Post-harvest manipulation of rind colour in 'Mauritius' litchi (Litchi chinensis Sonn.) fruit.

Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 1996.Litchi fruit are non-climacteric, and are able to endure relatively low storage temperatures compared to other subtropical fruits. Unfortunately however, the litchi rind is relatively thin and lacks a thick, durable cuticle. Consequently, post-harvest desiccation is a major factor, and rind colour changes rapidly from red to brown, unless counter measures are taken immediately after harvest. Presently, the South African industry uses sulphur fumigation to prevent browning, but sulphur treatment is undesirable in many respects, only partially successful, and some overseas markets have lowered the permissible level of sulphur to 10 mg.kg-1 in the fruit flesh. Alternatives to sulphur fumigation were accordingly researched. The author tested the hypothesis that, in order to preserve the desirable red rind colour, it was necessary to break down rind cell membrane integrity, so that the vacuole-bound anthocyanin pigments can be exposed to zero pH solution, which effects rind colour preservation. Thereafter, rind desiccation must be reduced. A 2 s steam (95°C) treatment followed by 4 min immersion in zero pH solution resulted in fruit which retained excellent red rind colour, with normal pulp characteristics and tasted similar to control fruit after 28 days storage at 1°C. Ultrastructural studies showed that 2 s steam (95°C) treatment resulted in rind cell membrane breakdown, and this was enhanced when used in conjunction with 4 min in zero pH solution. In addition, electrolyte leakage studies showed that rinds of untreated control fruit had lowest electrolyte leakage, while those of fruit subjected to 2 s steam (95°C) had highest electrolyte leakage, making the previously compartmentalized and vacuole-bound pigments available for preservation in the desirable red colour. Polyphenol oxidase in litchi rinds was strongly inhibited by 2 s steam (95°C), but even more so when fruit were subjected to 2 s steam (95°C) followed by 4 min in zero pH solution. Energy dispersive x-ray microanalysis studies found that chlorine concentrations were relatively high on both the inner and outer surfaces of fruit subjected to 2 s steam (95°C) followed by 4 min in zero pH solution. Similarly, sulphur concentrations were high in rinds of sulphur-fumigated fruit, but this element was also present at low concentrations in nonsulphur- fumigated fruit. Rind colour of untreated control fruit lightened when stored at 30°C and hue changed from red to reddish orange. Rinds of fruit subjected to 2 s steam (95°C) only, lost colour rapidly and were a pale yellow hue 24 hr after treatment. The hue of fruit rinds subjected to 2 s steam (95°C) followed by 4 min in zero pH solution changed from reddish orange to red within 4 hr and then darkened up to 24 hr after treatment. Red colour was preserved in fruit held at 30°C for 72 hr, but lightened after 24 hr. HPLC of anthocyanin pigments found that the presumed cyanidin-3-rutinoside, pelargonidin-3-glucoside and pelargonidin-3,5-diglucoside all decreased in untreated fruit over 5 days storage at 30°C. Concentrations of presumed cyanidin- 3-rutinoside in fruit subjected to 2 s steam (95°C) followed by 4 min in zero pH solution increased immediately after treatment, peaked 24 hr later, but then decreased to about double the concentration of fruit treated on the day of harvest after 4 days at 30°C. Furthermore, no copigmentation or self-associations of anthocyanins took place in rinds of fruit subjected to 2 s steam (95°C) followed by 4 min immersion in zero pH solution. Semi-commercial trials showed that the steam: acid dip treatment is feasible, and has the potential to replace sulphuring as a fungicidal treatment. It also has the advantage of more permanently preserving the desirable rind colour, and in a more intense red colour

Californian thistle (Cirsium arvense): endophytes and Puccinia punctiformis

Californian thistle (Cirisum arvense) is a troublesome weed in pastures and cropping systems. The fungal biocontrol agent Puccinia punctiformis, commonly referred to as thistle rust, performs inconsistently on C. arvense. Problems with P. punctiformis establishment and control of C. arvense may be attributable to differing plant endophytic populations in various environments. This article provides an overview of the relationships between endophytes and their host, but also between endophytes and pathogens with a focus on rust pathogens. This review provides insights into reasons why P. punctiformis performs inconsistently and identifies gaps in our knowledge. Filling these gaps may help to improve performance of this classical fungal biocontrol agent

Effects of rootstock and training system on tree canopy, fruit quality and phytochemicals of ‘0900 Ziraat’ and ‘Regina’ sweet cherry cultivars

Both ‘0900 Ziraat’ and ‘Regina’ grafted on ‘Krymsk 5’, or ‘Piku 1’ rootstocks were trained to either Upright Fruiting Offshoots (UFO), Super Slender Axe (SSA) or Kym Green Bush (KGB) training systems. Vegetative growth of the tree, determined by measuring trunk cross-sectional area (TCSA), canopy volume and leaf area, differed significantly, depending on the cultivar x rootstock x training system combination. In general, ‘Krymsk 5’ rootstock resulted in trees with significantly thicker trunks (TCSA: 37.75 cm²) and increased leaf area (up to 86.97 cm²). Fruit weight and fruit quality parameters including Hunter a*, firmness, TSS and acidity were variable between rootstocks and training systems and often not significantly different between treatments. In some years however, significant differences were highly dependent on the training system and rootstock interactions. Higher concentrations of bioactive phytochemical concentrations for total monomeric anthocyanin and antioxidant concentrations were mostly associated with the UFO training system in conjunction with the ‘Krymsk 5’ rootstock suggesting that these are linked to increased tree vigour and increased leaf surface area

