Pest management in cereals and oilseed rape – a guide Autumn 2003 Contents BYDV vectors 4 Grey field slug 6 Gout 7 The impact of pests on yield and quality can be more variable than that of many diseases. bulb fly 8 However, they do pose a serious threat to UK crops and can reduce yield by 10% or more, Yellow cereal fly 9 sometimes much more. Wireworms 10 With increasing concerns about the environment, there is a need to balance pest Leatherjackets 11 control against encouraging other which Summer aphids 12 can actually benefit the crop. Orange wheat blossom midge 13 Integrated strategies seek to use cultural control options, encourage natural enemies and only use Peach-potato aphid 14 crop protection methods when they are fully justified – usually by the use of thresholds. Cabbage aphid 14 Developing such strategies depends on a sound Cabbage stem flea beetle 15 understanding of pests, their life cycles and their natural enemies.This guide brings together the Other flea beetles 16 latest knowledge from research funded by Defra and HGCA. Wessex flea beetle Turnip flea beetle Jon Oakley, a leading entomologist, has gathered here information that will be invaluable to Large striped flea beetle growers who seek to minimise pest damage, Pollen beetle 17 maximise the marketability of their crops and enhance the environment on their farms. Cabbage seed weevil 18 Brassica pod midge 18 Other pests 19 Frit fly Thrips Professor Graham Jellis Saddle gall midge Director of Research HGCA Rape winter stem weevil Cereal ground beetle Cabbage stem weevil The Home-Grown Cereals Authority (HGCA) has provided funding for some of the projects on which this guide is based but has not conducted the research or written this guide. While the authors have worked on Biological and cultural control 20 the best information available to them, neither the HGCA nor the authors shall in any event be liable for any loss, damage or injury Further information 23 howsoever suffered directly or indirectly in relation to the booklet or the research on which it is based. Front cover: Gout fly and parasitoids on wild flowers Reference herein to trade names and proprietary products without in a field margin. stating that they are protected does not imply they may be regarded as pest management in cereals and unprotected and thus free for general use. No endorsement of named oilseed rape – a guide products is intended, nor is any criticism implied of other alternative, but unnamed products.

2 Effective pest control ➤ Assess the risk of infestations. ➤ Minimise pest risk by cultural means. ➤ Maximise the effects of natural enemies. ➤ Only use treatments if economically justified.

General principles of pest management

For pests Yes Order that seed Have these seed treatments pests caused Yes treatment may control damage in Has risk (eg cabbage previous No of pest stem flea beetle, crops? increased? wireworm, No Do not use seed wheat bulb fly) treatment

For pests Yes Plough early, or use desiccant that Does cultivations previous crop BEFORE SOWING may control or stubble (eg green bridge regrowth No BYDV, increase risk? leatherjackets, frit fly)

Do slugs pose Yes Sow deeper and Monitor a particular roll after sowing using traps threat? Control (eg is there a of slugs history of slug Yes Apply problems, does Are slugs above molluscicide the weather threshold? No No

EMERGENCE favour the pest?) FROM SOWING TO SOWING FROM

Consider Monitor for No Will pest levels Yes treatment at pests that Is there a exceed correct timing affect growing risk of threshold? No crops imminent (eg pollen beetle, attack? No

AFTER Are natural wheat blossom Yes midge, gout fly) enemies present? EMERGENCE No Yes

3 BYDV VECTORS BYDV

Two different aphid species transmit yellow dwarf luteovirus (BYDV) to cereals and grasses in the UK. Very low populations, which may go unnoticed, can cause economic damage.

In autumn most aphids probably come from grasses, especially perennial ryegrass.Virus may also come from other cereal crops and volunteers.

Grain aphid Bird cherry- aphid Sitobion avenae Rhopalosiphum padi

The aphids may be green, The aphids are green to red or brown with black dusky brown with rust red legs. patches at the rear.

Transmits: The MAV and Transmits: The PAV and PAV strains of BYDV. RPV strains of BYDV.

Economic importance Economic importance

The grain aphid is the main and northern Britain. Losses can The bird cherry-oat aphid is the west England and in warm BYDV vector in eastern, mid be up to 2.5 t/ha. main vector of BYDV in south- autumns elsewhere.

Risk factors Risk factors Winter crops: In mild winters Spring crops: After mild Winter crops: Crops sown Spring crops: After mild significant spread may occur in winters BYDV may be early,particularly in a warm winters BYDV may be any crops exposed to transmitted to late-sown crops autumn, are most susceptible to transmitted to late-sown crops migrations of the winged by winged aphids. bird cherry-oat attack.These by winged aphids. aphids.These can continue into conditions allow aphids to breed November and infect later sown rapidly before frosts kill them. crops.

Life cycle Life cycles

The grain aphid is mainly 50% of the aphids) of -8ºC. The asexual strain The sexual strain asexual feeding on cereals and Grain aphids survive on crops – overwinters on cereals – overwinters as eggs on bird grasses all year round.The aphid through most winters. Numbers and grasses. cherry trees. is more frost-resistant than the increase during mild spells Aphids are frost-susceptible, the Most wild bird cherry trees are bird cherry-oat aphid with a when further BYDV spread LT50 being -0.5ºC. In colder found in northern Britain LT50 (lethal temperature for may occur. winters survival of this strain is although they occur across restricted to milder coastal the UK. districts. Eggs of bird cherry-oat aphid are very frost-resistant. Bird cherry trees are not infected by BYDV,so spring migrants are initially virus-free. Aphids of the sexual strain do not transmit BYDV within winter cereal crops.

4 BYDV VECTORS

Both species

Natural enemies

Ground beetles and spiders may attack aphids in the autumn and Grass banks and grassed field margins may assist predator survival, winter and parasitoids can be active in mild weather. Minimum tillage but can also harbour infective aphids. Grassed areas should be leaves more predators, but increases the risk of ‘green bridge’ transfer. considered in large arable fields of 20 ha or more.

‘Green bridge’ transmission Warm, moist soil conditions facilitate aphid movement through weedy stubbles to new cereal crops.The aphids can feed on new soil.‘Green bridge’ transmission is most likely in south-west crop roots, and transmit virus directly without appearing above England, on early-sown crops and in mild, damp autumns. ground level to provide a control opportunity. Any cereal aphid Aphids can transfer directly from grass or ploughed-down grass or species present may transmit virus – often the RPV strain of BYDV.

Cultural control

1. Clean stubble before preparing seedbed. 2. Leave at least five weeks between ploughing and sowing the new crop. 3. Consider applying a desiccant herbicide if cultivation to sowing interval is less than five weeks. 4. Delay sowing by a week to reduce BYDV spread by up to half. 5. Choose a moderately resistant spring barley variety (see HGCA Recommended Lists) if growing crops after mild winters or in milder districts.

