Table Of ContentINTEGRATEDCROPPROTECTIONINCEREALS
TheExperts'GroupMeetingon.IntegratedCropProtectioninCereals'wasorganizedby:
CommissionoftheEuropeanCommunities
Directorate-GeneralAgriculture
incollaborationwith
GlasshouseCropsResearchInstitute
DepartmentofEntomology& InsectPathology
Proceedings ofaMeeting oftheECExperts'Group/Littlehampton
25-27November1986
INTEGRATED
CROP PROTECTION
IN CEREALS
Editedby
R.CAVALLORO
CommissionoftheEuropeanCommunities,JointResearchCentreofIspra
K.D.SUNDERLAND
GCR!,DepartmentofEntomology &InsectPathologyofLittlehampton
PublishedfortheCommissionoftheEuropeanCommunitiesby
A.A.BALKEMA/ ROTTERDAM/ BROOKFIELD/1988
Thetextsofthevariouspapersinthisvolumeweresetindividually
bytypistsunderthesupervisionofeachoftheauthorsconcerned.
Publicationarrangements:P.P.RotondO.CommissionoftheEuropeanCommunities,
Directorate-GeneralTelecommunications,InformationIndustriesandInnovation,Luxembourg
LEGALNOTICE
NeithertheCommissionoftheEuropeanCommunitiesnoranypersonactingonbehalfof
theCommissionisresponsiblefortheusewhichmightbemadeofthefollowinginformation.
EUR11525
Publishedby
A.A.Balkema,P.O.Box1675,3000BRRotterdam,Netherlands
A.A.BalkemaPublishers,OldPostRoad,Brookfield,VT05036,USA
ISBN9061918448
©1988A.A.Balkema,Rotterdam
PrintedintheNetherlands
Foreword
In 1985 the twelve European Communities Member States grew 31.5
million ha of cereals (52% of the total crop area) and the total expen
diture on pesticides to protect this area was 1,350 million ECU (~~
manufacturer), In spite of this expenditure, farmers experienced recurr
ing problems with pests (invertebrate pests, diseases and weeds). Tackl
ing these problems with still greater inputs of pesticides runs the
risk of selecting for pest organisms that are resistant to pesticides.
In addition, public concern about food contamination and damage to the
environment make an exclusively chemical solution to pest problems
politically unacceptable.
With over-production of cereals in the Communities and intervention
prices moving closer to world market prices, any solutions to pest pro
blems that involve reductions in variable costs will also be welcomed by
farmers. There is, therefore, considerable interest in making use of
biological, biotechnical and cultural pest control methods, in combi
nation with a limited and controlled use of pesticides. This is the inte
grated approach to crop protection, taking into consideration toxicolo
gical, economical and ecological aspects.
The aim of the meeting "Integrated Crop Protection in Cereals" was
to bring together, from the EC-Countries, specialists in many aspects of
integrated control, to exchange information, discuss and make recom
mendations for future research. Not all areas could be covered during
the meeting, but the 33 papers presented included the most important
recent developments in research into integrated control of invertebrate
pests, diseases and weeds, together with economic appraisals of applying
such research to model farming systems.
It is becoming clear from work on cereals aphids (Hemiptera: Aphi
didae) that forecasting schemes, natural enemies and partially-resistant
cereal varieties can all play a valuable role in the reduction of direct
damage and virus spread by these pests. Successful short-term forecasts
of peak aphid abundance may soon be possible. Use of this information,
together with economic thresholds, will enable farmers to spray in an
efficient and timely way against a threatening aphid attack but will, at
the same time, provide a sound basis for witholding such sprays on
accasions when they are economically unnecessary. The resulting reduc
tion of pesticide inputs will allow an increase in the numbers of the
aphid's natural enemies. These include parasitic Hymenoptera, pathogenic
fungi and many types of predator (more than 300 species of beetles,
v
spiders, mites, etc.). There is a growing body of evidence that such
natural enemies can maintain aphid populations below the economic thres
hold under a wide range of conditions. The frequency with which they are
successful in doing this is likely to be increased if the crop has some
degree of resistance to aphid reproduction (antibiosis) or increases
aphid movement (antixenosis), thus enhancing the encounter rate of aphids
with natural enemies. Work is underway to investigate the biochemical
basis of crop resistance to aphids and also to assess the potential of
resistance for reducing virus spread (especially barley yellow dwarf
virus in maize). There are also some first indications that the natural
enemies of aphids may playa part in reducing virus spread in some areas.
