This article appeared in the August 2009 edition of the Kondinin Group’s monthly magazine Farming Ahead. The Kondinin Group holds the copyright on the article. Reproduction of this text in whole or part by any other publication or for any other cropping purpose is not permitted without permission of the Farming Ahead editor. For more information contact the Kondinin Group on (08) 6250 4555. pest control

Protecting germinating grain

photo: Andrew Weeks, cESAr consultants Weeks, Andrew photo: crops in southern Australia

More than 15 million hectares of crops such as cereals, oilseeds and legumes Louise are sown annually across Australia making cropping one of the country’s Lawrence largest primary industries. However, while annual Australian grain exports are For CSIRO ENTOMOLOGY worth more than $6 billion, growers spend several hundred million dollars each year on controlling invertebrate pests that attack emerging seedlings.

No control yet: The balaustium mite is found Crops are at their most vulnerable as in establishment pests. Redlegged earth across southern Australia and is a pest of seedlings, with canola seedlings being mite (RLEM), Halotydeus destructor, canola, cereals and lupins. There are currently the most at risk, while legume and cereal no pesticides registered for its control. resistance in southern Western Australia is seedlings are more resilient. It is east to one warning sign of this. see then, why control costs vary markedly The main invertebrates attacking between crops. emerging grain crops include mites, lucerne At a glance fl ea, slugs and beetles. For all crops, factors such as Controlling pests in emerging depth of sowing, seedbed Mites crops can be an expensive and The important mite pests in southern diffi cult exercise. fi rmness and environmental Australia include RLEM, blue oat mites conditions also affect (Penthaleus species), clover mite (Bryobia Different species require different praetiosa) and balaustium mite (Balaustium methods of control, with pesticide establishment. medicagoense). tolerance and susceptibility Pest feeding can kill seedlings or result in Earth mites varying widely among some poor crop density. This in turn leads to Earth mites (RLEM and blue oat mites) closely-related pests. increased weed competition, poor canopy are important establishment pests of many Integrated pest management structure, delayed fl owering, lower yields grains. They are widespread throughout (IPM) strategies can help control and, in some cases, the need for re-sowing. Victoria, South Australia, Western Australia pests but rely on an effective and While the recent shift to minimum or no- and Tasmania. RLEM is also present in southern New South Wales and blue oat effi cient on-farm pest tillage systems has helped conserve soil mites are present in northern NSW and monitoring programme. moisture and reduce wind erosion and fuel costs, it has also led to changes in the types southern Queensland. Understanding the biology of of pests in crops. Minimum tillage creates Earth mites are active in the cool, wet part pest species is essential for their micro-environments that suit both pest and of the year, between April and November. effective control. For example, in benefi cial organisms. For instance, no- Each mite can produce to two or three some species, the larval stage is tillage systems with stubble retention can generations and over-summering eggs most damaging, whereas in others favour slugs and snails. hatch during autumn. it is the adults. To avoid the need for pest monitoring and Earth mite species look very similar, to protect small profi t margins, growers which can lead to misidentifi cations and often use prophylactic pesticide applications incorrect management. Biology differs at sowing. But these broad-spectrum between species so growers need control pesticides also kill benefi cial species, which strategies that target them individually. could lead to secondary pests becoming an RLEM attacks a wide range of plants — increasing problem. Broad-spectrum pasture plants, fi eld crops, vegetables, pesticides also select for pesticide resistance broad-leaved weeds, fl owers — while blue

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oat mites are much more limited in their Clover mite host plants. Studying the differences in host Clover mite is from the economically- plant preferences enables cultural control important spider mite family. This mite is strategies, such as crop rotations, trap and widely distributed across southern Australia. border crops, and weed management, to be It damages canola and, to a lesser extent, developed. cereals. Clover mite can reproduce on Earth mites also differ in their tolerance lupins, wheat and pasture and can cause to pesticides. One blue oat mite species is significant damage to canola and lupins. highly tolerant of several pesticides and is Little is known about the life cycle of clover the cause of most chemical control failures. mite in Australia but adults probably go into It was recently discovered that RLEM is diapause during unfavourable conditions. resistant to synthetic pyrethroids. For Omethoate and bifenthrin are the only more specific information on effective pesticides registered for the control of these

