PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Skeletonization Caused by chewing insects
feeding externally on the surface of leaves, leaving
only veins, eg autumn gum moth and gumleaf
skeletonizer (Lepidoptera); elm leaf beetle
(Coleoptera); pear and cherry slug and callistemon
sawfly (Hymenoptera) and young snails.
Slater An animal belonging to the Class
Malacostraca, Phylum Arthropoda.
Sleeper weeds Weeds that appear benign for many
years then suddenly spread rapidly.
Slime mould A very simple fungus belonging to the
Phylum Myxomycota
Smut A fungus in the Phylum Basidiomycota which
causes a disease characterized by the presence of
black sooty spore masses in seeds and leaves.
Snail An animal belonging to the Phylum Mollusca,
Class Gastropoda.
Sodicity Soil containing levels of sodium that
affects its physical properties (stability). Applies to
soils rather than media,
Solarisation A process in which heat from the sun
may raise the temperature near the surface of soil or
potting media to levels high enough to kill or reduce
populations of some pests, eg mites, most soilborne
disease organisms (bacteria, fungi, nematodes), and
some weeds and weed seeds.
Sooty mould The dark hyphae of fungi growing on
the honeydew secreted by some Hemipterous insects,
eg aphids, lerps, scales, mealybugs, whiteflies.
Speckles, stippling Patterns of dots (feeding sites
of sap sucking insects) on leaves and fruits.
Spider An 8-legged animal belonging to the Order
Acarina, Class Arachnida, Phylum Arthropoda.
Spittle bug An insect belonging to the Order
Hemiptera (bugs) the nymph of which produces a
wet, frothy material for protection.
Splitting The cracking of fruit commonly due to
rain/too much water and too rapid growth.
Spore The reproductive unit of a fungus consisting
of one or more cells.
Spray adjuvant A substance added to a pesticide to
improve effectiveness or safety, eg wetting agent.
Springtail An insect belonging to the Class
Collembola, Phylum Arthropoda.
Sterile fungi A group of fungi not known to
produce any kind of spores.
Stick insect An insect belonging to the Order
Phasmatodea (leaf insects, phasmatids).
Stomach poison A pesticide that must be eaten by
an animal in order to be effective.
Stomates Small openings on leaves, twigs and
other plant parts which regulate the flow of water
from the plant into the atmosphere and admit carbon
dioxide from the atmosphere for photosynthesis.
Strain Descendants of a single isolate in pure
culture, an isolate, a race.
Streaking Dark longitudinal streaks on stems
infected with virus diseases, eg symptoms of tomato
spotted wilt virus on stems of broad bean.
Stunting Failure of a plant to reach normal size,
caused by insect pests, virus diseases, other agents.
Suppressive soils Soils in which certain diseases
are suppressed because of the presence in the soil of
microorganisms antagonistic to the pathogen.
Surfactant A spray supplement which lowers the
surface tension of a pesticide spray enabling it to
spread evenly over, and adhere to, the surface of an
insect, diseased plant surface or weed, overcoming
the repellent nature of the pest, disease or weed.
Susceptible Being prone to attack by a given
disease or pest organism.
Symbiosis Mutually beneficial association of
2 or more different kinds of organisms.
Symptom The visible response of the host plant to a
disease or pest, eg chlorosis, leaf curl, scab.
Systemic 1. A chemical that is absorbed and
translocated within a plant or animal. 2. A disease
that spreads within a plant.
Target organism. The pest, disease or weed to be
controlled.
Termite An insect belonging to the Order Isoptera
(termites, ‘white ants’).
Threshold Levels of pest or damage at which
treatment is necessary to manage a pest problem. May
be economic, aesthetic or environmental.
Thrips An insect belonging to the Order
Thysanoptera (thrips).
Tolerant The property of organisms (including
plants), to withstand a certain degree of stress, pest
attack, unfavourable weather and other agents.
Toxin A compound produced by plants, animals or
microorganisms which is toxic to another.
Translocation A substance taken in through the
plant surface and moved throughout the plant.
Uredospores. Rust spores produced by a fruiting
structure called a uredium.
Vector. 1. An insect, nematode, parasitic plant or
other parasite which can carry and transmit a disease
organism from one host to another. 2. In genetic
engineering the transmission of DNA into a host cell.
Vegetative Asexual reproduction of plants.
Veinbanding Regions along the veins of leaves
darker or lighter in colour than the tissue between the
veins, caused by some virus diseases.
Veinclearing Veins of leaves become translucent,
caused by some virus diseases, herbicide injury, etc.
Virescence See Greening.
Virus & virus-like ‘organism’ A submicroscopic
parasite consisting of nucleic acid and protein. A group
of related ‘organisms’, eg phytoplasmas and viroids,
have similar properties, ie can only multiply in living
cells, can spread from one plant to another and can
only be seen with aid of an electron microscope.
Wasp. An insect belonging to the Order
Hymenoptera (ants, bees, sawflies, wasps).
Wax A normal secretion of the epidermal glands in
insects, eg woolly aphid.
Webbing Fine silk produced from glands in
the mouth of ‘spider’ mites, eg twospotted mites
crawl over it and fasten their eggs to it.
Weed A plant that has or has the potential to have,
a detrimental effect on economic, social or
conservation values.
Weevil An insect belonging to the Order Coleoptera
(beetles and weevils).
Wetting agents A substance that reduces the
surface tension of a liquid, so it can spread across or
penetrate more easily the surface of a plant. May be
added to pesticide sprays to allow easier spreading on
leaves, or to the soil to aid the rewetting of soils.
Whey Liquid waste from cheese products.
White ant An insect belonging to the Order Isoptera
(termites).
Whitefly An insect belonging to the Order
Hemiptera, (bugs; hoppers; aphids, lerps, mealybugs,
scales, whiteflies).
Wilt A drooping of plants due to an inadequate
water supply, excessive transpiration, or a variety of
agents. True ‘wilt ‘ diseases are caused by fungi or
bacteria blocking the xylem vessels of the host plant,
eg Fusarium wilt and Verticillium wilt of various
plants and bacterial wilt of tomato.
Wireworm Larvae of click beetles (Elateridae,
Coleoptera).
Witches' broom Broom-like growth or massed
proliferation of shoots, caused by insects or mites,
other agents, and occasionally by fungal diseases.
‘Worm’, ‘weevil’ damage Damage caused
internally to fruit, nuts, seeds by larvae of various
insects with a complete metamorphosis, eg
caterpillars of moths (Lepidoptera), maggots of flies
(Diptera), larvae of beetles and weevils (Coleoptera)
and wasps (Hymenoptera).
Xylem. Water conducting tissue in plants.
Zoospore. A fungal spore with flagella capable of
moving in water.
Zygomycota A Phylum of Fungi with thick-walled
resting zygospores, eg bread moulds (Mucor, Rhizopus).
480 Glossary & Acronyms