Miscanthus: Planting and Growing (PB5421)

Pests and Diseases

Miscanthus species are susceptible to pests and diseases in the areas to which they are native (Asia) but, as yet, none of these has been reported in the UK. Commonplace cereal diseases known to occur in miscanthus include barley yellow dwarf virus (BYDV), which may limit yield. Also, stem basal diseases may infect stems in the autumn or winter, reducing stem strength. There are no reported insect pests in Europe that have significantly affected the production of miscanthus. However, two ley pests, the common rustic moth and ghost moth larvae, have been reported feeding on miscanthus and may cause problems in the future.

 

Harvesting

The annual harvest of the stem material can be carried out between January and March using a number of different machines, depending on availability and requirement of the end market. For energy cropping, a baled product is the most desirable. However, this type of harvest involves two operations before the bale is produced and this can result in high biomass losses.

The crop is first cut with a mower conditioner. Conditioning breaks up the rigid stems allowing accelerated moisture loss, and provides a light, rectangular windrow. This not only makes baling easier, but also helps in the drying of the material, by increasing the surface area and increasing air circulation in the swath.

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There are a number of different types of balers, each producing different bales, (e.g. rectangular, round and compact rolls), suitable for different scales of energy combustion. Large rectangular and round balers are capable of producing bales with a dry matter density of between 120 and 160 kg/m3 and weighing between 250 and  600 kg. These balers generally have a capacity of 1 ha/hr.

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A critical factor for an energy crop is the moisture content at harvest. The drier the crop, the higher the energy yield and bale value. Moisture contents as low as 15% have been reported in southern Europe - although the lowest moisture content achieved in the UK has been around 20%, with the average closer to 50%. This may be partly because, in the UK, plants are still in the vegetative phase when the first frost induces die back. By conditioning and allowing to dry in the field, the stem moisture content can be halved from 50% to 25%.

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