26 September 2014.

Flea beetle damage in oilseed rape.

Reports coming in this week imply that some crops have been severely damaged by flea beetles. In discussions with agronomists across the eastern region the message is that damage to crops is patchy. Some crops have undoubtedly been hit hard but these are in isolated areas rather than across the board. In these high risk areas agronomist estimate that 10-15% of crops will be lost. Pressure from flea beetle damage has been intense in these crops but they stress that damage is patchy and localised.

The factors that agronomists have identified as being important in determining the level of damage are:

• Seed bed conditions. Firm consolidated seed beds have less damage. Unconsolidated seed beds have given refuge to flea beetles and allowed them to attack newly emerging crops.
• Tight rotations; that is where oilseed rape features frequently in the rotation. Fields which have been in oilseed rape within the last two years are more at risk.
• Proximity to last years oilseed rape crops. Fields of oilseed rape neigbouring or contiguous with last years oilseed rape crops are at higher risk
• Heavy land. Soils with a high clay content are at more risk for two reasons, firstly they have been more difficult to consolidate and secondly where there has also been heavy rain these soils are now hard and restricting root growth of the oilseed rape plants.
• Sowing date. Late sown crops or crops sown just before the heavy rain storms at the end of August are more at risk.
• Mild winter of 2013/14. The very mild winter resulted in very little "winter kill" of flea beetles and as such they have multiplied up in last years crop. Evidence that there were high numbers of flea beetles found in grain trailers at harvest time.
• Historic problem. In areas where there has been significant damage this year, there was also a problem last year.
• Pyrethroid resistance. Resistance to pyrethroids in flea beetle is common and consequently there has been poor control from post emergence spray of pyrethroids in certain areas.

Winter Wheat

South. Drilling of Claire and Scout mostly completed, with Cordiale, JB Diego, Crusoe and Solstice drilling now underway, and Skyfall and WW2 from next week onwards. Most first wheats should get drilled by the end of September. Farms growing second wheat Cordiale/Solstice with Latitude planning to finish drilling by 5-7th October. Soils are still generally moist below the surface but are dry on top as we only had around 5-6 mm rain last week. Forecast for continuing dry and warm conditions over next 10-14 days means an emphasis on preserving moisture by rolling following drilling – seedbeds to date are generally very good.
Slugs: trapping of fields after oilseed rape pre-drilling is often indicating high slug populations – populations are, however, much lower on fields that have been disced/cultivated twice pre-drilling.
Frit fly: beware fields following spring oats as these are often high risk of damage from the summer generation of frit that invade panicles of oats.
Wireworm: some moderately high levels being found in lower lying fields after long-term grass.
Blackgrass: useful flushes in most stale seedbeds, which should reduce populations emerging with the crop. Problem fields having Crystal @ 4lt/ha + DFF (0.2lt/ha)  or Liberator @ 0.6lt/ha + Defy 2-3lt/ha at pre-/peri-emergence. Fields with difficult blackgrass are having Avadex applied after rolling & with seedbeds on earlier sown wheats dry, are planning on holding off with other residuals until per-emergence timing unless rain is forecast or seedbeds are moist.

Eastern Counties. Drilling well underway. Dry seed beds are hindering emergence.

East Midlands. Drilling has started this week with the majority starting end of week and into next week. Many are heeding advice to delay drilling where blackgrass is a problem. Some welcome rain earlier in the week but amounts small and not enough to really wet up soils.
Weed control: blackgrass emergence slow in stale seedbeds with dry conditions.

West Midlands. Crops range from still not drilled, sat in dust, whilst early crops are now at 3 leaf stage. Some have started on second wheats this week or have been patient and drilling winter barley this week, and finishing off with second wheat next week. Rainfall last Friday and Tuesday night has helped the heavier soils but still not enough on the very heavy cloddy soils to get the wheat going as yet (more heavy showers north of Telford will have helped the job along).
Slugs: still the same this week no major losses as yet but some evidence of feeding on emerged crops.

North East. Drilling going well.  Crops beginning to emerge.

Winter Oilseed Rape 

South. Crops range from 1 true leaf up to 5 leaves – 75% of crops are now around 3 true leaves.
Phoma: none seen to date, even on volunteers in nearby rape stubbles – but 5+ inches of rain in second half of August will be more than sufficient to trigger spore release at some point.
Flea beetle: shot holing of cotyledons/leaves still surprisingly hard to find to date, though low levels of activity are starting to appear.
Slugs: surprisingly problematic on a range of soil types, with a few fields/part fields needing redrilling last week. Wet back end of August clearly encouraged activity and hatching of eggs. 1.5% Metaldehyde pellets applied on rolls has prevented problems in 75% of crops, however, remaining acreage has required re-pelleting in many cases with a further 5kg/ha of 1.5% metaldehyde pellets.
Turnip Sawfly: first instar larvae being found in significant numbers now even in crops sprayed with a pyrethroid 7-10 days ago. Pyrethroid now being applied to most crops in next 4-5 days to control larvae.
Weed control: significant flush of blackgrass in many fields where there is a history of the weed.

Eastern Counties. Crops have grown away well in the last week and most now are established except in a few heavier cobbly areas of fields where there are lower populations of struggling smaller rape. Most advanced crops at 5 to 6 leaf stage, most 3 to 4 leaves. Recent rainfall varied from between 4 to 18 mm, this has helped especially with N uptake for some crops. Conditions now very drying again.
Phoma: none seen to date.
Flea beetle: little further feeding. After most crops treated once with a pyrethroid.
Slugs: continuing to apply pellets in thin areas (poorer seedbeds = heavier soils) of a few fields.
Leaf miner: present – pyrethroid sprays appear to have controlled some of the larvae. Some cabbage root fly damage, taking plants out (a few) on earlier drilled fields especially.
Volunteer control: Falcon activity on volunteer wheat has been slow during the prolonged dry spell.

East Midlands. Emerged crops continue to grow well with 4 leaves but later drilled still a bit patchy where dry soils and crops are still at early cotyledon to 1-2 leaf stage.
Flea beetle: still no damage seen or heard of locally and not a lot seen in water traps either.
Slugs: earlier crops growing away from any potential damage but later emerging ones still at risk although no reports of any significant damage

West Midlands. Apart from one very heavy block of land all crops are now at a minimum of expanded cotyledon, earlier sown crops are now really taking off with up to 6 true leaves. Light land crops were wilting mid-week.
Flea beetle: heavy land crops sat in dry are starting to suffer, plus non mesurol dressed crops.
Slugs: some fields have needed treating despite the dry.
Weed control: large number of volunteer cereals coming through especially after spring or winter barley. Fathen coming through pre ems on light land.

North East. Good start to new crop with good germination seen across fields. Most crops range from one to 3 leaf.
Flea beetle: low levels. Yellow traps out.