Farming News - Crop Report - Sclerotinia threat increases with rain
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Crop Report - Sclerotinia threat increases with rain
29 April 2010. Rain at last and more forecast for the weekend has raised the spectre of Sclerotinia. Many winter rape crops now flowering. Winter wheat crops remain short and tiller numbers are down but final leaf three has emerged in many early crops and many T1 fungicides have already been applied.
- Crops remain short, thin and open after prolonged cold dry spring
- Final nitrogen going on winter crops
- Winter barley has flag leaf emerging
- Disease levels in winter wheat remain low
Sclerotina Threat Increases with Rain.
HGCA funded research found fungicide performance only differed at high disease levels. When disease control and yield were averaged over all doses, Filan, Proline and Compass ranked above Amistar, Folicur and Priori Xtra. All fungicides for Sclerotinia are only protectant. A single spray at early to mid-flowering gave good protection for about three weeks. Click here to read results. In spring, soil temperatures of over 10ºC encourage sclerotia near the surface in moist soil to germinate.
Winter Oilseed Rape
South East. Mostly at early flowering – ES Alienor close to mid-flower in some areas and is still most advanced variety. Despite dry weather, crops generally looking quite useful, though could really do with a decent rain to wash in final doses of Nitrogen properly.
Light leaf spot: only very low levels in evidence.
Sclerotinia: despite lack of rain, night time air and soil temperatures are now high enough for apothecial development (7’c+). Sclerotia will now germinate freely and if we do get rain this weekend then infection pressure could be intense and potentially sustained until the end of flowering, leading to a very high risk year due to later flowering generally. Current forecast is for wetter weather to arrive at end of next week ie. at around early to mid-flowering – plan to get most crops sprayed with Proline/Folicur + MBC mixes ahead of rain at yellow bud to 1st flowers and repeat 14-21 days later.
Pollen beetle: as per previous week, a few warm days at end of last week saw large numbers of pollen beetle arriving in some crops, with 15-20 beetles being found quite widely in fields sheltered from winds and more backward crops having 5+/plant.
South West. Rapid growth continuing with fields starting to look more yellow than green. Growth has not been affected by the dry conditions as much as wheat since N uptake is much earlier in the rape crop.
Light Leaf Spot: new growth very clean.
Pollen beetle: exploded in some areas with the onset of warm weather and a few crops reached threshold. Recent cooler days have seen a reduction in activity and as crops flower risk diminishes.
Eastern Counties. Most advanced in full flower but least advanced only just coming into flower. Big differences between sites and varieties. DK Cabernet late to flower. Frosts have damaged some flower buds which have turned brown and fallen off – often the top cluster of buds. All planned N now applied. Several crops look spindly, they have raced through the growth stages and seem to have less leaf than in some years. Especially applicable to less fertile sites.
Sclerotinia: planning Proline + /- a low dose of Amistar at v early petalfall aimed at sclerotinia. Will follow up with Compass 3 weeks later on high risk sites.
Pollen beetle: Pollen beetle numbers escalated last week and at very late green bud / early yellow bud stage we treated a few crops which were late to flower. These were treated last weekend in view of the high temps. All other crops were coming well into flower and past the stage of risk.
East Midlands. Forward crops flowering with later crops still at yellow bud to first flowers (in some cases in the same field due to delayed germination in autumn and pigeon damage). Many crops look well in spite of lateness.
Light leaf spot: levels remain very low and no action needed.
Pollen beetle: numbers stabilised probably due to combination of cooler days and night frosts. Risk now falling as crops start to flower.
Sclerotinia: forecast of wet weather will raise risk of sclerotinia. Crops starting to flower getting Proline, but problem decision will have to be made between T1 in wheat or sclerotinia in rape and some risk assessment will have to be done. Priority will be cover on high risk rape crops.
West Midlands. Some crops now at 50% flower/ - first pods (primarily Castile with Vision close behind), with petal fall starting as well.
Will start applying Sclerotinia sprays end of this week/beginning of next week once have reached 17-21 days since canopy management spray/ state of crop re petal fall.
Light leaf spot: not seeing at any significant level.
