PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Living agents
Fig. 210. Leafcutting bee damage
to rose leaves. Bees cut out pieces of
leaves with their jaws to make nests.
Fig. 211. Sooty mould on an orange leaf. Black
fungal hyphae grow on the honeydew secreted by some sap
sucking Hemipterous insects, eg aphids, leafhoppers, lerps, soft
scales and whiteflies. Sooty mould disfigures plants. If the
insects producing the honeydew are controlled the sooty mould
will eventually dry out and fall off or can be hosed off leaves.
PhotoNSW Dept. of Industry and Investment.
Fig. 212. Wood rotting fungus in a
container. The mycelium which produces
the mushroom grows on uncomposted
material in the soil. PhotoCIT, Canberra
(P.W.Unger).
Fig. 213. Fairy rings in a lawn. The mycelium of the fungus
growing on the organic matter in the soil grows in all directions from
a central point to form a large invisible circle. Fruiting bodies or
form a ring, usually in autumn after the first heavy rains. In addition
and height. Bare patches may develop. PhotoCIT, Canberra (P.W.Unger).
Fruiting bodies
containing spores
(x 10) on leaves.
Slime moulds on
grass leaves
(natural size).
Female plant
Male plant
Fig. 214. Slime moulds (Myxomycota). Commonly
blackish fruiting bodies (1-2 mm high) appear in late
spring or autumn after prolonged wet weather. Slime
moulds exist as jelly-like blobs up to several centimeters
across which move very slowly feeding on
microorganisms and small pieces of plant material in
shady damp places. They are only noticed when they
move up onto grass or other low lying plants such as
strawberries or onions, to produce spores which usually
disappear after 2-3 weeks depending on the weather.
Fig. 215. Liverworts (Bryophyta) can be a
major weed problem in nurseries especially in
cool shady areas. They reproduce by both spores
and vegetative reproduction.
Non-parasitic pests and diseases 391