Fruit quality is largely determined before harvest, while postharvest treatments are generally aimed at maintaining this quality. Therefore an understanding of the effects of preharvest practices on quality is important, particularly in relation to storage. Preharvest factors can influence most, if not all, quality parameters. Evidence of effects on visual appearance (size, colour, blemishes), eating quality (flavour, texture), storage potential (ripening, physiological disorders, disease), and tolerance to physical disinfection and disinfestation control measures (heat, cold) are presented for subtropical and tropical fruit. General relationships were noted in temperate and tropical fruit between nitrogen and colour, disorders, and postharvest disease; fruit size and firmness, calcium, and disorders; calcium and ripening, disorders, and disease; and calcium, magnesium, and potassium. Ways of improving storage potential through fruit minerals are discussed. Such improvements could result in reduced postharvest inputs (storage and disease control). There is potential for predictive models for storage potential of tropical fruits based on minerals, as currently exists for disorder prediction in apples. However, consideration should be given to the interactions between management practices and the various balances that exist in plants, and the compromises often required in producing a quality product.

The fungal pathogens that attack tropical fruit appear to be non-selective in their choice of host. As a consequence, basic information about the biology and control of tropical fruit pathogens may be broadly applicable to a range of commodities. However, all the pathogens do not cause serious losses in all the fruit. Inter- and intra-generic differences in susceptibility of fruit to the major pathogens depend upon a range of host defences, as well as the availability of inoculum and ecological niche requirements. Definition of these factors is necessary for successful postharvest disease control. The challenges for the 21st century are to increase storage life and extend the period of freedom-from-disease beyond the stage of optimum eating quality. Researchers on tropical fruits face greater obstacles than their colleagues working on temperate fruit. There are fewer of them, working in an information vacuum, with much greater evolutionary gaps between the existing and the desired fruit attributes, such as disease resistance and length of storage life. Opportunities to reduce disease losses and extend storage life need to be exploited to the full as they accrue from increasing knowledge of fruit and pathogen biology, from harnessing the benefits of molecular biology, and from improving handling, storage, and transportation technology.

Mature rambutan fruits were collected from growing areas in the east and south of Thailand and stored at 13 deg. C or 25 deg. C for 17 days. Percentage of disease incidence at 13 deg. C was reduced and shelflife (as 50 percent of fruit remaining disease-free) was doubled as compared with 25 deg. C storage. The pathogenic fungi isolated from infected fruits were Colletotrichum gloeosporioides (two types), Gliocephalotrichum bulbilium, Lasiodiplodia theobromae, P estalotiopsis sp., Phomopsis sp. and Glomerella cingulata. The spectrum of the fungi varied with storage temperature. C. gloeosporioides and L. theobromae could severely infect other kinds of fruits. Chemical postharvest treatment gave unsatisfactory results in controlling disease. Further studies of biological control techniques for postharvest treatments are therefore warranted.

In Australia, the current recommendation for postharvest control of anthracnose (Colletotrichum gloeosporioides) in mango is a 5-minute heating (52 deg. C) benomyl dip or a 30-second unheated overhead spray of prochloraz on the packing line. This research demonstrated the diminishing efficacy of these fungicides during the long-term (4-6 weeks) cool or controlled atmosphere storage. When applied alone, both fungicides gave unacceptable control of anthracnose under long-term storage conditions (26 days in 5 percent O2 per 2 percent CO2 at 13 deg. C, then 11 days in air at 20 deg. C). A dual treatment consisting of hot benomyl followed by prochloraz was shown to give superior control of anthracnose under these storage conditions. It was shown that rain at harvest increased disease severity, resulting in reduced efficacy of hot benomyl treatment. Mangoes harvested during wet weather were also more susceptible to brush damage following hot benomyl treatment at 52 deg. C for 5 minutes. Brush damage was reduced or eliminated by applying benomyl at 50 deg. C for 4 minutes. Disease control, however, was not satisfactory. Mangoes harvested in wet weather require careful handling to ensure adequate disease control and to avoid brush damage.

A 2-year field study was conducted to evaluate the effects of maturity and storage on fresh-market onion (Allium cepa L.) quality. Four short-day onion cultivars ('NuMex BR1', 'NuMex Sunlite', 'NuMex Starlite', and 'Buffalo') were seeded in early October each year. Bulbs were harvested at five times; the first and second harvests were when 20% and 80%, respectively, of the bulbs in a plot had mature necks; the third, fourth, and fifth harvests were at 5, 10, and 15 days after the second harvest date, respectively. After curing for 3 days, bulb firmness, weight, and incidence of disease were evaluated for all harvests. Bulbs were re-evaluated after 10 and 20 days storage in a shed under ambient conditions. 'Buffalo' and 'NuMex Sunlite' bulbs had the lowest incidence of disease before storage. For all cultivars, average bulb weight increased and firmness decreased with delayed harvest. Percent diseased bulbs increased for all cultivars as harvest was delayed in 1991 but not in 1992. The optimum harvest time was at 80% maturity. In storage, average bulb weight and firmness decreased, and the incidence of bulb diseases increased.

In experiments on storage of carambola cv. B17 fruit it was shown that there were significant changes, which were greatly influenced by fruit maturity, the storage period, and temperature during storage. There was a highly significant correlation between fruit maturity and colour development of the fruit. Mature fruits can be stored longer at low temperatures since they are more resistant to disease development. Fruits harvested at 12 and 13 weeks after fruit set can be stored for 4 weeks at 5 and 10 deg C.

At harvest, lychee fruit of three maturity levels (M3 [31-60 percent surface red], M4 [31-90 percent surface red] and M5 [91-100 percent surface red]) were either treated with hot benomyl (500 ppm at 52 deg. C for 2 minutes) and air dried, or left untreated prior to PVC wrapping in punnets, and storage at 5 deg. C. The fruits were assessed weekly between 2 and 5 weeks after harvest. Browning of the pericarp and disease development were absent from fruit of M4 and M5 maturity levels 2 weeks after harvest, while less than 50 percent skin browning had developed on the M3 fruits. Browning had appeared on all fruits by 3 weeks after harvest. Similar levels and spectra of fungi were recorded on fruits of the 3 maturity levels, and were more prevalent in fruits that were not dipped in hot benomyl. Cladosporium sp. and Fusarium sp. were the most commonly detected fungi. Treatment in hot benomyl appeared to give greater control of side lesions than stem-end lesions.

The research was done to determine the effect of the storage after the fungicide applications in vineyard one day before the harvest of the grapes to control the grey mould disease which causes great losses during the storage of the table grapes. Kozak Siyahi grapes which were sprayed with fungicides in vineyard were placed in the rooms of the cold store where SO2 fumigation was treated and untreated. According to the results, in the room which SO2 fumigation treated, there was no rotting, also Sumisclex 50 WP (Procymidone % 50) and Sumisclex 50 WP + kortiram Forde 80 WP (Procymidone % 50 + Thiram % 80) treatments controlled the decay in the rate of 82.8 % and 73.1 % respectively in the room which SO2 fumigation was untreated, at the end of two months storage at 0 + 1 deg C and 85-95 % RH. In conclusion, the fungicides above mentioned were suggested for the shorttime storage in the conditions that SO2 fumigation was untreated