WEED MANAGEMENT IN SHORT-ROTATION POPLAR AND HERBACEOUS PERENNIAL CROPS GROWN FOR BIOFUEL PRODUCTION

Weed management is a key element of any crop production system. Weeds are a particular problem in the production of short rotation woody and perennial herbaceous biomass crops due to the shortage of registered herbicides and integrated weed management systems. Herbicides will be an important component of weed management of biomass crops. However, p roducers should take a broader view of weeds and incorporate all avail able weed management tactics in these production systems. In both shor t rotation poplar and herbaceous perennial crops, weed control during the establishment period is most critical. New plantings of these spec ies grow very slowly and do not compete well with weeds until a canopy develops. Effective weed control can double the growth of short rotat ion poplar crops and affect the variability of the resulting stand. In crops like switchgrass, uncontrolled weeds during establishment can r esult in stand failure. Cultural practices such as site preparation, u sing weed-free seed, fallowing, selecting the proper planting dates, c ompanion crops and controlling weeds in previous crops must be combine d with herbicides to develop integrated management systems. Weeds may also cause problems in established stands through competition with the biomass crop and by contaminating the product. Effective and economic al weed management systems will be essential for the development of sh ort rotation woody and herbaceous perennial biomass crop production sy stems. Published by Elsevier Science Ltd.