Chemical control

Applying a seed treatment incorporating Spray timing imidacloprid (Secur) can provide about six BYDV starts to spread within the crop 1. Calculate ‘T sum’ by subtracting 3ºC from weeks’ protection, less at very low seed when the second wingless aphid generation the daily mean temperature and adding rates. It may not replace the need to spray. emerges. Spread, initially slow, accelerates as the result to the running total. In mild seasons the threat of aphid the third wingless aphid generation 2. If ‘T sum’is 170 (second generation could infestation may continue through the winter. appears. Aphid breeding is governed by be starting) A pyrethroid spray will kill most wingless temperature, so a ‘T sum’system of – consider a tank-mix insecticide if aphids. accumulated day degrees above 3ºC can be treating the crop for another purpose. Chemical control is ineffective on spring- used to predict best spray timings. 3. If ‘T sum’is 340 (significant spread sown crops. Temperature accumulation should be imminent) started from: – apply a spray treatment as a priority. Action thresholds six weeks after sowing for imidacloprid- A crop should suffer little yield loss from No satisfactory thresholds for treatment treated crops fresh BYDV infection after GS 31 or after a exist. date of emergence for other crops prolonged cold period. A month with mean one week after application for pyrethroid- daily temperatures below 5ºC will severely treated crops. reduce grain aphid survival.

An example of the effect of date of crop emergence on need to spray in a mild winter

26 Nov Early emerged crops are most at risk of BYDV infection. Decisions on whether to 19 Nov t n treat crops emerging in September must e ix be made by the start of October. The 12 Nov treatment window is wider for later- tm m emerging crops. 5 Nov a k e 29 Oct r tan Use ‘T-sum’ (see above) for specific t locality. 22 Oct o n rity 15 Oct 8 Oct high prio Date of crop emergence Date of crop 1 Oct 24 Sept 17 Sept too late Sept Oct Nov Dec Jan Feb Mar Month

5 CEREAL & OILSEED RAPE PESTS Grey field slug Deroceras reticulatum

Many slug species are found in arable fields. Only the grey field slug is of economic importance on cereals and oilseeds.

The grey field slug is mottled grey and of medium size.

Economic importance Chemical control Slugs are most damaging to the four true-leaf stage (GS 1.4). Slug pellets are effective at the soil surface for 4–7 days, but only kill seeds and seedlings. Cereals are After these stages slug grazing actively feeding slugs. In mild, damp weather pellets only kill a vulnerable up to the fourth leaf does not generally threaten proportion of sexually active mature slugs. Juveniles often escape as stage (GS 14); oilseed rape to plant survival. they remain in the soil. Pellets have limited impact. Damage may resume within a month or, if conditions improve, weeks of treatment. Risk factors Action thresholds All cereal and oilseed crops, Such conditions allow access to Action thresholds for cereals are The threshold applies to particularly if grown on heavier, seeds and germinating seedlings based on slug numbers caught cereal crops. Slightly lower wetter soils and sown in loose, and also favour slug survival. in refuge traps – before or after numbers are probably worth cloddy seedbeds, are vulnerable. treatment. These can be made controlling in oilseed rape. from plant pot saucers or tiles, Trapping, and treatment if the Natural enemies baited with layers mash, or threshold is exceeded, is proprietary mats can be generally advised: Several predators eat slugs. purchased. Catches reflect before sowing if the field has Ground beetles are probably the numbers of slugs active on the a history of slug damage most common in arable fields. surface, not in the soil.Traps before sowing if wet weather only give useful information delays sowing in a prepared when mild damp night seedbed conditions encourage activity. following sowing if seedbed A catch of four or more slugs tilth is poor and further a trap generally justifies consolidation is not possible Cultural control treatment, provided conditions the crop is slow to emerge or remain favourable. to grow to GS 1.4 and when Cultivation in dry conditions consolidation prevents access to damage is visible. leads to physical damage and seed as well as encouraging desiccation. seed-to-soil contact, and rapid Cereal seed should be sown at germination. A Cambridge roller least 12 mm deep. For all is suitable. combinable crops soil Life cycle

There are two generations each year.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Distinct spring (and autumn) Distinct autumn (and breeding peaks lead to two spring) breeding peaks overlapping generations at any time. lead to two overlapping generations at any time.

The grey field slug breeds year round exploiting any mild, damp periods. Mature adult slugs each lays up to 500 eggs.Typically many eggs and young slugs die from desiccation which keeps populations stable. If weather conditions are particularly favourable and mortality low, populations may increase to very high levels. Slugs feed opportunistically on a wide range of plant material changing from male to female as they mature.They are inactive in unsuitable conditions and resume feeding in mild, damp, still weather.

6 CEREAL PESTS Gout Fly pumilionis

Larvae feeding in stems cause a ‘gouted’ appearance – swollen main stem and primary tillers with leaves puckered and torn above. In winter crops, damage is first seen in December, but mainly in January/February. Infested spring- sown crops show damage in June and July which prevents ear emergence from the flag leaf. Upper surface black with yellow beneath, Damage tends to be highest in sheltered fields three black stripes on thorax. near woodland.

Economic importance Cultural control

The pest is present across the tillers, with a developed crown Sow winter wheat and barley Sow spring crops as early as UK, but only causes economic root system can survive and in sheltered fields near practicable in areas where damage from the south coast to compensate for damage at lower woodland after late damage is prevalent. the midlands in wheat, barley levels of incidence.Where half September. and triticale. Incidence appears the crop or more is damaged, to be moving north. In 2002, yield losses range from 0.25 high levels of damage were seen tonnes/ha to total crop failure. Chemical control in early-sown crops as far north Shoots damaged by spring Chlorpyrifos and pyrethroid as Staffordshire and Lincolnshire. generations lose 30% of grain insecticides, used to control frit Winter damage kills affected yield on average. Late-sown fly and BYDV vectors tillers and any still dependent on crops suffer losses up to half of respectively, will give useful the mother plant. Unaffected their potential yield. control of the autumn generation where sprays are Risk factors applied before eggs hatch. In 2002, treatments after early Crops emerged by the end of south of England, late May in October were ineffective. September are at greatest risk the midlands. Crops at, or from the autumn generation. beyond, GS 37 by this time Action thresholds Late-sown winter and spring suffer little damage. Limited evidence suggests that crops are at greatest risk from are immune, but gout fly treatment is economic in winter the spring generation. Egg-laying can attack couch grass. crops if eggs are found on more commences in mid-May in the than half of the plants at GS 12. No threshold exists for spring- Larvae feed by secreting Natural enemies sown crops. enzymes to break down surrounding tissues.This causes Larvae of the parasitoid wasps, no obvious damage to shoots. Stenomalus micans and As the stem extends this break Coelineus niger, feed inside the develops into a line of damage. gout fly larvae.They can kill 80% or more of gout fly larvae. Adult wasps are active slightly later than gout and could be vulnerable to late insecticide applications. Stenomalus micans Life cycle

There are two generations each year.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Larvae Larvae Pupation Adult flies Larvae Larvae Adults shelter in Larvae feed. Adult flies feed. pupate in hatch. Eggs crawl into pupate hatch wooded areas and stem. laid on leaf sheath in leaf before hedgerows. uppermost and feed on sheath. harvest. Eggs laid on unfurled leaf sheath upperside of first leaf and beneath unfurled leaf. hatch in ear. 7–10 days.

