Mamaki – Fertilization and branch bending trials for continuous leaf flush and soil fertility

Progress report for FW20-368

Project Type: Farmer/Rancher
Funds awarded in 2020: $20,000.00
Projected End Date: 08/31/2021
Grant Recipient: Mamaki Ola
Region: Western
State: Hawaii
Principal Investigator:
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Project Information

Abstract:

Māmaki (Pipturus albidus) has recently become a high demand commodity crop (Sugano, et. al, 2019). Māmaki, an endemic Hawaiian understory plant of native forests from sea level to elevations up to 6,000 feet thrives in 40%- 60% shade cover (Krauss, 1993, 2001;Wagner et al. 1990). In order to scale up māmaki production in non-forest settings, there are two problems to solve. First is providing partial shade to the growing māmaki, and the second is keeping the māmaki in continuous leaf flush

            The three approaches to the problems:

  1. Grow the māmaki in an agroforestry setting (as suggested by Sugano, et. al.) intercropping with fast growing moringa (Moringa oleifera)and pigeon pea (Cajanus cajan), and ground cover of butterfly pea (Clitoria ternatea);
  2.   Branch bending (i.e., ground layering) of māmaki to encourage new stem and leaf growth; and 
  3.   To sprench (foliar feed / soil drench combination) with nutrient rich compost teas. 

 

There is a dearth of research and outreach on māmaki. We propose to:

  1.   Gather the Shaka Beverage Farm Hui in Hilo to share and openly discuss the results of the research; followed by 
  2.   Two field days open to all farmers – one each at Māmaki Ola and Wrenn farm; and
  3.   Work with a small group of K- 12 educators to create māmaki related lesson plans and thus educate the next generation on sustainable agriculture. 

 

This project intends to show the potential of growing māmaki in a small-scale, regenerative, beyond sustainable manner while decreasing farm inputs and working towards economic abundance for local farmers.

Project Objectives:
  1.   Agroforestry system for commercial māmaki farm: determine optimal fast growing shrubs/trees with market value (e.g., moringa and butterfly pea) and with fertility value (pigeon pea and butterfly pea – nitrogen fixers) for intercropping with māmaki – modeling agroforestry systems, providing shade to the māmaki, and ground cover/compost cropping;
  2.   Branch bending: determine if branch bending (i.e., ground layering) is a viable method to encourage new stem and leaf growth, and

3.    Continuous leaf flush: determine optimal fertilization methods to keep mature māmaki plants in continuous leaf flush.

Mamaki Ola Farm – Latitude 19.398242, Longitude -154.925791.

Wrenn Farm  – Latitude 19.566509 Longitude -154.952637

Drought wiped out 50% of māmaki seedlings planted in the 2018 season. 

The technical advisor will visit each farm on alternating months. 

Both producers, working in tandem with one another, will be on site during advisor visits to each respective farm to: 

1) collect data and immediately input the data onto a Google Sheet in a shared Google Drive, 

2) discuss progress and process, and 

3) brainstorm ideas. 

Mr. Mermel and Dr. Koh will be responsible for note-taking and documenting the process.

Cooperators

Click linked name(s) to expand
  • Wrenn Bunker-Koesters - Producer
  • Dr. Ming Wei Koh - Producer (Educator and Researcher)
  • Zach Mermel - Technical Advisor

Research

Materials and methods:

 

Since past research has determined that māmaki needs 40%-60% shade, and thrives in an agroforestry setting, all plots will be intercropped with moringa and pigeon pea, and be planted with a ground cover of butterfly pea. Sprench is a combination of spray and drench to apply fertilizers to both the leaves and substrate. Both farms will establish five test plots of approximately  (40 ft x 25 ft) 1000 ft2each in the same growing area. Growing areas are open, field-like setting, not forested environments. 

Plot 1:  Weekly sprenching. Monthly pruning of branches for harvests of stem and leaves. 

Plot 2: Weekly sprenching. Branch bending, monthly harvesting of new stems/shoots and leaves.

Plot 3: Once every three weeks sprenching. Monthly pruning of branches for harvests of stem and leaves. 

