According to USDA statistics, the market demand for grape tomatoes is increasing significantly from year to year. This is a direct reflection of the consumer’s need for fresh and healthy snacks that are easy to store and process in the kitchen. On the positive for farmers, grape tomatoes are less prone to pathogens compared to other types of tomatoes and produce large quantities of fruit that have a long shelf life. On the negative side, the indeterminate growth habit of most grape tomatoes require high labor inputs for trellising and harvesting. In addition, many farmers have addressed this problem by creating extremely tall trellis’s (over 10′) making harvest challenging and potentially dangerous.
In this project we compared 2 standard Florida Weave supports, one with 72 inche posts and one with 96 inch posts, and the third was the curved top or tunnel system. The tunnel system used 90” T posts set 36’ apart with a curved bar mounted on the top at a 90 degree angle creating a tunnel. The last one used the long vine, indeterminant habit to our advantage by creating an canopy-like trellis using standard items found on farms and in farm stores. The hanging fruit are accessbile from the ground or through the use of short step ladders.
While the catastrophic infection of blight on the test plot prevented a measurement of harvest yield and labor, these observations about the superiority of the curved top or tunnel system were indisputable:
1) The vines no longer needed to be topped. 2) The fruit were hanging through the mesh allowing for fast and easy harvesting. And 3) Applications of fungicides could be efficiently done using standard high pressure sprayers by operators standing on the ground.
Multiple presentations at farmer meetings demonstrated this project and a fact sheet and article are forthcoming.
This project began in 2008 with construction of a modified V trellis based on similar systems used in raspberry production as an early proof of concept. This original attempt at improving the efficiency of grape tomato harvesting was in response to summer intern requests to reduce the amount of time required to harvest these tomatoes as part of the annual tomato variety trials. However, the strings that ran from trellis to trellis as in the raspberry system were insufficient to encourage the vines to efficiently use the trellis without constant attention. Also, the site that this proof of concept was installed on has strong prevailing winds from the west that literally pushed all the vines onto the east side making the trellis unstable. This led to the original SARE Mechanical Harvesting project application where we compared I, V and an angled trellis using Tenax Hortonova mesh and a shaker mechanism to harvest the fruit. The mesh made hand harvesting all but impossible as the vines became a tangled mess. The shaker worked quite well, but dislodged far too many unripe fruit. This shaker method would only be usable where all or most of the fruit ripened at the same time. Paste tomato growers use chemical enhancers to compress their harvest window into a single picking. However, commercially machine harvested paste tomatoes only need to be red in color as flavor is not an issue, whereas, grape tomatoes are prized for their flavor. Since nearly all grape tomatoes today are indeterminate, there is the need to pick vine ripened fruit on a continual basis. Making that process as labor efficient as possible seems the most prudent direction.
The 2012 field trial was based on all of the lessons learned in both the earliest proof of concept V trellis, the mechanical harvesting trial and eliminating the very tall trellis’s currently used by growers.
- Vine shaking tool created using a battery powered reciprocating saw fitted with a hook welded to a detoothed saw blade
- This V trellis modeled on raspberry cane trellis systems was the proof of concept for all of the future trellis systems
- V trellis system. Like Incline trellis, training is eliminated, but only machine shaking can be used due to the tangle of vines
- Field Image from Kuhn Orchards showing the talls posts required to trellis their grape tomatoes.
- Incline trellis using Tenax mesh. This eliminates the training, but creates a tangle of vines
This project is the most recent chapter in a program that began in 2008 with a proof of concept trial as described in the introduction. The objective for 2012 was to develop a trellis system that took advantage of the very long vines produced by all of the current grape tomatoes while at the same time reducing or removing the need for ladders or scaffolds to harvest ripe fruit. We also wanted to compare this system to those commonly used by growers.
Due to communication problems with a collaborator who left the study, the original farmer cooperators did not follow through on implementing the study on their farms. Nonetheless, three trellis systems were installed at the Penn State Southeast Agricultural Research and Extension Center in 2012: One was a standard Florida Weave on 72” new oak posts, the second was standard Florida Weave on custom cut 96” posts, and the third was the curved top or tunnel system. The tunnel system used 90” T posts set 36’ apart with a curved bar mounted on the top at a 90 degree angle creating a tunnel. The vines were trained up to the top of the posts using Florida Weave, then allowed to lay over 48” Tenax Hortonova layed over the bars and secured on using 8” black electrical straps. The curved bars were cut from used greenhouse bows with the mounting end bent using an acetylene torch. Our goal was to simply slip these over the T post tops, but the interior of the bent pipes was just a bit too small and we had already installed the T posts in the field.