7 CEREAL PESTS Wheat bulb fly Delia coarctata

Wheat bulb fly larvae attack shoots of wheat, barley and from January to April.They bore into plants, feed at the shoot base and eat through the central leaf which dies, causing the classic deadheart symptom. Larvae lack legs and are white to pale yellow with a blunt tail end.

Economic importance Chemical control

Yield loss depends on tiller destroyed.Well-tillered crops Tefluthrin seed treatments are density at the time of attack. generally withstand up to 100 effective with later sowings, but Crops still at the single shoot larvae/m2 without economic may not fully protect earlier- stage in February are most impact on yield. sown crops. Drill treated seed vulnerable and may be totally no deeper than 40 mm. Chlorpyrifos egg hatch Risk factors sprays are applied between the Egg start of egg hatch in January All cereals, except oats, can be crops (eg vining peas) if and its peak in February or attacked.Adults fly up to half a cultivated between mid-July March. Egg hatch is monitored mile from previously-attacked and mid-August each year to provide fields to lay eggs. They lay eggs row crops, eg sugar beet, information on timing and the on stubbles after cultivation and potatoes and onions but not need to add, or switch to, prefer freshly-turned soil. Under brassicas. dimethoate for later sprays. hot, dry conditions they lay eggs Frequency of attack depends on Dimethoate is applied when between row crops, especially if the population of vulnerable first deadhearts first appear in Larva hatching the foliage is wilting. on the farm: March. It should be applied Eggs may be laid on: more than 25% – regularly before larvae move off to attack bare soil following fallows, 10–25% – occasionally other shoots in late March. Plant samples may be set-aside, or early harvested less than 10% – rarely. examined to determine Action thresholds numbers of larvae present Natural enemies Egg numbers can be estimated when deadhearts are first The main egg predators are Aleochara bipustulata may from soil samples. Each year found. Stripping off the outer ground beetles and their larvae. parasitise the pupae, and kill up ADAS forecasts (available leaf sheath can reveal a brown Small rove beetles, particularly to 50% of them. through Dow*) the proportion stain where larvae are feeding. of fields likely to exceed A small entry hole in the leaf Cultural control threshold levels: sheaf confirms that a larva has above 5 million eggs/ha – entered.The thresholds assume Avoid cultivating fields destined Early sowing reduces the damage inevitable, extra plant populations of at least 200 for wheat in late July and early impact of wheat bulb fly, but measures needed plants/m2: August.This reduces numbers of increases survival of larvae and 2.5–5 million eggs/ha (sowing 10% tillers attacked @ GS 20 eggs laid, especially if fields for numbers on the farm the next Sept–Oct) – damage likely 15% tillers attacked @ GS 21 oilseed rape, and other non-host year. less than 1.25 million eggs/ha 20% tillers attacked @ GS 22 crops, are worked at this time. (sowing Nov–Mar). Late sown onwards. crops may suffer damage.

Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Larvae hatch and invade shoots of Adults feed on Eggs laid on wheat, rye and barley. saprophytic fungi on bare soil host plants. and Larvae attack 3–5 Larvae between further shoots. pupate at base of row crops. Overwinters as eggs. plants.

* Dow AgroSciences Technical Hotline – 0800 689 8899

8 CEREAL PESTS Yellow cereal fly Opomyza florum

Yellow cereal fly, like wheat bulb fly, causes ‘deadheart’ as larvae enter through the top of the shoot.The yellow cereal fly larva does not leave an entry hole; wheat bulb fly larva does.The larva, yellow and with a pointed end, looks similar to frit fly, but occurs later in the winter.

Economic importance Cultural control

Each larva damages only a single withstand a considerable Establish at least 200 shoot so economic impact is number of larvae by producing plants/m2 in vulnerable generally low. Most crops can compensating tillers. situations.

Risk factors Chemical control Crops at low plant populations sheltered fields close to Pyrethroid sprays applied to Action thresholds and early-sown crops in woodland are at greatest risk. control BYDV vectors also No action thresholds have been control yellow cereal fly. established. Natural enemies No treatments are recommended once larvae have The eggs and pupae are the predation by ground beetles. entered plants. most vulnerable stages to

Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Eggs overwinter. Adult flies hatch. Flies move to early- sown wheat crops in Eggs hatch. Adults spend the summer in late September. Larvae enter and feed on wheat shoots. woodland. Larvae Eggs are Eggs overwinter. leave the laid at the shoots to base of pupate in plants. soil.

Arable and cropping and the environment – a guide assesses how any one management decision affects all other decisions in an integrated cropping system.

9 CEREAL PESTS Wireworms Agriotes lineatus Agriotes obscurus

Wireworms are the larvae of click beetles. Yellow larvae with distinct legs at the front and two dark spots at the tail, bite into stems at the soil surface causing a hole with tattered edges. By the time this is evident, wireworms have usually moved along rows to attack further shoots.

Economic importance Cultural control

Wireworms have become a cereal/ley rotations. Heavy Consolidate seedbeds to Consider including a spring more serious pest since the infestations can cause yield loss restrict movement. crop in the rotation. withdrawal of organochlorine of up to 0.6 t/ha in cereals. Control grass weeds. insecticides and the increase of Peas, linseed and flax are winter cropping.They can now more tolerant of damage than affect all winter cereal or winter other crops. Chemical control

Risk factors Seed treatment with tefluthrin Action thresholds or imidacloprid controls Populations can be very patchy Crops at highest risk are sown predominant winter cropping, moderate attacks. so estimating numbers is within two years of ploughing particularly with grass weeds, is difficult. Examining soil cores in out permanent pasture. at risk. the field for larger wireworms or However, any rotation with in the laboratory for smaller ones is costly and rarely Natural enemies justified. Use a seed treatment if The main natural enemies are wireworms exceed the fungi and parasitic wasps. threshold of 750,000/ha. Some residual damage is likely if numbers exceed 1.25 M/ha.

Life cycle

Wireworms have a 4–5 year life cycle.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Adults active. Adults active. Egg laying.