Plot 4: Once every three weeks sprenching. Branch bending, monthly harvesting of new stems/shoots and leaves.

Plot 5: No sprenching, both Branch bending, monthly harvesting of new stems/shoots and leaves and monthly pruning of branches for harvests of stem and leaves. 

 

Objective 1– Agroforestry system for commercial māmaki farm– intercropping and ground cover. 

Sugano, et. al., 2019, “We are currently evaluating an agroforestry approach to provide shade for māmaki when grown outside of its natural forest habitat. Establishing trees prior to transplanting māmaki may provide an agroforestry environment which plants may also acclimate

faster to.”

We propose to establish moringa and pigeon peas prior to planting māmaki in the trial plot. We will install butterfly plants along-side the māmaki. While there were no conclusive results in the Waimanalo trials (Sugano, et. al., 2019) regarding moringa, the moringa plant was listed as a likely suitable intercropped, companion plant to māmaki. Pigeon pea is well adapted to many Hawaiʻi Island ecosystems and is a nitrogen fixer. Both moringa and pigeon pea will also be used as mulching and composting materials. 

The innovative use of butterfly pea as ground cover/compost cropping for māmaki, has yet to be researched. Oguis, et. al., 2019 and Alderete-Chavez et. al., 2011 document the applications of butterfly pea as ground cover, compost cropping, nitrogen fixer, and is drought tolerant. Furthermore, moringa and butterfly pea have commercial value. Moringa leaves currently have a market value of $4/lb in Hawaiʻi. Butterfly pea flowers is an ingredient of one the Shaka Beverages teas and Shaka Beverages has indicated they will buy the flowers along with the māmaki.

Research questions and data:

  •     Was having intercropping enough to keep the māmaki in continuous leaf flush?
  •     How quickly did the moringa/pigeon pea establish themselves and start providing 40-60% shade to the māmaki?
  •     How often could moringa/pigeon pea be pruned for composting materials while still providing 40-60% shade for māmaki?
  •     Did having a ground cover such as the butterfly pea limit soil erosion/loss, weed suppression?
  •     Before and after treatments soil testing – UH Manoa CTAHR lab. 

 

Objective 2 – Branch bending.

Sugano, et. al, 2019 reports “Māmaki is extremely vulnerable to pruning. Twig borer infestation and secondary infections often occur after pruning. Pruning should be minimized, but if pruning is necessary, utilization of a pruning seal should be considered.”While both Mamaki Ola Farm and Wrenn Farm have yet to observe twig borer infestation, both have noted that pruned stems are susceptible to rot if there is a lot of rain. 

Māmaki produces adventitious roots. Dr. Ming Wei, lead applicant and the Māmaki Ola farmer, has observed that bending of māmaki branches enables those roots to take hold in the ground, and the now horizontal branches produce many more new shoots, while being stabilized by the roots. Research into branch bending in hot and humid East India of guava trees provided evidence that branch bending was the more conducive to new shoots emerging compared to shoot pruning (Table 1, Samant, et. al., 2016). Branch bending in pears induced significant increment in leaf area (Aly, et. Al., 2012), and in roses, higher biomass of individual flowering shoots (Kim and Leith, 2004). 

We will experiment with branch bending lower and middle branches. 

Research questions and data:

  •     Monthly measurement of number of shoots emerged m-1 of branch, length/size of the shoots, and size of leaves on the shoots.
  •     After shoots are harvested, weekly observations for any indications of rot.

Progress report 3/15/2021 – please see results and discussion for more details. 

The branch bending trials were a failure. Please see slide deck. https://docs.google.com/presentation/d/1gcTBQEU4BP2syfYJ8Zifrxbj0uvdujblXgI9ILzchAY/edit?usp=sharing

The branches that inspired the research were bent close to the ground and that allowed the branches to put adventitious roots and eventually root. The branches that were espaliered did not have the advantage of obtaining nutrients from another sources. Once there was any stress on the system, eg. drought, the whole branch died.

We had to change the objective and research to pruning methods to keep the plants in leaf flush.

