The effect of timing and intensity of weed harrowing in triticale-lupin mixture on weeds and crops

The aim of the study was to find the most beneficial time of weed harrowing with its intensity represented by the number of passes with spring-tine harrow executed on one day in a mixture of triticale (×Triticosecale Wittm.) and narrow-leaved lupin (Lupinus angustifolius L.). The randomized complete block design was applied in field conditions in 2015–2017. It comprised one factor, the timing and the intensity of post-emergence weed harrowing with the spring-tine harrow. The plots were harrowed once, twice, or three times on one day at six consecutive growth stages of triticale: BBCH 10, 11, 12, 13, 21, 22. Harrowing did not increase the grain yield of the triticale-lupin mixture, and when repeated three times at BBCH 21, it decreased the grain yield. The cereal was more resistant than lupin to timing and intensity of harrowing. The weeds were best controlled by a single cultivation conducted at the first leaf of triticale. This method caused a significant reduction in the density and the biomass of weeds at the anthesis of triticale and a reduction in the weed biomass at the full maturity of the mixture. Increasing intensity of harrowing by repeating cultivations had relatively weak influence on the weeds.