Phoma: unsprayed crops still have low levels.
Pollen beetle: still of no major concern, one client has footpath right through the middle of his crop and noticeable that there were up to 10 beetles per plant on the edge and virtually none in the middle (which is what we have always known!!). Backward crops need monitoring.
North east. Early varieties Castille and Excalibur in full flower. Other varieties a few days behind.
Light Leaf Spot: despite higher temperatures still not seen any significant levels.
Sclerotinia: Despite the recent low rainfall the soil is moist and warming up. It only has to be 10 degrees C for sclerotia development. Heavy dews are also enough to allow petal sticking. A 2 spray programme is planned for most crops starting with 0.4 kg/ha Filan at early petal fall. For most crops this will be in next 7 days.
Pollen beetle: there have been no instances of pollen beetle at threshold levels in the forward crops, but there have been in some later sown and/or pigeon damaged crops where the threshold is much lower.
Winter Wheat.
South East. Despite warmer nights, drying soils and slow N uptake continue to slow slow crop growth in last week – if we do get rain this weekend will see an explosion of growth as surface roots are now appearing. Growth stages range from late GS30 to GS 32, with September sown crops now mostly at GS 31-32. Leaf 3 now fully emerged on main shoots of September sown Solstice, Gallant and Einstein, with tip of leaf 2 1/3 emerged in more precocious crops – T1 fungicides now being applied to most September and early October sown crops when leaf 3 is fully emerged on main shoots. Final N doses now being applied to all crops on lighter soils in hope it gets washed in soon and next week on medium/heavier soils. With such delayed growth this year, very low soil N levels and poor rooting, nitrogen availability will be key to protecting yield potential.
Brown rust: none seen.
Yellow rust: first isolated foci found in Oakley where no T0 applied – no other symptoms been found anywhere.
Mildew: still no active pustules found.
Septoria: very evident on all older leaves – only top 3 leaves appear free from symptoms.
Eyespot : beginning to find stem lesions in September and early October sown crops of Xi19, Cordiale and Solstice, but current conditions are not really very favourable.
Weed control : Polygonums – large flush of polygonous species now appearing quite widely.
South West. Growth has slowed as continuing dryness inhibits N uptake. Only crops on high mineralisable soil N fields look lush and dark green. We had a similar situation in 2007 when a dry period was followed by rain resulting in extremely rapid mid season growth. We are monitoring PGR strategies carefully, we do not want to further stress thirsty crops but we must guard against lodging in compensatory growth later. Most crops now at GS 31 - 32 with early September drillings with leaf 3 out. Despite claims of newer varieties Claire remains preeminent early driller with it’s slow spring growth habit. Grafton which is touted as a replacement is now racing away with final leaf 3 emerged. It looks thick even when drilled at 125 seeds in early September. I hope it stands as well as claimed.
Brown rust: none seen.
Yellow rust: none seen.
Mildew: will need to be monitored closely in moisture stressed crops.
Septoria: still confined to lower leaves.
Eyespot: lesions in early drillings are rarely penetrating beyond the leaf sheath..
Weed control : spring flushes are well under way with many wild oats at 1 to 3 leaves in known problem areas. One germination trigger in dormant wild oats is rising soil N levels so do not stop looking too early.
Eastern Counties. Crops range from GS 30 to GS 32 with final leaf 3 emerging. Soils dry enough to perform most field operations. Main nitrogen application complete on most crops.
Brown rust: odd pustules on susceptible varieties; Duxford, Zebedee, Cordiale.
Yellow rust: no active disease seen.
Mildew: disease present on late drilled crops and on susceptible varieties, Solstice, Conqueror and Claire, but not active.
Septoria: apparent in most crops, in particular on early drilled and forward crops.
Weed control : wild oats now at GS 1.2 - 2.4 where not controlled in the autumn. Some spring wild oats germinating.
East Midlands. Many crops now have leaf 3 showing and only Nov drilled crops after maize have leaf 4 with 3 tip. In spite of crops catching up in terms of growth stage they are not catching up in terms of height with some crops at leaf 3 emergence looking like leaf 4 crops. Dry weather is acting as growth regulator and in some cases growth regulator is being eased back.