This was not an easy decision as the proposal was originally built on the branch bending.

New objective 2 – Pruning methods for continuous leaf flush.

The PI, Dr. Koh and Mr. Koestler have begun pruning in a specific manner to promote leaf flush and to decrease rot opportunities.

Criteria:

Research questions and data to collect:

  • Bi-weekly measurement of number of shoots emerged from the area of pruning.
    • How soon before these shoots are harvestable?
    • Are these shoots “water shoots” or do they become woody quickly?
  • After shoots are harvested, weekly observations for any indications of rot.

 

Objective 3– Continuous leaf flush by sprenching of high nitrate compost tea. 

Tea Time for the Tropics edited by Radovich and Arancon, SARE publication, 2011 provides evidence that high nitrate compost teas made from mature vermicasts and mature compost have relatively large amount of plant available nitrogen, the element needed for leaf growth and flush. This research project will have a new application of this tested method on māmaki

Māmaki Ola farm already has a continuous feed vermi-system based on research and design by Dr. Norman Arancon. We will be establishing a similar system for Wrenn Farm. 

The proposed sprenching sequence above will help determine how often sprenching is needed.

We will purchase a chipper shredder to be shared between the farms to process moringa, pigeon pea, and other carbonaceous material into compostable size. We will build aerobic compost piles and also feed the worms with these materials. 

Research questions and data:

  • Compost tea will be tested monthly for nitrates using a simple strip tests.
  • Pre-post testing at UH Manoa CTAHR lab – test the compost tea for nitrates. 
  • We will measure the size and weight of leaves during monthly harvests and compare among the plots 1 through 4. 
  • We will take monthly photos of selected trees to see if they stay in leaf flush or go into fruiting. 

Success looks like:

Māmaki in continuous leaf flush, fertile soil due to composting 

 

Research results and discussion:

Objective 1

Research questions and data:

  •     Was having intercropping enough to keep the māmaki in continuous leaf flush?
  •     How quickly did the moringa/pigeon pea establish themselves and start providing 40-60% shade to the māmaki?
  •     How often could moringa/pigeon pea be pruned for composting materials while still providing 40-60% shade for māmaki?
  •     Did having a ground cover such as the butterfly pea limit soil erosion/loss, weed suppression?
  •     Before and after treatments soil testing – UH Manoa CTAHR lab. 

The intercropping was not enough to keep the māmaki in continuous leaf flush. The māmaki plants still produced some berries. The moringa/pigeon pea established themselves very quickly in about four months. The pigeon pea could be pruned every other month, and the moringa once every 4 months while still providing 40-60% shade for māmaki. The ground cover not only limited soil erosion/loss and suppressed weeds, the butterfly pea grew very rigorously and could be pruned (chop and drop) as mulch and eventually composted into soil.

Related data. 

In addition to a plot with the leguminous ground cover, Mr. Wrenn Koestler had a plot with weedmat as a permanent ground cover. On this plot, he made holes at regular intervals to intercrop māmaki, pigeon pea, butterfly pea, and moringa. Sadly, the māmaki did not do well. He had to transplant new plants twice, while the other crops took off. Even though there was weed suppression, this method dis not contribute to māmaki growth. Please see slide deck for picture and more explainations. https://docs.google.com/presentation/d/1gcTBQEU4BP2syfYJ8Zifrxbj0uvdujblXgI9ILzchAY/edit?usp=sharing

Objective 2

As stated in the section above, the branch bending proved to be cost and time ineffective.  Māmaki, Pipturus albidus, is in the stinging nettle family Urticaceae, a flowering, softer wood shrub/small tree. We speculated espaliering māmaki like apples or pears, but this did not work out, and the branches died. We did base this theory on the observation that māmaki branches close to the ground put out adventitious roots, and eventually rooting themselves, creating wide-spreading canopy. However, ground layering is not the same as branch bending. Please refer to the accompanying slide deck for pictures and more explanations. https://docs.google.com/presentation/d/1gcTBQEU4BP2syfYJ8Zifrxbj0uvdujblXgI9ILzchAY/edit?usp=sharing

In the next report, we will delve into more details on the NEW objective 2 which is a specific pruning practice. 

