Crop Notes September 2011

Following harvest is an ideal opportunity to carry out soil analysis. With fertiliser accounting for a considerable proportion of cereal variable costs (over 50 percent in the case of winter wheat), it is important that this input is used efficiently. In addition, fields with a low pH can be identified and rectified with applications of lime. This final input is often overlooked but having the correct lime status is absolutely vital to ensure efficient use of fertiliser and good grain yields.

Care should be taken to control aphids that are the vectors of Barley Yellow Dwarf Virus (BYDV) as this disease can cause high yield losses in autumn sown cereals.

Crops following grass, weedy stubbles, or set-aside are particularly at risk from wingless aphids moving directly over this ‘green bridge’ of grass onto the young crop. To prevent this, the ‘green bridge’ should be destroyed by desiccation with glyphosate seven to ten days before ploughing. If the ‘green bridge’ has not been destroyed prior to cultivating, then an aphicide approved for BYDV vector control should be applied at brairding.

This can be done by sowing earlier with a reduced seed rate. Winter barley seed rates can be cut by 20 percent if the crop is drilled before the end of September. However, the big savings can be made with winter wheat which tillers prolifically if sown early. Early drilled wheat (that is, before the end of September) has been grown at Greenmount for a number of years and has performed as well as October and November drilled crops. The seed rate must be reduced by 40-50 percent. This would mean 65-90 kg of seed per hectare being the target planting rate.

Direct drilling of early sown winter barley

Harvesting can ‘make or break’ a potato crop. Mechanical damage is one of the most important factors affecting potato quality and is largely controllable. All those involved in harvesting and handling should be made aware of the importance of damage and bruise prevention. Damage can occur with drops from harvesters into boxes or trailers, bruising caused by insufficient soil on the web, and crushing due to oversize tractor tyres running in the drill bottom.

Early identification of damage can save substantial amounts of money in terms of reduced waste and rejections. Samples of the harvested crop should be taken daily, washed and inspected for damage. Excessive damage often leads to increased problems in store and eventual down grading of the produce.

Aim to dry your potatoes as quickly as possible to prevent the development of skin blemish diseases and soft rots. Drying within 48 hours using positive ventilation systems significantly reduces the development of diseases such as silver scurf.

The curing period immediately following harvest, often referred to as the ‘wound healing period’, is one of the most important storage phases. Wound healing occurs most rapidly at high temperatures and high humidity. However, these conditions also favour the development of rots and skin diseases. Maintaining the crop at 12 to 15 Centigrade and 85 percent relative humidity for a period of about two weeks, often referred to as ‘dry curing’, allows wound healing to take place, whilst minimising the risk of disease development. Ventilating the store on dry afternoons during the curing period will normally provide suitable conditions for this to take place.

The potato harvest gets underway