Because of the perceived importance of natural enemies, attention is
being given to the development of rigorous and repeatable methodologies
for evaluating the side-effects of agrochemicals on beneficial organisms.
Allied to this, research is being carried out on methods of mitigating
the deleterious effects of any pesticides that must be applied; these
methods include the use of low-dose pesticides and unsprayed headlands.
Similar approaches to those described above are being taken towards
control of the corn stalk borer, Sesamia nonagrioides (Lef.) (Lepidop
tera: Noctuidae), in maize. However, for this pest, there is also poten
tial for control by mass-trapping individuals lured into fields by sex
pheromones.
Some approaches to the integrated control of diseases are similar
to those employed for invertebrate pests (e.g; the use of forecasting
schemes and partially-resistant cereal varieties). Leaf spot (Septoria
tritici Rob. ~ Desm.) is spread by rain splashes which transmit spores
from the basal leaves upwards into the canopy. A system that involves
monitoring of inoculum levels before stem extension and the degree of
rain splash (using simple apparatus) between stem extension and anthesis
is showing potential for forecasting the need to apply fungicide sprays.
It is hoped that such schemes will, in the future, provide a rational
basis for reducing fungicide inputs without endangering the health of
the crop. Research on some diseases of more recent economic importance,
such as barley yellow mosaic virus, is concentrated, initially, on deve
loping reliable bioassays. Several diseases are transmitted through the
seed and there is still much work to be done (e.g. initiating certifica
tion schemes and seed treatment programmes) in some of the Member States
to improve seed health. Seed treatments can reduce the requirement for
foliar fungicides. This is advantageous in many ways; for example, it
has recently been established that some fungicides are sufficiently in
secticidal to disrupt biological control of pests in cereals. Many fo
liar diseases respond extremely rapidly to circumvent the effect of host
resistance genes and fungicides. A powerful approach to reducing the
severity of these problems is to increase the diversity of varieties and
fungicides on various scales, including the within-field scale. It was
found, for example, that, for plots of wheat inoculated with yellow rust
(Puccinia striiformis Westend), a single fungicide spray given to plots
of a varietal mixture (with different resistance factors) gave the same
VI
yield advantage as three sprays given to a susceptible monoculture.
Similarly, the yield of barley under attack by barley mildew (Erisyphe
graminis DC. f. sp. ~ was the same whether the seeds of one or
three components of a three variety mixture were treated with fungicide.
Treating just one component, however, will reduce not only costs and
environmental contamination but also selection pressure for fungicide
insensitivity. The principle of diversification for reducing the inciden
ce of barley mildew is also applicable on the European scale. Analysis
of the progeny of spores sampled along transects from France to Denmark
and from England to Austria, revealed distinct geographical patterns for
virulence against barley resistance genes and for resistance
to the principal fingicide active ingredients. Spore populations of any
given strain drift about 100 km per year, mainly from west to east on
prevailing winds. Therefore, given sufficient trans-national coordina
tion, a country about to be attacked by a particular strain, could be
ready to deploy the optimal varieties and fungicides against that
particular strain.
At present, chemical herbicides are very extensively used for weed
control. Although the study of biological control of weeds in cereals is
in its infancy, initial results are very promising. For example. the
pathogenic fungus Alternaria tenuissima (Kunze ~ Nees et Nees) Wilt
shire gave biomass reductions of velvetleaf (Abutilon theophrasti Medi
cus), comparable to that of several types of commercial chemical herbi
cide.