 

Objective 3

The sprenching of compost tea yielded great results. The farmer-ranchers do note that the nitrogen source could be compounded by the nitrogen fixing pigeon pea and butterfly pea.

Method:

Both farmers, Dr. Koh and Mr. Koestler used the same vermi-castings provided by the worms raised at Dr. Kohʻs farm.

We used the exactly the same equipment to brew the tea, we purchased two of everything. Compost tea bubbler, pump and strainer from the Tea Lab, 10-gallon plastic bin with a lid, and Milwaukee back-pack battery-operated concrete sprayer. We both brew for 30 hours.

Dr. Koh and Mr. Koestler spray the day after māmaki harvest day, Friday or Sunday, respectively.

Weekly testing of the compost tea using simple aquarium testing strips, showed medium to high levels of nitrates.

We observed consistent leaf flush and quick regrowth after pruning. The leaves grew to be medium (3 inches wide, 5 inches long) to large (5 inches wide, 7 inches long) consistently. There have been no signs of root rot caused by Rhizoctonia, Phytophthora and Pythium as cited by Sugano et. al. (2019).

We also observed no branch or twig rot, nor any twig borer infestation. This was a concern raised again by Sugano et. al. (2019), who reported “Māmaki is extremely vulnerable to pruning. Twig borer infestation and secondary infections often occur after pruning. Pruning should be minimized, but if pruning is necessary, utilization of a pruning seal should be considered.” We did not seal the twigs with a seal, we just sprayed compost tea the day following harvest.

We saw no difference in the plots sprenched every week or every three weeks. This is likely because the plots are all close together and the breezes blow the light mists of compost tea all over the farm. The plot that was not sprayed at all, seemed a little lackluster, but it was difficult to tell. Again, we could not prevent mists of compost tea from wafting over. Furthermore, microbes are not static, and can move around. We do not know if they spread from the sprayed areas to the un-sprayed areas in the soil.

We started leaf sales the same time this project started – April 2020. To note, Shaka Tea takes in the product as “wet” – branches cut about arms length with leaves. Shaka Tea processes by washing, hang drying, stripping the leaves, dehydrating the leaves at a precise temparture and length of time, and then pays for the dried product at $20/pound. There is obviously a great loss of weight. We would like to see the returns eventually at 20%, which means the branches are not so woody, and the leaves are large. The attached spreadsheet from our buyer, Shaka Tea, begin in July 2020 – January 2021 – 2 tabs one for Wrenn and one for Dr. Ming Wei – Māmaki Ola Farm.

When we first started, there were a lot of inconsistencies.

1. Woody branches vs. water sprouts. Since we were working on structurally shaping our older shrubs, there was a lot of woody branches.

2. Our leaves were inconsistent in size and weight. Some weeks yielded a lot large leaves and other weeks did

Then we applied the intervention – leguminous ground cover, shade from moringa, and most importantly compost tea sprenching. Now, the harvest is more consistent. 

In hind sight, we should have included a control māmaki farm that would not conduct any of the interventions.

Participation Summary
2 Farmers participating in research

Educational & Outreach Activities

8 Consultations
12 Curricula, factsheets or educational tools
1 On-farm demonstrations
1 Online trainings
2 Published press articles, newsletters
8 Tours
4 Webinars / talks / presentations
1 Workshop field days

Participation Summary

20 Farmers
8 Ag professionals participated
Education/outreach description:

Progress report 3/15/2021

Māmaki Ola Curriculum Development and Implementation Professional Development Course for Educators

June 30, 2020 – December 6, 2020

Course at a glance:

Date

Topic 

Notes

June 30

Cultivating a strong sense of place – culturally and ecologically 

Place-based introductions with padlet

July 2

Ecosystems and Symbiosis – patterns of place, what do ecosystem services mean?

Indigenous farming – regenerative agriculture

Climate zones, direction of winds, rains, mahina, moʻolelo of places, moʻolelo of māmaki

Guest Speaker: Dr. Noa Lincoln, CTAHR, UHM.