Larvae feed. Pupae

Adult click beetles cause no economic damage.They live for about a year and lay eggs in grass fields. Larvae then feed for five years before pupating in the spring. Numbers increase over the years; highest populations occur in old permanent pastures.Wireworms feed in ploughed-down turf for about six months before moving to the surface to damage the next two crops.

10 CEREAL PESTS Leatherjackets Tipula paludosa Tipula oleracea

Leatherjackets (grey, legless larvae of cranefly, or daddy longlegs) feed below the soil surface making stems at the surface appear ragged. Stems break and keel over. Wireworms and other minor pests cause similar effects.

Economic importance Chemical control

Yield losses can range up to total infestation levels. Loss depends Chlorpyrifos is the only crop loss at the highest mainly on September rainfall. approved chemical.

Risk factors Action thresholds Assess leatherjacket numbers, Attacks on all cereals and move to feed on the new crop. before ploughing, by oilseeds frequently occur This leads to damage suddenly examining soil samples or following grass, where appearing some weeks after flooding plastic pipes, driven populations build up.Adults do crops emerge. into the ground, filled with not fly far and infestations take Dry September weather can brine. Proprietary brine-based some years to develop. Larvae reduce numbers considerably as testing kits are available. continue feeding in ploughed eggs and young leatherjackets Assess leatherjacket numbers, down turf.When it rots they are vulnerable to desiccation. in established crops if damage is seen, by scratching soil Natural enemies either side of crop rows. Treat with chlorpyrifos if: A range of viral, bacterial and • over 50 leatherjackets/m2 for protozoan diseases attack spring cereals (5 in 12 pipes) leatherjackets. Rooks are • 5 leatherjackets/m of row in A plastic pipe driven in the attracted to patches of spring cereals. ground is filled with brine. leatherjacket damage and may Lower levels may cause indicate infestations. Predatory significant damage in spring soil insects, eg ground beetles, oilseed rape and linseed. eat eggs and young larvae.

Cultural control

Plough early before most eggs are laid to reduce carry-over.

Life cycle

Two species cause economic damage.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Tipula paludosa Larvae Pupae Adults Larvae Larvae emerge. pupate near soil Flying adults lay eggs. Eggs scattered on surface. soil surface, mainly Eggs in grassland. hatch.

Larvae feed in winter whenever soil temperatures at night exceed 5ºC.

11 CEREAL PESTS Summer aphids

Grain aphid Rose-grain aphid Sitobion avenae Metopolophium dirhodum

The aphids may be green, The aphids are green with red or brown. a dark green strip along the body.

Life cycle Life cycle

The grain aphid spends all year winters which reduce natural The rose-grain aphid These aphids remain on the on cereals and grasses and may enemies more than the more overwinters as very frost hardy leaves and do not move up to overwinter on winter cereals cold-hardy aphids. eggs on roses. It migrates to the ear. (see BYDV vectors). Fresh Initially, grain aphids feed on crops in spring. migrations infest crops from April leaves. During grain filling they Rose-grain aphids are onwards. move up to ears and feed from susceptible to all grain aphids’ Colonies overwintering on the phloem supply to grain. natural enemies, so do not crops tend to be infested by Numbers increase most rapidly thrive in crops already parasitoids. Grain aphid during settled, dry weather.They colonised by grain aphids.After numbers may rise initially, but will increase until checked by hard winters when both grain the parasitoids limit further crop senescence, unless reduced aphid and natural enemies are population increase. Outbreaks by heavy rainfall or natural scarce, rose-grain aphid may tend to occur after colder enemies. cause problems. Both species

Economic importance Cultural control

Yield losses can reach 4 t/ha, exceed threshold levels. Only Measures, such as grass strips, grass mixture are less likely to but losses of 0.25–1 t/ha are very severe infestations produce proposed to increase natural harbour pests and will more usual where populations visible symptoms in crops. enemies of crop pests, can encourage parasitoids and provide harbourages for aphids. hoverflies. Risk factors Wildflower strips with diverse All cereals are at risk.Winter eg drought-affected crops or Natural enemies barley is less affected due to its crops damaged by other pests earlier senescence. Impact is and diseases. Dry settled weather greater where soluble stem during early grain filling carbohydrate reserves are low, increases the risk.

Chemical control Pyrethroids are the main choice Action thresholds to control ear infestations, but Treatments should only be are less effective on earlier considered if aphid numbers are infestations on the undersides increasing. Spray when: of leaves. Pirimicarb provides 50% tillers infested before more selective control of GS 61 aphids.Additionally, it has a 66% tillers infested from Specific to aphids Polyphagous predators vapour action which penetrates GS 61 to two weeks before Parasitic wasps, hoverflies, Ground beetles, soldier beetles, further into the crop. the end of grain filling. lacewings, ladybirds are rove beetles, spiders may help to attracted to aphid infestations mop up low numbers early in the and can provide control of season, thus slowing potentially damaging numbers. development. Some fungal diseases are also specific to aphids.

12 CEREAL PESTS Orange wheat blossom midge Sitodiplosis mosellana

The orange-coloured larvae feed on wheat, barley and rye grain during grain filling. Larvae are up to 3 mm long.They lack legs, but have a prominent head capsule. Adult midges, also orange, and about 3 mm long, are found during ear emergence.They rest at the crop base during the day and fly up to the ears in the evening to lay eggs.

Economic importance Cultural control

Each larva reduces grain size Damaged seeds are susceptible Reduce the frequency of Grow resistant varieties, by 30–50%. Pericarp damage to attack by pathogenic fungi, wheat crops in the rotation in eg Welford. allows easier water entry, often especially Fusarium more sheltered fields. resulting in sprouting in the ear graminearum; they may fail and reduced Hagberg falling to germinate or produce Chemical control number. weak seedlings. Apply chlorpyrifos to wheat Action thresholds Risk factors crops within a week of Thresholds refer to numbers of finding a threshold number of midges laying eggs in the Potentially damaging larval more vulnerable to attack when midges laying eggs on the evening.The midges can be populations may be found in any weather conditions are marginal ears. counted at night using a torch field where wheat has been for flight. Pyrethroid sprays applied for or in early morning.They fly off grown over the past five years. Midges can fly half a mile or aphid control may give some as temperatures rise. Higher soil populations are likely more in mild evening weather. control of the midge if the If several nights are suitable where wheat crops have been They accumulate in the most timing coincides with flight, but during ear emergence, count frequently grown during this sheltered fields at the this control is unreliable and midges each evening and use period. vulnerable growth stage and not a label recommendation. the average figure. Crops growing in fields with attack new crops. For feed crops – high resident populations are 1 midge/3 ears. For milling and seed crops – Natural enemies 1 midge/6 ears. Consider using yellow sticky The most important natural 80% and give useful control. By traps hung at ear height at the enemies are small parasitic not spraying below threshold start of ear emergence to wasps, especially Macroglenes levels, parasitoid numbers may monitor activity. In crops at the penetrans. During the day they increase and provide longer- threshold levels, expect to catch search for and lay their eggs in term midge control. about 10 midges in each trap midge eggs.This does not reduce Polyphagous predators also through ear emergence. crop damage, as the parasitoid kill adults and can kill larvae Ignore midge activity after the larva does not develop until the dropping to the ground if dry start of flowering, as eggs laid midge larva has overwintered. soil prevents them burrowing after this stage do not develop Parasitism levels can exceed to safety. properly. Life cycle Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Cocoons, containing larvae, can survive for up to five years in the soil. Each year some reactivate and pupate if soil surface is moist. Some Larvae feed for two larvae weeks, then drop to pupate. the soil to form cocoons. Eggs laid within florets in suitable host crops. Eggs hatch in one week. Adults fly.

