Weed control efficiency depends on the information about its interference on the crops. The interference of weed on tomato plants of a processing variety, transplanted directly into the field was evaluated. The field experiment was carried out, in a randomized block design with three replications, at Embrapa Hortaliças in Brasília, Brazil. Plots were laid out with increasing periods of time in the presence or absence of weeds. In the first case, plots remained under weed interference from seedling stage until the following periods (days) of the tomato life cycle: 1-28, 1-35, 1-49, 1-63, 1-77 and 1-91(whole cycle, harvest). After these periods the weeds grew freely until harvesting time. In the second case, plots were weeded from seedling stage until the previously described periods. After these periods weeds were removed by hand through the rest of the tomato cycle. Among 24 of the most frequent weed species, Bidens pilosa, Brachiaria plantaginea, Nicandra physaloides and Oxalis latifolia presented higher dry matter accumulation. Tomato production was reduced by 75.5% and the critical period of interference occurred from the 33th to the 76th day after transplanting.
Lycopersicon esculentum; weed competition; transplantation; critical period of interference
