International apple & pear research – Feb/Mar 2018
Snippets of the latest apple and pear research from all around the world covering cultivars and nursery; production; pests and diseases; post-harvest; and quality and health.
Cultivars and nursery
B9 interstems benefits
Romania: Using B9 interstems on vigorous rootstocks maintained the dwarfing character of B9 and substantially increased the number of feathers over B9 alone. See: Producing plant material at intermediate grafted apple.
Rootstocks for Fuji
Brazil: The yield of Fuji apples was greatest on JM3, JM7, JM8 and M7 rather than JM2 or JM5 and there was no rootstock impact on fruit size. See: Productive performance of ‘Fuji’ apple trees on ‘JM’ series rootstocks, in São Joaquim/SC.
Improving feathers and branch angles
US: Four applications of MaxCel® or Promalin®, beginning when the leader growth reaches 70cm, increases feathers and improves branch angles. See: Use of plant growth regulators for feathering and flower suppression of apple nursery trees.
Production
Net colour matters
Chile: Pearl-coloured nets provide better light for apple colouration than red nets, and both coloured nets reduce the incidence of sunburn. See: Influence of using of Pearl and Red nets on micro-climate conditions, fruit sun damage and fruit color development in ‘Gala’ and ‘Fuji’ apple orchards.
Pear pollinators
Belgium: In pear trees, pollinating insects forage on neighbouring trees within a row, with few movements across rows, with honey bees and bumble bees visiting 8.5 and three flowers per tree respectively. See: Cultivar placement affects pollination efficiency and fruit production in European pear (Pyrus communis) orchards.
Asian pear fertility
Poland: A study of 23 Asian pear cultivars found that none were self-fertile. See: Evaluation of pollen quality and self-fertility in selected cultivars of Asian and European pears.
New PGR for stress
Japan: Abscinazole is a new plant growth regulator that inhibits the breakdown of ABA, allowing for improved plant tolerance of stress. See: Salt tolerance in apple seedlings is affected by an inhibitor of ABA 8′-hydroxylase CYP707A.
Birds in organic orchards
US: Birds in organic apple orchards have little effect on codling moth fruit damage and do minimal direct fruit damage, while orchards provide a habitat for diverse bird communities. See: Bird use of organic apple orchards: frugivory, pest control and implications for production.
Cadmium tolerant rootstock
China: Of four apple rootstocks tested Malus baccata is the most tolerant of cadmium in the soil. See: Integration of cadmium accumulation, subcellular distribution, and physiological responses to understand cadmium tolerance in apple rootstocks.
Altitude affects dormancy
South Africa: In addition to winter temperatures, altitude is important for dormancy, with high altitudes causing deep dormancy and low altitudes shallow dormancy and protracted release. See: Diverse patterns in dormancy progression of apple buds under variable winter conditions.
Crabapples as pollinators
US: Pollination studies found that while crabapples were good pollinators of Gala and Fuji apples they were incompatible with Honeycrisp. See: Pollen tube growth and fruit set in apple.
Leaf:fruit ratio
India: Thirty leaves per fruit was found to be optimal for maximum fruit size and yield per tree. See: Determining leaf:fruit ratio for high productivity in apple (Malus pumila) under intensive orcharding system.
Pre-grading harvesting robot
China: Studies have found it is feasible to develop an apple harvesting robot that pre-grades fruit to eliminate small or damaged fruit. See: Design and experiment of an online grading system for apple.
Apple tree biochar
China: Apple tree branches were converted into biochar at different temperatures and higher temperatures (600°C) improved the biochar surface area, pore volume, thermal stability and fixed nutrients. See: Effect of temperature on the structural and physicochemical properties of biochar with apple tree branches as feedstock material.
Inter-row mulch options
China: In a rain-fed apple crop, yield and water use efficiency were improved by the use of black plastic mulch under the trees and a summer crop of rapeseed in the inter-row space, compared to plastic mulch and sprayed inter-row spaces. See: Black plastic mulch combined with summer cover crop increases the yield and water use efficiency of apple tree on the rainfed Loess Plateau.
Pests and diseases
Phytophthora symptoms
Syria: Phytophthora cactorum has been isolated from all apple trees with symptoms of collar rot leading to small pale green leaves, sparse foliage and reddish-brown discoloration of bark. See: Fungal pathogens associated with crown and collar rot of apple trees in southern Syria.
Fungicide for black spot
Italy: Captan has been shown to have a high performance against black spot of apples compared to standard, commonly used fungicides. See: Control trials of apple scab and pear brown spot with captan.
Pheromones and codling moth
US: Pear ester added to pheromone dispensers significantly improved control of codling moth. See: Addition of pear ester with sex pheromone enhances disruption of mating by female codling moth (Lepidoptera: Tortricidae) in walnut orchards treated with Meso dispensers.
