Farming News - AICC agronomist report on cold weather damage to crops

AICC agronomist report on cold weather damage to crops

17 December 2010. We review the state of the winter crops after a particularly harsh cold spell with more to follow.

Soil Protection Review
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South East.
Winter Wheat
. The earliest sown crops of Claire, Scout and Solstice now at two tiller stage whilst later sown crops range from one to three leaf stage. There has been no real growth for nearly three weeks now as ground has been almost permanently frozen or snow covered – slightly concerned that frost heave may damage later sown wheats, particularly those on chalks and lighter soils.
Winter Barley.
Crops mainly at the early tillering stage with no signs of any crop damage so far.
Winter Oats
. Crops range between three and four leaf stage and concern that frost heave could be a problem for later sown crops with low biomass.
Winter Oilseed rape
. Crops range from 5 to 6-8+ true leaves with the bulk of crops are now around 5-6+ true leaves. Cold conditions of last 3 weeks has knocked crops back, but no concerns regarding crop loss as yet as snow cover only gone in last 5 days or so.

South West.
Winter wheat.
All emerged wheats now three leaves to tillering.  Some late crops were power harrow drilled into fresh ploughing before the worst of the frost, however these are yet to emerge. Some crops have been paled by herbicides but are generally recovering well. Opportunities taken to apply P and K on frozen ground.
Winter barley
. Forward barley crops have had old leaves knocked about by frost and grass weed herbicides but the growing parts of the plant are green and healthy.
Winter oilseed rape.
Even later sowings have up to 6 leaves so are well placed to tolerate the colder weather.  Earlier drillings have lost old leaf in the frost.  Large flocks of pigeons are now active across the region which have defoliated field corners near woodland.

Eastern Counties.
Winter wheat. Early sown: Crops at the early tillering stage and are generally in good condition.  Both mildew and Septoria tritici are evident at low levels in susceptible varieties.  Some leaf area has been lost through mildew pressure followed by frost.  Winter losses are not likely to be of any concern in these crops.
Conventionally sown:  Crops at the three leaf stage.  Crops are variable, often reflecting variable drilling conditions, soil structure and soil type.  In some instances of poor soil structure and particularly on heavy soils manganese and nitrogen deficiencies have been exacerbated, with plants displaying severe symptoms.   In many cases BYDV treatments are still outstanding.  Winter losses, particularly from frost lift are only likely to be of concern in very small and backward crops.
Late sown.  Drilling of winter wheat is continuing behind sugar beet in some cases.  Many late drilled crops are thin, often with patchy emergence.  Small plants (1-2 leaves) are showing visible symptoms of water-logging, manganese and nitrogen deficiency. Probable medium-high winter losses are expected, particularly from frost lift. 
Winter barley. Early sown: Up to GS 2.5.  Crops are generally in a good condition at the end of the autumn and able to withstand the poor conditions.   Both net blotch and mildew were evident in forward crops and susceptible varieties, and have been treated with an appropriate morpholine in light land situations.  Crops are likely to emerge from the winter without any significant detrimental winter losses.
Conventionally sown:  GS 1.3-2.1.  Crops are variable, often reflecting variable drilling conditions, soil structure and soil type.  In some instances of poor soil structure and particularly on heavy soils manganese and nitrogen deficiencies have been exacerbated, with plants displaying severe symptoms.   Winter losses may be a concern in some small and backward crops.
Late sown:  Few crops were ‘late  sown’, with most crops at the stages discussed above.  Late drilled crops are displaying typical symptoms of patchy emergence and seasonal nitrogen and manganese deficiency, exacerbated by the cold and waterlogged conditions.  Probable medium-high winter losses, particularly from frost lift are forecast in these crops.  Few, if any herbicides or insecticides have been applied in these situations.
Winter oats. Early sown: Up to GS 2.5.  Crops are generally in a good condition and able to withstand the poor conditions.  These crops are likely to emerge from the winter without any significant detrimental winter losses.
Conventionally sown:  GS 1.3-2.1.  Crops are variable, often reflecting variable drilling conditions, soil structure and soil type.  In some instances of poor soil structure and particularly on heavy soils manganese and nitrogen deficiencies have been exacerbated, with plants displaying severe symptoms.  In many cases, although not all (C65%) pre-emergence herbicides have been applied.  Winter losses may be a concern in some small and backward crops.
Late sown:  Few crops were ‘late  sown’, with most crops at the stages discussed above.  Late drilled crops are displaying typical symptoms of patchy emergence and seasonal nitrogen and manganese deficiency, exacerbated by the cold and waterlogged conditions.  High winter losses, particularly from frost lift are forecast in these crops.  Few, if any herbicides or insecticides have been applied in these situations.
Winter oilseed rape
. Most early sown crops have really good ground cover with large leaves although now losing outside leaves. The slightly later drilled crops look ‘just right’ not too forward sitting close to the ground and plants large enough to survive the winter. However, late drilled crops are likely to suffer high levels of winter kill where they are backwards going into the winter.  Many which were late drilled were subsequently slow in establishing, with limited root growth, and are showing significant symptoms of waterlogging and seasonal nitrogen deficiency, evident in chlorosis and necrosis of older leaves.  Some late drilled crops are still to receive an autumn phoma treatment.  Small, thinly established crops will be most susceptible to pest and vermin damage in the next 2-3 months.

East Midlands.
Winter Wheat.
Early sown wheat crops are dealing with the cold snap apart form looking a bit pale in places but no major problems.  Later sown wheat generally looking fine but sitting still at the one leaf stage. Our experience of crops like this last year showed they came through fine when weather warmed up in spring.  No signs of any frost lift but no real capping on soils.
Winter Oilseed rape.
All crops are looking OK at the moment even later ones look fine. The main worry now will be if we get frosty weather without any snow cover, when pigeons will be a problem.

West Midlands.
Winter Wheat.
The early sown crops are now tillering and show little signs of any frost damage. Later sown crops at the one to two leaf stage are also coping with the low temperatures although there are some signs of frost scorch on exposed fields. The last sown are still to emerge which is probably the safest place to be right now.
Winter Barley.
As with the wheats these crops have stood up to the cold so far but some crops are proving irresistible to rabbits with little chance of recovering with continued frost.
Winter Oats
. So far so good with no signs of frost damage even on naked oats.
Winter Oilseed Rape.
Many crops have good ground cover and the only obvious sign of the recent frost is loss of outer leaves. Most later sown crops managed to put on enough leaf before the mercury dropped and have produced a big enough plant to survive. Late sown crops, which fortunately there are few, are not enjoying the frost and it is possible these crops will not survive the winter particularly if the pigeons find them too.

North east.
Winter Wheat.
Crops were drilled in two stages as operations were stopped by heavy rain. All early sown crops have emerged from the snow with good colour, but some of the later drilled ones look severely stressed and have lost nearly all colour. Some of this is due to the cold they have just endured, but now it is the sodden state of the seedbeds.
Winter Barley.
Crops are well tillered and appear to have survived the wintry conditions very well.
Winter Oilseed Rape.
All crops were drilled in good conditions and were well established before the wintry weather started. Crops that had full ground cover have opened up now as leaf stems have been broken by the weight of the snow. Also, frosty conditions seem to make plants more erect and allow better spray penetration to get herbicides directly onto the ground.