Crops Notes September 2009

The cereal price has taken a substantial drop this summer and looks as if it may be slow to recover. With this in mind many of us will be looking at ways to reduce establishment costs of winter cereals. 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.

Strategies for Barley Yellow Dwarf Virus (BYDV) prevention should start prior to sowing. Crops following grass, weedy stubbles, and set-aside can be infected by wingless aphids which walk directly from this 'green bridge' onto the emerging cereal crop. This green bridge should be destroyed 7-10 days prior to ploughing, using glyphosate. The cereal crop should then be sown no sooner than 14 days after herbicide application. This treatment is also a very cheap way to control perennial weeds and reduce the annual weed burden. It is even more important this year with the loss of many of our tried and trusted autumn herbicides.

This summer has seen many outbreaks of blight due to the humid, showery weather with growers finding spray application windows few and far between. This is bound to lead to higher levels of tuber blight than usual this autumn. We can try and reduce these by completing the spray programme with at least three sprays of a product with tuber blight activity (Infinito, Ranman, Shirlan). It is critical that the crop is protected until the haulm is dead: blight can attack green leaves when the crop is senescing or even after a desiccant has been applied and this can lead to tuber infection. To reduce the risk, a fungicide should be applied with the desiccant (check product labels for approved tank-mixes) and protected from blight until the haulm is dead.

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^o C 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.

Potato harvesting in Armagh

September drilling of winter wheat