13 OILSEED RAPE PESTS Peach-potato aphid Myzus persicae

The peach-potato aphid feeds on oilseed rape, many other field and protected crops as well as weeds. Individuals may be green, yellow or light red. Like cabbage aphids, they are found under leaves.

Economic importance Chemical control

Only very heavy aphid Aphids transmit the beet Aphids that colonise crops in E4 strains resistant to infestations cause direct western yellow virus, which autumn may have survived pyrethroids, pirimicarb damage. Numbers may increase causes temporary reddening of through many generations on and OPs. after serious outbreaks of infected plants in spring.Virus treated crops.This may lead to Seek expert advice on insecticide-resistant aphids on infections have been low in high levels of insecticide alternative insecticides if potatoes. recent years. resistance restricting insecticide control is poor. Neonicotinoid choice. seed treatments, such as Risk factors Three forms of insecticide Chinook, currently control all resistance occur: resistant forms for several Earlier-sown winter crops tend spring crops tend to be at Kdr resistance to pyrethroids weeks following emergence. to be at greatest risk during greatest risk after mild winters. MACE resistance to pirimicarb warm autumns. Later-sown Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Adults infest other crops. Adults infest crops and transfer Asexual females virus in mild autumns. overwinter. Cold weather reduces Asexual females survival. overwinter. Cabbage aphid Brevicoryne brassicae

This aphid is covered by grey, waxy scales. It is found under leaves and causes puckering and yellowing. Later infestations move on to developing flowers and pods.

Economic importance Action thresholds

The cabbage aphid carries severely infested after mild Cabbage aphid may cause direct spring rape plants are infested turnip mosaic virus and winters and allow infestations damage in spring if over 13% of before petal fall. cauliflower mosaic virus. on winter rape to increase to winter rape plants or over 4% of Spring rape can become damaging levels.

Chemical control Natural enemies The parasitoid, Diaeretiella A waxy covering protects Pyrethroid insecticides may not rapae normally provides good cabbage aphid from contact control cabbage aphid. Consider control. insecticides, which can limit using use a higher rate of choice. pirimicarb plus added wetter. Life cycle

Aug Sept Oct Nov Dec Jan Feb Mar Apr May June July

Infests winter rape. Overwinters on brassica plants. Multiplies rapidly when mild and may cause direct damage.

14 OILSEED RAPE PESTS Cabbage stem flea beetle Psylliodes chrysocephala

Adult beetles, 3–4.5 mm long, blue-black or light brown in colour, are sometimes seen crawling across the top of trailer loads of grain at harvest.

The adults return to crops just after emergence and chew ragged holes in cotyledons and early true leaves. Eggs are laid. On hatching, larvae bore into petioles and continue feeding close under the surface.These are distinguished from larvae of other pests by their black head and black plate at the tail end. Later, larvae move into the main stem to feed under the growing point.

Economic importance Chemical control

Large numbers of adults feeding seed crops in East Anglia. It now Chinook seed treatment If no adult spray applied, apply in the autumn kill plants, covers England and Wales and is reduces adult feeding and treatments to control larvae if: occasionally causing total crop spreading in Scotland. numbers of eggs laid. over 5 larvae/plant failure.The pest originally Crushers may reject A pyrethroid spray should over 50% petioles damaged. attacked mustard and brassica contaminated seed. control feeding adults and larvae that have not entered the Risk factors main stem.Treatments persist well through the winter. Earlier-sown crops often attract Warmer autumns favour egg- One spray usually suffices. most cabbage stem flea beetle. laying and earlier hatch of larvae. Action thresholds Natural enemies Consider applying an early pyrethroid spray if adults have The main natural enemy is the Parasitoids remain as pupae in eaten: wasp Tersilochus microgaster, the soil until the next crop, and over 25% of the leaf area at which parasitises larvae in may be damaged by ploughing. the 1–2 true leaf growth stage spring. Minimum cultivation after rape or All parasitoids may be favours parasitoid survival. over 50% of the leaf area at vulnerable to pyrethroids. the 3–4 true leaf stage the crop is growing more Cultural control slowly than it is being destroyed. Delaying sowing reduces the numbers of adults attracted and of eggs laid.

Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Larvae Adults Eggs laid at Eggs hatch. pupate in move to the base of soil. new crop, plants if Adults emerge and Adults mate and mild. Larvae continue to feed on foliage. ‘rest’ in eat leaves Larvae continue to hatch if mild and feed in moist, for a week hatch if mild and feed petioles. sheltered or so. in petioles. places. Larvae feed on main stem behind growing point.

15 OILSEED RAPE PESTS Other flea beetles Wessex flea beetle Turnip flea beetles Large striped Psylliodes luteola Phyllotreta cruciferae, flea beetle Phyllotreta nigripes, etc Phyllotreta nemorum

Attacks crops in the autumn. Attack crops in autumn and spring. Attacks crops in spring.

These beetles are smaller than cabbage stem flea beetle. Adults jump away when disturbed.

Economic importance Risk factors The Wessex flea beetle is of Turnip and striped flea Wessex flea beetle is most likely most susceptible to turnip and increasing importance in beetles are principally pests of to damage earlier sown crops, striped flea beetles.Any crops southern England. An initial spring brassicas. especially if slow to grow away may be at risk if growth is outbreak in Wiltshire has spread Crop damage has increased in September. checked by sunny, dry weather. to other areas. Crops can be following the withdrawal of Later sown spring crops are severely checked. lindane. Natural enemies There are some wasp parasitoids. Cultural control

Delay sowing autumn crops and Sow spring crops as early as sow in a well consolidated soil conditions and weather seedbed to improve seed-to-soil allow. contact and germination.

Chemical control Chinook seed treatment may be Action thresholds used on winter, but not yet on No thresholds for treatment spring, crops. exist. Pyrethroid sprays on growing crops only provide 3–4 days respite, but may help a crop survive until wetter weather returns. Base spray decisions on same criteria as for cabbage stem flea beetle.

