Crop Watch – South Autumn/ winter 2006

21 November 2006

James Boswell – H L Hutchinson, Kent
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james boswellOilseed rape
Suspected club root has been confirmed in Kent. This disease is normally only visible in the spring, but due to a very mild autumn, patches are already developing in fields that have had oilseed rape in the rotation in the recent past. In some severe cases fields have had to be re-drilled with winter wheat.

With soil temperatures remaining abnormally high (3 degrees above average), it is still too warm for propyzamide or carbetamide to perform consistently. With falling soil temperatures, early December applications may be more appropriate.

With most osr crops receiving a phoma spray 4-6 weeks ago, re-infection is now taking place, and another application is necessary on susceptible varieties.

Winter barley in a min till situation continues to turn various shades of pale green due to straw and trash utilising residual nitrogen. Also some crops have been slightly whitened by diflufenican/ flufenacet applications.

Winter wheat herbicide and BYDV (Barley Yellow Dwarf Virus) sprays are almost complete on all but very late-drilled crops, with early applications of isoproturon/ pendimethalin/ picolinafen mixes working particularly well on large volunteer osr and cleavers.

Worrying amounts of disease can be found in many early-drilled crops, with mildew especially prevalent in Claire and Hereward, and brown rust in the most susceptible varieties, notably Alchemy and Einstein.

Winter beans have been drilled and are being sprayed pre-emergence with propyzamide and clomazone for cleaver and grassweed control. Bean area is reduced due to increasing problems with Bruchid beetle damaging samples, despite every effort to control the pest.


14 November 2006

Swaran Bachoo – Agrovista, Hants/ Wilts
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Swaran BachooCereal drilling is 100% complete. The recent cold weather has considerably slowed crop growth and most crops are sufficiently frost hardened to be sprayed with herbicides without the fear of adverse crop effects.

September-drilled wheat crops are well tillered. Alchemy and Claire are showing signs of mildew infection. Barley crops are at the 5-6 leaf stage and are showing trace levels of mildew and net blotch.

Most crops have been sprayed for grassweeds and broadleaved weeds.

Where no black grass herbicides have been used, crops should be treated as a matter of priority since from now on the number of good spraying days is usually limited and unsprayed blackgrass can be extremely difficult to control in the spring.

Last year we were not able to spray for blackgrass until early April, and although we were able to achieve reasonably good control with Atlantis (mesosulfuron+iodosulfuron), there was subsequent loss in yield.

Carefully check the blackgrass growth stage and if it is beyond three leaves and there is suspicion of either enhanced metabolic or target site resistance then the only option is to apply Atlantis in mixture with a good residual partner.

Oilseed rape crops sprayed in late October for phoma are fairly clean, but those sprayed in late September or early October are showing signs of phoma reinfection and will need to be re-sprayed with a flusilazole-based product perhaps in mixture with a growth regulatory-type fungicide.

Some crops of Astrid and Castille are showing signs of light leaf spot, which is a rarity in this part of the country. Where LLS is noticed, add carbendazim to the mix, but be careful, since frost damage at this time of the year can be confused with LLS damage.

Some fields of oilseed rape have charlock present. Spray on a frosty day, ensuring that the crop is well waxed to avoid crop damage.


6 November 2006

Nick Brown – Chemega (ProCam Group), Berks/Bucks/Oxon
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Nick Brown thumbThe arrival of the first frosts this autumn will hopefully slow down some of the more forward crops of cereals and oilseed rape.

Oilseed rape, with a few exceptions, looks very well. The cooler, drier weather will reduce phoma pressure, however I have already applied a second phoma spray on one farm due to significant re-spotting four weeks after the first application. Most crops sprayed a fortnight ago will need further treatment this autumn.

Cabbage stem flea beetle larvae are more numerous than the last few seasons and with the new threshold of two per plant, more crops will need treatment this year.

Soil temperatures are still around 12 centigrade and until they drop to nine or below it is too early to use Kerb (propyzamide)/ Carbetamex/ Crawler (carbetamide).

Aphids are rife in cereal crops and large numbers are even present on some one leaf crops! Early-drilled cereals desperately need an insecticide and seed treatments are beginning to run out of steam.

Early results show that two thirds of blackgrass samples submitted for resistance testing last season showed reduced sensitivity to Atlantis (mesosulfuron-methyl + iodosulfuron-methyl-sodium), ranging from moderate to severe.

