Slug activity has increased recently and as expected, this has been most pronounced in crops following rape and where seed-beds have been cloddy. Later-drilled, slower emerging crops have been hit in particular.
Propyzamide (eg Kerb Flo) and Carbetamide (eg Crawler) applications should be stalled until soils cool. Propyzamide is more effective when applied in cool conditions as this improves its persistence. Also, weeds are more easily controlled when their growth is less active but not entirely shut down.
Firm seedbeds, high soil moisture content and recent frosts also improve the efficacy of these actives. Where a visible phoma threshold has not yet occurred a latent infection will be developing within the plant. In these cases a pragmatic approach to control is advised eg by mixing the fungicide with a scheduled propyzamide application for grassweed control.
Risk of Barley Yellow Dwarf Virus infection has been high this autumn. All crops that have emerged so far should be protected by seed treatment or foliar insecticide. If conditions remain mild then early September-sown crops treated with Deter (now 8 plus weeks post-emergence) should receive a foliar application of cypermethrin to continue protection until aphid migration ceases. Even if cold conditions occur, crops that emerged in late October/early November should still be treated to prevent build up of aphid colonies that may have already established within the crop.
Blackgrass is emerging and has been seen pushing between clods where pre-emergence herbicides where applied to dry, cloddy seed-beds. Atlantis – autumn or spring application? Apply Atlantis in the autumn where blackgrass and sterile brome are the main targets and blackgrass populations are “more difficult” to control, due to high populations or more resistant types. Spring applications should be considered where a mixed population of black-grass with wild oats and or other bromes and cleavers are likely.
Autumn applications should be made at the one to three leaf stage of the blackgrass while the weed is still actively growing. Conditions must allow the spray to dry on the leaf. Avoid spraying later in the day when damp conditions may occur before the spray dries on the leaf.
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26 June 2009
Crops have responded well to a much needed drink and wheat drilling has generally caught up. Crops drilled into better seed-beds after the rain are emerging more evenly than the earlier-drilled wheats which can vary from early tillering to just emerging in the same field.
In most cases pre-emergence herbicides have been applied but it remains to be seen how well they work. Where volunteer beans need to be controlled we are waiting for the crop to reach two to three leaves before applying the one remaining mecoprop-based product with autumn use on the label. All other CMPP-based products are no longer registered.
Alternative herbicides for volunteer bean control are limited to low rate clopyralid (comparatively expensive) and the autumn sulfonylureas.
However, sulfonylurea use in the autumn impacts on subsequent applications – particularly where Atlantis or Pacifica are planned. Where seed hasn’t been treated with Deter a foliar insecticide application is planned as aphids are evident in crops. At this rate I can’t see a lot of autumn Atlantis being applied due to the delayed emergence of crops and blackgrass. Slugs have not been particularly evident so far due to the long dry period in August and September but since rainfall they have materialised rapidly in crops following oilseed rape and in patches in some fields with a history of slug problems.
Oilseed rape crops have improved considerably since the rain which has helped to mineralise nitrogen and encourage growth. Crops that established early have recently received an application of metconazole to regulate growth and protect against phoma infection. Although phoma lesions aren’t widespread there are a few hot spots and wetter conditions will start to encourage disease development.
Most crops that haven’t already been sprayed with fungicide will be sprayed in the next couple of weeks. Although soil temperatures are falling gradually it is still too warm and dry for the application of propyzamide and/or carbetamide. Soil temperatures are still in excess of 10C.
20 September 2009
Growers who had the patience to wait for rain before attempting to drill into dry cloddy seed beds were rewarded with 20mm of rain on 6 October.
These winter cereal crops were drilled into ideal seed-beds and with warm soil temperatures and moisture, it has not taken them long to emerge. All crops drilled at this time have been treated with a pre-emergence herbicide, based around flufenacet.
Where blackgrass resistance is known, programmes have started with tri-allate as the base, followed by flufenacet mixtures. Where the variety is not sensitive, chlorotoluron has been added.