Brown rust: none seen.
Yellow rust: none about.
Mildew: none seen at all.
Septoria: dry weather is holding it back with little or none on leaf 4 and only low amounts on leaf 5
Eyespot: can still be found but levels dropping and only on older leaf sheath with little penetrating. However wet weather now may well increase risk on susceptible varieties and no risk is taken on quality wheat.
Weed control : deciding on any broad leaf weed follow up will have to wait until effects of Atlantis and Othello are seen - at present some good control but may need tidy up if rain brings up a flush of weeds. Wild oats starting to show.
West Midlands. Majority of T1 applications now on, applying magnesium sulphate with T1 on light land. Late sown wheat (typically Oakley and Solstice) has had cyproconazole in with herbicide 10 days ago T1 will be applied next week. Final split of nitrogen is being applied this week and next.
Yellow rust: none seen.
Mildew: traces on Humber and JB Diego.
Septoria: low levels on bottom leaves.
Eyespot: already through to main stem in early sown crops of Gallant and Humber. Visible in Alchemy, Diego and Solstice. Proline or Tracker at T1.
Weed control: Brome control needed - Broadway Star applied 17 days ago beginning to show effect.
North east: internodes still short but most crops now at GS31, and a few at GS 32. Maybe waiting another 7 days would be better, but a lot of final N applications being applied this week because conditions are ideal. Decisions on late N for protein will be made mid-May.
Brown rust: none seen. The T1 planned for varieties susceptible to brown rust is Opus + Tracker. T1 is planned for last week in April to early May. For varieties with good resistance to the rusts the major product will be Proline + Bravo. This group includes Scout, Gladiator, Cassius and Glasgow.
Yellow rust: no infection seen. The T0 application of Cherokee has controlled it well so far. A strob is planned at T1 for all susceptible varieties. This will be provided by Firefly + Bravo and includes the varieties Viscount, Oakley and Robigus.
Mildew: gone in the frost.
Septoria: still a big reservoir of infection on older leaves in most crops, but overall no different to most years at this time.
Eyespot: no obvious infections seen.
Weed control : all herbicide applications for blackgrass completed at least 2 weeks ago now. In most fields control looks Ok, but there are some instances now where there have been dense patches and the control looks poor.
Winter Barley.
North East. Some forward Retriever at GS 37, but for most crops will be a few days until flag leaf emerging.
Eastern counties. Crops in good condition and actively growing and range from GS 2.2-30 with majority at GS 30. First fungicide applications of prothioconazole+ fenpropimorph+ azoxystrobin ongoing and nearing completion on some forward crops.
West Midlands. Flag leaf emerging /out on carat, cassia leaf 2 out, also flag leaf out on light land stressed crops, some are looking pretty ropy and thin due to tiller loss.
East Midlands. Crops have caught up with flag leaf now appearing. Main concern is that no crops are above knee height so no late growth regulator needed but dry weather has hit many crops with some signs of stress, especially on lighter soils.
South West. Final leaf 2 emerging on the earliest drillings.
South East .Growth stages now range from GS32-37. All T1 fungicides been applied at around GS 30-31. T2 fungicides being planned for around 2 weeks time.
Sugar beet
Early drilled beet have established exceptionally well and evenly and are beginning to grow away -now at early 4 leaf stage. However the late drillings have yet to establish and several seeds are still sitting in dry soil. We had max. 5mm of rain over weekend which may have helped on some of the finer seedbeds. Emergence of beet is patchy and so is weed emergence. However, we are spraying a cheap holding herbicide or first FAR on these weeds so they do not get away before a real flush of weeds emerge.
We are well into the middle of our herbicide programmes with the earlier beet and so far all is going to plan as we have had many good spraying days. Volunteer potatoes are slow to emerge but they may be ready for treatment next week.
Spring Beans: at 2-6 pair leaves and bean weevil damage showing and some crops will require spraying.
Winter beans: growing away from chocolate spot but some crops have high level of weevil damage and backward ones will be sprayed. Flower buds visible in some crops.
Linseed now emerging and being hit hard by flea beetle.