Pests and diseases

This page is intended to provide information about general approaches to pest and disease control (emphasising organic or low-toxic techniques) plus some information about some types of common pests and diseases of garden plants in Queensland.

For information on particular plants, go to the part of the site dealing with that plant or group. See: List of Plants

News

UQ a Part of RNA Revolution

Akin to vaccines for plants, RNA treatments have the potential to fight many different pests and diseases. A hurdle is delivery to appropriate sites within plant tissues. However, the University of Queensland has been developing a carrier technology they call BioClay™, which could help unlock the potential of double-stranded RNA (dsRNA) to provide safe and efficient plant protection. Whitefly is very troublesome because it not only sucks the sap of plants, but can also transmit viruses. What's more, it's difficult to control. However, the effectiveness of an RNA/BioClay spray against silverleaf whitefly has now been demonstrated, which UQ is hailing as a breakthrough. The whiteflies ingest the dsRNA, which attacks vital genes in the insects. By targeting genes specific to silverleaf whitefly, beneficial insects are not harmed. The next step towards making this a commercial product will be on-farm testing with industry partner Nufarm. Source: UQ research to revolutionise pest control around the world (May 2022)

More Online Information

General

Controlling Pests & Diseases - General

Some common types of pests & diseases

Older News

Delicious Dough

Researchers might just have discovered the cheapest, safest and most effective lure for slugs and snails yet. Observation of six species across three American states showed that bread dough - simply made with flour, water and yeast - was more attractive to the pests than a commercial bait or other food lures tested, including beer. Another benefit is that the dough can keep working for days. The exact reason for bread dough's allure to slugs and snails is not known, but is probably something to do with the fermentation process. Source: Slugs and snails, destructors of crops and gardens, could be controlled by bread dough (August 2021)

New Weapon in Woody Weed War

A more efficient way killing of weed trees has been developed by the University of Queenlsand in association with Gatton-based BioHerbicides Australia. A dry from of glyphosate is packaged inside a capsule which is inserted into the trunk with a specially designed applicator called the Injecta. Testing of the technology for the control of large Chinese elms growing in native vegetation along Franklin Vale Creek, near Grandchester, shows several advantages over the old methods. In the past, herbicide would typically be applied via cuts or holes in the trunks or over the stump. The capsule method uses less chemical with less risk of environmental contamination and is faster and safer for the operator. Less personal protective equipment is required and no chainsaws, axes or heavy backpack sprayers are involved. Source: Giant weeds slain by UQ innovation (July 2020)

Fire Ant Regulations Updated

Fire ants haven't been in the news much lately, but the threat hasn't gone away. The Queensland Government have recently amended biosecurity regulations, which includes changing movement controls from a 3-zone to a 2-zone system. Check the updated rules at the Qld Govt Fire Ants Portal. You'll also find more information about fire ants, how they spread and how to recognise them. (June 2020)

Cities scale up pest attack

Recent research recording the incidence in several American cities of a debilitating scale on a species of maple tree predicted larger insect populations in the warmer south than the cooler north. Instead, they found the amount of impervious concrete and asphalt in the vicinity of the tree was more strongly correlated with infestation levels than temperature. Source: Dying Trees in Cities? Blame It on the Concrete (March, 2019)

A wild defence

Wild tomatoes have some way of discouraging whitefly from settling on the surface of the plant, a study has shown. When pest was given a choice, they were 80% more likely to settle on the commercial variety 'Elegance' than wild type Lycopersicon pimpinellifolium. Such resistance is part of reason for popularity of wild and heritage varieties amongst home gardeners, but yields are too low for large-scale production. Researchers suggest returning some of these genes back into commercial varieties and emphasis the importance of preserving wild species. Source: Breeding wildness back into our fruit and veggies (February, 2016)

Clay sprays have potential

Kaolin (aluminosilicate clay) has been shown to have insecticidal properties in temperate regions, but this was largely untested in the tropics until Columbian researchers studied greenhouse whitefly on bean. They found that kaolin treatment was nearly as effective as synthetic chemical insecticides, Furthermore, a high application rate reduced transpiration and increased chlorophyll content compared to untreated plants, which could also make it useful in times of drought stress. Source: Kaolin effectively controls whitefly in beans (January, 2016)

Fighting plant disease with nanoparticles

Silver nanoparticles are an emerging new anti-fungal treatment for plants. Researchers in the USA have found that silver nanoparticles prepared with an extract of wormwood (Artemisia sp.) are effective against Phytophthora. They say that it works on all stages of the pathogen's life cycle without affecting plant growth. The multiple modes of action means development of resistance is unlikely. Source: Researchers Find a "Silver Bullet" to Kill a Fungus That Affects More Than 400 Plants and Trees. (May, 2015)

