01 November 2013. St Judes storm heralded a mixed bag of weather this week which has kept most field activities on hold. A dip in temperature on Wednesday morning brought the first air frost of the autumn to some regions. However, crops continue to grow at an unusual pace and reports of winter wheat with two to three tillers and complaints of wet knees from walking oilseed rape crops.

Phoma has at last woken up to the fact that it is autumn and really ought to be infecting crops of winter rape. Threshold levels have been reached in crops in the Hereford and Worcester although else where it is only recorded at low levels. Mildew is beginning to take a hold in some winter barley crops. Slugs are become active again with fresh hatches damaging wheat after oilseed rape.

• Phoma levels increasing now at threshold in SW Midlands
• Slug activity increasing
• Large oilseed rape crops may need PGR
• Blackgrass emerging quickly
• Manganese deficiency showing on light land
• Mildew developing in some barley and wheat crops
• BYDV - use T Sum to predict risk

BYDV T sum
‘T sum’ system of accumulated day degrees above 3ºC can be used to predict best spray timings. Temperature accumulation should be started from: six weeks after sowing for imidacloprid-treated crops date of emergence for other crops one week after application for pyrethroid-treated crops.
1 Calculate ‘T sum’ by subtracting 3ºC from the daily mean temperature and adding the result to the running total.
2. If ‘T sum’ is 170 (second generation could be starting) – consider a tank-mix insecticide if treating the crop for another purpose.
3. If ‘T sum’ is 340 (significant spread imminent)

source HGCA.

Winter Oilseed Rape 

South. Crops now range from 4True leaf to 6-8+ True leaves – more than half of crops are now  5-6+ true leaves. Mild conditions continue to favour rapid growth and around half of crops are likely to need a PGR Fungicide.
Phoma: leaf spotting now being found more readily in the last week, but most crops are still only showing around 5% infection levels and mainly on older leaves. Recent rains are however likely to initiate further spore release and leaf infection symptoms before too long – with this in mind all backward crops and those with poor Phoma resistance ratings should be sprayed as a priority in the next 7 days.
Slugs: good seedbeds and dry soils have minimised problems.
Aphids: no Myzus Persicae adults seen to date.
Turnip Sawfly: low levels of larvae now being found on undersides of leaves in crops that have not had a pyrethroid applied – damage looks very similar to slug grazing.
Weed control: moderate/high levels of blackgrass emerged/emerging in some crops, particularly after spring barley, indicating low dormancy in shed seed. Aramo (1lt/ha) been applied where required and timed to target blackgrass before tillering. Worst fields where Aramo has struggled previously, are getting Centurion Max applied when crop is at 4 leaves+ - control from earliest applications is looking very good so far (98%+). Kerb is planned to be sequenced later in November/December.

Eastern Counties. Crops now seem to have enough growth to survive the winter and only a few are very far forward (early drilled light land). Generally establishment is uniform across fields with better headlands than last year (although there has still been some rabbit and partridge grazing). Even direct drilled crops have moved on and made  a reasonable stand. Wet again another 35mm of rain. Light land fields will travel OK.
Phoma: just beginning to see a low level of spotting. If we have some good spraying opportunities over the next week will get on with phoma sprays, prothioconazole with a second graminicide needed on many fields (where not applied already).
Flea beetle: although seed treatments worked well we did have some difficulties on open cloddy seedbeds where adult beetles can feed below ground. A reminder that the more open seedbeds or subcasting will probably be more prone to early flea beetle damage next year with loss of emerging rape when we can no longer use neonicotinoid seed treatments.
Slugs: very little slug activity although it has increased during recent wet weather, grazing can be seen on larger lower leaves in the canopy. Most crops are well-established and just a few later drilled crops with smaller plants need attention with a slug pellet application required.
Weed control: planning Astrokerb targeted at poppies on light soils, probably apply soon before canopy completely shades weeds. Hoping it may give some control of hedge mustard.

East Midlands. Crops still continue to grow but rate has slowed a bit – later drilled crops now at 4 leaves with forward at 7-9 leaves.
Phoma: first spotting seen in last few days and fungicides due to go on when weather window allows with later small crops first priority, but levels still below 10% although expect this to rise in next week. Metconazole to go on stronger crops although if weather continues to delay something may be added to boost the eradicant activity.
Slugs: a few backward crops showing some damage and will require a low rate of pellets
Weed control: Kerb to go on when soils cool but this may well mean splitting the phoma sprays out as Kerb application is delayed. Excellent results on blackgrass control from Centurion Max. Very good results from Centurion Max even on ryegrass shown to be fop and dim resistant. Headland usage has shown definite de waxing to a line.

