Pest 8 - Red-headed cock chafer

These are the larvae of scarab or cock-chafer beetles. They were removed from the soil they were dug out of and placed on asphalt for the sake of this photo. 

McMaugh refers to the larvae as white curl grubs. They are whitish with an orange-brown distinct head and long jointed legs. They usually rest curled into a semi-circle. Most larvae feed on plant roots, but some feed around the base of low-growing plants. Strawberry plants may have their roots eaten right to the crown. They can be a serious problem in potted plants. A wide range of plants are attacked. 

Control is achieved naturally through birds, fungal and viral diseases, predaceous insects like ground beetles. In potted ornamentals and in turf they can be controlled by fenamiphos granules (Lawn Beetle Killer) applied as directed. 

Beetles mate in summer and eggs are laid in soil usually where there is no thick grass cover. beetles form a tunnel to the surface and emerge at night to feed on leaves which they chew off at ground level. Feeding continues through summer, autumn and winter. In late spring, the larvae pupate and the next generation of adults emerge in summer. 

Ref : Judy McMaugh, pg. 139, 209

Pest 7 - Galls caused by insects on Allocasuarina

Various species of insects, especially coccoids (Hemiptera) form distinctive galls on Casuarinaceae; some of these may be mistaken for fruiting cones but they are actually modified vegetative branchlets. Coccid galls also affect eucalyptus species. They are a group of sap-sucking insects whose saliva stimulates plant cells to grow in such a way as to form a gall that looks somewhat like the fruit of the allocasuarina. Control is usually unnecessary, but removing young galls from the plant may reduce future infestations. 

Above is a photo of a psyllid gall on the same allocasuarina species in the Domain near the Botanic gardens.

Ref : Judy McMaugh, pg 148, Australian National Botanic gardens website.

Pest 6 - Echium leaf miner

There are a number of different insects whose larvae feed inside the leaves. These are referred to as "leafminers." Adults may be beetles, wasps, sawflies, moths or flies.

In the case of the Echium leaf miner, the pest is a caterpillar feeds underneath a blister-like, brown papery patch in between the veins on the undersurface of the leaf. The adult is a moth pictured below :  Photo: courtesy of Ken Bond, Dept of Zoology, Ecology & Plant Science,

University College, National University of Ireland, Cork, Ireland)

Echium leaf miner was officially introduced in the mid to late 1980s in South Australia to control the noxious weed Echium plantigeneum or Patterson's Curse. In the photos above it is affecting leaves of an ornamental species, Echium pininana, found in the Asian Woodlands section of the Royal Tasmanian Botanic Gardens. 

Ref :  Judy McMaugh pg. 179, University of Technology Sydney Website, pers. comm. Marcus Ragus

Bacterial Leaf Spot on Fuchsia

Bacterial Leaf Spot affects a range of hosts and is caused by a variety of bacterial organisms. Hosts include cucurbits, lilac, lettuce and pelargoniums. These photos show the ill-defined, black spots with irregular edges which can coalesce. Copper-based sprays may help. 

reference : McMaugh, pg. 224-225

Anthracnose on Rose

Anthracnose is a fungal disease which shows up on roses as black small, circular spots with distinct and clear-cut edges. As the spots enlarge, the centre dries out and becomes grey. The centre may eventually fall out to give a shot-hole appearance. The leaves may yellow, but not to the same extent as in black spot disease of roses. Defoliation is not as serious either. Spots can occur on stems and flowers rarely. Spores are spread by wind and is worse in cool, humid conditions. Rosa Multiflora,  used as rootstock is commonly affected. 

Control is by improving air circulation around the plants and ensuring they receive sun almost all day long. Chemical control includes copper oxychloride spray or zineb sprays which are used to also target black spot. 

Reference : McMaugh, pg. 219

Disease 3 - Rust on Rosa and Fuchsia

Above photo showing rust on the undersurface of fuchsia leaf from Botanic Gardens

Above is a close up of rust fruiting bodies through a hand lens. Fungus within the leaf produces stalks with spores on the end, with the continued growth of these stalks bursting the epidermis of the leaf in that area. The masses of spores are then blown about by the wind. 

Below are photos showing what rust looks like on both sides of rose leaf.

Rust is a collection of fungal diseases that refers to the orange-brown spore masses which are produced on affected plants. There are a large number of different fungal rust species which all lead to the presence of rust disease on susceptible plants. 

Host Range : ornamentals, fruit, vegetables, field crops and weeds. Generally a particular species of rust can attack only certain host species, but there are some special species of fungal rust that can attack different genera. 

Symptoms : Leaves, stems and fruit can be attacked. 

On leaves, the upper surface becomes speckled with small yellow patches which can coalesce. On the under surface there are corresponding orange-brown or rusty spots. In heavy infection there may be premature defoliation and serious weakening of plant. 

A few rusts stimulate plants cells to grow into gall-like structures (eg. acacia)

Disease Cycle : Rust can overwinter as thick walled spores on infected plants, on debris from infected plants, within the soil and on seed. Wind can blow the spores onto new hosts. Can also be spread from water splash from infected host plants. Generally speaking, most rusts favour high humidity, but vary in their preference for temperature. 

Control : 

cultural : avoid planting too thickly, avoid overhead irrigation in rusts that favour moist conditions, use resistant varieties (although this can cause emergence of new strains), do not vegetatively propagate from diseased plants or use seed from these plants, remove and burn diseased plants and prunings, control susceptible weed species.

chemical : copper or sulphur-based sprays (sulphur based can cause scorch on some plants in temperatures over 30 degrees celsius ). Most widely used fungicide is mancozeb. 

Reference : Kerruish, G-36

                     McMaugh, pg. 277

Disorder 1 - Fasciation in Dodonaea

This is an example of fasciation involving the flowering parts of this Dodonaea shrub found on the TAFE campus. 

Fasciation is a condition of plant growth in which the apical meristem (or growing tip - an area of undifferentiated plant cells found in buds and tips of roots, its main function to initiate growth in young plants at the tips of roots and shoots) becomes elongated perpendicular to the direction of growth. Normally, growth is focused around a singular point and produces cylindrical growth. In fasciated plants, the area of growth is flattened, fan shaped, ribbon-like or generally highly contorted. This can involve stem, root, fruit or flowerhead. 

Causes include a genetic mutation in the cells, bacterial infection, mite or insect attack, chemical or mechanical damage. Usually it is benign and can be left alone if tolerated. Pruning affected areas may or may not remove the condition in that area of the plant.

Reference : Wikipedia