July 7

Recap of “what do ecosystem services mean?”

Lāʻau Lapaʻau and 

Seed propagation

Lauren DeMent to lead recap. 

Guest Speaker: Carly Wyman, Hui Mālama Ola Nā ʻŌiwi 

July 9

Hawaiian grown hydration 

Guest speakers: Rethink your Drink – Department of Health; and 

Bella Hughes and Harrison Rice, Shaka Beverages. 

July 10 or 11 or 17 or ….

Field trips:

JULY 10 Oahu – Poamoho CTAHR

July 11 Hawaii – Lower Puna Māmaki tour

Maui – pick up your plants from Maui Nui Native Nursery 

Kauai – ???

July 14

Agriculture-based entrepreneurship 

Guest speakers: Dana Shapiro, Ulu Coop; Bella Hughes, Shaka Beverages 

July 16

Four themes for the curriculum

Developing curricular materials – writing books, articles, etc 

Start Mapping the curriculum – what units, who takes on what lesson, what resources needed 

Guest speaker: Janice Crowl, Author of the

Pulelehua and māmaki book 

July 21

Ethnobotany of Māmaki and entrepreneurship ideas

Guest speaker: Jani Puakea Forester

on dye-ing and cultural uses 

July 23

Map the curriculum – what units, who takes on what lesson, what resources needed 

 

August 11

3 pm

Units/Lessons drafts ready – share out to whole group 

Start planting māmaki and launching entrepreneurship ideas 

 

August 25

3 pm

Units/Lessons drafts ready – share out to whole group

Start planting māmaki and launching entrepreneurship ideas

 

September 8

3 pm

Pilot lessons – how did it go

Entrepreneurship mentoring 

Mentors: Bella, Mosese

September 22

3 pm

Refine lessons and start on curriculum dissemination presentations 

Start on e-book

 

October – November 

Dissemination presentations 

Teacherʻs own School and Community 

Online

In person 

December 6, 2020

PDE3 Portfolio due

 

Outcomes and Objectives

Objective 1: Increased nutritional knowledge of māmaki.

Objective 2: Increased environmental knowledge of māmaki.

Objective 3: Increased consumption of healthy beverages such as water or mamaki tea instead of sugar based drinks.

Objective 4: Increased outplanting of māmaki in school learning gardens.

Objective 5: Increased exposure to agriculture-based entrepreneurship models that elevate Hawaiʻi I and have an abundance mind-set.   

The outcomes of the curriculum

Students will: 

  1. Practice deep observation – kilo of mamaki shrubs planted at school learning gardens; 
  2. Learn experientially how elements of the Hawaiian ecosystem are intertwined;
  3. Apply the learning from #2 to climate change solutions, specifically – caring for forests and planting more trees (like māmaki);
  4. Reach for drinks like water or māmaki tea instead of sugar based drinks; and 
  5. Be exposed to entrepreneurship models that elevate Hawaii and have an abundance mind-set.   

Deliverables: 
Lessons on māmaki. 

One teacher portfolio is attached. 

Results:

20 teachers state-wide attended this semester long training and curriculum development. These teachers developed way to send māmaki leaves and plants home as part of weekly their distance learning packets. Shaka Tea provided more than 80 cases of tea for the teachers to send home with the distance learning packets. 

Five different nurseries or farms from 4 different islands – Oahu, Hawaii (2), Maui, and Kauai provided māmaki seeds and plants for their own islands. More than 250 māmaki trees were outplanted in schools/homes on those islands – in spite of school lock downs. 

250 students participated in distance learning māmaki lessons, including agri-preneurship projects creating new māmaki tea blends for sale.

Three of the particpaiting teachers have begun farming māmaki on a small scale on their own properties. 

 

February 4 and 18, 2021

6 – 7 pm

Online presentation of compost tea for fertility and māmaki pruning methods. 

Audience: Current māmaki farmers in the Shaka Tea Hui (group), but open to all.

Presenters: Dr. Koh and Mr. Koestler. 

Recordings attached. 

 

 

OLD starts here

May 2021

Presentation of methods, research and findings 

Audience: Current māmaki farmers, but open to all.

