Crops notes January 04

January is an ideal month to carry out soil sampling before any slurry or farmyard manure is applied to the fields. Soil sampling is an essential starting point when planning the fertiliser requirements of any crop. Soil samples should be taken every 4-5 years to maintain an up to date nutrient status for the field. Conacre ground should be sampled as soon as possible as there will be less historic information available and the result could be used to determine the value of the land. For example, for main crop potatoes a field with P and K indices of 2 and 0 respectively will require approximately £56/ha (£23/ac) more fertiliser than a field with P and K index’s of 3 and 2 respectively to supply the same crop requirement. Also the pH level of the field will have a big effect on the success of a spring cereal crop and it is best to ensure this is correct before drilling the crop.

Agrochemicals and fertilisers are major variable inputs in growing crops and the way they are applied has a great influence on their efficiency. It is therefore essential that the equipment used to apply them is well maintained and accurately calibrated.

Sprayers should be calibrated regularly. One of the most important areas of the sprayer are the nozzles. Nozzle output should be measured to check that it is the same as the value in the calibration chart for that type of nozzle. Nozzles with a variation of more than 5% should be renewed. Having the sprayer checked through the Voluntary Initiative sprayer testing scheme would be a good way of checking it is working properly. Money spent maintaining the sprayer is money well spent as a properly calibrated sprayer will reduce wastage of agrochemicals and will improve their performance

Fertilisers account for up to 37% of the variable cost of winter cereal production. As an indication of the efficiency of your spreader it is worth noting crop striping. This only becomes evident at application rates 20% above or below the target. Therefore fertiliser spreaders should be checked for their distribution accuracy and improvements made where necessary.

Fertiliser type and quality can affect spread patterns, and so it is important that good quality products are used and machines are calibrated for different products.

Winter cereal crops have generally emerged well. Growers should continue to monitor crops over the winter period for signs of slug or leather jacket damage and treat if necessary. The threat of aphids has now reduced but crops not sprayed or those sprayed very early in the season should be inspected on sunny days for signs of aphid activity. If aphids are present they should be sprayed to prevent the spread of Barley Yellow Dwarf Virus. Where autumn herbicides have not been applied every effort should be made to apply them as soon as possible after crop emergence before the weeds get too large.

The winter wheat crops at Greenmount have established extremely well. Designated fields received a pre-cultivation application of glyphosate, which has resulted in very low weed levels. A herbicide application in the new crop of isoproturon + diflufenican/pendimethalin will be applied in early January.

All stores should be checked regularly to ensure no problems are developing during the storage period. Growers should already be planning for next season to ensure good quality seed stocks are available at planting. Where home saved seed will be used it should be graded and stored correctly to ensure sprouting is controlled. It is also advisable to get a sample "hot box" tested to check for the health status of the seed and inspect it closely for skin borne disease. The "hot box" test is a simple, effective method of determining the potential storage quality of crops. It shows up the likelihood of seed to develop tuber blight, soft rot and dry rot by storing tubers under favourable conditions for disease development that is warm (15-20 °C) humid conditions for 10-14 days.

Growers are encouraged to manage the risk of PCN and are reminded of the PCN advisory service available through the Applied Plant Science Division of DARD Science Service at Newforge Lane. PCN Sampling Packs and Guidance Notes on soil sampling can be obtained from local Agricultural Development Centres from 5 January 2004. Interpretation of results from soil analysis, carried out at the nematology laboratory, Newforge Lane together with advisory options, should enable growers to minimize the risk of PCN contamination and in the selection of suitable fields for potato production. Results will remain confidential to the grower and infested land will not be scheduled.

PCN can be spread via field-to-field contamination through soil movement, including that caused by machinery, wind and water movements. At high infestations plants will wilt during the day due to insufficient water uptake, top growth is poor with progressive yellowing of the leaves. Premature death results and final yields of potatoes are greatly reduced. A further indirect result of PCN invasion is provision of entry sites for various soil pathogens so that secondary fungal and bacterial diseases such as soft rots may also develop.

Extended rotation practices should always be part of PCN management. With high population levels, seven or more years rest from potatoes may be needed to reduce the infestation to a level at which cropping with potatoes is economic.

Further advice can be obtained from DARD Nematology Section, Newforge Lane, Belfast at 028 9025 5280 or 028 9025 5217 or by contacting your local Crops Development Adviser.

DARD Farm Management Notes for January 2004 have been prepared by Greenmount Campus, College of Agriculture, Food and Rural Enterprise - Tel: 028 9442 6771. We acknowledge the contribution from Veterinary Service. For further information contact your local Development Adviser.