Recently by Swaran Bachoo

Winter this year does not seem to want to go away. Last week we had some very cold nights with temperature dropping down to -6C. There has been frost every night making spraying of any form impossible, although I did see one lone sprayer outlast week.

Oilseed rape is now looking particularly sick as a result of continuing de-waxing effect of the frost and could do with some good growing conditions. Light leaf spot is obvious in the rape crops and requires immediate action, however spraying under these conditions could lead to crop damage and the fungicide would not be effective.

Oilseed rape crops are at the right stage for the application of Galera herbicide but with high diurnal temperature variation this material will not work and there could be significant crop damage. Similarly any herbicide application to any crop should be avoided for risk of damage and lack of efficacy because for any crop protection chemical to work good growing conditions with reasonable night temperatures are required.

At last the cold snap and hopefully the main of the winter is over. It is the worst I have known for the last 30 years with snow covered fields and roads like ice rinks. I ventured out one day back in January but after an hour on the road I hastily retreated back home.

All crops except the middle of October late-drilled crops of Oilseed rape have come through the weather pretty well. Once these smaller crops have started to grow and the temperature is above 8C then it would be advisable to apply some early nitrogen to encourage leaf growth and root development. There is a  large amount of phoma present on the untreated crops of rape and variable amounts can also be seen on the new growth in some of the autumn treated crops.

These crops will need urgent treatment with a robust rate of a fungicide such as Capitan (flusilasole) as soon as weather conditions allow. Also, look out for light leaf spot, which is at level higher than I have ever seen in my 34 years of experience in the field. Where light leaf spot is noticed then use Proline (prothioconazole) or add carbendazim to the Capitan.

Over the last seven days we have had a phenomenal amount of rain. Last week Tuesday there was 3.5cm leaving the heavier ground impassable.

On the plus side all the crops are now evenly emerged and making rapid growth in the mild weather. Slug numbers are diminishing on the treated fields. However, where no treatment has been carried out there are signs of severe grazing and these fields should be carefully monitored. Under the present wet conditions I find that pellets bases on methiocarb such as Rivet give the best control.

Winter wheat crops are at the two to three leaf stage and clean. Winter barley crops are at the three to four leaf stage and have signs of Net blotch and Rhynchosporium, particularly on varieties Flagon and Casatta.

The problem is particularly worse on the min tilled fields where the infection has been picked from the trash in the field. Usually it is not economic to spray barley in the autumn against disease as the cold frosty weather would normally control the diseases, but in the absence of frosts at present watch the disease progress.

The mild weather with no frosts so far means the crops are fairly soft. Don't use any complicated herbicide tank mixes, especially those containing insecticides for fear of crop scorch. Some slight scorch is already evident, even where fairly simple mixes have been used.

Remember that barley is more easily damaged than wheat and that some fields are carrying foliar disease. Where blackgrass has emerged and is at two to three leaf stage then Atlantis (mesosulfuron + iodosulfuron) should be planned in winter wheat. This is particularly important where no residual herbicide has been used.

Oilseed rape crops are growing very quickly and the biggest plants have eight to 10 leaves. Untreated crops are now showing symptoms of Phoma and it would be pertinent to consider an application of a fungicide.

As the crops are well advanced with GAI of nearly three it is worth considering a plant growth regulator fungicide based on metconazole or tebuconazole. The fungicides can be tank-mixed with aphicides to control turnip yellow virus as the seed dressings will be running out of steam in larger plants.

Look out for blackgrass in oilseed rape crops where the graminicides or earlier residuals may not have worked. Consider using Precis (propyzamide) once temperatures have dropped.

 

Over the last ten days we have had some very welcome rain after a drought of nearly six weeks.

Oilseed rape crops are very uneven and patchy due to lack of moisture.

The most forward plants are at the six-leaf stage and some are at merely the two-leaf stage, however with nearly 15mm of rain the crops should grow fast and even out. Surprisingly, winter wheat drilled in the third week of September has emerged fairly evenly and is at the one leaf stage.

All the winter rape has now been treated with a graminicide to control the volunteer cereals. Any crops not treated should now be treated as a matter of urgency since with the rain the volunteers will grow rapidly and compete vigorously with the small rape plants.

The majority of the harvest is now complete, apart from a few fields of wheat which still remain. With improved weather forecast for this week, the prolonged harvest will, at last, be finished. On the plus side, yields have been good. Winter wheats have averaged about 10t/ha, winter barleys at 7.8t/ha and spring barleys 6.75t/ha, but many spring barley crops have failed the malting quality due to high nitrogen levels.

