tropical fruit crops Flashcards
Avocado production stats
$104m export value
local = 6 M
22000 tones produced
3,782,000 trays exported
over 4,000 ha of trees planted
avocado grower considerations
biennial profile of the avocado crop where the volume in successive seasons can vary significantly
site selection: aspect, wind, water, soil, winter temperature and light intensity
disease-free and true to planting material
export requirements
packaging
avocado canopy management
effective pruning:
help manage and balance between leaf growth, fruiting and root growth on trees.
create light and ensure ages of wood second-year wood more likely to flower
ease of access
what contributes to tree decline in avocados
pathogens: conditions favourable for pathogens, defective phosphorous acid injection methods, increased pathogen virulence, pest pressure (mites)
environment: excessive soil moisture, unfavourable temperatures, lack of adequate mulch
how to prevent tree decline in avocados
soil selection: well-drained, well-aerated
phytophthora resistant rootstocks
irrigation management: don’t over water
chemical control: young trees, foliar phosphate application
in organic nutrition/ fertiliser: balance vegetative growth with reproductive N
organic amendments: mulching essential
where are oranges grown
Kerikeri and Gisborne
when are oranges available
fresh june - February
feature of naval orange
the fruit inside the fruit
seedless
when is lemon available
fresh June- march
what rootstock is used for citrus
NZ is dependant on the one type trifoliate orange or tri
fruit quality is influenced by the rootstock
what factors is essential for the rootstock
genetic compatibility with plant and rootstock
resistance to CTV and tolerance to phytophthora
resistance to cold and wet soil
desired rootstock effects for citrus
improved sugar-acid ratios
larger fruit
thinner rinds
increased or decreased tree vigour
improved yield efficiency and larger storage life
what are site factors for citrus
the occurrence of heavy frosts, kills young trees and severely damage the fruit.
microclimate of the site is crucial. frost pockets ECT
gentle north-facing slope well-drained
higher heat unit accumulation in northern areas can bring forward ripening and quality.
key crop establishment factors for citrus
shelter
drainage
cultivar
soil testing
tree spacing
irrigation
nutrition
citrus health problem
the citrus Tristeza virus CTV is the biggest threat to worldwide citrus production
1940 it resulted in a quick decline in citrus on sour orange rootstocks
its spread by field aphids and infected bud wood
how to deal with pests in citrus
IPM
its demanded by markets to get rd of pests while improving environmental sustainability.
key elements to any IPM system
monitoring - the pests present, abundance and crop stage
threshold- the point at which losses are occurred
selective controls - controls that affect the target pest and not other organisms
biological control is favoured as it is natural
use of broad sprays must be minimised where possible
avoidance - managing the crop to avoid outbreaks
key produces of mangos
India, China and Thailand Mexico
factors of a mango tree
long lived
35 meters tall in tropics 10m in subtropics
straight trunk with grey coffe bark cracks
leaves evergreen, alternate,simple
growing conditions for mango
tropical conditions
requires low temprature to influence flowering
deep, fertile and well drained soil
full sunlight.
low management crop
fert 2-3 times per year
harvesting factors for a mango
mature 4-5 months after flowering
once fully mature stem will snap easily with a slight pull
maturity identified by the development of shoulders
post harvest factors for mangos
have to de sap the mango
hot water treatment if going to the USA for control of fruit fly
hydro cooling after a hot bath to guard against hot water damage
then packed or stored at 12 degrees until packed
mango waxed for appearance
storage factors for mango
controlled atmosphere
CA of 3-5% oxygen and 5-8% CO2
postharvest life is 2-4 weeks in air and 3-6 weeks of CA
problems with mangos
sap-burn - solved by dipping in lime
jelly seed - solved by proper pre-harvest calcium applications
chilling injury - green mangos exposed below 12 and rioe below 10