Entomology C S IRO P hoto: RLEM control during spring, see Farming mites in Australian broadacre crops. Nasty: The redlegged earth mite attacks a wide Ahead March 2009, No 206 or go to Lucerne flea range of plants — pasture plants, field crops, www.farmingahead.com.au. vegetables, broad-leaved weeds and flowers. The lucerne flea, or clover springtail, Balaustium mite (Sminthurus viridis), has become a serious Balaustium mite found across southern pest throughout Mediterranean areas of Australia, is a pest of canola, cereals and southern Australia. It lives on the soil lupins. While its life cycle is unclear, other surface and feeds on leaves. closely-related mites go into diapause (a Lucerne fleas have two or three generations dormant state during an animal’s life cycle on mainland Australia between March and

onsultants that enables it to survive unfavourable November, sometimes more in irrigated conditions). The balaustium mite probably pastures. It over-summers as eggs that hatch produces at least two generations a season following cool temperatures and rain, and is active from March-December. around the same time as crop and pasture seedlings emerge. Lucerne flea populations No pesticides are registered peak during late autumn, when severe damage can sometimes necessitate re- for the control of this mite sowing, and decline through winter, peaking hoto: Andrew Weeks, C ESA R C Weeks, Andrew P hoto: and it appears that many of again during spring with the onset of warm, Wide-spread: The clover mite is found across moist conditions. southern Australian and damages canola those registered for earth and cereals. Lucerne flea is primarily controlled using mites are ineffective. organophosphates. However, in the

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laboratory, lucerne fl ea is much more tolerant is the surface application of baits formulated than RLEM to several organophosphates with metaldehyde or methiocarb. Application and synthetic pyrethroids. Under laboratory needs to coincide with the moist conditions conditions, methidathion was the most that make slugs active. New molluscicides effective against lucerne fl ea. using iron and copper as the active toxins will lessen the effects on non-target Slugs invertebrates. However, chemical control In the high-rainfall areas of southern alone will not eliminate slugs where stubble Australia, where stubble retention is is retained. becoming increasingly popular, herbivorous Cultivation and burning directly confl ict slugs are increasingly prevalent. During the with minimum-tillage and stubble retention. Australian summer, slugs remain dormant This highlights the need for integrated in moist refuges and reproduce whenever approaches to slug control, such as rolling the conditions are suitable. photo: cSiro Entomology cSiro photo: after sowing to consolidate the seed bed, a Resistant: The blue oat mite is highly tolerant There are two main slug pests of Australian practice gaining some acceptance in of several pesticides and is the cause of most grain crops: black keeled slug (Milax gagates) Australia. Generalist predators may control chemical control failures. and reticulated or grey fi eld slug (Deroceras slugs in some minimum-tillage systems reticulatum). Reticulated or grey fi eld slug and grasslands adjacent to crops provide starts breeding during autumn and peaks effective refuges for beetle predators. during spring. It is surface active and requires moist places to hide. The black Beetles keeled slug, a burrowing species, is adapted Among the beetle pests of cereal crops are to drier environments. Its juveniles are the bronzed fi eld beetle (Adelium brevicorne), generally prevalent from late winter. grey false wireworm (Isopteran spp.) and Winter cereal damage ranges from vegetable beetle (Gonocephalum misellum). hollowed grain, which prevents germination, Several weevils, in particular, vegetable to grazing on seedlings. Emerging canola weevil (Listroderes diffi cilis) spotted vegetable cotyledons are particularly susceptible. weevil (Steriphus diversipes) and mandalotus Slugs are active when it is cool and moist weevil (Mandalotus spp.) are also signifi cant and crop growth is slow. Differences in pests though their prevalence differs across biology between species can affect control regions and crops. photo: Andrew Weeks, cESAr consultants Weeks, Andrew photo: options and chemical effi cacy. For example, Serious threat: The lucerne fl ea is a pest of black keeled slug is more tolerant of Vegetable weevil signifi cant concern across the Mediterranean conventional molluscicides. The most The vegetable weevil is found in all States areas of southern Australia effective control option at crop establishment and Territories. While adults and larvae feed

52 Farming Ahead August 2009 No. 211 www.farmingahead.com.au cropping pest control photo: John coppi, cSiro John coppi, photo: cSiro John coppi, photo: Mcclenaghan, cSiro David photo:

Slippery pest: Slugs are active during cool, On display: A tray of weevils that form part of the Australian National moist conditions when crop growth is slow. Insect Collection.

on a wide range of plants, canola is the only blanket sprays. Decreasing host weeds in feeding damage from adults has been grain crop where feeding damages seedlings. paddocks can also reduce numbers. observed in canola. They can be controlled These weevils, which produce one Spotted vegetable weevil through desiccation of weeds in paddocks generation per year, lay eggs on plants or the The spotted vegetable weevil is found in before sowing. Seed dressings can also soil surface from mid-March–September. all States except the Northern Territory. reduce larval-feeding. Larvae feed on leaves and pupate in the soil. Their eggs, probably laid in the soil, hatch Mandalotus weevil Adults emerge between September and when there is suffi cient moisture for seed October, and go into diapause during the germination. Larvae burrow under the soil Mandalotus weevils have been recorded hotter months. to feed on grasses, cereals and capeweed. in the Mallee districts of South Australia Most damage is along crop edges or where Adults emerge from spring through to and Victoria, parts of southern NSW and on host weeds are present in crops. They can be early summer. the Yorke and lower Eyre Peninsulas of controlled using a border spray at crop Cereals only suffer economic damage South Australia. Several species can cause emergence without the need for disruptive from larvae when numbers are high. Some economic damage to germinating crops.

