New method for the devitalization of imported horsetail (Equisetum hyemale)

Despite being rated as one of the world’s worst weeds, Equisetum hyemale was until recently imported into New Zealand for use by the floristry industry, subject to devitalization. It was subsequently found that imported stems were not being successfully devitalized and importation was banned. This study, in two trials, used different dilutions of six herbicides, including Roundup, the one listed in the MAF Biosecurity NZ standard, to investigate if it were possible to render stems non-propagable without destroying their commercial use. This research found that a Sharpshooter (oryzalin) formulation at 1 and 1:2 dilutions of the field application strength was the only herbicide that completely devitalized the stem material with minimal impact on stem quality. Roundupat the concentration required by MAF Biosecurity NZ destroyed the stems, while 1:5 and 1:10 dilutions reduced the ability of the stems to be propagated, but still caused stem damage. AGPRO activated amitrole, Duplosan, Agritone and Kamba were not successful as devitalization agents

Reduction in field emergence and seedbank density of Galinsoga quadriradiata and other weeds after contrasting false seedbed strategies in organic vegetable fields

Mechanical weed control in low competitive, organic vegetable production systems is challenging, particularly in fields with large populations of Galinsoga spp. (Asteraceae). Various false seedbed techniques are used prior to crop planting or sowing to prevent weed emergence, albeit with variable success. This study investigated the impact of machinery type (flamer, hoe and harrow), number of passes (2 and 4), tillage depth (1-4 cm) and intensity (double and single hoeing, and hoeing with or without additional harrowing) on weed emergence and seedbank density in 0-5 cm topsoil of organic vegetable fields. False seedbed machinery that did not or minimally disturb the soil was most appropriate for preventive control of Galinsoga quadriradiata (Hairy galinsoga) and total weed seeds, with reductions in seedling emergence up to 99% and 73%, respectively, for flaming, and 74% and 67%, respectively, for 1 cm deep hoeing, 1 month after false seedbed creation. Compared with 1 cm deep hoeing, 1 cm deep harrowing was 16% less effective in the control of emerged seedlings, while flaming was highly effective in preventing weed seedling emergence, even after a low number of passes. Tillage intensity was less important than tillage depth for the reduction in weed emergence and seedbank density. Overall, tillage was more effective for seedbank reduction than flaming

A new hoe share design for weed control: measurements of soil movement and draught forces during operation

This research introduces a new share design (L-share) that reduces the undesired random soil movement, providing a more controlled disturbance of the upper soil layer. Purpose: The aim of this study was to evaluate draught forces and soil movements when operating the new share. Materials and Methods: Experiments were conducted in a laboratory set-up using a soil bin with a fine loamy soil texture. The soil was compacted to a bulk density of 1500 kg m−3, with a penetration index of 486 kPa and a mean water content of 10%. The cultivation depths were 30, 50 and 70 mm and the operation speeds were 0.84, 1.67 and 2.31 m s−1. Cubes were used to measure soil movement by recording the displacement from their initial positions. The soil surface and furrow profile were measured by using a 2D laser range scanner. Results: The results showed that increasing operation speed and cultivation depths generally increased draught forces and soil movement. Changing the cultivation depth from 30 to 50 mm resulted in a 63% greater longitudinal force (Fx), and 71% greater Fx when increasing the cultivation depth from 50 to 70 mm. Conclusion: The study showed that the new L-share mounted on a modified spring tine only causes minor soil movement and thereby minimising the undesirable soil movement