Improving Hawaii’s mango industry by introducing and comparing two innovative techniques that have increased production and quality of the fruit while improving on efficiency and management of the orchard. Ultra high density plantation (UHDP) techniques for mango will be demonstrated by planting 310 trees on a 1/2 acre of land. The open Tatura trellis system will be utilized on a 1/2 acre of land by planting 250 mango trees on five rows of trellis. This project will evaluate the costs of installation per acre, the expected return on investment, potential increase of production, labor demands, and orchard maintenance.
The objectives of the Mango Loa project are to demonstrate and compare the ultra high density plantation techniques for mango production versus the open tatura trellis system and the traditional standards for planting mango.
The mango tree is a sub-tropical evergreen tree that is widely dispersed throughout the tropics. The trees are long lived, often over 100 years while still producing fruit. If left unpruned, trees will grow between 60 and 100 feet tall in 25 years. Traditionally, mango orchards were planted at a density of 35 to 40 trees per acre, with a spacing of 35 feet. Mango trees will quickly grow very tall and wide, and over time orchard maintenance becomes hard and labor intensive. In most cases pruning occurs every second or third year and requires climbing trees, tall ladders, and pole saws, making the task costly. Orchards planted at this density often begin production at five to seven years, which is a lot of time to go before production begins. Harvesting requires long pickers that often causes blemishes on the fruit and is prone to knocking down adjacent fruits, -while mechanical lifts are very expensive. Canopy maintenance is nonexistent and treating for pests or diseases become very difficult. Maintaining the ground cover and weeds is very time consuming. All of these things add up to a lower quality fruit, a greater cost of production, and a longer wait for the orchard to begin production. The Food and Agriculture Organization (FAO) lists the global average for mango production at 3.5 tons/ acre.
Ultra high density plantation (UHDP) techniques for mango have been developed in India and involves planting with densities over 300 trees per acre. For this project we have planted at a density of 550 trees per acre. Uhdp orchards require training and pruning the mango trees to achieve the desired canopy shape and height at a seven foot height and width. Due to the short stature of the trees it takes three years for the trees to reach its production size, therefore shortening the estimated return on investment from five to seven years to three years, cutting the wait for production in half. The lower canopy allows for thorough inspections of the entire tree for pest and disease management and treatments can be better applied. Harvesting is done by hand, foregoing the damage that can be caused by long pole pickers. Pruning requires only hand tools and there is no need for climbing, ladders, or power equipment. The high density of trees leaves less area to be mowed saving time and labor to focus on other areas. UHDP mango orchards have been producing yields from 8 to 12 tons/ acre of very high quality fruit. A disadvantage of UHDP orchards is the tendency for fruit to hang down to the ground and broken branches when trees become overloaded. Another factor in deciding whether to plant ultra high density fields is the cost of installation. In Hawaii, buying grafted trees from nurseries are very expensive, with grafted mango trees being sold from $40 to $60 per tree, so grafting your own trees are essential, however time and space consuming it is.
The open tatura trellis system is a V style trellis where trees are planted in staggered double rows while being trained up the trellis with a two dimensional flat canopy. For this project we are planting 250 trees on five rows of trellis. This technique has been developed in New Zealand and is being utilized in Australia, while gaining popularity in Southeast Asia, where it is being used on a variety of tropical fruits. This system was developed to help protect the fruit trees during intense storms and typhoons that have devastated orchards in the past. the results were amazing, on a farm in Australia where they trellised avocados and were hit by a category 4 hurricane, not only did the trees survive the storm, but some fruit actually remained on the tree and were harvested. What these fruit growers found with the trellis is that the trees thrive with the added support, increasing production and quality of fruit above the level seen with UHDP orchards. The open tatura trellis system has some of the same advantages as UHDP orchards; production begins at three years, relative ease with harvesting and pruning, a more efficient use of the land, with an increase in production and quality of fruit. This system has produced as much as 20 tons/acre. The trellises address some of the shortcomings of the stand alone UHDP system; the support keeps the fruit from bending and breaking the branches and eliminates the need to weigh down and bend the branches while training the canopy, which can be cumbersome. Another factor with the open tatura trellis is that it provides the framework to cover the entire row with bee netting, which will keep fruit flies away from the fruit. The frames will also allow the farmer to cover the rows with plastic in the event you need to withhold water to force flowering, which is a trait of many tropical fruit trees. The major limiting factor of this system is the cost, which is pretty substantial.