In response to this, and as an anti resistance strategy, where good control has been achieved with a pre-emergence spray, my advice this autumn has been to apply an isoproturon or chlorotoluron-based mix at one to two leaf stage of the blackgrass.

Where blackgrass is large, or populations are significant and Atlantis mix is the only option, consider Hawk (clodinafop-propargyl + trifluralin) as a mix partner for greater efficacy. With current soil temperatures we probably have until the end of November to get these applications on.

With this evidence of increased resistance, waiting until spring and then putting Atlantis on well-tillered blackgrass in potentially cold soil conditions is probably a recipe for disaster and will help drive resistance even further!


30 October 2006

Tod Hunnisett – Chichester Crop Consultancy, Hampshire
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Tod Hunnisett 100x100The recent very wet and exceptionally mild weather has brought a few problems.

Despite my earlier observations slug activity and grazing has increased over the last two weeks and various crops have had pellets applied. However, most of this has been in well established, quick growing crops so the applications have been more to keep “on top of the job” rather than fire – brigade treatments.

Some fields, particularly in the south east, have had so much rain they can barely be travelled on. Pre–emergence strategies have gone out the window and some crops are at risk from Barley Yellow Dwarf Virus as aphid levels are still very high and insecticide seed treatments will be running out of steam.

Hopefully colder and more settled weather will allow us to get things back on track.

Every crop of winter oilseed rape I’ve looked at over the last two weeks has had some level of phoma. Fortunately most crops are big enough to allow time to get fungicides on, but any backward crops should be treated as a priority.

I am holding off with post emergence herbicides for either broadleaved weeds or difficult blackgrass (where carbetamide is to be used) until the weather cools down significantly.

Winter beans are about to go in at any time. More and more crops are now being drilled rather than ploughed in which is great provided they get in deep enough (aim for 10 cm at least) and the seedbed is clean of weeds.

Also traditional seed rates can be cut significantly; you can virtually drill to a stand of about 20–25 seeds/m2.


23 October 2006

James Boswell – H L Hutchinson, Kent
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James BoswellWith fewer spraying windows available, decisions must be taken on which crop takes the highest priority.

Winter wheat drilling is almost complete, but the latest drilled crops have not been rolled and a close eye needs to be kept on slug activity. Aphid numbers are rising in cereals and a water-based more persistent pyrethroid will be most appropriate on lush, soft growth.

Gout fly egg numbers remain lower than expected, but thick early drilled crops are now showing serious powdery mildew infection.

Late drilled oilseed rape crops are struggling with downy mildew and phoma infections are materialising in early drillings. It is still too early for propyzamide or carbetamide to be effective, as soil temperatures are too high.


16 October 2006

Swaran Bachoo – Agrovista, Hants/ Wilts
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Swaran BachooAll crops are growing at a rapid pace in the balmy weather and recently drilled wheat and barley is emerging within seven days.

Barley drilling is complete and some 70% of the wheat crop is in the ground. Seed rates will now need adjusting to 275 seeds/ m2. On light soils the rate will need to be increased to 290 seeds / m2 as these soils tend to shed more tillers early in the spring.

Also note that varieties such as Solstice and Malacca are shy to tiller, so increase seed rates to 320/ m2.

Grass and broadleaved weeds have appeared in large numbers in early drilled fields. The problem is particularly serious under minimum-tillage, where cleavers are at the one whorl stage and other broadleaved weeds are 2.5cm across.

Herbicide programmes need to be put into action soon or there could be a yield penalty especially where resistant blackgrass is a problem.

Bear in mind that high rates of grass weed herbicides can cause lasting damage to the plants by virtue of “luxury uptake” in warm temperatures such as now. The problem can be accentuated where an aphicide is tank mixed. In this case try using a water based formulation of the aphicide, such as Pearl Micro (deltamethrin).

Aphids are present in most cereal fields and it is time to spray those drilled in the third week of September. Use the 170 day degree T-sum formula to determine spray timing.

Oilseed rape crops are at 4-6 leaf stage and are showing variable levels of Phoma. I am surprised at the lack of the disease in ES Betty considering it has a resistance of four.

Some early-drilled fields have reached the 20% threshold level and have already been sprayed with flusilazole, but may need to be sprayed again in four weeks time if the disease comes back – as is likely with the present weather pattern.


10 October 2006

Nick Brown, Chemega (Procam Group) (Berks/Bucks/Oxon)
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Nick Brown thumbRape crops are continuing to establish well with the earliest drillings having six to eight leaves and later sowings at two to four leaves. The risk of damage from slugs on most crops is now diminishing.