West Midlands. All crops especially light land crops are growing extremely rapidly. There are some very forward crops about and may need an autumn PGR. In general crops looking well in complete contrast to last autumn.
Slugs: no new damage seen.
Leaf miner: in some crops but not at damaging levels.
Phoma: levels increasing especially in the south of the region where now at threshold.
Weed control: follow up graminicides for second flush of bromes and volunteer cereals going on.


North East. There are some large canopies developing as the mild autumn weather continues. Average temperature for the week: 12.5 degrees, Rain 20.7 mm for the week.
Slugs: a little activity.
Phoma: still no disease seen.
Weed control : various weeds seen emerging, shepherds purse, few cranes bill, chickweed etc.

Click here to view the Rothamsted Phoma forecast

Winter Wheat

South. Crops are still emerging around 10 days after sowing - earliest sown crops (20th Sept) now @ GS22, with most crops being between GS13-21. Could do with weather settling down now to enable post-emergence spraying to get caught up. Wet after recent rains - heavier fields are now starting to get wet in places following around 5 inches of rain in the last 2 weeks.
Aphids: none seen yet, but can be readily found on volunteers in oilseed rape. Pyrethroid will be applied 6-8 weeks after Deter dressed crops were drilled.
Slugs: Slug activity becoming increasingly evident, particularly in crops after oilseed rape and second wheats on heavier soils, following another 40-50 mm of rain in last 7 days. Most of damage appears to be being caused by juvenile/pin-head grey field slugs and/or black keeled slugs (Arion spp), with damage of the latter often indicated by subterranean damage leading to yellowing of main shoots – most effective pellet in either case is a methiocarb based treatment.
Weed control: rains have thoroughly wetted seedbeds now which is activating the pre-emergence herbicides, but where blackgrass is emerged and already at two leaves, planning overspraying with Atlantis in next two weeks. There has been a significant flush of bromes on some headlands.

Eastern Counties. Rain and wind has has slowed progress with the sprayer and for some the drill.  Crops range from emerging to first tillers. The mild weather has meant that some fields have emerged within 8 days of sowing.
Aphids: above average numbers of aphids around. BYDV follow up sprays may be needed this year.
Slugs: there are a minority of fields after rape where slugs continue to graze the emerging wheat crop.
Weed control: where contact products were applied to wet foliage on a dull, misty day, with rainfall the following morning, control from these mixes has been poor. Herbicide uptake is obvious in some crops.

East Midlands. With the wetter weather crops have slowed a bit, but forward crops at 3-4 leaves and later drilled crops at 1-2 leaves. In spite of heavy rain fields are quite good on top but too wet for cultivations or drilling but in some fields sprayers would carry but wet headlands and patches hinder many. However,  the combination of wind and rain has meant that no fieldwork has been possible.
Aphids: none seen.
Slugs: odd fields show damage requiring treatment and slug levels have risen with the wet but a lot of slug pellets remain in store.
Weed control: blackgrass at 1-3 leaves and requiring treatment when weather allows. On fields with resistance and with no pre em or Avadex to date due to conditions they may well have to be burnt off. Pre ems working now but thicker areas have had a lot of plants left.

West Midlands. Most forward crops are at pretty much 100% ground cover, with minimum of three tillers. Apart from crops drilled in the last 7 days after beet and maize all crops are up with anything from 1 leaf to 1 tiller (with the exception to the three tiller stuff ). Rain: 50mm last week, 50mm the week before and 25mm the week before that so 125mm for October = very wet.
Slugs: renewed activity in some fields after oilseed rape.
Aphids: can be found.
Mildew: becoming more obvious on quite a few crops of Grafton, Leeds and JB Diego.
Weed control: recent rains have helped activate pre-emergence herbicides. Bromes are more obvious this year on headlands.

North East. Crops range from emergence to GS 21. All first wheats are in now. Fields are wet after recent rains and conditions are too wet to travel on some days.
Aphids: few winged aphids sighted.
Slugs: seen surface grazing, increased activity from last week.
Weed control: more blackgrass emergence this week. Pre emergent herbicides are working well now that there is some moisture.

Winter Barley.

South. Earliest sown crops now at GS13-21.
Eastern Counties. Most crops now in but later sown crops have patchy emergence due to dry seed beds. Main varieties are Cassia and Glacier with a bit of Volume.
West Midlands. Most forward crops at 2 tiller stage. Light land crops have high levels of mildew. Manganese deficiency showing up on light land.
East Midlands. Crops at 3 leaf and look well although some yellowing showing where pre ems used, but on the whole plants look healthy.
North East. Earliest sown now at first tiller stage. Powdery mildew seen on Glazier.