Sound as pest control

Test plants exposed to recordings of feeding vibrations later showed greater production of mustard oils when fed on by actual caterpillars. Other types of vibrations did not increase these chemical defences. Besides revealing new ways that plants interact with their environment, the research points to ways that natural defences might be stimulated by growers. Source: Plants Respond to Leaf Vibrations Caused by Insects' Chewing, MU Study Finds (July 2014)

Confuse-a-pest

Exposed complex mixture of plant aromas in a greenhouse of tomato plants, confused whitefly had trouble feeding in a UK study. The effect was temporary (no more than 15 hours), but could point to ways to delay attack until plant defenses can be activated. Source: Whitefly confused by cacophony of smells (April 2014)

Tarantula venom insecticide potential

University of Queensland (UQ) researchers have found a component of Australian tarantula venom that's highly toxic to some insect pests including cotton bollworm and termites. It's possible that new environmentally-friendly insecticides could be based on the discovery. Source: Spider venom to target insect pests (September 2013)

Study shows imidacloprid effects on honeybee larvae

An English study has shown that "a very low exposure" to imidacloprid (one of the neonicotinoid insecticides recently restricted in Europe) affects activity of some honeybee genes. The changes observed in larvae could reduce their ability to survive when additional stresses like disease or bad weather occur. Similar changes in gene activity reduce the life span of the well-studied fruit fly. Source: Insecticide causes changes in honeybee genes, research finds (July 2013)

APVMA response to European neonicotinoid ban

The Australian Pesticides and Veterinary Medicines Authority (APVMA) has published an updated (May 2013) outline of their review of these chemicals currently underway. Read it here: Neonicotinoids and honey bee health in Australia. A draft report for consultation is "mid-2013". (For more on the European ban, see news item below.)

Attracting predators with Alyssum

A Washington State University study in which sweet alyssum was grown near apple trees has shown a reduced incidence of wooly apple aphid due to the enhanced predator populations. Six different flowers including marigolds and zinnia were considered for the study, but alyssum was chosen because it attracted the most syrphids (hoverflies), the larvae of which feed on aphids. However, during the study few hoverfly larvae were found. rather, a diverse array of spiders and predactory insects appeared responsible for most of the aphid decline. Protein markers sprayed on the flowers and later identified on predators indicated they had indeed visited the flowers and so were presumably attracted by them. Source: Flower power fights orchard pests (May 2013)

Fire ant detection by air

From 1st May 2013, helicopters fitted with special remote-sensing cameras will recommence fire ant surveillance in the Brisbane region. With the help of computer analysis, the cameras use near-infrared and thermal imaging to locate nests from 500 feet. The work is done in the cooler months of the year, when the heat of nests can be most easily detected (Fire ants have no where to hide). Check the Aerial survey flight schedule 2013 online to see if there are upcoming flights in your area.

Europe to move on neonicotinoid ban

The European Commission looks set to proceeed with a controversial proposal to severely restrict the use of three neonicotinoid pesticides, on the basis of a threat to bees. Included in the group is imidacloprid, formulations of which are popular with home gardeners in Australia. According to the European proposal, home gardeners will not be able to use the chemicals at all. The proposal will be reviewed within two years. More information:
Bees & Pesticides: Commission to proceed with plan to better protect bees European Commssion media release
Bee deaths: EU to ban neonicotinoid pesticides BBC
Bees and the European neonicotinoids pesticide ban: Q&A The Guardian, UK
(April 2013)

Giant African Snail in Brisbane

A snail the size of a cricket ball was spotted at a Brisbane container yard and identified by Department of Agriculture, Fisheries and Forestry (DAFF) as a Giant African Snail. No evidence of other snails or eggs but follow-up surveillence will be conducted. These snails have the potential to wreck much damage if they establish in Australia, growing up to a kilogram in weight and able to attack hundreds of plant species. Source: Caught trying to escape at snail's pace (March 2013)

Beetle and bug battle baddie

A new biocontrol agent to fight cat's claw creeper is to be released in Queensland. Larvae of the the leaf-mining jewel beetle (Hylaeogena jureceki) from South America eat the plant's leaves. This species joins the leaf-sucking tingid bug in the fight against this Weed of National Significance. Source: Fighting nature with nature (October 2012)

Ladybirds aren't bluffing

The colour of ladybirds acts a warning to birds that they aren't good to eat. An Australian-UK collaboration has confirmed that there is indeed a relationship between the intensity of the red coloration and the toxicity of the insect, proving a definite incentive for predators to avoid the most brightly coloured individuals. Furthermore, producing the colour and taste comes at a cost to the ladybird and is affected by the quality of its diet. Source: I'm bright red and I taste foul - the message behind colour and the ladybird's spots (June 2012)