Year one began by starting 600 seedlings of “common” mango. This mango is polyembrionic, meaning one seed will produce between one and ten seedlings. Polyembrionic seeds are also clonal, in that they are identical, which will give the orchard uniformity because all the seedlings are the same. “Common” mango seedlings take from 10 to 18 months to get big enough for grafting. Six varieties were selected for propagation; four commercial varieties (Rapoza, Nam Doc Mai, Kiett, and Manzanillo) and two local varieties (Haden and Pirie). Grafting was used for propagation; cleft grafting was used if the scion wood matched the rootstock and side grafting was used if they were different sizes. Both methods produced excellent results. Grafting began after the flowering season, which in Hawaii is about March, and continued from March to September, until there was 350 grafted mango trees.
Field preparation began by hiring a bulldozer to clear the field of brush and grass. next, the field was laid out with ten rows and thirty trees per row at an 8′ x 10′ spacing, each row is 250′ long. A mini excavator was used to dig the holes at 2′ x 2′ width and depth. The next step was to back fill the holes adding a half pound of 16-16-16 and half pound of neem cake to each hole. Once a row was back filled, 1/2″ black tubing was laid down and covered with three foot wide black ground cover.
With the field prepped and laid out, it is time to start planting. I began by planting all four sides, then I planted a row in the middle to use as site points to try to line up the trees. I am currently half way through planting the field.
The end result of the field planting was 10 rows with 31 trees per row. The primary
responsibility over the next year is to train and prune the trees to get the desired shape. The first goal is to set a single trunk at 3 feet. Trees are staked up as needed and flowers are removed so the trees can focus on vegetative growth. Suckers appearing below the graft point or out of placed are removed as soon as possible. At this point the tree will flush with new growth and this must be thinned to two, three, or four shoots that will be trained to establish the scaffold branches. The scaffold branches will provide the main shape and support for the canopy. As the scaffold branches are forming it is important to choose branches that are evenly spaced at a 45 degree angle. if the branch is to horizontal it will bend down to the ground when set with fruit or it will not be able to support the weight and break. The branch will then flush new growth, after the third flush it should be between 18 inches to 30 inches. At this point, the terminal bud is removed, which will force multiple buds to flush, thickening the canopy. This brings the height of the tree to five feet. the most developed trees in this field are now at this stage. The majority of time is spent maintaining the ground cover and weeding around the trees, walking the field, pruning and training branches.
This years planting will incorporate all the same components of the stand alone UHDP field, with one added element, the open tatura trellis system. Five rows have been laid out, each row is 250 feet long with two lines of 1/2 inch poly tubing with 2 gallon/hour drip emitters every 10 feet. This is overlaid with three feet wide black weed mat. The open tatura trellis system plants in staggered double rows 20 inches apart. Trees are planted 10 feet apart in rows while being trained up the trellis. Each row of trellis will have 25 trees on each side, with 50 trees per row times 5 rows for a total of 250 trees on a 1/2 acre field.
On each end of the rows ground anchors were constructed, these anchors will be the main support to hold the tension from the wire. Each hole was 36 inches deep by 20 inches long by 8 inches wide. A wire basket was made with a 12 inch piece of 5/8 inch rebar with 5/8 inch by four foot long chain attached and placed within the basket to add strength to the concrete. Two bags of 80 pound Quickcrete was used per hole. The chain will
come out of the ground and the wire will be looped through the link and then attached to a strainer to tension the wire.
Making a template to follow when auguring the holes is essential to getting the right angle when setting the posts. The open tatura trellis system is a “V” style trellis with a 20 inch “open’ area between posts. The posts are set at a 72 degree angle. The trellises will be constructed using 5 inch by 10 foot post buried 24 inches down with a cross piece tying the two posts together. However, the work constructing the trellises are just beginning now and the process will be updated once completed.
|UHDP materials/ acre|
|Open Tatura Trellis||$6,878|
When examining the cost for the materials needed to install one acre of mango using ultra high density plantation (UHDP)methods, it comes to $6,084. Hawaii doesn’t have a good resource for grafted trees, wholesale trees from nurseries range from $30 to $50, and with 550 trees per acre that comes out to $16,500 for the trees alone, bringing the installation cost to $22,584. However, the cost for the materials needed to make your own grafted trees come up to around $2.80 per tree and the 18 months process it takes to grow and graft the trees. So, there is real incentive to raising and grafting your own trees. Stand alone UHDP mango fields in India have reported harvests of 8 tons per acre, over double the global average of 3.5 tons per acre. In Hawaii, mangoes sell for $1.00/lb to $2.50/lb, depending on the season, making it a reasonable expectation to gross $20,000 per acre. When you factor in the costs for the materials needed to build the trellises plus the costs of the UHDP field, it comes to $12,962 per acre, assuming the farmer is making his or her own trees and not purchasing. In Australia, farmers have been using this system for about a decade, and have reported mango harvests as high as 20 tons per acre, doubling the production of the stand alone UHDP field. Add to that the 40% reduction in time before production, from 5 years to 3 years, increases the draw to incorporating these techniques into the orchard.
