A strategic approach to weed management for the Australian vegetable industry (VG15070)
What’s it all about?
This investment was established at the end of 2016 to deliver weed management tools and approaches. The four-year project is identifying and improving integrated management strategies for high-priority weeds, and is developing guidelines and a host of resources for growers. Its work will ultimately help reduce the dependence on herbicides and tillage for weed control, which can become ineffective when used repeatedly.
The team reports progress in all aspects of their research into weeds including…
Weed seed banks in soil
Soil seed banks form a key source of weed infestation in vegetable crops since weed seeds can survive in soil for decades and give rise to weed plants year after year. To study the size and distribution of weed seed banks in vegetable fields, a survey was carried out across all states and territories of Australia.
Soil samples were collected from 36 vegetable farms to a depth of 20cm. Weed seeds for three depth categories (0-5 cm, 5-10 cm and 10-20 cm) from each farm were counted using the seedling emergence method and identified to species or genus level.
A total of 63 species were recorded in soil seed banks. Species causing the most problem for growers were marshmallow, fat hen, blackberry nightshade, chickweed, milk thistle and dwarf nettle. The preliminary results indicate that weed management strategies in vegetable crops should focus on depleting the seed bank in the top 10 cm.
Data analysis continues, so keep an eye out for further updates from the survey.
Field trials on tillage and irrigation
The team is conducting a series of trials to assess the effects of tillage and irrigation methods on the movement of weed seeds down into the soil. They are testing it on various soil types.
Integrated weeds management manual
The team has begun developing an integrated weeds management manual which will incorporate findings from the team’s research studies as these progress.
Economic analysis of weed management techniques
Field trips and farmer interviews are underway to calculate the costs and benefits of innovative weed management practices in vegetable production, compared to widespread practices.
Results are in for an initial cover crop trial in Myalup WA while others are underway to investigate the economics of cover cropping for weed suppression.
Other field and pot experiments
Hand weeding in Australia and globally has been studied with findings summarised for inclusion in the upcoming manual.
A review of commercially available hand weeding implements for vegetable production systems has also been completed, with the aim of identifying the most relevant implements for further evaluation. A field trial of these implements is planned to test effectiveness and efficiency of implements including a rotary cultivator, long-handled draw hoe and a goose foot hoe. In addition, the physical effects of the various tools on the people using them will be considered.
Another study is looking into the effect of plant age and other agronomic factors on the control and recovery of pigweed (Portulaca oleracea).
A number of graduate students are taking part in the studies to build capacity in the area of weeds in vegetable production, providing long term benefit for research in the industry. One project looked at the effect of mulch types in controlling nutsedge, finding that those that let no light through were much more effective than transparent or semi-transparent films.
Another student project evaluated whether vinegar, eucalyptus oil and salt have the potential to control weed seed germination and growth. Although the herbicidal effect was not as strong as glyphosate, vinegar and eucalyptus oil showed moderate control of weeds at early growth stages.
- Read about the cover crop trial in Myalup, in an article on page 22 of the Summer 2018 edition of WA Grower magazine.
- Read preliminary findings on managing weeds using cover crops, from trials in Forthside.
- Read an article on the benefits of cover cropping for weed management including results from Tas and WA trials published on page 16 of the January edition of the Vegetables Australia magazine.
- Watch a short video about the Myalup cover crop trial methodology and goals and another on early results from the trial.
- Download a copy of the 16 page guide to identifying and managing nutgrass, a highly resilient perennial weed, in vegetable crops.
This project is a strategic levy investment in the Hort Innovation Vegetable Fund