Turnip sawfly larvae on the other hand are causing serious damage in some crops in southern areas. Defoliation can occur quite quickly in the worst infestations so continue to check crops and treat with a cabbage stem flea beetle-approved pyrethroid if obvious and increasing damage is seen.

The incidence of phoma is also increasing with 30% of crops in some areas already treated while many more will need a fungicide in the next week to ten days. Work to a threshold of 10% infection and don’t be tempted to delay spraying to fit in with future herbicide applications.

Plover (difenoconazole) or flusilazole-based sprays should provide four weeks cover. With such an early appearance of phoma a second spray in most cases, and even a third in some, will be required to protect crops this season, but wait for fresh spotting before reapplication.

Wheat and barley crops are establishing well with some early drilled crops starting to tiller. With the exception of crops following rape slug problems seem lower than last year in most areas. Pre-emergence sprays, on the whole, seem to be doing a reasonable job.

Many of the early sowings have had an insecticidal seed dressing, expect about six weeks protection from BYDV from these treatments. Aphids are easy to find in crops not treated and some of these crops have already been emerged for two to three weeks. The risk of secondary spread within these crops is now high and an insecticide should be applied very shortly. Don’t compromise these early crops by delaying insecticide applications to coincide with any follow up herbicide sprays planned for later in the autumn


3 October 2006

Tod Hunnisett – Chichester Crop Consultancy, Hampshire
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Tod Hunnisett 100x100Ideal conditions for many in September have meant that wheat drilling is well under way, with many people finished well in advance.

However the recent rains have made applications of pre-emergence sprays difficult and blackgrass is coming through with the crop which may well compromise the effect of the sprays.

In that situation the addition of IPU (isoproturon) or CTU (chlorotoluron) may be necessary, but with crop growth as soft as it is, some scorch is inevitable. I realise super–early drilling is attractive from a management point of view, but it does create challenges for managing grassweeds.

If you are using anything containing pendimethalin and drilling depth is less than recommended (32mm or 1 ¼”) then wait until the crop has reached one leaf.

If you have a bad blackgrass problem, be patient, use glyphosate, think pre-emergence and get it in deep.

Oilseed rape is well emerged with many crops having a two-stage emergence i.e. a variation between cotyledon and six true leaves.

I wonder how many crops have been treated for slugs in the last two weeks when Turnip Sawfly (or some other caterpillar – just look in your garden) has been the culprit.

Any pyrethroid applied for flea beetle seems to have done the trick and now that our Indian summer has been replaced by an English foul autumn I hope that any remaining caterpillars will realise the error of their ways and will rapidly disappear.

I have been pleasantly surprised at how low slug activity has been in emerging cereal crops. The searing temperatures in July must have desiccated the surviving adults so egg and juvenile populations are lower than expected given the number of slugs that were about in late June.

This makes monitoring even more important and my preferred method is to spread a small area of metaldehyde pellets and go back within 24 hours to look for slug trails.


25 September 2006

James Boswell – H L Hutchinson, Kent
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James BoswellThere is a big variation in oilseed rape establishment, with some crops at the six leaf stage and others needing the recent showers to germinate.

Most rape crops have needed some slug control and other backward crops are showing signs of cabbage stem flea beetle damage.

There has been a good flush of grass weeds that will need treating. Care is needed on product and rate choice with the new Pesticides Safety Directorate approvals for all ACCase herbicides restricted to one application of an individual active regardless of rate and two applications of ACCase products per crop.

Wheat drilling is well underway but there are big differences in seed rates(75kg ha –130kg), which may lead to later complications.

Most seedbeds are good and a pre emergence herbicide may be appropriate on difficult grass weed fields, but with wheat emerging within seven days, product flexibility is important.

With recent rains, slug activity is evident – even on firm, fine, rolled seedbeds – with grazing taking place but no grain hollowing seen yet. With forward wheat now approaching growth stage 11, close monitoring of gout fly eggs is also necessary.


19 September 2006

Swaran Bachoo – Agrovista (Hants/ Wilts)
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Swaran BachooOilseed rape crops have come through the dry seedbeds well and are generally looking good.

There was some flea beetle damage and widespread Downy mildew infection, but the rain we had last week has freshened crops and they are growing away from these problems.

But, the rain has brought forward the slug problem. Significant numbers of grey and black field slugs have been noticed. On cloddy seedbeds, some damage has already been seen on small plants.

