Recently by Nick Brown

A quick glance at the calendar tells me it is December this week, hard to believe after the mild weather we have had recently.

Rape crops continue to race away and some are carrying huge canopies going into the winter. Soil temperatures have now declined enough to start applying Kerb (propyzamide) or Crawler (carbetamide) but given the size of some crops getting a residual herbicide down to the soil surface will be a problem. In large canopied crops we may have to wait until frosts open the crop up.

Phoma levels are low at the moment and opinion is split on the merit of adding a second fungicide whilst traveling through the crop. Aphid numbers are still high in crops and I am adding an insecticide to control these: cabbage stem flea beetle and rape winter stem weevil.

More advanced wheat and barley crops are carrying high levels of disease especially mildew. I have treated a few barley crops on light land, but I dont think the disease is worth treating on wheat crops at the moment, hopefully once we finally get some frosts this will sort the problem out.

Oilseed rape crops are romping through the growth stages with some very large canopies present. The warm conditions are suiting the crop rather too well. Even so, I was rather surprised to find DK Cabernet, drilled at the end of the second week in September, already over 30cm tall.

The dry conditions have slowed the spread of phoma significantly. South of Oxford, the disease has now come into the crop and I have applied a fungicide/aphicide mix. But further north, phoma is still absent and I am holding off for the time being. 

Unfortunately, the dry conditions have conspired against decent pre-emergence weed control in cereals. All sorts of problems are evident, some crops have a carpet of blackgrass in them and swathes of volunteer rape, which indicates just how little activity the herbicides have given.

The current unseasonably warm conditions have helped bring harvest to an end with the last few late crops of linseed and beans finally cleared.

Rape crops have enjoyed the warm conditions as well, putting on a huge amount of growth in the last few days. Most herbicide applications have gone on now and volunteers and broadleaved weeds have mostly been taken care of. Blackgrass levels are generally lower than last year and, yet again, Aramo (tepraloxydim) co-applied with a decent ammonium sulphate water buffer seems to have done an excellent job in this area at least.

I hear reports of phoma, but cannot find any in my crops as yet. My advice would still be to wait until the first lesions are seen before applying a fungicide. You will only get four weeks cover so applying now, before any phoma is seen, will simply result in a repeat application in early November. Leaf miner damage is very noticeable in quite a few crops but doesn't warrant spraying.

Harvest is finally drawing to a close with the last few fields being cut. Overall results have been better than hoped for. Heavy, moisture-retentive land has seen near record yields of oilseed rape and wheat. Rape on some farms has averaged as high as 5.5t/ha and first wheat as high as 12t/ha average.

Rape yields held up remarkably well on light land, but unfortunately wheat crops on brash or gravel proved disappointing with yields often down at about 6.5t/ha. Bushel weights across the board have been very good and as high as 86kg/hl on feed wheats.

Rape drilling is going well with 75% of the crop drilled so far. Initially slug activity looked low, but recent rains have increased activity. I have pelleted most crops drilled so far and the remainder will receive a dose of metaldehyde in the next few days.

As this difficult and challenging season draws to a close perhaps the most difficult decision of the season remains, when do we desiccate some of these oilseed rape crops?

If you are one of the lucky ones with even crops and no secondary flowering then the decision will be no harder than normal. Unfortunately, this only applies to about half my crops, the remainder vary from having some secondary flowering, to still flowering, to plants with nearly mature seed on the main raceme.

In some cases I wonder how we can possibly time the desiccant correctly. If we go, timed with the maturity of the main raceme, as normal, then significant red seed will be in the sample. If on the other hand we try and wait till more of the late flowering side branches are mature then we will risk seed shedding from the, by then, brittle pods at the top of the plant.

The lack of rain and constant winds are not improving the humour of farmers or agronomists at the moment. We have, however, been quite fortunate in this area compared to some, receiving 25mm of rain on the 6th/7th of May.

But, predictably, on the light land all memories of that have disappeared. Brashy soil types look awful and have already suffered significant and irreversible yield losses. Heavy land is hanging on, but won't do for much longer without some rain.

Oilseed rape crops seem to be hanging on reasonably well, but canopies are definitely thinner that normal and crops that didn't receive nitrogen in February and consequently struggled to pick nitrogen up all season are the worst affected.

Spring barley is really struggling with most crops putting flag leaves out at 6-8 inches tall. It will soon be time to apply a second fungicide to these, but it will require some rain to justify this on most of the crop.

I started my Crop Watch column last month by saying rain was desperately needed. Since then, we have had no significant rainfall and the situation is getting critical, especially on light soil types.

Oilseed rape seems the worst affected on light soils and some crops are refusing to flower and are sitting at the yellow bud stage with flowers aborting before they open. Pollen beetle are not the cause as the aborting flowers are clearly undamaged by the pest.

Crops on thin, brashy soils have been hit hardest, but damage is variable. Some crops grown on brash look really well, while others look awful - a dirty yellow colour with few if any open flowers. DK Cabernet seems one of the worst affected varieties and most hybrids generally look much better.

Last month I complained about the wet conditions. Since then we have had the driest March I can remember. Can we now have some rain please?

Crops are currently quite stressed, nitrogen uptake is being limited by the dry conditions and this has steadied up the growth of most crops. Oilseed rape crops on light gravely land needs rain soon if potential yield is not going to be compromised.  

Wheat crops are currently recieving their T0 fungicide applications based round a chlorthalonil/triazole mix. As far as growth regulation is concerned, I am using half rate chlormequat at the moment and not using any Moddus (trinexapac-ethyl). The risk of phytotoxic effects with PGR mixes in the current dry conditions is quite high.

IIf needed, and if it ever rains, a more robust growth regulator mix will be used at T1.

The recent spell of wet weather has brought activity out in the field to a complete standstill and soils are as wet now as at any time since drilling last autumn. I have temporarily abandoned the quad, but trying to walk round heavy land at the moment with wellies with 10kg of mud stuck on them is not my favourite occupation.

Winter bean crops have been very slow to emerge this year, the arctic conditions last December really slowing them down. Thankfully, it was relatively dry so little seed has rotted and now temperatures have improved they are slowly moving. Despite the slow start plant populations seem good.

Oilseed rape crops look well, and most of the phoma has now been controlled. The range in canopy size is huge and the more forward crops are probably only a week or so off the flower buds visible stage. Some of these require an application of Galera (clopyralid + picloram), which really needs warm conditions to work well. It will be quite a challenge to get these applications on before the flower buds become visible.

Three colder-than-average winters in a row, are we now seeing a pattern? I suppose the next question worth asking is will the recent run of drier-than-average springs be repeated again this year?

Crops have generally come through the winter well. Oilseed rape crops that didn't have a second phoma spray in with the Kerb (propyzamide) or Crawler (carbetamide) have now, south of Oxford at least, got quite a lot of fresh phoma in them. Given the price of oilseed rape at the moment, I have written recommendations for these in the last few days.

Kerb applications applied just before the really cold spell in early December appear to be struggling in places. I suspect that it was rather too dry and cold for uptake of chemical at the time of application.

Visually, the blackgrass looks a healthy colour, but if you pull plants up and look at the stem bases they are very swollen and I am confident that, now conditions have been conducive to uptake, control will eventually be good.