Life cycles

The life cycle of the Wessex flea beetle is not fully understood. Adults appear and cause damage in September.

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Turnip and large striped flea beetles

Hibernation Migrate to crops and feed on leaves. Adults emerge Hibernation Lay eggs at plant base. from late July. Direct feeding Larvae feed on roots. can damage crops.

16 OILSEED RAPE PESTS Pollen beetle Meligethes aeneus

These small, shiny, black beetles may arrive from the green bud stage onwards.They lay their eggs in the buds. Larvae later feed mainly on pollen in the flowers. Larvae have a head capsule and six legs.

Economic importance Cultural control

Loss of pod sites from pollen Varietal associations and Sow spring crops as early as possible. beetle damage, albeit sometimes restored hybrids may lose more severe, rarely reduces winter yield because male fertile plants oilseed rape yields. Crops are attacked and cross- Chemical control usually compensate for earlier pollination is reduced. Resistant strains of beetles have losses, producing more and Spring crops are much more Action thresholds appeared in France and Apply chemical control larger seeds on lower racemes. vulnerable than winter crops. Sweden. Investigate control measures if the thresholds are failures to establish the level of exceeded: Risk factors resistance of the population. Winter oilseed rape Only use pyrethroid sprays over 15/plant at green-yellow Pigeon and frost-damaged After all buds on winter crops during green to yellow bud bud winter crops that remain at the have opened beetles migrate to stages if thresholds are over 5/plant for backward green and yellow bud stages for other egg-laying sites, causing a exceeded. crops longer are susceptible. second flush of migration to over 2/plant for varietal Varietal associations, restored spring crops. associations. hybrids and later-sown spring Spring crops are less able to crops may also be at greater risk. compensate for damage than Spring oilseed rape The use of ‘canopy winter crops and so often over 3/plant at green bud. management’ to optimise justify treatment. (In Scotland 1/plant at potential pod number may green bud stage.) increase susceptibility to pollen beetle.

Natural enemies Three wasp parasitoids Minimum cultivation after commonly attack the larvae: oilseed rape will enhance wasp Phradis interstitialis, Phradis survival. morionellus and Tersilochus heterocerus.

Larvae feeding in flower Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Hibernation Adults migrate at over 15ºC. Feed Adult beetles Hibernation on pollen inside buds or in open hatch and feed flowers on oilseed rape plants. on a variety of Eggs laid in buds. plants. Larvae and then pupae.

17 OILSEED RAPE PESTS Cabbage seed weevil Cultural control Delaying sowing of spring crops reduces Ceutorhynchus assimilis numbers of adults attracted and of eggs laid. This small black weevil with a curved snout lays its eggs into developing oilseed rape pods during flowering. Chemical control A brown scar indicates the egg-laying puncture, usually causing a kink in the pod. One white larva with a brown Apply a pyrethroid spray approved for head capsule develops inside the pod, eating the seeds. use during flowering if the threshold is exceeded.This should be applied by petal Economic importance Risk factors fall and before too many eggs are laid. Numbers rarely exceed damaging levels Cabbage seed weevil tends to be of greater Action thresholds on winter oilseed rape.The pest is importance in the northern britain. over 0.5/plant important in allowing entry of brassica pod in northern midge. It may be more important on spring Natural enemies Britain oilseed rape. 1/plant The parasitoids Trichomalus perfectus, elsewhere. Mesopalobus morys and Stenomalina gracilis generally keep numbers in check. Life cycle

Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Overwinters as adults that fly The weevils lay eggs directly Larva develops Adult weevils hatch in August and hibernate in into oilseed rape crops soon after into the pod, chemically within the pod, non-crop situations. flowers open. marking pods to deter any eating 3–4 seeds further egg-laying. before burrowing out and dropping to the soil to pupate.

Brassica pod midge Cultural control Block oilseed rape fields and rotate the Dasineura brassicae crop around the farm to reduce the impact of immigrant pests. These small, dark orange midges appear during flowering.They lay eggs through holes left by seed weevils in developing pods. Many small, white larvae with no obvious head occur in each Chemical control affected pod. They cause swelling and eventually pod burst. Sprays for seed weevil provide incidental control of pod midge by reducing egg- Economic importance Risk factors laying sites. With damage greatest on headlands and As the adult midge is a weak flyer, crops on Action thresholds affected pods very conspicuous, this pest headlands are more exposed to immigrant No thresholds for treatment exist. can be over-rated. midges; thus largest yield losses often occur However, spring oilseed rape yields can in small narrow fields. be severely reduced. Natural enemies Several wasp parasitoids, including Omphale clypealis and Platygaster subuliformis may attack pod midge, killing up to 75% of larvae. Life cycle Larvae can hatch over a three-year period after rape. In June and July partial 2nd or 3rd generations attack late winter and spring rape. Jan Feb Mar Apr May June July Aug Sept Oct Nov Dec

Larvae overwinter in Adults emerge. Adults mate. Fly to oilseed Larvae overwinter in cocoons in soil. cocoons in soil. rape. Lay eggs in cabbage seed weevil holes or plant damage. Larvae feed. Pods swell and burst. Larvae drop to soil. Some develop to give 2nd and 3rd generations of adults.

18 OTHER CEREAL AND OILSEED RAPE PESTS Frit fly Thrips frit Limnothrips cerealium Limnothrips denticollis

There are three generations of Third generation flies hatch Thrips fly to cereal crops in Larvae also feed under the frit fly a year, all of which can from harvested grain, May and lay eggs in the boots of glumes and on developing grain occur on ryegrass. sometimes causing a emerging ears.Yield loss may causing black spotting, and First generation flies appear temporary nuisance in stores. follow if young thrips reduce possibly reduced flour quality. in May and lay eggs in cereal Eggs may be laid on ryegrass, sap flow by feeding on stems Control measures are not and grass stems. Larvae allowing larvae to transfer to and flag leaf sheaths. usually justified. causing a classic deadheart any following winter cereal symptom can severely crops sown within five weeks damage late-sown spring oats. of ploughing out the old ley. Second generation flies Plough early if possible or appear one to two months control by chlorpyrifos sprays later and lay eggs in applied pre- or early post- developing oat and wheat emergence if the risk is high. grains. Larvae then feed on the grain.