Winter cereal crops drilled before the rain, and where moisture was not retained, are at various degrees of emergence making herbicide decisions quite interesting.
Slug activity has been low, however with some moisture available slug eggs may be encouraged to hatch.
Therefore, any areas where the seed-bed is far from ideal will need to be monitored. Hopefully this year will see a large reduction in the use of slug pellets, thus preserving product availability.
Deter seed dressing has been the best investment so far, avoiding the need to use an aphicide. As crops are at different grow stages this would have been challenging.
Some parts of fields have been up for three weeks and some have not emerged. Crops like this will probably require further insecticide applications, which from an environmental view is not ideal.
So far, the only disease found on winter wheat is mildew and this is on drought-stressed land. Oilseed rape crops have responded well to moisture and autumn-applied nitrogen. Unlike last year, many crops will be treated with a growth regulating fungicide, tank mixed with a phoma and light leaf spot product.
Autumn-applied herbicides appear to have worked extremely well, particularly where they have been tank mixed with a graminicide. The metazachlor plus Aramo ( tepraloxydim) have worked well on emerged blackgrass. Most crops will have more than nine leaves, which is the cut off point for Aramo use.
At present high soil temperatures and lack of soil moisture are preventing any applications of propyzamide and carbetamide-based products.
12 October 2009
As I write clouds are gathering, but cynicism does not get my hopes up about rain.
We did have a welcome few hours on Monday, which left between 5-12mm depending on where you were.
This has softened soils but the wind and sun has dried a lot of this up.
Decisions on patchy rape crops are to be left until next weekend to see if the rain has triggered germination of the seeds that were planted into dust.
A lot more leaf miner damage has been seen but I have found pupae so hopefully the worst is over for this year.
The perils of late-applied Atlantis this year on minimum tilled rape have appeared on one crop of rape I’ve seen, which is more noticeable as the other half of the field was not treated.
This I hope will grow out of it. Other rapes that have got away are looking very well with no phoma at the moment.
Rothamsted’s forecasting tool shows it should show up imminently in some areas, so vigilance will be necessary.
A few crops have reached the stage where a plant growth regulator is being used to slow them down and a few aphids have been noticed on volunteer cereals.
These need to be monitored as they could be Turnip Yellow’s vectors. Blackgrass is appearing in many fields but those with resistance issues should not be tempted to use Kerb/Carbetamex yet as soil temperatures are far too high.
Cereal drilling has now started up again after a lull where people had done as many fields as they could before all the steel wore out! Early crops are coming through but are quite patchy.
Winter barley fields with blackgrass have had a robust pre-emergance treatment applied as the options post-emergence are very limited. Many wheat fields will now receive a peri-emergence or early post-emergence treatment, particularly if we get the rain this weekend.
5 October 2009
At last, significant rainfall looks likely this week.
Just in time to boost, and in some cases save, struggling rape and cereal crops.
Hopefully this moisture (assuming it rains as forecast) will enable growers to complete final cultivations on fields previously too dry and cobbled to be drilled.
Following moisture, any outstanding pre- or peri-emergence applications should be completed as soon as possible as these will work best before the target weeds have emerged and started to grow.
In oilseed rape, moisture should speed up growth as soils are still relatively warm and plants will be able to utilise any applied nitrogen.
Also expect a surge in volunteer growth as a second flush is activated.
Very few phoma lesions have been seen, but continue to monitor crops and treat once a threshold of 10% plants infected is reached.
This season, this is likely to be from the third of fourth week of October.
In all fields, slug populations will have been knocked by the dry conditions. However, it’s worth reiterating that when soils become moist the threat of slugs will quickly re-occur. Be vigilant and set bait traps, paying particular attention to backward or struggling crops.
Cereals not treated with an insecticidal seed dressing, e.g. clothianidin, should be protected from aphids and the consequential BYDV infection. Treatment is typically applied at the one-to-two-leaf stage, but remember aphids can feed as soon as the crop is green.