Comparison of Regular Atmospheric Storage versus Modified Atmospheric Packaging on Postharvest Quality of Organically Grown Lowbush and Half-Highbush Blueberries

The aim of the study was to determine the effect of modified atmosphere (MA) packages on the external quality of organically grown lowbush blueberry and half-highbush blueberry ('Northblue') and the nutritional value of the fruits. Fruits were divided into plastic punnets and stored as follows: regular atmosphere (RA), punnets without packing; punnets sealed in a low-density polyethylene (LDPE, Estiko) bag; punnets sealed in an Xtend (R) blueberry bag (Stepac). Fruits were stored at 3 +/- 1 degrees C. Compared to RA conditions, the Xtend (R) package prolonged the postharvest life for 15 days for lowbush and 9 days for half-highbush blueberries. Fruit dry matter (DM) and titratable acidity (TA) were higher in the Xtend (R) package. Fruit SSC decreased in the LDPE packages and increased in the Xtend (R) packages during storage. Based on the decreased soluble solids content (SSC) and titratable acidity (TA) ratio (SSC:TA) values during storage, it can be concluded that the taste of the fruits became sourer in all packages. Anthocyanin biosynthesis of lowbush blueberries was suppressed in MA, but this effect was not noticed for 'Northblue'. Regarding fruit firmness, shrivelling, and decay, there were significant differences between the MA packages, but the genetic differences were more important: half-highbush blueberry fruits were firmer and less shrivelled

Effects of soil drenching of water-soluble potassium silicate on commercial avocado (Persea americana Mill.) orchard trees infected with Phytophthora cinnamomi Rands on root density, canopy health, induction and concentration of phenolic compounds

Please read abstract in the article.The National Research Foundation of South Africa and by the South African Avocado Growers Association.http://www.tandfonline.com/loi/tjps202015-07-31hb201

2017 pest management guide for wine grapes in Oregon

Second revision March 24, 2017. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalogThis pest management guide is developed for use by vineyard managers in Oregon. It provides recommendations for chemicals, formulations, and usage rates of products that are intended to prevent, manage, and control vineyard diseases, insects, mites, weeds, and vertebrate pests. When considering a pesticide, evaluate its efficacy and its impact on beneficial arthropods, honey bees, and the environment. Not all registered pesticides are listed in this guide. These recommendations are based on research, label directions, and vineyard-use experience for Oregon

2020 pest management guide for wine grapes in Oregon

This guide is developed for use by managers of commercial vineyards in Oregon. It provides recommendations for chemicals, formulations and usage rates of products that are intended to prevent, manage and control vineyard diseases, insects, mites and weeds. When considering a pesticide, evaluate its efficacy and its impact on beneficial arthropods, honey bees and the environment. Not all registered pesticides are listed in this guide. These recommendations are based on research, label directions and vineyard-use experience for Oregon.Revised March 2020. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

2018 pest management guide for wine grapes in Oregon

This publication reviews the growth stages of grapes. For each growth stage (or group of growth stages), the document lists the more effective pesticides used to control insects, weeds, and disease, their rates, and application timing for Oregon grape growers. It also covers the effectiveness of various fungicides for control of grape diseases; strategies for controlling powdery mildew, botrytis bunch rot, and spider mites; methods of controlling vertebrate pests and weeds in vineyards; and resources for organic growers. It also includes a vineyard airblast sprayer calibration worksheet.A more recent revision exists. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

2019 pest management guide for wine grapes in Oregon

This publication reviews the growth stages of grapes. For each growth stage (or group of growth stages), the document lists the more effective pesticides used to control insects, weeds, and disease; their rates; and application timing for Oregon grape growers. It also covers the effectiveness of various fungicides for control of grape diseases; strategies for controlling powdery mildew, botrytis bunch rot, and spider mites; methods of controlling weeds in vineyards; and resources for organic growers.Information within this publication may be outdated. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalo

Protecting grapevines from winter injury

Winegrape production in the Pacific Northwest has expanded into areas where low winter temperatures periodically cause cane damage or death. In the Walla Walla Valley, for example, minimum temperatures plummeted to below -20°F for several days in 1996 and 2004, killing most exposed canes. Cane temperatures most certainly remained below 0°F during this time. If vines are grown on their own roots (i.e., not grafted), regrowth and training of new canes from below-ground plant parts is possible. Fruit and wine production is reduced, however, during the time required to retrain the canes. Regrowth of ‘Merlot’ canes is especially problematic, as new canes tend to be stunted and nonvigorous. Canes can be protected from freeze damage by burying them or covering them with mulch. This publication describes three systems that may help prevent injury from winter freezes.Published March 2008. Reviewed July 2013. Please check for up-to-date information in the OSU Extension Service Catalog: http://extension.oregonstate.edu/catalo