Effect of rhizome fragment length and burial depth on emergence of Tussilago farfara

Mechanical control of Tussilago farfara is carried out mainly by soil cultivation. The aim is to deplete the energy stored in the rhizomes. The treatment includes cutting the rhizomes, to stimulate increased shooting, followed by renewed soil cultivation to destroy the shoots and incorporate them into the soil. Factors generally regarded as important in the control of perennial weeds are extent of fragmentation and burial depth. In this study, the importance of these two factors on T. farfara emergence was studied in detail in two pot experiments. Rhizomes were cut into different lengths (5-25 cm) and buried at various depths (1-42 cm) in pots filled with peat soil or clay loam. Shoot germination, emergence and early plant performance were studied. Intensive fragmentation and deep burial (possible to achieve using conventional tillage) are not enough to completely hinder emergence of T. farfara; 6-cm fragments emerged and developed normal leaves from 42 cm depth, regardless of soil type. However, there were higher total emergence and emergence rates in peat soil than in clay soil. Burial depth was correlated with time to emergence; burying rhizome fragments, not longer than 25 cm, to at least 20 cm depth gave a time to emergence of at least 20 days. The delay of weed emergence should allow good establishment of a crop and ensure a significant competitive effect against T. farfara.