RAPID ACCESS TO THE LATEST REGIONAL CROP PEST AND DISEASE LEVELS
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Crop Report: 27 April 2007

Report compiled by Farming Online from reports received from members of the Association of Independent Crop Consultants

Pest Alert - South East. Mealy Aphids in Winter Oilseed rape, foci right across some fields, high numbers, and very early to arrive. Threshold is 13% of plants infested.

Disease Alert - Brown and Yellow rust widespread. Yellow rust in crops of Robigus in Eastern Counties. Brown rust in Alchemy and Solstice in South and East.

Crop development - Are wheat crops bolting? Some rain for some at the beginning of the week has dissipated with the drying winds and a return to warm, dry conditions are causing autumn sown wheat crops to race through their growth stages. There is concern that the heat and lack of rain may be causing them to bolt rather than develop naturally. Spikelet counts are so far normal in September sown crops, being in the mid twenties. But tiller numbers are down. Grain set and weight will be an important component of yield this year. Keeping crops going for the next three months is the challenge. Winter barley crops are suffering the same fate but have less time to go. Whilst, winter oats are only just beginning to wake up with very little growth throughout April. Winter rape is coming to the end of flowering and setting pods and appears to have suffered the least from the dry April. See also www.leaf-emergence.co.uk to compare winter wheat variety development by sowing date and site.

Highlights
Winter rape
  • Mealy aphids in the South East, South West and East Midlands.
  • Sclerotinia risk increased in the West.
  • Mid pod set.
 
Winter Wheat
  • More crops at final leaf 2 emerging, forward crops at Flag leaf emerging.
  • Brown rust in Alchemy causing concern.
  • Yellow rust in Robigus raises doubts about the variety.
  • Dry conditions still hindering N uptake.
  • Eyespot still obvious in some crops.
  • Brown rust developing in the South and East.
  • Take-all showing up in second wheats.
  • T1 fungicides applied.
 
Winter Barley
  • Crops at GS31-40.
  • Disease levels low.
  • First signs of BYDV.
 
Spring Beans
  • Bean weevil damage rife.
 
Soil Temperatures
  • Still around 10-12°C. Reports of large cracks in heavier soils and light land parched.

Winter Oilseed Rape
Sclerotinia control
Photo Farming Online.
South East: All crops now at mid-flower (20-30 pods on main raceme). To date pod set looks encouraging and with a long flowering period looking likely as side racemes extend, hopefully yields will be respectable.
Sclerotinia: continuing very dry weather and soil surfaces, coupled with very little petal sticking, means that the risk of infection remains very low. Mealy aphids:foci right across some fields, high numbers, and very early to arrive

South West: Petal fall well underway with little flower left on the main raceme of forward crops. Canopies are still very upright and open with excellent pod set.
Mealy aphids: levels are high for so early in the season.

East: Crops all in full flower, earliest now at petal fall with 20+ pods set on main raceme. Still holding off on decision on flowering fungicide on low risk sites. Other fields have been sprayed. Crops generally very short.

East Midlands: Crops well forward with many crops at mid to late flowering - up to 50 pods on some racemes. Flowering could well be coming to an end some 2-3 weeks earlier than usual as temperatures pick up again. Odd cases where lower petals show sulphur deficiency even when sulphur N applied. Probably due to N (and Sulphur) not being taken up quickly enough in the dry as a lot lay on the surface for some time. All nitrogen applied 2/3 weeks ago but poor uptake. Some crops look starved, and some Bastille and Amstrad very short. Mealy aphids: found on some crops - numbers are low but some racemes heavily infected - this is usually a late season problem which generally needs no control measures but worrying that they are in early this year. Crops will be monitored for build-up, but as crops are well into petal fall then hopefully will not be a problem. However, having seen odd plants going "blue" due to stress of aphids nothing would surprise in this weird season.

West Midlands: Main stems have set majority of pods, crops now at 30% pod set. Sclerotinia sprays already applied to high risk crops. Monitoring of Sclerotinia at Rosemaund has shown a big jump in spores recently.

