresis, for gliadins and polyacrylamide, for glutenins. 11 and 8 respectively, proteinograms were outlined. The data obtained through this technique allows the characterization and identification without any doubt of the cultivars. The knowledge of genetic codification of gliadins and glutenins to the level of allele and the recognition of these alleles in the electrophoregrammes obtained also lead to the promotion of some data regarding other characters of the cultivars, as for example: resistance to disease, yielding ability, bread making quality.

Information is given on the situation of beans in Latin America, in terms of producing regions, national consumption and exports in various countries, classes of beans grown, production structure, and constraints to production. Main limitations to bean production are diseases and insect pests, which significantly lower on-farm yield. Web blight, BGMV, and anthracnose are some of the main diseases affecting beans. The most important insect pests in Latin America include leafhoppers (Empoasca spp.), cutworms, the pod weevil (Apion godmani), the Mexican bean beetle (Epilachna varivestis), slugs (Vaginulus plebeius and Limax maximus), and storage insects (Acanthoscelides obtectus and Zabrotes subfasciatus). Soil related constraints, drought, the use of unsuitable cv., and socioeconomic factors are also classified as limiting bean production. Major disease problems per country and a climate classification of bean-producing regions are given in table form