A lot of rape crops were drilled in the last 10 days in weedy min-tilled stubbles, with a view to spray with a metazachlor-based herbicide and glyphosate pre-emergence. Unfortunately the weather beat us again. The rape seed has chitted and the crop has just started to come through. These fields will now need to be sprayed post-emergence without the glyphosate as soon as the majority of the crop has emerged. Spraying before this stage can lead to crop damage, especially if there is heavy rain on light soils, but spraying later will lead to an ineffective weed control.

Winter wheat drilling will start after the end of the second week of September and winter barley soon after. But before that we will create a stale seed-bed and spray off with glyphosate to reduce the grassweed burden and also the risk of aphid infestation. Before drilling the cereal crop, carefully work out the seed rate based on the 1000-grain weight. Take into account the target plant population, drilling date and seed bed conditions. A low seed rate non-competitive crop can lead to difficulty with blackgrass control. Where blackgrass is a problem, delay the drilling and use a higher seed rate.

In damp cloddy seed beds slugs could lead to serious plant loss. In oilseed rape crops, slugs are already grazing leaves and cutting the off the stems. Before drilling the seed lay layers, mash slug traps in the shape of a W to determine the need for slug pellets. Remember the new guidelines which prohibit the use of slug pellets round headlands next to water and ditches and the maximum dose of 700 grams metaldehyde per field between January and December in any one year.

If you are growing winter barley you really have to be prepared to throw everything at blackgrass control pre-emergence since the post-emergence options are now so limited. I will use Defy/DFF/flupyrsulfuron-methyl (Lexus) mixes at robust rates which worked exceptionally well for me last year.

In the middle of last week we had about 8mm of very welcome rain. The ground is now damp, and with the air temperature averaging 12C crops are growing rapidly.

Grassweed control is now complete and Atlantis (iodosulfuron + mesosulfuron) applied three weeks ago is working well.

Early drilled wheats are at GS29 and have been treated with a T0 fungicide plus a reduced rate PGR. Where required, a dose of trace elements has been included.

Traces of Septoria tritici are visible on new growth in Humber, Oakley and Solstice. All three varieties were severely affected by septoria in late June last year and I can clearly remember that towards the end of the month there was sudden senescence in most of the leaves.

Most oilseed rape crops have been sprayed off with Roundup Ultimate (glyphosate), and those which are very uneven will be sprayed next week with Quad (diquat) when 90% of the seed in the middle third of the raceme is brown.

Timing will be critical to make sure that the later maturing seed is at the correct stage and that there is no loss from the early maturing pods.

Winter wheats are at the cheesy ripe stage (GS80) and some second crops are showing signs of take-all, accentuated by the dry, hot weather. Sartorial lesions are now obvious where treatments were not correctly timed, but it is too late to make economic applications.

Winter barleys are maturing fast and will be harvested in the next week.The light chalky soils are desperately dry and rain will be most welcome for grain-filling, albeit too late for winter barley and perhaps spring barley.

Rain on Saturday and Sunday was a welcome relief; we had 15-20mm. Until then the weather had been terrific for people on holiday, but not so good for those growing crops.

We'd had temperatures of 24C plus, and with no more than 16mm of rain in the previous three weeks and constant wind, soils had badly cracked and dried out.

Winter wheats are at full ear-emergence to mid-flowering (GS59-65). Most have had a T3 fungicide and the rest will be treated this week.

The T3 application should be considered an extension of the flag leaf spray and is a critical part of the fungicide programme in disease-prone varieties.

The recent warm weather and some rain has enabled the crops to make rapid growth.

Those that were seven days behind earlier in the season are now at the same growth stage as they were last year.

Winter barley is at GS 49, awns just visible, and will be sprayed, weather permitting, this week with Jaunt (prothioconazole + trifloxystrobin + fluoxastrobin) + chlorothalonil.

Please note that the latest timing for the use of chlorothalonil at the T2 is GS 51(before first spikelet visible).

Most spring barley drilling is complete and seed drilled 10 days ago is shot and should come through during next week.

All winter wheats and barleys have been treated with 37kg/ha of nitrogen plus 45kg/ha of SO3, and second wheats have had the same sulphur and 75-80kg/ha of N. Late September and early October drilled wheats are at GS24.

Oilseed rape crops will soon be at the stem extension stage and have already been treated with 40kg/ha of nitrogen and 75kg/ha of SO3. During the next few days the bulk of the planned remaining N should be applied to backward crops as there is only about 25kg/ha in the soil - only half the amount found last year. Remember the crop can take up to 3kg/ha of N a day during stem extension.

Well established rape crops can wait for their main dressing until the end of March.