In some cases a pass of straight insecticide may be required (e.g. where pre-emergence herbicides have been applied). This may seem tedious but don’t underestimate the value of this spray. On all crops, whether having received a seed treatment or foliar-applied insecticide, a follow-up application may be required depending on the length of the autumn season.
As we approach the second half of October, thoughts turn to drilling winter beans. Check thousand grain weights of seed stocks and plan the seed rate, aim to establish approximately 18 plants/sqm. Plan for robust pre-emergence herbicide applications as post-emergence options are limited and often expensive, unreliable or both!
28 September 2009
I am slightly surprised to come back from the lush, sunny Dordogne to the East Anglian “Sahara”, which was quickly evident in the noise and dust of farm machinery.
Rape that went in three weeks ago has generally come up well and is now at three to six leaves. But slightly later drillings are struggling in the dry. This has meant many planned sprays haven’t gone on yet, be they pre or post-emergence.
Volunteer barley, however, is growing well and is being taken out now as the shading on the smaller rape plants will not help.
Slugs are not a problem, but flea beetle is having to be addressed even where seed dressings were used, particularly on very small uneven stands.
There appears to be quite a lot of leaf miner damage and a report of turnip sawfly in a crop north of Norwich.
One forward crop also has some phoma appearing though conditions for spore release have not been fulfilled. Trash maybe? Blackgrass is beginning to appear in some fields even if the rape isn’t.
Winter cereal drilling is very much a mixed bag. Some crops are at two to three leaves, some have been drilled into dust and won’t appear until it rains, and many fields are being left due to the poor state of the seed-bed. Phone calls are mainly to ask “should I or should I not apply herbicides?”
That will depend on the crop being grown and the main problem weeds it will have.
There is going to be a big push this autumn on the update seminars for the PA4 slug pellet certification scheme, to help reduce the occurrence of metaldehyde in water, More details will emerge over the coming weeks.
21 September 2009
Continuing dry conditions in the east are resulting in very uneven oilseed rape establishment.
Where the better seed-beds on lighter soils have caught the odd shower of rain, plant populations are sufficient to make a crop. Thankfully most rape plants have managed to find moisture and have survived.
Nevertheless on heavier soils and in poorer seed-beds rape establishment is down to 10-20% and these situations require a good amount of rain to fully moisten the seedbed and encourage further germination. Even then low plant populations and reduced plant vigour may result in a poor crop going into winter.
There has been quite a lot of leaf miner damage to OSR plants although this is mainly restricted to cotyledons. In some places flea beetle have been active even where the more persistent seed treatments have been applied. Dry conditions may have reduced systemic movement of the insecticide active ingredient within the plant. A foliar insecticide may need to be applied in these situations.
Wheat drilling has started albeit into dust and clods. Seed rates need to be adjusted upwards in these dry conditions to take account of likely emergence date and cloddy seed-beds. Although slugs are not active at the moment, resulting seed-beds, when it does rain, will be conducive to slug activity.
Fields destined for pre-emergence herbicides will be sprayed as soon as possible after drilling rather than waiting for moisture. The herbicide active ingredients that we are using, other than tri-allate, are not readily volatilized in dry, bright conditions so will not degrade rapidly in dry seed-beds.
Most of them are taken up both by the roots and the shoots of germinating weeds. Shoot uptake is more important in dry conditions when herbicides may not reach the rooting zone of weeds. Trials results and field observation during the dry autumns of 2003 and 2007 showed that pre-emergence herbicides continue to provide high levels of weed control even in dry seed-beds.
————————————————————15 September 2009
The 22.6mm of rain we had at the beginning of September has completely disappeared, and some of the later emerging oilseed rape on heavy land looks in need of a drink. However I will not tempt fate by saying we need some.
Where rape has been established in the conventional way it has all been treated pre-emergence with the first dose of herbicide. My preferred product choice has been Shadow or Katamaran Turbo (dimethanamid-P + metazachlor + quinmerac), as it worked exceptionally well last year.