A future installation would remove a small amount of metal off of one tang of the top of the T post so they would slide on. We used U bolts for this purpose as a temporary fix.
Each of the three systems were planted with 4 plants each of 17 varieties of the latest and best (as determined by variety trials) grape tomatoes. Nutrients were applied based on bi-weekly tissue sampling. Pest management was based on scouting coupled with local and regional disease forecasts. As Septoria leaf spot, and Early blight are constant threats to tomatoes in the Mid-Atlantic, a preventative program using Regalia plus copper alternated with Actinovate was applied weekly starting at two weeks after planting and continued throughout the season. Late blight specific materials were added in late-July as that disease struck other plantings on the research farm.
The standard 72” trellised tomatoes required topping the plants by late-July. The taller (96”) stakes solved much of the problem, but also required topping by mid-August. In both cases the topping (pruning) of the vines that ran off the top of the trellis were necessary so that harvesters were not battling with an overhanging tangle of vines and so that applications of preventative fungicides could be applied evenly.
The curved bars mounted to the trellis post tops solved several problems: 1) The vines no longer needed to be topped. 2) The fruit were hanging through the mesh allowing for fast and easy harvesting. And 3) Applications of fungicides could be efficiently done using standard high pressure sprayers by operators standing on the ground. As the image shows, the vines naturally lay onto the mesh eliminating any further hand training labor.
Two pest problems impacted this project in 2012: 1) Yellow striped armyworms infested the planting. This pest while not unknown in the Mid-Atlantic has never been a tomato pest before. However, the extremely mild winter allowed for high populations to overwinter. Several applications of third generation pyrethroids were necessary to get them under control. Just as we were starting to harvest fruit that were insect damage free, Late blight began infecting the vines. This is one of the downsides to working on a research farm as there was little to no Late blight on area farms in 2012. Another researcher accidently brought Late blight infected plants onto the farm. By the time this was noticed, all of the tomato trials on the farm were light to severely infected. Late blight specific fungicides were added to weekly preventative materials which greatly slowed the rate of vine collapse, but could not stop the disease.
As the image showing the hanging fruit indicates, this method of trellising works. However, shortly after this image was taken, the vines rapidly degraded making comparisons of relative yields and labor requirements impossible.
Simply put, this system works well to solve the primary problems of indeterminate grape tomatoes. After the vines reach the top of the trellis posts, they naturally fall onto the mesh and the fruit hangs through the mesh. All of the components are sterilizable, durable, and reusable. This system makes both harvesting and pest material applications safer and more efficient.
Education & Outreach Activities and Participation Summary
This project was one of the features at several field days held at the Penn State Southeast Agriculture Research and Extension Center (SEAREC) in 2013. Dates include: 7/18/2013, Legislators Field Day, 7/25/2013, Greenhouse Growers Field Day and 8/6/13, PA Vegetable Growers Field Day. It was also showcased in 2012 at the PA Vegetable Growers Twilight meeting at SEAREC and at the Legislators field day on 7/18/12 and Greenhouse Growers Field Day on 7/25/12.
An article summarizing the results of this program is forthcoming and will be published in the Penn State Vegetable and Small Fruit Gazette and sent to SARE.
See attached powerpoint from the Tri-County Vegetable Growers Winter meeting on 2/13/13 and Shippensburg Auction meeting on 2/20/13.
No economic analysis is possible due to the project needing to be stopped just as the first fruit were ripening on the cureved bars creating the tunnel.
Several growers that attended field days at the Penn State Southeast Agricultural Research and Extension Center, Manheim, PA, indicated that the current system creating what is essentially a tunnel would work well in their high tunnels to reduce the need to rolling scaffolds and ladders later in the season. The PI will follow up with these growers in 2013 in order to measure their adoption.
Areas needing additional study
This modification of adding a curved bar to the trellis top, then installing horticultural mesh over the bar seems to have worked well. It eliminated the need for ladders or scaffolding to harvest fruit, was inexpensive to build and install and since all components were metal, easy to sterilize between seasons. Since Late blight killed the vines just as the first fruit were starting to use the trellis, no economic analysis is available. Completing a season with all costs including harvest labor coupled with yields would be very useful.
Grape tomatoes that are determinate, so can be trellised on to normal 5-6’ height poles would be helpful as well. Conversations with breeders indicate that some are in the early breeding stages, but not ready for release yet.