Fungicide applications methods
Italy: Trials using anti-drift air-injection spray nozzles on one side of apple trees at the same rate of application per hectare to both sides of the trees showed a downward trend in disease control. See: Efficacy evaluation of fungicide application with anti-drift air-injection nozzles spraying one side of apple tree rows.
Brown spot fungicide
Italy: Tests of nine new and old fungicides against brown spot of pear identified that thiram was the least persistent while captan and fluazinam gave the best performance. See: Semi-field trials evaluating the persistance of the most commonly used fungicides for the control of pear brown spot caused by Stemphylium vesicarium.
Low-drift spray nozzles
Italy: The use of low-drift spray nozzles reduced spray drift with no impact on efficacy while the use of spray additive to reduce drift had no effect on drift or efficacy. See: Evaluation of spray-drift reduction methods in apple orchards and vineyards and assessment of their efficacy and side-effects.
Post-harvest
Pear cold storage
Brazil: Cold storage life of Packham pears was lengthened by 60 days with the use of passive modified atmosphere packaging. See: Extended cold storage of winter pears by modified atmosphere packaging.
Box size and bruising
South Africa: Apples in the bottom layer in cardboard boxes suffer less bruising in transport and larger cardboard boxes induce larger bruise sizes. See: Compression damage susceptibility of apple fruit packed inside ventilated corrugated paperboard package.
Hot-water treatment
Italy: Hot-water treatment (45°C for 10 minutes) reduces infection rates of post-harvest diseases after treatment due to stimulated auto defence responses in the apple.
See: Defense response against post-harvest pathogens in hot water treated apples.
1-MCP usage in apples
Brazil: Apples treated with 1-MCP have reduced anaerobic metabolism, such that treatment reduces the risk of low oxygen fruit damage when dynamic controlled-atmosphere methods are used. See: 1-methylcyclopropene suppresses anaerobic metabolism in apples stored under dynamic controlled atmosphere monitored by respiratory quotient.
Beneficial yeast
Uruguay: Two strains of the yeast Candida sake have been found that produce compounds which inhibit the growth of Penicillium, Botrytis and Alternaria post-harvest rots of apples. See: Volatile organic compounds produced by Antarctic strains of Candida sake play a role in the control of postharvest pathogens of apples.
Biocontrol of rots
China: Biocontrol of apple post-harvest rots with Pichia caribbica is enhanced if it is applied with glycine betaine. See: Mechanisms of glycine betaine enhancing oxidative stress tolerance and biocontrol efficacy of Pichia caribbica against blue mold on apples.
Oils protect against fungus
Iran: Post-harvest application of essential oils is effective against Botrytis and Penicillium; however, mixed oils can give synergistic effects, with the mixture cinnamon, rosemary and thyme oil providing excellent control. See: Synergistic effects of some essential oils against fungal spoilage on pear fruit.
Quality and health
‘Melting’ texture in pears
US: Development of a melting texture in European pears is associated with increased pectin enzyme activity and the production of water-soluble pectin. See: Compositional changes in cell wall polyuronides and enzyme activities associated with melting/mealy textural property during ripening following long-term storage of ‘Comice’ and ‘d’Anjou’ pears.
Vitamin C in apples
Russia: Apple cultivars with elevated levels of vitamin C have been identified, and growing apples at high latitudes increases the vitamin C content of the fruit. See: Ascorbic acid and apple breeding for its higher content in fruits.
Polyphenols boost physical performance
France: In a human trial the consumption of a high dose of apple and grape polyphenols one or 12 hours before physical exertion improved performance by 10 per cent.
See: An acute dose of specific grape and apple polyphenols improves endurance performance: a randomized, crossover, double-blind versus placebo controlled study.
Apple pomace potential
Austria: Apple pomace is an underutilised waste product with the potential to be processed for its nutritional and pharmaceutical properties. See: Apple pomace as potential source of natural active compounds.
Compound development
Italy: Polyphenol composition of apples varies between biodynamic and conventional production but volatile organic compounds do not indicate they are under strong genetic control and thus more stable across production systems. See: Polyphenols and aromatic volatile compounds in biodynamic and conventional ‘Golden Delicious’ apples (Malus domestica Bork.).
Apple pectin inhibits bacteria
Serbia: Apple pectin oligosaccharides inhibit the growth of Escherichia coli and Staphylococcus aureus (golden staph). See: Apple pectin-derived oligosaccharides produce carbon dioxide radical anion in Fenton reaction and prevent growth of Escherichia coli and Staphylococcus aureus.
Provenance detection for pears
China: Nanguo pears are a fruit of geographical indication, and a method of analysing fruit has been developed to detect fruit that does not come from Liaoning province. See: Research progress on origin traceability technology of fruits and application prospects of origin traceability of Nanguo pear.