Rape crops established via the sub-soiler technique that are at the fully expanded cotyledon stage are about to be treated post-emergence in mix with a graminicide. Product choice depends on whether black grass is present.
With such dry conditions, there is very little evidence of slug activity. Where headlands have been treated I have recommended ferrous phosphate based products.
The pest that is active is flea beetle. It shows the advantage of using a seed treatment with good activity against it, as any germinating untreated seed would have been bitten off below ground level. At least the seed dressings have allowed the crop to emerge and get to fully expanded cotyledon and beyond stage.
Winter wheat drilling has started but only on fields that do not have serious grassweed infestations. Where blackgrass is a problem fields should be drilled later to allow any germinating blackgrass to be treated with glyphosate pre-drilling.
Seed rates on these fields should also be kept up. I always remind growers it is easier to manage a thick crop than a thin one. I am also reminding growers that in order to get the best performance from pre-emergence herbicides they need to create good seed-beds with tilth, which in some cases on heavy land may prove difficult. The three things to remember are drill, roll, spray.
We can no longer rely on Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium) as the final solution to blackgrass control, but it is part of an integrated programme. I am waiting with interest for the results of the blackgrass samples that I sent for resistance testing in mid-July. My bet is that at least half will show resistance to Atlantis.————————————————————-1 September 2009
It’s been a dry start. Despite dry soils, growers have forged ahead with rapeseed drilling and in the main seed-beds have adequate tilth and the seed is well covered. As crops begin to emerge slowly some seed remains dormant waiting for rain; thankfully there’s little evidence of chitted seed that has struggled and died.
Those who have delayed early residual herbicides because of the dry conditions should be ready to apply these soon after most of the crop reaches the expanded cotyledon stage – before weed emergence.
As cereal volunteers become competitive, aim to take them out swiftly with the first contact graminicide; this may be necessary soon, particularly where the crop follows barley.
Where relevant these graminicides can be mixed with the post-emergence spray, but always check product labels for compatibility. Following rain, struggling rapeseed will appreciate 30kgN/ha.
Despite dry conditions there is some evidence of slug grazing. Fields should be monitored for the pests’ activity from drilling to the two true leaf stage and pellets applied as and when necessary. Remember metaldehyde stewardship guidelines and manage applications so that the maximum dose and number of applications for individual products are not exceeded.
Focus on achieving good seed-beds for winter cereals which are ever more important as grassweed control becomes more challenging. Residual pre-emergence herbicides work best on fine, moist, friable seed-beds.
6 July 2009
Oilseed rape crops on light land are rapidly approaching the correct stage for glyphosate application. Those on better bodied soils are hanging on and will probably be at the right stage for desiccation in five to seven days time depending on the whether.
I try and go as late as I can as we’ve found this keeps the oil content up.
While examining crops it’s been evident that there is very little sclerotinia infection. I’m looking out for signs verticillium wilt which looks like being the next big disease problem to hit the crop.
There is very little damage from seed weevil or bladder pod midge, which makes it very gratifying that the right decision was made not to include an insecticide with the mid-flowering spray.
Winter barley harvest is not far off, but nobody seems to be getting too excited about it due to total lack of interest from the market.
Second wheats are beginning to show classic take-all symptoms. Even though crops lost tillers during the spring drought they appear to have compensated by producing more grain sites per ear. Whether this will be expressed in yield has yet to be seen.
Crops that went into poorly structured soils are also starting to exhibit all the foot root problems, which will only be detrimental to yield.
Very few blossom midge larvae can be found in the ears, again confirming that it was the right decision not to spray.
Aphid numbers are increasing in untreated crops, but most are past the vulnerable stage. Only late-drilled and spring crops need treating.
Dried pea crops have really appreciated the dry whether; let’s hope it stays dry for their harvest. They’ve received their second fungicide, insecticide for pea moth and aphids, plus manganese.
Spring beans look extremely respectable, and like the peas have been treated with a second fungicide for downy mildew and a triazole for protection against brown rust.