Some volunteer cereals were sprayed last week and the remaining will be sprayed with a graminicide this week. As crops reach the two true leaf stage, start monitoring for Phoma infection. With the recent warm weather, if there is further rain then Phoma infection could arrive early this year.

Early wheat drilling started last week into good seed beds. Typically, seed rates have been 240-250 seeds/m2.

Alchemy, which yielded up to 10.75 t/ha, is quite popular this year. The seed rates for this variety will need to be adjusted as it tillers profusely. By February last year it had produced 1100 tillers/m2 from a seed rate of 240 seeds/m2.

Slug baiting using poultry layers mash should be carried out on susceptible fields, especially those following oilseed rape. Nine traps should be laid in a ‘W’ shape across the field (thirteen traps if the field is larger than 20ha).

If slugs are found, then a good quality slug pellet based on methiocarb should be applied as soon as possible.

As drilling proceeds any cereal fields where blackgrass is a problem will be sprayed with a pre-emergent herbicide such as Trooper (flufenacet + pendimethalin) + Grounded (oil) or Liberator (flufenacet + diflufenican) + Grounded.

Where any volunteer weeds are present then Roundup (glyphosate) will be added to the mix.


12 September 2006

Nick Brown, Chemega (Procam Group) (Berks/Bucks/Oxon)
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Nick Brown thumbOilseed rape crops in most areas are growing away well. Some of the recently drilled crops have been planted in dry soils and these need rain to prevent uneven establishment.

Slugs remain a worry, especially on autocast and direct drilled crops with lots of surface trash.

Volunteers are emerging and in some places are starting to tiller. Early control with a graminicide needs to be done soon to prevent competition with the crop – aim to return later to control blackgrass in problem areas.

Where good volunteer control occurred pre-drilling and populations are not competing with the crop, a single hit later on with a product active on blackgrass should be used.

Early drilling of wheat has started. Thousand seed weights in some cases are low this year. For mid September drillings a good guide would be 200-250 seeds/metre depending on soil conditions and expected slug problems.

This should be increased by about 20-25 seeds per week. On fields with high blackgrass populations don’t cut the seed rate back to far, lack of competition from the crop will make control more difficult.

A high proportion of wheat crops will receive a pre-emergence spray this year. Trials work has shown substantial differences in control depending on the nozzles used for application.

One hundred litre drift reducing nozzles gave the worst results. An increase to 200 litres with standard nozzles was much better. Twin caps with two 100 litre nozzles work very well, they give better coverage of clods.

Hawk nozzles alternately facing forwards and backwards along the boom have worked very well in trials and have the added advantage of working at 100 litres. Considering the cost of pre emergence sprays investing a modest sum to ensure better application would seem very worthwhile.


5 September 2006

Tod Hunnisett – Chichester Crop Consultancy (Hampshire)
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Tod Hunnisett 100x100We appear to have been more fortunate than many. Most of our cereal harvest was completed by the end of the first week of August with very good quality crops, nearly all making malting or milling.

Premiums plummeted as the crops came in only to go back up again as the trade realised not everybody was going to be as lucky.

The general overview is as follows: cereals good to spectacular with a few disappointing winter oats on the heaviest ground and some wheat crops on the very light soils not yielding like they looked they would.

Oilseed rape has been disappointing; winter and spring beans poor and linseed disastrous on all but the best soils. Many farmers will be questioning even harder the economic sense in spring break crops when fallow looks quite attractive.

Much winter oilseed rape has been drilled and the moisture that has inconvenienced harvest has meant that most is now up in rows.

After last year’s crop’s disappearance due to slugs, most fields have had a low rate of metaldehyde pellets; last year 6kg/ha made the difference between a crop and total failure.

Only the most poppy prone fields have had pre-emergence treatments based around trifluralin and metazachlor/ quinmerac (e.g. Novall) and most crops will get an early post–em mixed with a graminicide.

Fields going into wheat have been moved and are greening up nicely having been sprayed with or awaiting glyphosate.

The thing to remember is that if you only have time to spray it once then it should be done as close as possible to the time of drilling. Spraying too early without spraying-off a second flush will result in germinated grassweeds transplanting themselves into the following wheat crop. Then you have a problem before you’ve even started.


View previous Crop Watch reports for the South:
Autumn/ winter 2006
Spring/ summer 2006
Autumn/ winter 2005
Spring/ summer 2005

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