Educational & Outreach Activities
The most useful outreach tool at this point has been Facebook, where I created a group “The Mango Loa Project”, and have been chronicling its’ progress. There is a good number of Hawaii farmers following along with a lot of interest. Through the group, I have also been able to reach people all over the world. I have been in contact with people from Florida and Arizona, India, Thailand, and Australia about my project and the movement towards ultra high density. This year’s Hawaii Tropical Fruit Growers state conference’s main theme was high density and trellising tropical fruits. This was another great opportunity to meet farmers throughout the state, where I was able to display a poster of the project and talk about the things I’ve been doing. There is a lot of interest for high density planting and at the moment my project is the largest trial in the islands. I had my first field day in May, where I presented my project and hosted a grafting workshop to 25 attendees, which for Kauai Island is a pretty large number. A fact sheet was distributed at this event. I also had two visits to the local high school’s agriculture program, where I did a grafting workshop with the students as well as a discussion on sustainable agriculture and pruning fruit trees for small spaces. Sadly, two events scheduled last year were canceled due to the severe flooding on the North side of the island that forced the cancellation of the mango festival and a scheduling conflict interfered with the Kauai farm and garden fair. I am currently scheduled to be a presenter at both events later this year. It is a little hard to have regular farm events and to get farmers to show up, but I have been able to visit three farms and consult with farmers about planting new fields using ultra high density plantation (UHDP) techniques. My next field day is scheduled for the end of January , where the topics will be UHDP year two and the most important tasks and a demonstration on the open tatura trellis system (OTTS); there is a lot of interest on this topic. I expect there to be more participation at this event because this is the direction that Hawaii’s tropical fruit farmers are heading and Kauai doesn’t have an open tatura demonstration on the island. The one event I attended that was a discussion on the topic showed that a good number of farmers want to incorporate these techniques on their farms, but need to see more examples before they commit to the financial investment of planting orchards using UHDP and open tatura trellis systems. Once this year’s field is planted I will have the data needed to do a detailed cost analysis of the UHDP vs. open tatura trellis system vs. traditional orchard layout. A power point presentation is in the works and will be a guide to UHDP techniques and OTTS, a how to presentation that will be made at this year’s annual garden fair and mango Festival. This year I am opening up my farm to the nonprofit organization GoFarm Hawaii; this group trains aspiring farmers in the classroom and field. They visit farms to volunteer and get hands on experience, this year my farm will be one of the participating farms.
Training and pruning
understanding ultra high density
Open Tatura Trellis System and the benefits
Hawaii is in the process of rebuilding its agricultural industry. The collapse of the sugar plantation left a huge gap in agriculture and up until this time has yet to recover. Tropical fruits is in high demand and Hawaii’s farmers are trying to meet the need. The Mango Loa project and the use of ultra high density plantation techniques has the potential to improve the entire tropical fruit industry. Densely packing the fields with trees will allow for a more thorough use of an acre of land, leaving less space available for weeds to grow. The low trees are managed completely from the ground. Pruning, while labor intensive, require nothing more than clippers and a hand saw. Low trees will allow for easier inspection and application of chemicals. Harvesting will be conducted by hand reducing the risk of damage and improving the quality of the fruit. Also the low trees will allow for easier protection of the fruit from bird, bug, and critter damage; bagging the fruit or installing bird netting can be better accomplished. The use of drip irrigation and Fertigation (the use of irrigation to distribute nutrients) allow for a more efficient use of inputs. India, where these techniques are being developed, report that using these methods enable one farmer to manage as much as 10 acres of mango. Reducing labor costs and the need for expensive special equipment, while increasing production through better practices, will go a long way in improving the sustainability of Hawaii’s farmers.
It is pretty clear that this generation of consumers do not like chemicals sprayed on their fruits and vegetables. In order to address this legitimate concern, as farmers we have to incorporate new innovative techniques to reduce our reliance on chemicals. Hawaii is the host to a number of destructive insects and the fruit flies may cause the most damage. Alongside these insects are the birds that can decimate an entire orchard. These are a couple of concerns that make tropical fruit farming in Hawaii prohibitive. These techniques allow for better management of the orchard and more efficient use of inputs. In the case of the trellises, it provides the framework to then cover the entire orchard with bee netting, which will keep out fruit flies as well as birds, and it is the netting that will ultimately do the most to increase production. Ultra high density plantation (UHDP) methods and the open tatura trellis system (OTTS) is the direction that the world’s tropical fruit farming is heading. These techniques are now being employed in South Africa, India, Thailand, Australia, and South America, as well as the United States with apples and peaches.