Sugar beet, growing rapidly in the past three weeks, is meeting in the row. But it’s worrying to see the amount of bolters appearing – even in low bolting varieties.
The crop will receive its first fungicide for protection against foliar diseases in the next 10 days. Black aphids can be found but not in great numbers.
29 June 2009
As I write we’ve just endured 39mm of rain in under an hour.
Fortunately, there was no wind, so the fear of flattened corn hasn’t materialised as yet.
Winter barleys are turning rapidly. On light land crops have burnt out in patches, but on the heavier soils they’re ripening naturally. I’ve no idea how yields will go, as the ears are quite full, but tiller numbers are lower than last year.
Spring barley is very thin after the prolonged period without rain just as it was tillering, although it looks better than it should in many fields in this area. Late N uptake may cause problems with malting quality.
The interesting crop this year that I have on several acres is red wheat, which offers a large end price, provided the specs are met.
Initially, like spring barleys, it emerged very well and hope sprang. Then the drought set in and they have struggled, as N input levels were set quite low to achieve the high protein required.
The crop’s inability to have picked up N during the main growing period has been the problem; and with small ears and low tillering, yields are liable to lower than expected – but combining will tell.
Wheats have also suffered with fewer tillers. But with relatively low disease levels all the leaves can receive sunlight and so are contributing to yield. This, I hope, may mean longer ear-fill and maybe a better quality if the weather plays ball.
In sugar beet it’s time to remove weed beets where they’re now very evident.
The weather hasn’t helped with weed control, particularly of late bindweed and tough knotgrass, and some headlands are not pretty.
Oilseed rape desiccation is round the corner and some decisions will be easy. But, unfortunately, others will cause quite a few headaches given the uneven, weedy crops we have to contend with. Who’d be an agronomist?
15 June 2009
Most combinable crop spraying is almost complete, although some wheats are still receiving T3 treatments to top up foliar disease control.
Some oilseed rape crops this year will cause desiccation problems due to their uneven development and maturity. There will probably have to be some fiddly part-field spraying with glyphosate at different times to accommodate this variation.
An alternative is to apply a pod sealant and then follow up with glyphosate once the more backward areas of the field have reached the appropriate stage for treatment.
The sealant will help protect the more mature areas of the crop from damage when the sprayer travels through it. But this technique will require careful selection of water volumes and nozzles to avoid the pod sealant preventing full uptake of the later-applied glyphosate.
Quality wheats have been sprayed at ears emerged or just into early flowering to try to control fusarium species and associated mycotoxins.
As milling wheats reach milky ripe stage they will receive a top-up of foliar urea or a stabilised nitrogen product to boost protein levels. The need for this late addition of nitrogen was a topic of discussion at Cereals with the crop nutrition research scientists.
Their work with NIR looks promising, but not yet ready to be applied practically. Nevertheless, given the uncertainty over nitrogen uptake and loss this year (especially where urea has been used) it would seem too risky to drop the late nitrogen treatment on promising milling crops.
Now is the time to assess the effectiveness of treatments, especially of grassweed herbicides, during the season.
Generally where robust pre-emergence residuals were applied they worked well allowing surviving grassweeds to be tidied up with Atlantis or Pacifica (iodosulfuron + mesosulfuron)in the spring.
Where these products have been used as the only grassweed treatment, due to lack of opportunities to spray in sequence with autumn residuals, poorer control has sometimes resulted.
The question is whether poor control is down to unsatisfactory application technique and conditions or to herbicide resistance.
Any surviving areas or patches of blackgrass will, therefore, be tested for resistance using the rapid Petri-dish test developed by Rothamsted. This can produce a result in as little as six weeks allowing grassweed control decisions to be made before establishing the following crop.
Areas or fields where blackgrass control has been poor will need to be focused on to maximise cultural control perhaps even resorting to the plough to bury seed or use the stale seed-bed plus glyphosate approach.
Where Atlantis target-site resistance is identified it will be necessary to consider alternative herbicide strategies using pre-em and early post-em residuals.