In the complex cereal agroecosystem, many interactions are possible
between the various measures taken to control invertebrate pests, diseas
es and weeds. In addition, cereals usually form part of a crop rotation,
and pest control measures taken on one crop can influence events on the
next. Acknowledging this dimension to pest control, long-term studies of
farming systems have been undertaken in England, in Germany and in the
Netherlands. These studies compare intensive farming systems. typified
by high inputs of fertilizers and pesticides (often applied prophylacti
cally), with supervised or integrated systems where pesticides are usual
ly only applied if an economic threshold is exceeded. In such studies,
it is not uncommon to find. in the intensive ~ystem, a progressive
reduction from year to year in the numbers of beneficial organisms.
accompanied by a greater severity of pest attack. Although yields are
usually greater for the intensive systems, variable costs are also
greater. Economic appraisals are showing that intensive systems are not
always more profitable than integrated systems.
It is hoped that publication of this volume will give some impetus
to the further development by researchers, and the adoption by farmers
of integrated methods of pest control.
The Commission of the European Communities are to be congratulated
for bringing together a group of specialists in this field and thereby
stimulating greater efforts in this important area of crop protection.
R. Cavalloro
K.D. Sunderland
VII
STRUCTURE OF THE MEETING
Scientific Committee
Cavalloro R. - C.E.C. - Joint Research Centre, I-Ispra
Sunderland K.D. - G.C.R.I. - Department of Entomology & Insect
Pathology, UK-Littlehampton
Wratten S.D. - Southampton University - Department of Biology,
UK-Southampton
Sessions' Organization
Opening Session Chairman: R. Cavalloro
Session 1 Pests Chairman: S.D. Wratten
Session 2 Diseases and Weeds Chairman: P. Lucas
Session 3 Farming systems Chairman: A. EI Titi
Closing Session Chairman: K.D. Sunderland
Local Secretariat
Miss Ruthanne Smith
Institute of Horticultural Research
Worthing Road
Littlehampton, West Sussex, BNl7 6LP
Proceeding Desk
Mr. Pier Paolo Rotondo
Commission of the European Communities
Directorate-General Telecommunications, Information, Industries
&Innovation
2920 Luxembourg
VIII
Tableofcontents
Openingsession
TowardstheEuropeandevelopmentofanintegratedandbiologicalcontrolincereals 3
R.Cavalloro
Welcomingaddress 9
KD.Sunderland
Session1. Pests
PresentstatusofcerealpestsinSpainwithspecialreferencetocerealaphids 13
P.Castaiiera
TowardstheintegratedpestcontrolincerealsinItaly 25
S.Barbagallo&L.Suss
Forecastingofcerealaphidabundance 33
AFGDixon,I.C.Entwistle& M'I'Howard
Potentialinteractionsbetweenvarietalresistanceandnaturalenemiesinthecontrol 41
ofcerealaphids
KD.Sunderland,R.J.Chambers& OCR.Carter
EffectsofhydroxamicacidsontheresistanceofwheattotheaphidSitobionavenae 57
SD.Wratten,D.Thackray,HNiemeyer&P.I.Edwards
ImportanceofMicrohymenopteraforaphidpopulationregulationinFrenchcereal 61
crops
AFougeroux,C.Bouchet,I.NReboulet&MTisseur
ThepotentialofTachyporusspp.(Coleoptera:Staphylinidae)aspredatorsofcereal 69
aphids
G.P'Vickerman,WDowie& KE.Playle
Acontributiontoacheck-listofStaphylinidae(Coleoptera)ofpotentialimportance 81
intheintegratedprotectionofcerealandgrasscrops
I.A.Good& P.S.Giller
Theoccurrenceofspidersincerealfields 99
AMFeeney& T.Kennedy
IX