North East: Crops at mid-flower now, with just a few pigeon or flood damaged areas still a bit behind. 20-30 pods set on main stems now. Sclerotinia: this is a high-risk area due to short rotation and very high acreage of rape over may years. Despite dry conditions will apply fungicide when 10 - 20 pods set on main stem. Seed weevil: found above threshold levels in some crops so best to assume numbers will rise over next few days.
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Winter Wheat
Flag leaves emerging.
Photo Farming Online.
South East
Crop development: A combination of recent warmth, generally low residual N status and continuing dry weather, hampering N-uptake, is forcing many wheat crops into stress induced physiological development with accelerated leaf emergence. So much so that many September and early October sown crops range between GS 33 (Claire/Alchemy) with leaf 2 up to 2/3 emerged up to GS 37 (late September sown Xi19). All late September and early October sown crops of Einstein and Solstice now have leaf 1 up to 1/4 emerged - most of these crops were only at tip of leaf 3 emerging around 18-21 days ago. Late October/early November sown crops are now at GS32 with leaf 3 emerged and leaf 2 around 30-50% emerged. All crops of Soissons drilled in October/November are now at GS 37-45, with ear emergence likely next week. It now seems increasingly likely that in many cases, assuming disease pressure remains low, crops will only receive one further fungicide at around ears half-emerged. This will need to be robust enough to cover sustained brown rust pressure. A combination of delayed N-uptake and the unusual weather conditions this Spring, have reduced yield potential even on the better soils (substantially so on poorer soils). There is widespread tiller abortion in crops leaving many canopies much thinner than usual. This also needs considering when planning fungicide spend. Still very dry and it is now 6 weeks since any notable rainfall.
Brown rust: still very widespread on lower leaves all September sown crops of Alchemy, Claire and Solstice, with active pustules still evident in crops where T0 triazoles applied.
Septoria: lesions very obvious on all older leaves of all September/early October sown wheats - lesions can be found on leaf 4 of early sown Solstice and Xi19.
Eyespot: can still be found in earlier sown second wheats and Solstice/Robigus as first wheats.
Yellow rust: in Robigus in the Halstead region, and Buntingford, Herts, all on hilltops, some only on North face. Could be Northerly wind from Cambridge area.

South West
Crop development: Crops breaking all records for leaf emergence. Flag leaf tip (GS 37) is common in September sowings of Alchemy, Einstein, Mallaca and Solstice and there are still 4 days left in April. This is about 1.5 leaves ahead of normal. Only Claire seems to be behaving like a late developing wheat although leaf 2 can still be detected in early sowings. Even Humber seed crops, which is claimed to be a slow developer, are racing on. A late frost as in 1992, which destroyed Soissons ears could be very serious, especially if coinciding with hot tank mixes, so be careful. Field conditions: Very dry we have still had only small amounts of rain.
Brown rust: levels very high in Alchemy, where no T0 triazole was applied patches of yellow tipping not unlike yellow rust patches are obvious. This tipping and rust infection is confined to leaf 4 and 5. Epoxiconazole plus fenpropimorph treatments have kept it from leaf 3 upwards. Most common in Alchemy, Zebedee and Claire but has been detected in Robigus. The rust epidemic has been favoured by high April temperatures and a profusion of susceptible hosts. The virulence of the Alchemy strain is alarming.
Mildew: levels still very low even on very susceptible varieties.
Septoria: levels not increasing with all spring emerged leaves totally clear.
Yellow rust: outbreaks in Robigus now contained.
Eyespot: dry April has slowed development and penetrating lesions rare.

East Midlands
Crop development: Most crops at leaf 2 with odd ones showing flag leaf tip. Backward crops have leaf 3 emerged. Big decision will be on T2 timing - it could be a long time from T2 until harvest depending on how May and June turn out, which puts a T3 spray more likely than in many seasons, especially on dirtier varieties. Some rain (about 6 mm), only 3 mm rain in 6 weeks in some areas, has helped a bit but not enough if weather warms up again. Continued dry weather is resulting in plant tiller numbers reducing while crop is making slow growth. Soils generally dry and rain has not penetrated any clods. Second split of main N due to go on but farmers have been holding back in dry weather until some moisture to take it in. Granules from earlier applications still on the ground.
Mildew: levels very low.
Septoria: T1 spray now on most crops and - leaves 4 and 5 are clean due to chlorothalonil at T0 and dry weather. Brown rust: not a problem so far.
Yellow rust: only present in Robigus - there is a big question mark over the future of Robigus amongst farmers.
Eyespot: crops quite clear.

West Midlands
Crop development: Range GS 23-37. Mid September sown Einstein now has flag leaf 10-30% emerged with some plants at full flag. Alchemy has flag leaf emerging just. Bulk of remaining crops are at leaf 2 emerged or emerging. Rain has at last arrived with 8-12 mm, north and west of the Severn, on Monday night. Land to the east received half of this. Wheat on lighter or drier land continues to loose tillers leaving some very open crops. Yield potential has already been reduced in these crops.
Brown rust: still very little present even on Alchemy.
Mildew: beginning to develop on some late sown crops.
Septoria: high levels on older leaves, especially Einstein.
Eyespot: low levels on Alchemy, Einstein, Robigus and Solstice.
Yellow rust: no reoccurrence seen on treated crops.
Slugs: feeding on aerial parts of plants on damp mornings. Rain has brought yet another flush up onto leaves some places have severe shredding.
Bromes: patches, some dense, after min-tilled crops.

