SFF Project Summary
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Last updated: 28 May 2009
Arnica montana a grower's guide for commercial production in New Zealand [1.31M PDF]Last update: March 2007
This project has been evaluating the effect of various weed treatments in the commercial production of arnica. Arnica (a mountain plant used extensively in the herbal industry) has been shown to grow successfully in the lower half of the South Island. However it is a very poor competitor with weeds. Trials have been conducted in Methven, Dunedin, Oamaru, Southland and Styx (Central Otago). Weed treatments have included mechanical weeding, weedmat, biofilm, ecocover (an organic paper product), mulch and organic interceptor.
Methven site: This is the most northerly site and it was not clear if the plants would be successful. There are some flowers from spring planting and plants show vigour matching other sites. There have been some plant losses from fungus. It is unclear if this is a result of this season weather patterns.
Flower yields: The Styx site has produced 200kg fresh flowers, from 10,000 plants (= 45kg dried). This equates to approx 10kg fresh flowers per 15m of bed. These plants are 12 – 24 months old.
The Flagstaff/Dunedin site produced 85kg fresh flowers ( = 15.5kg dried)
Weed invasion: Mat treatments (weedmat, ecocover and biofilm) plants show greater growth and vigour. This growth has been noted even when the treatments have not lasted a season. Biofilm in particular has proved vulnerable to wind and pecking and ripping by birds.
The Styx site has remained the most clear of weeds. It is noted this site used sterile seed beds at initial planting. The other sites have significant weed invasion. This became more significant as the season progressed. The plants appear to compete more successfully when planted closer together than the initial plantings of 25cm X 30cm. Spring planting in Methven and Flagstaff whilst achieving 5% flowering are now 80 – 90% invaded by weeds.
Harvesting: The trials are now producing significant numbers of flowers however it has become apparent harvesting may become a high cost input. Trialists are picking 3-5kg fresh flowers per hour. Faster picking is achieved if plants weed free and if picking done only 2-3 times rather than spread over many picking times. Picking speed will increase as plants mature and become more abundant on each stem.
At this time mechanical harvesting is not possible because of the variation of flower head height. Two trialists found picking speed improved if done by ‘finger rake’ but this did increase the amount of debris and was only very successful with massed flowering.
There are also considerations around the optimum time to harvest the flower. This will be important if the market is dependant on levels of sesquiterpene lactones (higher as flower matures) . Weleda tells us the homeopathic market interested in how plant grown, moisture content and if free of adulteration; herbal market interested in levels of sesquiterpene lactones.
Flower times across sites have shown great variation (also compared to last season).
Market Potential: Weleda continues to be very optimistic about the long term market. At this stage they have interest from overseas buyers for tons of plant material. The market is requiring plants to be grown organically.
October 2006
Plant losses over the winter have been very low but some crown rot is starting to develop at the Waipiata and Weston sites two site which have been extremely dry since April 06. At the Invercargill and Weston sites some of the plants that were thought to have died from crown rot last summer are re-sprouting this spring.
Weedmat has given the best weed control. Plants under the Weedmat have also come away earlier in this spring. A narrower row spacing used on the ‘Eco cover’ treatments (biodegradable paper mat) at the Dunedin site is giving better suppression of the inter row grass weed than on the other treatments because the arnica plant canopy rapidly filled in the inter row area this spring.
Results from the autumn 2006 planting been mixed across the 5 sites. Plants were quite small when planted and made little or no growth before shoot growth died down for the winter. At the Waipiata site a lack of snow cover and severe frost heave has had a major effect on plant survival. In contrast at Methven site small plants were covered by deep layer of snow for a long period over winter and were protected from severe frost and there has been extremely good plant survival. Weed invasion has also been a significant problem with the autumn planting. Coming out of the winter there has been a major weed invasion of species such as shepherds purse and chickweed. Weed mat and the ‘Bio-film’ (biodegradable corn starch film) have given the best weed control with autumn planting. Unlike the spring plantings the ‘Bio-film’ where the ‘Biofilm’ was destroyed by high winds soon after planting with the autumn planting it has maintained its integrity up to late October 06. Recently however, extremely strong winds combined with warmer day temperatures (>20 °C) have caused the film to break-up.