Location: Shaka Beverage HQ, 288 Kilauea Ave. Hilo HI 96720. 

4 hours

Technical Advisor and both farmers will create a slide presentation on the methods, research and findings. The format of the presentation will encourage critical thinking and discussions about scaling up and localizing applications of the methods. The discussion during this presentation will help refine the content and format of the field days. The presentation and discussion will be recorded and Dr. Ming Wei will write a short report to disseminate back to SARE and this Hui. 

 

Summer 2021 – June and August 

Two Field days

Audience: Open to all producers, with focus on farmers considering becoming māmaki farmers, Locations: Māmaki Ola and Wrenn farms

6 hours each day

Technical Advisor and both farmers will create simple brochures on the methods for distribution to the participants. On-site demonstrations of intercropping, branch bending, and compost tea nitrate testing and sprenching. 

Guest speakers: Technical Advisor – Zach Mermel; Shaka Beverage LLC President – Bella Hughes; and Vermi-compost expert – Dr. Norman Arancon. 

The on-site demonstrations will be recorded and Dr. Ming Wei will write a short report to disseminate back to SARE. Videos of the demonstration will be posted on www.c4gts.org and any other site willing to host the videos. 

 

July 2021

Educators create māmaki curriculum.

Audience: Educators/teachers – all subjects including agriculture teachers. These educators will be recruited from the Hawaii Island School Garden Network. 

Location: Māmaki Ola Farm as base with farm tours of at least 2 more māmaki farms – Wrenn and one more. 

Day 1: On site-demos at Māmaki Ola, guest speaker, begin planning the lessons

Day 2: Farm tours in the morning and continue writing lessons in the afternoon

Day 3: Guest speaker, complete writing the lessons and share with each other. 

Farm tours of both farms, on-site demonstrations of intercropping, branch bending, and compost tea nitrate testing and sprenching. Specific time set aside to write lessons. 

Guest speakers: Technical Advisor – Zach Mermel; Shaka Beverage LLC President – Bella Hughes; and sustainable agriculture expert – TBD. 

Lesson ideas for the curriculum

  1.   What is regenerative agriculture?
  2.   How to conduct deep observation – kilo of māmaki (relate to science inquiry)?
  3.   What are native, endemic, introduced plants?
  4.   Hawaiian ecosystems, symbiotic relationships of māmaki and Kamehameha pulelehua (butterfly) – how elements of the Hawaiian ecosystem are intertwined?
  5.   Climate change solutions, specifically – caring for forests and planting more trees (like māmaki);
  6.   Biodiversity – why is the use of intercropping and ground-covers a beneficial form of imitating nature?
  7.   Healthy beverages like māmaki tea
  8.   Hawaiian entrepreneurship

Lessons will be posted on www.c4gts.org and any other site willing to post the lessons. 

 

Learning Outcomes

18 Farmers reported changes in knowledge, attitudes, skills and/or awareness as a result of their participation

Project Outcomes

12 Farmers changed or adopted a practice
12 Farmers intend/plan to change their practice(s)
3 Grants received that built upon this project
6 New working collaborations
Project outcomes:

Kalea – Brochure Protect HI Native Species Madelyn – Brochure Protect HI Native SpeciesMadelyn – Brochure Protect HI Native SpeciesThere is growing excitement about māmaki as a commercial crop in Hawaiʻi. It continues to be the only exportable endemic plant. Māmaki must be treated with the utmost respect as it is a culturally significant plant. We have been recommending that plants for medicinal and cultural uses are kept separate from plants for commercial production. As a farmer in Hawaii, there is a deep sense of place when  growing an endemic plant at scale. The landscape is that of endemics instead of an imported crop. Through the WSARE website/search, two graduate students from UH Manoa CTAHR (College of Tropical Agriculture and Human Resources ) have found this māmaki project. A PhD. student researching agroforestry as a farming method, and a M.S. student interested in māmaki production farming.