Saddle gall Rape winter midge stem weevil Haplodiposis marginata Ceutorhynchus picitarsis

Blood-red coloured larvae hatch Rape winter stem weevil adults now spread to other areas. from eggs and feed under the lay eggs in the autumn. Larvae Pyrethroid sprays applied to leaf sheaf causing saddle-shaped feed in the stem base through control cabbage stem flea galls. Damage restricts sap flow the winter. Large numbers may beetle and aphid vectors are to the ear and can lead to severely stunt the crop. Initially effective against this weevil. lodging through stem breakage at Adult midges lay rafts of red limited to Lincolnshire and the point of galling. Damage is eggs on leaf surfaces in May. Cambridgeshire, the pest has most serious on cereal-dominated rotations on clay soils.

Cereal Cabbage ground stem weevil beetle Ceutorhynchus pallidactylus Zabrus tenebrioides

This pest attacks crops in harvest and on spilt grain and Stem weevils lay their eggs in Adults are difficult to England, from Oxfordshire and stubble re-growths. oilseed rape stems in May. distinguish from those of seed Cambridgeshire southwards. Damage is worst in all-cereal Larvae in large numbers can weevil. For practical purposes Larvae burrow into soil, pulling rotations and with minimal reduce seed filling and, in assess together. down and eating shoots from cultivations. A non-cereal break extreme cases, kill plants. Treat if threshold of 2 weevils October to May. Adult beetles crop or early ploughing will a plant of any species, is feed on cereal ears before provide good control. exceeded.

19 BIOLOGICAL AND CULTURAL CONTROL

Many pests have natural the rate of pest increase and weather conditions – natural severe pest damage may occur enemies. Sometimes, these restore the balance between enemy numbers and their due to reduced natural enemy predators and parasites provide pests and natural enemies. beneficial effects may be numbers. sufficient control to prevent any Broad-spectrum pesticides reduced. In such cases, more serious crop damage occurring. often control both pest and Some predators are specific to natural enemies removing the particular pests. benefits of natural control. Enhanced use of natural Often, pesticides are applied enemies forms a part of just after damage or infestations ‘Integrated Crop Management’. are identified. Such treatments The deliberate introduction of will prevent beneficial pests predators is not viable in broad- from multiplying to populations acre arable crops. that will significantly reduce Where natural enemy numbers pest numbers. are initially low, serious pest If a pesticide application is damage may occur. Pesticides not fully effective – due to dose, Rove beetle may be needed to slow down timing, application technique or

Main natural enemies

Predator Larvae eat Adults eat Comment Parasitic wasps – Hymenoptera – Parasitica

Parasitoid populations depend wholly on pest numbers, rising in response to outbreaks and declining as pest numbers fall. Endoparasites – live within and consume a single host individual.

Stenomalus micans Gout fly larvae Nectar Initially host larvae develop to full size.Then, parasitoid larvae start to feed, killing them before pupation.

Macroglenes penetrans Orange wheat Parasitoids do not prevent crop damage, but can give longer-term blossom larvae population control if 80%+ of pest larvae are parasitised.

Aphidius rhopalosiphi Grain aphids Nectar Adult parasitoids are very sensitive to insecticides, so timing must be accurate. Diaeretiella rapae Cabbage aphids

Ectoparasites – the larvae develop outside the host’s body and may consume several individuals.

Trichomalus perfectus Cabbage seed weevil The adult wasp inserts its egg through a hole bored into the pod by the weevil for egg laying. Spiders – Araneae

Erigone atra Webs typically trap Spiders are particularly vulnerable to pyrethroid insecticides. Lepthyphantes tenuis around 30% of aphids flying through the crop as well as wheat blossom midge adults and small flying insects. Hoverflies – Syrphidae

Syrphus ribesii Each larva can eat Nectar Wild flowers in field margins attract hoverflies if local pollen Episyrphus balteatus c. 400 aphids on arable sources are scarce. Oilseed rape and other flowering crops crops. A ratio of attract large numbers. 1 larva: 30 aphids can Adult hoverflies feed on pollen. control severe infestations.

20 BIOLOGICAL AND CULTURAL CONTROL

Enhancing predator survival Cultivation and agronomy Local management has more In marginal habitats, the same Cultivations can influence pest Rotations influence pest influence on predators than on management practices can carry-over within a field: numbers available to attack pests. Many natural enemies encourage both predators and Effective destruction of the succeeding crops. survive in the soil, whereas pests.A mix of diverse grasses old crop, followed by a gap of Pest attack is often most many pests migrate to and wild flowers should at least five weeks, reduces severe at the edge of the field alternative habitats. minimise pest carry-over. carry-over. nearest to where the same crop Parasites are favoured by Alternative host plants for Soil consolidation can hinder was grown in the previous year. minimum cultivation, although many cereal pests, eg ryegrass pest movement from These edge effects can be crop regrowth must be or meadow grasses, should be ploughed down residues to minimised by growing several controlled to discourage pests avoided.Tussocky grass beetle germinating seeds. fields of the same crop together and diseases. banks may not be appropriate if in a block. Rotations should be beetle pests attack crops planned to maximise distances growing nearby. between fields or blocks of crops over succeeding years.

Predator Larvae eat Adults eat Comment Ground beetles – Carabidae

Present in fields all year round.

Pterostichus madidus Slugs and other Slugs and other Also eat weed seeds and plants. P. melanarius invertebrates invertebrates

Trechus quadristriatus Eggs of wheat bulb fly Eggs of wheat bulb fly Favoured by minimum cultivation and stubble re-growth. and cabbage root fly and cabbage root fly

Bembidion ustulatum Springtails and other Springtails and other pests pests Overwinter in field margins, flying adults forage in crops during summer.

Demetrias atriapillus Wide range of Cereal aphids and Partially control low aphid populations. Agonum dorsale invertebrates other prey in foliage Favoured by beetle banks and grass margins. Soldier beetles – Cantharidae

Cantharis fusca Slugs and soil insects Aphids and other pests Adults hibernate off-crop. Rhagonycha fulva Ladybirds – Coccinellidae

Adalia bipunctata Aphids Aphids Adults hibernate off-crop. Eggs are laid among aphids. Coccinella Larvae are voracious and can reduce aphid populations. septempunctata Rove beetles – Staphylinidae

Tachyporus hypnorum Mildew and aphids Mildew and aphids Adults climb cereal stems at night. Hibernate in long grass in T. obtusum in cereals margins and beetle banks.

Aleochara bipustulata Pupae of wheat bulb Develop as parasites on fly pests. A. bilineata fly and cabbage root fly

21 BIOLOGICAL AND CULTURAL CONTROL Enhancing natural enemies

Attract hoverflies and parasitic wasps; also provide food for wild birds, butterflies Field margin strips and bees.

Action Do not

Sow a seed mixture containing grasses, eg sow ryegrass which harbours many pests fescues and bents, and wild flowers – use sow umbellifereae, which attract many quite low seed rates to reduce costs. Plants flies, if carrots, parsnips, celery or market of particular benefit for attracting hoverflies brassicas are grown. and parasitic wasps include cow parsley, hogweed, wild celery (umbellifereae) and yarrow, scabious and knapweed (compositeae). Margins are best sown on the east or north sides of fields to reduce hedgerow shading. Provide within-field hibernation sites for ground and rove beetles, spiders and Beetle banks nesting sites for ground-nesting birds, eg partridges and skylarks.