June 2006
Autumn planting has occurred in Ranfurly, Dunedin, Methven, Southland and Oamaru using a variety of weed control treatments. Mechanical weeding will be the consistent treatment through all sites.
The Methven site had joined the trial. It is at the northern extreme of the anticipated flowering range. Rob is trialling weed mat, bio film, mechanical weeding and also planting in harvested crop stubble.
Ranfurly site: Minimal weed invasion through the season (less than 10%). Eco cover and Bio film have proved unsuccessful treatments due to damage by wind almost immediately after planting. The plants have grown well particularly in the plot treated with wood chip mulch. The mulch seems to have suppressed weeds and helped retain moisture in this very dry site. There have been about 100 plants flowering this season with very few plant losses.
Dunedin site: There has been significant weed invasion in the plot, clover, hawkweed and some couch (up to 90%). The plots managed by mechanical weeding have been the least affected by weed invasion (approx 30% invasion) and have been relatively easy to keep clean. About 10 plants have flowered this season with very few plant losses.
Oamaru site: The Allan’s hosted a field visit in March. Their plot has also had minimal weeds invasion (10-20%). Plots treated with Stomp prior to planting appear to have suppressed weeds by maintaining a ‘crust’ on the surface. This site has also struggled to prevent wind destroying the Eco cover and biofilm. The Eco cover also degraded rapidly at the edges ‘dug’ into the ground. There have been no flowers this season and very few plant losses.
Southland site: Has had some plant losses (approx 10-20%) This may have been because of delayed planting causing stress and resulting in fungus infestation. Orgainic interceptor has proved a very unsatisfactory weed control treatment in Southland due to the cooler temperatures. There have been no flowers this season.
The group is planning a field visit to the Methven site in late spring, date to be arranged.
March 2006
Proposed outcomes
- Completed collation of weed invasion and plant survival data, for both autumn and spring 2005 plantings.
- Second autumn planting with weed control treatments at 3 regional sites.
Progress to date
- Autumn planting has occurred in Ranfurly, Dunedin, Methven, Southland and Oamaru using a variety of weed control treatments. Mechanical weeding will be the consistent treatment through all sites.
- The Methven site had joined the trial. It is at the northern extreme of the anticipated flowering range.
- Ranfurly site: Minimal weed invasion through the season (less than 10%). Eco cover and Bio film have proved unsuccessful treatments due to damage by wind almost immediately after planting. The plants have grown well particularly in the plot treated with wood chip mulch. The mulch seems to have suppressed weeds and helped retain moisture in this very dry site. There has been about 60 plants flowering this season with very few plant losses.
- Dunedin site: There has been significant weed invasion in the plot, clover, hawkweed and some couch (up to 90%). The plots managed by mechanical weeding have been the least affected by weed invasion (approx 30% invasion) and have been relatively easy to keep clean. About 10 plants have flowered this season with very few plant losses.
- Oamaru site: The Allan’s hosted a field visit in March. Their plot has also had minimal weeds invasion (10-20%). Plots treated with Stomp prior to planting appear to have suppressed weeds by maintaining a ‘crust’ on the surface. This site has also struggled to prevent wind destroying the Eco cover and biofilm. The Eco cover also degraded rapidly at the edges ‘dug’ into the ground. There have been no flowers this season and very few plant losses.
- Southland site: Has had some plant losses (approx 10-20%) This may have been because of delayed planting causing stress and resulting in fungus infestation. Organic interceptor has proved a very unsatisfactory weed control treatment in Southland due to the cooler temperatures. There have been no flowers this season.
- A meeting has been arranged for Saturday May 13 2006, Mosgiel Library. The trialist will each present a summary of time spent managing their plots, their observations and experiences with autumn planting.
