Preliminary results on physical weed control in processing spinach

A field experiment was carried out in Central Italy (Tiber Valley, Perugia, 43oN, elev. 165 m) to evaluate applicability and efficacy of some physical weed control methods in processing spinach, sown at two different inter-row distances (0.125 and 0.25 m). With rows 0.125 m apart, pre-sowing herbicide application (cycloate at 3635 g a.i. ha-1), harrowing and post-emergence flaming were applied, while with rows 0.25 m apart the treatments were pre-sowing herbicide application (same herbicide as above), finger-weeding, split-hoeing and post-emergence flaming; untreated plots were added as checks. Physical weed control was performed at the “4-6 true leaves” stage of the crop and at the “cotyledons” to “6 true leaves” stages of the weeds. Pre-sowing chemical application caused a growth reduction and, as a consequence, a delay in harvest date in comparison with physical weed control. Flaming caused a temporary wilting of the crop which then fully recovered, although unmarketable deformed leaves at final harvest were about 12% of total yield (on mass basis) with rows 0.125 m apart and about 7% with rows 0.250 m apart. Finger-weeding and split-hoeing on rows 0.250 m apart, as well as harrowing on rows 0.125 m apart, did not injure the crop. On fresh mass basis, the percentage of weed control with rows 0.250 m apart was 97% by pre-sowing herbicide application, 90% by flaming, 88% by split-hoeing and 64% by finger-weeding; with rows 0.125 m apart the weed control efficacy was 82% by pre-sowing herbicide application, 30% by flaming while harrowing showed no control. Crop yield was not affected by row distance and only slightly by weed control method.