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

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.

NEW INFORMATION for the FINAL REPORT starts here

Final report

Results since 3-15-2021

This final report will contain two main components. 

• Reporting on the new Objective 2: Pruning methods for continuous leaf flush, using an Analysis of the sales data.

• Outreach efforts since 3/15/2021. 

Taken from the 3-15-2021 report:

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:

• Pruning at the node on the stem when it becomes small. Please see slide deck https://docs.google.com/presentation/d/1gcTBQEU4BP2syfYJ8Zifrxbj0uvdujblXgI9ILzchAY/edit?usp=sharing

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.

Results from Objective 2: Pruning methods for continuous leaf flush, using an analysis of the sales data.

An average of three to four shoots emerge from the area of pruning. These were harvestable in four weeks depending on:

1. Moisture and 
2. Light. 

Note that both farms continued their weekly sprenching of compost tea, keeping fertility a constant. 

Moisture is a huge factor for māmaki shoot growth. This Summer 2021 was a relatively wet summer for the Puna area where both farms are located. The rains along with slightly longer summer days encouraged rapid shoot growth. We could get harvestable shoots in four weeks. 

Māmaki sales to Shaka Tea Data

To note: a. Farmers bring in harvested shoots, Shaka Tea processes and dries the māmaki and pays for the dried product. Shaka Tea has to do all the processing to meet the Food Safety requirements for itʻs product which is sold internationally. This keeps another variable constant. Both farmsʻ māmaki are weighed on the same scale and processed by the same people using the same machines. 

1. Water shoots with soft stems and leaves provide more “bang for the buck” as the whole shoot can be processed into tea. The twiggy/woody shoots need to be stripped separating the leaves from the woody stem - less return. 

Māmaki Ola Farm committed to the branch bending, which ended up being unsatisfactory. 

FacePlant Farm or Wrennʻs farm conducted the fertility trials and immediately began pruning in the manner described above.

The % return wet to dry tells an interesting story. Please refer to the attached spreadsheet. 

From July 2020 to January 2021, with only 2 exceptions, the average return for Māmaki Ola Farm was around 13%. After January 2021, Māmaki Ola moved away from branch bending and adopted the same pruning practices of Wrennʻs Farm. The return average, from February 2021 until mid-June 2021, for Māmaki Ola Farm was now around 17%. 

Wrennʻs Farm average has been close to 17% during the whole duration of this research project. 

This provides evidence that the pruning practices produced the desirable usable water shoots, in a fairly consistent manner. 

We are very interested to see how this may change as we enter the fall/winter months, with slightly shorter days. When you look at Wrennʻs Farm data, you can see the fall 2020/winter 2021 returns were slightly lower than spring/summer. We will be able to use Māmaki Ola data fall 2021/winter 2022 to contrast. 

There have been no observable indications of twig borers or twig rot, contrary to the original research by Sugano et. al. (2019). Shaka Tea reports that all their farmers have now adopted this method of pruning with very similar returns and results. 

Outreach/Education

More than 120 folks registered for the two-part webinar series for interested and new farmers. Titled Māmaki - Community, Conversation and Currency, the webinars were attended by 60 folks on an average from the whole state of Hawaiʻi and with a few folks from the US Mainland and Micronesia. All three personnel on this WSARE project, Zach Mermel (technical advisor), Wrenn Bunker, and Dr. Ming Wei presented, along with Dr. Ahmad Amjad from UH Manoa CTAHR (College of Tropical Agriculture and Human Resources). The flyer is attached and here are links to the Zoom recordings of the two webinars. https://drive.google.com/drive/folders/1CovN02gTpWygAe00q0KQWUbkPqZEX5Dw?usp=sharing

In addition to the total of four webinars to which we committed for this grant project, Dr. Ming Wei conducted an additional live workshop to a very limited group of new and interested gardeners and farmers, at the Hilo Panaʻewa Farmersʻ Market. Please see attached flyer for the COVID precautions we took. This workshop was hosted by the Cooperative Extension Service, College of Tropical Agriculture and Human Resources, University of Hawai‘i at Mānoa.

Next Steps 

Further research: 

Variety trials. Dr. Amjad Ahmad of UH Manoa CTAHR has been awarded a Hawaii Dept. of Agriculture Specialty crops grant to fund this research, and will work with the farmers in this project. Both Māmaki Ola and Wrennʻs Farms will be involved. 

We plan to write a proposal for:

1. 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. 
2. Pruning/pollarding. Based on the success of this project, we plan to have more careful study into proper practices to increase water shoots and leaf flush. We want to figure out how soon we can pollard and then prune a māmaki tree - at 6 months old, 8 months old, or 12 months old?
3. Longevity of plants. Based on b. We want to know how long a plant can keep producing if we are pushing the plant to keep shooting - 2 years, 3 years, 5 years or more?

Māmaki Cooperative Feasibility Study 

Dr. Ming Wei is actively pursuing funding for this idea. Any suggestions are appreciated. 

Goals of the Coop.

1. Servicing gardeners and small farmers who don't grow enough to sell in bulk to Shaka Tea. Pay them for their wet leaves, combine and then sell to Shaka. Need $ for a person to coordinate and collect data. 

1a. The Coop collection can also be processed and then sold dried to high end tea collectors on the US Mainland or elsewhere. 

2.Creating in partnership, a co-crop nursery. So donʻt just sell/give out one type of plant. Create agro-forest "kits" eg. breadfruit with māmaki and olena, or pigeon peas, moringa, māmaki and butterfly pea (the combination researched on this WSARE project). Work with the ʻUlu Coop folks and more. We had so much interest on the webinars for such a system. 

3. Keep endemics endemic. Work with policy/leg. to keep māmaki (and any other endemic) in Hawaii. Cannot take out seeds or live plants. No out sourcing.