Punch planting, flame weeding and delayed sowing to reduce intra‐row weeds in row crops

Rasmussen J, Henriksen CB, Griepentrog HW & Nielsen J (2011). Punch planting, flame weeding and delayed sowing to reduce intra‐row weeds in row crops. Weed Research51, 489–498. SUMMARY: Punch planting has recently been suggested as a technique to reduce intra‐row weeds in organically grown row crops. The technique is to punch holes in the ground and seeds are then inserted, with a minimum of soil disturbance outside the hole. Two series of experiments with a tractor‐mounted prototype of a dibber drill (MK III) are presented. In the first series, three crop establishment procedures were compared over 2 years at five different sowing dates in sugar beet and direct‐sown onion. The crop establishment procedures were as follows: (i) normal sowing and mechanical control of weeds in the stale seedbed (N), (ii) N + pre‐emergence flame weeding (N + F) and (iii) punch planting and flame weeding to control weeds in the seedbed prior to crop emergence (P + F). The difference between N and N + F treatments quantifies the effect of pre‐emergence flame weeding, and the difference between N + F and P + F quantifies the effect of punch planting. Punch planting reduced the average intra‐row weed density by 37% in onion but had no main effect in sugar beet. In the second series of experiments in carrot, which compared the N + F and the P + F treatments only, punch planting reduced the average intra‐row weed density by 34%. Pre‐emergence flame weeding reduced the average weed density by 59% in onion and by 47% in sugar beet. Delayed sowing without pre‐emergence flame weeding only reduced weed emergence in 1 of 2 years, whereas delayed sowing had a more pronounced effect in flame‐weeded (N + F) and punch‐planted plots (P + F). In sugar beet and onion, there were complex interactions between crop establishment procedure, year and delayed sowing, which are partly explained by weather conditions and species‐specific germination patterns. It was concluded that technical improvements to the dibber drill (MK III) are required to take advantage of punch planting to reduce intra‐row weed densities.