Action Do not

Plough up rigs from opposing sides to use if cereal ground beetle is a problem. create a bank splitting larger fields. Sow with tussock-forming grasses, eg cocksfoot, red fescue and . Avoid spraying adjoining crop with insecticides. Beetle banks provide the greatest benefit in large fields where non-crop habitats are limited.

Minimal cultivation Enhances parasite activity on oilseed rape pests and survival of spiders.

Action Do not

Use minimal cultivations, wherever possible, use after oilseed rape if in an area prone to enhance carry-over of natural enemies to disease. and enhance spider survival. Ploughing reduces numbers of natural enemies which pupate in the soil, eg parasitic wasps. Rotational ploughing is advisable where herbicide-resistant grass weeds or cereal ground beetle pose problems.

Allow specific natural enemies, eg parasitic wasps, ladybirds, hoverflies and LERAP* and lacewings to build up on host pests. conservation headlands

Action Do not

Follow label requirements for missing reduce the buffer zone for pesticides with insecticide sprays on headlands in the an A LERAPs classification (includes most summer and follow LERAPs guidelines for insecticides) buffer zones near watercourses. spray insecticides on a conservation Conservation headlands, with reduced broad- headland after 15 March. leaved herbicide use, enhance the benefit.

* Local Environment Risk Assessment for Pesticides

22 FURTHER INFORMATIONCEREAL PESTS

HGCA guides HGCA Research Review (oilseeds)* Arable cropping and the environment – a guide, 2002 OS1 pests of oilseed rape

HGCA Topic Sheets HGCA Project Reports (oilseeds)* Posted free to levy payers on request. OS14 The status and potential of parasitoids of seed weevil and pod 32 Minimising pesticide usage on cereals and oilseed rape midge on winter oilseed rape 38 Dealing with wheat bulb fly OS43 Alternative seed treatments to gamma-HCH for controlling cabbage 39 BYDV control based on aphid monitoring stem flea beetle on winter oilseed rape 45 Summer pest control on wheat OS54 Seed dressings to control slug damage in oilseed rape 48 Seed treatments for pest control in winter oilseed rape OS57 The further development of seed treatments to control cabbage stem flea beetle and other pests on winter oilseed rape OS60 Control of slug damage in oilseed rape by seed treatment – HGCA Research Reviews (cereals)* development and field tests 10 The biology and control of cereal aphids 28 Orange wheat blossom midge: a literature review and survey of the Websites 1993 outbreak HGCA: 33 Impact of changes in arable agriculture on the biology and control of www.hgca.com wheat bulb fly Crop Protection Association: www.crop-protection.org.uk HGCA Project Reports (cereals)* Game Conservancy Trust: 47 Slug forecasting in cereals www.gct.org.uk 53 Research on slug behaviour: I The role of soil water in regulating the activity of terrestrial slugs II Cultural methods to reduce slug damage Leaf: in cereals www.leafuk.org 56 Improving the forecast of BYDV high risk conditions in autumn-sown Maltsters’ Association of Great Britain: cereals www.ukmalt.com 67 Control of wheat bulb fly in winter wheat: I Chemical methods II (includes list of Agrochemicals accepted by the British Beer and Pub Association and Varietal susceptibility Brewing Research International for use on malting barley). 87 Monitoring aphids and virus to improve forecasts of barley yellow Pesticides Safety Directorate: dwarf virus www.pesticides.gov.uk 106 Orange wheat blossom midge: survey of the 1994 outbreak 110 Determination of factors affecting grain aphid movement with Rothamsted Insect Survey: reference to spread of BYDV in the autumn and winter and www.rothamsted.bbsrc.ac.uk/insect-survey/ forecasting direct damage in the summer Voluntary Initiative: 112 Assessing modern cultivars of winter wheat for damage by the grey www.voluntaryinitiative.org.uk field slug 120 The epidemiology of a new leatherjacket pest (Tipula oleracea) of winter cereals in northern Britain Books 129 Key factors for modelling secondary spread of barley yellow dwarf The UK pesticide guide, CAB International, 2003. virus Pest and Disease Handbook, D V Alford, Blackwell Science, 2000. 135 Aphid and virus dynamics to improve forecasts of barley yellow dwarf virus risk Biocontrol of Oilseed Rape, D V Alford, Blackwell Science, 2003. 148 Effects of polyphagous invertebrate predators on cereal pests 155 Aphid sex pheromones to enhance parasitoid efficiency Legislation 173 Integrated farming systems (a field-scale comparison of arable rotations) I Experimental work II The economic evaluation of input In Great Britain, the storage, supply, advertisement, sale and use of pesticides are decisions regulated by The Control of Pesticides Regulations 1986 (as amended) (COPR), The 198 Evaluation of opportunities for dissemination of national pest and Pesticides (Maximum Levels in Crops, Food and Feedingstuffs) (England and Wales) disease information Regulations 1999 (as amended) and in Scotland by The Pesticides (Maximum Levels 205 Development and validation of decision support methodology for in Crops, Food and Feedingstuffs) (Scotland) Regulations 2000, and commonly control of barley yellow dwarf virus referred to as the MRL Regulations. Similar legislation exists in Northern Ireland. 206 The importance of barley yellow dwarf virus (BYDV) infection in This legislation implements Part III of The Food and Environment Protection Act spring barley and opportunities to manage the disease 1985 (FEPA). 226 Improving the efficacy of chemical control of wheat bulb fly 229 Appropriate aphicide doses for summer aphid control on wheat

NOTE: *Project Reports and Research Reviews are available at cost from HGCA.

23 Acknowledgments This guide represents a knowledge transfer project.The guide describes general principles developed through HGCA and/or Defra-funded research. Written by Jon Oakley, ADAS and edited by Dr Clive Edwards, HGCA; and Geoff Dodgson, Chamberlain. The editors acknowledge the helpful comments made by many experts including: John Young,BASF; Dr David Cooper, Defra; Professor Graham Jellis, HGCA; Philip Morrall, Bairds Malt and Stan Sole, Crisp Malting on behalf of MAGB;Alan Bide and Steve Cook, Hampshire Arable Systems; Sue Mattock, Dr David Richardson and Martin Roberts, Defra PSD; Julian Hasler, NFU; Dr Richard Harrington, Dr Wilf Powell and Professor Ingrid Williams, Rothamsted Research; Dr Andy Evans, SAC Edinburgh; Michael Tate, Syngenta. Design by Chamberlain.

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