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There is probably one generation per year The limited uptake of IPM for canola have shown that these non-crop of mandalotus weevils with larvae present establishment pests has several causes. For landscape components can be managed to in the soil during October and November. a start, broad-spectrum insecticides are easy enhance pest control. For instance, These weevils damage germinating canola to use and cheap. Then there are a number shelterbelts with ungrazed groundcover and, to a lesser extent, cereals, peas, lupins, of complicating issues. The skills and harbour benefi cial organisms that suppress beans, vetch and medic pasture. In canola, training needed to identify and monitor RLEM, blue oat mites and lucerne fl ea in they feed on leaves and can also cause above both pest and benefi cial species are lacking adjacent paddocks. Cleared or grazed ground ring-barking. and there is little information on economic understories do not. thresholds for invertebrate pests. As yet Other establishment pests ‘proven’ alternatives to broad-spectrum Putting a plan into action Other common invertebrate pests of chemicals are few and some establishment Developing an IPM programme is only the germinating crops are cockchafers (for pests are sporadic. Added to that are low start. It must then be successfully example, blackheaded pasture cockchafer), grower confi dence in IPM and low margins implemented. One essential is an effective cutworms (common cutworm), snails in some grains. and effi cient on-farm pest monitoring (vineyard snail) and earwigs (European programme. Effective extension of research The heavy reliance on broad-spectrum and earwig). Their impact varies between areas has underpinned IPM adoption in persistent pesticides at crop emergence is a and seasons and they are generally regarded horticulture and cotton. problem for IPM as this is likely to disrupt as minor or sporadic pests. vital natural enemies. Alternative strategies Demonstration trials and Challenges for IPM strategies that could be used in IPM include selective While many growers are using or ‘soft’ chemicals and the use of seed training workshops were management practices that would fi t dressings. It is, however, essential these also important. The grains comfortably into integrated pest management measures are cost effective. The imminent (IPM) strategies, implementation of IPM introduction of transgenic crops with industry can learn from this. across the whole of the grains industry in increased host resistance in the Australian Australian grain growers are facing southern Australia remains a challenge. For grains industry could be an important IPM increased international competition and so a start, more information is needed on many tool but they must be used wisely. food safety and pesticide residue issues are of the key establishment pests and their Tailoring IPM to the landscape important. As a result, restrictions on natural enemies. IPM strategies also need to include the pesticide use have become more stringent. The primary aim of IPM-suitable cultural effects of agricultural landscapes. There is This, combined with resistance to pesticides control practices is increased crop yield but limited information on the role of features in some species and increased awareness of they could also help in decreasing pests. such as remnant vegetation, shelterbelts environmental issues, has become a driver For example, controlling weeds lowers and native grasslands in managing crop for IPM. Avoiding prophylactic sprays, competition with crop plants but also establishment pests. However, studies on implementing monitoring programmes that eliminates breeding sites for some pests. grass strips and shelterbelts adjacent to correctly identify pests and careful assessment of ‘non-target toxicity’ will result in control measures that drastically reduce negative impacts on natural enemies. These have become drivers for a move towards IPM. Whenever and wherever IPM strategies are developed, they will need to be fl exible so that they can be modifi ed to include new pests, novel cropping systems and cropping in new regions.

ACKNOWLEDGEMENTS This article on ecosystem services is a summary of a paper by Svetlana Micic, Ary Hoffman, Geoff Strickland, Andrew Weeks, Judy Bellati, Ken Henry, Michael Nash and Paul Umina on Pests of germinating grain crops in southern Australia: an overview of their biology and management options which appeared in the Australian Journal of Experimental Agriculture 48 (12): 1560–1573. It is one of a suite of papers published in this special edition of the journal. Svetlana Micic and Geoff Strickland are from the Department of Agriculture and Food, Western Australia (DAFWA), Ary Hoffman, Andrew Weeks, Michael Nash and Paul Umina are from the Centre for Environmental Stress and Adaptation Research (CESAR), The University of Melbourne and Judy Bellati and Ken Henry are from the South Australian Research and Development Institute (SARDI). CSIRO research

CONTACT Svetlana Micic, DAFWA (08) 9892 8444 [email protected]

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