Advanced Trellis Methods and Mechanical Harvesting for Grape Tomatoes

Final Report for ONE09-093

Project Type: Partnership
Funds awarded in 2009: $9,815.00
Projected End Date: 12/31/2009
Region: Northeast
State: Pennsylvania
Project Leader:
Steve Bogash
Penn State Cooperative Extension
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Project Information

Summary:

Grape tomatoes are tough and easier to handle as compared to cherry tomatoes which are very tender and have a tendency to split when handled roughly or when fully ripe. Although still under 10% of the total tomato market, grape tomatoes are the fastest growing segment. The labor involved in harvesting can be a huge challenge as similar numbers of grape tomato plants requiring 4-5 times as long to harvest as round, slicing tomatoes. In a proof of concept trial in 2008, it became apparent that grape tomatoes showed some promise as a machine harvested crop through shaking and sorting later in a cool location out of the sun.

Three trellis systems were installed on the Penn State Southeast Research and Extension Center (SEAREC) and at the Dickinson College Farm (Mt. Holly Springs, PA). Each system was planting with 2 varieties of indeterminate red grape tomatoes. The shaker harvester was a modified battery powered reciprocating saw with a hook replacing the blade. While it was much faster to harvest like quantities of fruit using the shaker system versus hand harvesting, the abundance of unripe fruit not only reduced marketable yields, but created the need for substantial sorting post harvest and incredible amounts of wasted unripe fruit.

Either of two developments can make shaker harvesting practical for grape tomatoes: 1) A variety of grape tomato that retains its fruit more firmly until it is very close to ripe. Or, 2) A variety of grape tomato that ripens most of its fruit at about the same time like many determinate slicing tomatoes.

Introduction:

The market for cherry and grape tomatoes continues to heat up. According to USDA, ERS statistics, the consumption of cherry / grape tomatoes increased by 302% from 1999-2003 (latest data available). Grape tomatoes are in especially high demand at farmers markets and in grocery outlets as they have good shelf life and are ready-to-use. For growers, they can open the market window 2-3 weeks before any slicing tomatoes are available as they ripen much quicker. Although very high yielding and potentially highly profitable, efficient harvesting and vine management of these tomatoes remains a problem. Most cherry and grape tomatoes are grown using various methods of modified Florida Weave or large cages. Both of these methods have proven well-suited to larger, slicing tomatoes, but do not meet the requirements of efficient production and harvesting of these smaller tomatoes. Specifically, most of the commonly used varieties of cherry and grape tomatoes are indeterminate with the potential to create very large, challenging to manage plants. Also, harvesting is very labor intensive. This project will evaluate various methods of trellising, pruning and harvesting grape and cherry tomatoes along the lines of primocane raspberry trellising and vertical grape systems using wooden stakes.

Limitations on labor availability as well as the costs associated with labor and the need to get fruit out of the field early in the day to prevent the buildup of field heat in the fruit make efficient harvesting vitally important.

Project Objectives:

-Develop farm-ready, economical trellis systems for grape tomatoes that can work well with simple, inexpensive shaker apparatus.
-Develop an inexpensive shaker tool for tomato vines that is accessible to small growers and easy to maneuver in the field.
-Create presentations, demonstrations and publications to encourage the adoption of this technology should it prove workable.

Cooperators

Click linked name(s) to expand
  • Jennifer Halpin
  • Alexandru Surcica

Research

Materials and methods:

Two alternative trellis systems along with the standard vertical Florida weave were installed at both the Dickinson College Farm and Penn State Southeast Research and Extension Center (SEAREC). All three systems were planted with 2 varieties of grape tomatoes replicated 3 times on the trellises. One alternative system was a “V” using 3/8” concrete reinforcing rods (rebar) that met at ground level into a welded post that was driven into the ground 9seeimages 2 & 5. The posts were set at 30 degrees off of vertical. Tenax Hortonova was strung between the posts to support the vines. Later a single strand of #14 galvanized wire was added at the top of the bars for extra stability. The second system was a single angled post that was connected to vertical “T” posts at the base (see image#4). A strand of #14 galvanized wire connected the angled pole to the “T” post at the top. A piece of short square tubing was welded at the base to retain the pole there. (see images attached).
Vertically trained and trellised plants were hand harvested while the angled treatments were harvested using the shaker and tarp to collect the fruit (see image 6).

Research results and discussion:

In year one of this project (our proof of concept) we determined that there was potential in shaking grape tomatoes as during normal hand harvesting some alternative trellis systems, many ripe fruit were shaken off simply in the course of the harvest. In 2009, we installed the 3 trellis systems are described in the materials and methods (see images) and determined that angled trellis’s make shaking over a tarp easier over vertical trellis systems. Unfortunately the removal of so much unripe fruit during shaking became a problem. The “V” trellis was angled so sharply that hand harvesting was impossible and the weight of the vines tended to make the support fabric (Hortonova) sag heavily. The angled trellis with the poles set at approximately 15 degrees off vertical shaker harvested well and also allowed for easier hand harvesting as much of the fruit hung away from the bulk of the vines.

We’ve now got a shaker mechanism that is easy to use, inexpensive to make and readily accessible to growers. Also, the angled trellis offers a real improvement to the efficiency of hand harvesting in that fruit hangs slightly away from the vines. Florida weaving the vines onto the angled trellis is not only less expensive that using the Hortonova fabric , but also makes for tidier vines that are easier to hand pick and potentially useful for shaker harvesting. The missing piece in this equation is a variety of grape tomato that either retains its’ fruit more firmly until ripe or ripens more evenly

Participation Summary

Education & Outreach Activities and Participation Summary

Participation Summary:

Education/outreach description:

An educational session was done at the Mid-Atlantic Fruit and Vegetable Conference that is attached along with the proceedings article.

Project Outcomes

Project outcomes:

Economic Analysis

The amount of waste / unripe fruit removed by the shaker was overwhelming with more that 70% of harvested fruit needing to be removed and disposed of as unripe. One of the advantages of hand labor is that sorting and for some growers packing can occur at the same time as harvesting. Without varieties of grape tomatoes that mature more evenly, shaking simply removes too much unripe fruit. This reduces yields which increases the cost of plantings and requires 2-3 times as much labor to resort and repack the fruit. See the attached tables with yields and harvest times for Tami G and Smarty grape tomatoes on the 3 trellis systems.

Farmer Adoption

See comments in “Areas Needing Additional Study”. We have many of the pieces ready to make machine harvesting farmer ready, but still have one of two pieces still missing. Several farmers that attended a field day where we demonstrated the system have suggested that use a tomato ripening hormone to solve our problem. That was tried in 2010, but we lost the high sugar content that makes grape tomatoes so appealing. The fruit were uniformly red, but highly variable in flavor.

Assessment of Project Approach and Areas of Further Study:

Areas needing additional study

Either of two developments can make shaker harvesting practical for grape tomatoes: 1) A variety of grape tomato that retains its fruit more firmly until it is very close to ripe. Or, 2) A variety of grape tomato that ripens most of its fruit at about the same time like many determinate slicing tomatoes.

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.