PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
TOLERANT
VARIETIES contd
Plant selection for drought tolerance. Many plants survive on little water but:
– All plants need some water especially when first planted until establishment or
when in a hot sunny position. Carefully monitor till established.
– Some are naturally tolerant to drought, eg cacti and succulents, grey foliage plants,
some culinary herbs, grasses.
– Try not to plant new plant out in the hottest months or if you do, plant at night and
consider a temporary shade structure.
– Select plants that come from parts of the world that are similar to the area to be
planted.
– Do not assume that Australian native plants are drought tolerant; many come from
high rainfall zones or cool mountain zones.
– Look for plants with adaptations to enable them to withstand drought, eg small
narrow leaves, grey or silver foliage, furry texture, water retaining succulent leaves,
modified or absent leaves, summer dormancy.
– Are some of these plants likely to become future weeds?
PLANT QUARANTINE.
Quarantine prevents the import or export of food or feed products containing
excessive pesticide residues.
PROBLEM-TESTED PLANTING MATERIAL.
Certification schemes ensure that seed of good genetic quality, physically undamaged,
stored correctly and free of weed seed is available to growers.
PHYSICAL & MECHANICAL METHODS.
Wind machines or helicopters may protect crops from frost.
Shade clothes can protect crops from damage due to suncorch, frost, hail,
wind. UV resistant fabrics can provide climate control, temperature reduction,
energy savings, light spectrum management and protection from insects and birds
which comply with ISO 9002 and EQNet Standards and increase yields. Insectproof
greenhouses prevent aphids from attacking plants and spreading virus
diseases and are used routinely for plant quarantine purposes.
Minimize overhead irrigation and wind damage to trees and flowers,
prevent and repair wounds to trees and shrubs caused by cars and machinery.
Genetic defects, eg fasciation can be pruned out.
AVOID SPRAY DRIFT
Follow label directions
PESTICIDES & OTHER CHEMICALS.
Occasionally registered pesticides may be used for non-parasitic living
problems, eg liverworts, algae, mosses, but there are few problems of this type, eg
– Kendocide (dichlorophen) is currently registered to remove liverwort and algae
and moss from synthetic courts, pavements, lawns and pots.
– Insecticides are used to rid plants of insects that produce non-parasitic honeydew
on which sooty mould grows.
Plant growth regulators (PGRs) are widely used in the horticulture and may be
applied as soil applications or foliar sprays (page 403, Table 70).
– Many are used to modify plant form and development, improve crop quality
and/or reduce production time. Some are rooting powders.
– Others are naturally occurring plant hormones that control development in
plants, others are synthetic chemicals that either mimic the action of a plant hormone
or interfere with the action of natural hormones.
– Some are regulated by pesticide legislation. They vary in shelf life, from at
least 2 years to indefinite. Some may injure some plants, bees and wild life. Others
may have long withholding periods, eg months.
Leaf anti-transpirants, soil wetting agents, water storage gels.
– Foliage anti-transpirants reduce water loss by up to 50% from leaves and protect
plants from extremes of drought, heat, sun, wind and frost and improves survival rate
of cuttings (page 405, Table 71).
– Soil wetting agents improve water retention properties of certain hydrophobic soil
types (page 405, Table 71).
– Water storage agents absorb and store water applied to soil or potting media for
release to plant roots when needed. When mixed with water, crystals swell up to
many times their weight in water, store water near plant roots (page 406, Table 71).
Pesticide and other chemical injury, excess residues.
– Avoid spray drift. Symptoms of chemical damage vary from sluggish growth to
severe leaf burn or yellowing. Upgrade training in pesticide applications.
– Damage from chemicals and chemical applications is not uncommon, eg in
enclosed spaces as in greenhouses, herbicides when applied to pots (some plant
species are always sensitive), disinfectants, gas leakage from heaters.
– Wettable powder formulations are less likely to cause plant damage than some
solvents in some liquid formulations, eg emulsifiable concentrates.
402 Non-parasitic pests and diseases