Economically, dried māmaki fetches a high price, ranging from $20/pound – $80/pound. Shaka tea, who purchases from the two farms on this project, reports that the RTD (ready-to-drink) māmaki tea market is growing steadily. And in spite of COVID-19, the last quarter was the best in sales. Shaka Tea needs more farmers producing māmaki. Both farmers, Dr. Ming Wei and Mr. Koestler have been approached individually by separate and different investors/markets about growing more māmaki and/or helping to start a new māmaki-based business.

Ecologically, māmaki provides many services. Habitat for the endangered Hawaiian endemic butterfly, pulelehua Kamehameha; food for forest birds; understory plant that helps to create soil with its decomposing leaves; and roots that hold in the soil and rocks.

Māmaki fortunately, does not have many pests. There is a newly identified pest, that may be game changer, but right now, māmaki is not the kind of crop that needs a lot of pest control. Therefore, this is an easy crop to grow organically without the need for insecticides, etc. The two brochures attached are products from the Māmaki Ola curriculum development and implementation teacher training. Two teachers, one from Maui and one from Hawaiʻi Island teamed up and taught their students about invasive species. The Ramie moth appeared on Maui in late 2018, and started devasting the Maui māmaki forests. Students on Hawaiʻi Island wanted to prevent this from happening on their island. The first reported sighting of ramie moth on Hawaiʻi Island was around the same time these student brochures came out, the Fall of 2020. We have been circulating these brochures among farmers and conservationists. The HI Dept. of Agriculture pest advisory came out in February 2021, after we had already been sharing about the pest.

This project is also showing that the māmaki fertility needs can be met in inexpensive, regenerative ways, by generous application of compost tea, supplemented by the nitrogen from companion legumes.  Farmers do not need to constantly purchase fertilizers.

The following is from Zach Mermel, Technical expert:

Economic benefits: Documentation of strategies that were not cost effective (e.g., branch bending; use of weedmat as permanent ground cover likely resulted in the high mortality rate for installed mamaki), and those that were (e.g., hand pressing ripened mamaki fruits into exposed lava rock resulted in germination and maturation of harvestable plant) 
Environmental benefits: Application of compost tea to planting area was an environmentally friendly alternative to chemical fertilizers. Multi-month observations of the farm plots helped determine preferred strains of mamaki (e.g., the Haleakala strain, from Maui), which can now be propagated more widely, for a larger number of growers. 
Social benefits: The educational presentations have offered a conversation platform for farmers of Pipturus albidus to share their successes, challenges, and experiments with one another. This creation of a community of collaborative mamaki cultivators is itself a sustainability success metric.

 

Success stories:

Three māmaki farmers have begun their own worm “farms” with worms from Dr. Ming Wei, and begun making and spraying vermi-cast compost tea. They report greening of leaves, and observe overall improved health of their māmaki plants. Two farmers have begun pruning their trees in the same manner as the two farmers in this project and are reporting no rot, and considerable new growth.  

Recommendations:

We were a bit overly ambitious in our number of research topics. We perhaps would have been better served (and obtained more robust data) if we focused just on one or two research queries (e.g., optimal planting distance between mamaki plants, paired with compost tea applications).

This project raised several important areas for further study. 

Variety trials. Dr. Amjad Ahmad of UH Manoa CTAHR has applied for the Hawaii Dept. of Agriculture Specialty crops grant to fund this research, and will work with the farmers in this project. 

Density trials, optimal planting distance between māmaki plants. We have noted that māmaki plants thrive when planted close together. However, this will make commercial harvesting difficult. What is the optimal distance to achieve both – plant community and ease of harvesting. 

Pruning/pollarding. More careful study into proper practices to increase leaf flush and mitigate rot. 

How long can we push the plant? This is of most interest to Dr. Ming Wei. We started harvesting some plants at 6 – 7 months, keeping these plants low. These plants are responding positively to the pruning/pollarding and to the compost tea spray. They out out soft water sprouts with large leaves. The return wet harvest:dry leaves is close to 15%. Keeping the plants at chest height make them easy to manage. We want to know how long can a plant sustain this kind of heavy, regular pruning. And once this is established, we can then design and plan for rotational planting. 

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.