Crops notes November 2007

Although most of the potato crop is harvested, those who still have crops in the ground will need to take extra care during harvesting, as cold potatoes damage more easily. Check soil temperatures and avoid harvesting in cold conditions as potatoes are much more susceptible to bruising below 10^oC. If soil temperature falls below 5^oC stop harvesting altogether. Check damage levels regularly, for both external damage and bruising, so that all stages in handling can be assessed to ensure minimal damage. Make every effort to maintain a good soil cushion on the main web of the harvester, minimise agitation and reduce drop heights. Minimise the drop between the harvester cart elevator and the bulk trailer or box. Fall breakers or padded landing areas should be used to reduce impacts.

To reduce the development of skin blemish diseases such as silver scurf and soft rots, tubers should be dried as quickly as possible after lifting. Drying immediately for at least 48 hours using positive ventilation systems has been shown to significantly reduce the development of silver scurf. If soft rots are present, this drying time may need to be increased to at least 96 hours.

This season, attempt to continue drying throughout the curing period. The more the crop is dried, the lower the risk of rotting. The wound-healing period should be kept to a minimum of two weeks. Humid air in the store should be changed by ventilating on dry afternoons. Crops that contain more than 1percent blight or soft rots should not be cured but marketed as soon as possible as there is a high risk of widespread rotting during storage. Following curing, store temperature should be reduced slowly by approximately 0.5^oC per day to the desired holding temperature. If possible continue to ventilate periodically throughout the storage period as a precaution against rots.

The high grain prices and dry October have encouraged many farmers to drill winter cereals. We should all take a tip from experienced growers and apply a residual herbicide to wheat and barley crops while weeds are small. Annual meadow grass, in particular, will be difficult to control once it has begun tillering. The choice of herbicide treatment may be influenced by the weed species present, but a broad-spectrum product containing isoproturon + diflufenican, pendimethalin or picolinafen e.g Panther, Encore or Flight, is likely to be suitable.

Winter wheat Wheat is much more tolerant of later sowing than barley or oats. However, seed rates should be increased to combat the effects of lower soil temperatures, cloddy seedbeds and pest attack, which combine to reduce the percentage plant establishment as sowing is delayed. Seed rates of between 400-500 seeds/m2 would be appropriate for sowings in November with the higher seed rates being used in more difficult conditions and as sowing is further delayed. This would translate to seed rates in the range of 180225KG/ha (11.5-14 st/ac).