tropical fruit crops

Question 1

Avocado production stats

Answer 1

$104m export value

local = 6 M

22000 tones produced

3,782,000 trays exported

over 4,000 ha of trees planted

Question 2

avocado grower considerations

Answer 2

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

Question 3

avocado canopy management

Answer 3

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

Question 4

what contributes to tree decline in avocados

Answer 4

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

Question 5

how to prevent tree decline in avocados

Answer 5

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

Question 6

where are oranges grown

Answer 6

Kerikeri and Gisborne

Question 7

when are oranges available

Answer 7

fresh june - February

Question 8

feature of naval orange

Answer 8

the fruit inside the fruit

seedless

Question 9

when is lemon available

Answer 9

fresh June- march

Question 10

what rootstock is used for citrus

Answer 10

NZ is dependant on the one type trifoliate orange or tri

fruit quality is influenced by the rootstock

Question 11

what factors is essential for the rootstock

Answer 11

genetic compatibility with plant and rootstock

resistance to CTV and tolerance to phytophthora

resistance to cold and wet soil

Question 12

desired rootstock effects for citrus

Answer 12

improved sugar-acid ratios

larger fruit

thinner rinds

increased or decreased tree vigour

improved yield efficiency and larger storage life

Question 13

what are site factors for citrus

Answer 13

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.

Question 14

key crop establishment factors for citrus

Answer 14

shelter

drainage

cultivar

soil testing

tree spacing

irrigation

nutrition

Question 15

citrus health problem

Answer 15

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

Question 16

how to deal with pests in citrus

Answer 16

IPM

its demanded by markets to get rd of pests while improving environmental sustainability.

Question 17

key elements to any IPM system

Answer 17

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

Question 18

key produces of mangos

Answer 18

India, China and Thailand Mexico

Question 19

factors of a mango tree

Answer 19

long lived

35 meters tall in tropics 10m in subtropics

straight trunk with grey coffe bark cracks

leaves evergreen, alternate,simple

Question 20

growing conditions for mango

Answer 20

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

Question 21

harvesting factors for a mango

Answer 21

mature 4-5 months after flowering

once fully mature stem will snap easily with a slight pull

maturity identified by the development of shoulders

Question 22

post harvest factors for mangos

Answer 22

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

Question 23

storage factors for mango

Answer 23

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

Question 24

problems with mangos

Answer 24

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