East
Crop development: Crops mainly at GS32 with a few forward crops at GS 37 T0 and T1 sprays seem to be holding the rusts. Some wheat, particularly later drilled showing drought stress. Both Yellow and Brown rust are prevalent on susceptible varieties, on Robigus it has taken around 7 - 10 days for the 'T1' mix to clean up existing infections.
Brown rust: is active on a number of varieties, Alchemy worst affected with disease readily seen on leaf 5 and creeping onto leaf 4 in some crops, and must be carefully watched. At the current rate of progress on some early fields, flag leaf spraying may commence from around 10th May.
Yellow Rust: there are obvious foci in some crops of Robigus, developing quickly if untreated. Yellow patches seen from a distance on some fields.
Mildew: treatable levels and spreading up on Solstice.
Septoria: no increase - lower leaves on most varieties have the disease.
Eyespot: at low levels.
Take-all: Some had predicted that the warm wet conditions back in the autumn would favour take-all; and where soils 'slumped' back in late February / early March there are telltale patches beginning to develop on some fields of second wheat. These effects would appear to have been exaggerated by the lack of moisture moving N into the crop over the last two months. Monitor these areas, and make necessary economies in terms of fungicides + other inputs where possible.

North East
Crop development: Later crops at GS 31-32, most forward crops at GS32 -33. Yet another 7 days with no measurable rainfall. Wheats not showing any signs of drought stress so far, they are growing well but without the lushness of a 'normal' season. Some growers applying last split of N to feed wheats this week, but most waiting another 7 days as advised.
Brown rust: at treatable levels in most crops of Alchemy but less so in even lower rated Cordiale.
Mildew: as with Brown rust it has mostly disappeared now.
Septoria: despite dry conditions there are still high levels on older leaves so robust control required at T1.
Eyespot: dry conditions make severe damage less likely but even now stem bases are rarely dry.
Yellow rust: very few actual pustules can be found, but there is a lot of dead leaf where developing disease has been controlled by T0 cyproconazole. Will need close monitoring to watch for an earlier flare up than may expect.


UPDATE Leaf Emergence in Winter Wheat. Comparing this year's growth rate with last year's.



Comparison of leaf development 2006 vs 07. Crops sown at Andover trial site. The crops were sown on the 11 - 12 September, in autumn 05 and 06.

The graph shows the rate of leaf emergence over time and shows that these varieties have reached the same growth stage 14 days in advance of last year.

See leaf-emergence.co.uk for more sites and varieties. This study is sponsored by Bayer Cropscience.

They're not faster. Just earlier.

The top leaves of the canopy are not emerging any quicker than they did last year. In 2006 these varieties averaged 18 days between the appearance of final leaf 3 and the flag leaf. In 2007 it's taking about the same amount of time. But it has happened a fortnight earlier.

In 2006 the flag leaf averaged 9 days to emerge. At the current rate of growth flag leaf emergence, in 2007, will take the same amount of time.

Forecasts for another warm weekend suggest that these varieties will be ready for their flag leaf fungicide by the end of next week with full flag emergence predicted to occur around 5 May.

In 2006 ear emergence started around 30 May and flowering about 10 June. Assuming crops this year develop over the same time span as in 2006 then expect September sown crops to start flowering by the end of May.
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Winter barley
Awns emerging
Photo Farming Online.
South East: Most crops of Sequel/Pearl are now at GS45-49 with awns emerging, whilst Boost is at early ear emergence. Where Net blotch: where T1 sprays applied in first 10 days April, net blotch has not moved from base of canopies. However, in any later applications net-blotch has jumped up all leaf layers.

South West: Awns now emerging with ear half out on forward sites in South Somerset.Rhynchosporium: after worrying levels early this season progress has been slowed by the dry weather. Brown rust: well controlled by T1 mixes. Mildew: at very low levels.

Midlands: Awns now showing in forward crops, some 2 weeks earlier than usual. Crops not all that tall so dubious as to whether a late growth regulator is required in many cases. In the West, crops range from GS 32-49. Carat is the most forward variety with awns emerging, Siberia is a close second. Crops are short but mainly free of disease.

East: Developing rapidly. Most fields GS 39 but some awns emerging (GS 49). Generally, low levels of disease particularly rhynchosporium.

North East: Flag leaf emerging in most crops, and fully emerged in some. Very dry, but most crops not showing severe drought stress. Some have flag leaf emerged and are very short so not risking any PGR, but all 6-rows. Net blotch: significant level in Carat and Pict, but Saffron only very low level.
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Spring Beans
Sitona weevil in spring beans
and typical "U" shaped notching
on leaf.
Photo Farming Online
South West: Early February sowings emerging vigorously and evenly. Sitona weevil notching now showing up.

Midlands: Many crops at 2 leaf but being attacked by weevils so getting insecticide as they do not want holding back due to late emergence. Pre-em herbicide variable in the activity - where light soil have not done much at all. Spring beans now drilled - first crops emerging but immediately being attacked by weevils - so cyper being applied to all crops.

North East: Crops emerging to one true leaf.
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Crop Report compiled by Farming Online from reports received by members from the Association of Independent Crop Consultants


 
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