Alternatives to conventional fungicides for the control of citrus postharvest green and blue moulds

Purpose of review: This article reviews research based on the evaluation of postharvest control methods alternative to conventional chemical fungicides for the control of citrus green and blue moulds, caused by the pathogens Penicillium digitatum and P. italicum, respectively. Emphasis is given to advances developed during the last few years. Potential benefits, disadvantages and commercial feasibility of the application of these methods are discussed. Findings: Substantial progress has been accomplished in selecting and characterising new effective physical, chemical and biological control methods. However, their widespread commercial implementation relies, in general, on the integration of different treatments of the same or different nature in a multifaceted approach. For satisfactory penicillium decay control, this postharvest approach should be part of an integrated disease management (IDM) programme in which preharvest and harvest factors are also considered. Limitations: The lack of either curative or preventive activity, low persistence, high variability, inconsistency or excessive specificity are general limitations associated with the use of alternatives to synthetic fungicides as stand-alone treatments. Furthermore, the risk of adverse effects on fruit quality, technological problems for cost-effective application, or the availability of new conventional fungicides for traditional markets are additional reasons that may hinder the broad commercial use of such treatments. Directions for future research: As we learn more about the fundamental basis underlying host-pathogen interactions and how they are influenced by direct or indirect protective effects of existing or new single alternative treatments, more effective methods of applying and combining complementary approaches for additive or synergistic effects will emerge. Research should provide appropriate tools to tailor the application of these nonpolluting postharvest control systems and, further, the complete IDM strategy for each specific situation (ie, citrus species and cultivar, climatic and seasonal conditions, destination market, etc)

Near-harvest applications of Metschnikowia fructicola, ethanol, and sodium bicarbonate to control postharvest diseases of grape in central California

The yeast Metschnikowia fructicola, ethanol, and sodium bicarbonate (SBC), alone or in combinations, were applied to table grapes on vines 24 h before harvest to control the incidence of postharvest diseases. In four experiments, all significantly reduced the total number of decayed berries caused by Botrytis cinerea, Alternaria spp., or Aspergillus niger after storage for 30 days at 1degreesC followed by 2 days at 20degreesC. In three experiments, a mean gray mold incidence (caused by B. cinerea) of 34.2 infected berries per kilogram among untreated grape was reduced by Metschnikowia fructicola at 2 x 10(7) CFU/ml, ethanol at 50% (vol/vol), or SBC at 2% (wt/vol) to 12.9, 8.1, or 10.6 infected berries per kilogram, respectively. Ethanol, SBC, and SO2 generator pads were similarly effective. M. fructicola effectiveness was not improved when combined with ethanol or SBC treatments. Ethanol and yeast treatments did not harm the appearance of the grapes. M. fructicola and SBC left noticeable residues, and SBC caused some visible phytotoxicity to the rachis and berries. Ethanol applied at 50% (vol/vol) reduced epiphytic fungal and bacterial populations by about 50% compared with controls. M. fructicola populations persisted on berries during storage when applied alone or after ethanol treatments, whereas SBC reduced its population significantly

Effects of Chitin and Its Derivative Chitosan on Postharvest Decay of Fruits: A Review

Considerable economic losses to harvested fruits are caused by postharvest fungal decay during transportation and storage, which can be significantly controlled by synthetic fungicides. However, considering public concern over pesticide residues in food and the environment, there is a need for safer alternatives for the control of postharvest decay to substitute synthetic fungicides. As the second most abundant biopolymer renewable source in nature, chitin and its derivative chitosan are widely used in controlling postharvest decay of fruits. This review aims to introduce the effect of chitin and chitosan on postharvest decay in fruits and the possible modes of action involved. We found most of the actions discussed in these researches rest on physiological mechanisms. All of the mechanisms are summarized to lay the groundwork for further studies which should focus on the molecular mechanisms of chitin and chitosan in controlling postharvest decay of fruits

Screening Fresh Oranges With UV Study Pinpoints New Value of Detection Tactic

Fresh, deliciously sweet navel oranges, on display at your local supermarket, may have been quickly inspected with ultraviolet (UV) light when they were still at the packinghouse. Usually, the purpose of this special sorting and screening is to see if circular spots—which glow a bright, fluorescent yellow and may be about the size of a quarter or larger—show up on the fruit’s peel. More often than not, these spots, which scientists refer to as “lesions,” are telltale indicators of the presence of microbes that cause decay, namely Penicillium italicum, responsible for blue mold, or P. digitatum, the culprit behind green mold. It isn’t the microbes that are fluorescing under the packinghouse UV lamps. Instead, it’s tangeritin, a natural compound in citrus peel oil. When the peel is damaged, such as by decay, tangeritin moves closer to the peel surface, or perhaps seeps out of it, becoming easier for UV to detect