           |
|
- Growing Tomatoes in Cages can Maximize Yield and Quality
- By Carl J. Cantaluppi, Jr.
and Joseph E. Knight, III
North Carolina State University
Maximizing tomato yields is a subject that many tomato growers would be eager to learn about, especially when increased yields can mean increased profits.
It is known that letting tomato vines sprawl on the ground with no support yields the most fruit per plant. But many tomatoes succumb to fruit rots due to soil contact, thereby reducing total marketable yields.
A study was initiated in 1996 and repeated in 1997 in order to study two different tomato-growing systems. The traditional tomato growing system that is currently used in the Northern Piedmont of North Carolina is the “stake and weave” system, which utilizes a close spacing of 1.5 feet between plants in the row and involves pruning the suckers that grow between the leaf axils starting from the base of the plant and removing them when they are very small. Depending on the variety, one or more suckers are removed below the first flower cluster.
After the transplants are set into the ground, a wooden stake, one inch square and about five feet long is driven into the ground about one foot, placing one stake between every other plant. After the plants reach one foot in height, a nylon twine is tied to the first stake at the end of the row and is wound around it, keeping the twine taut as it is being strung around each stake down the row. When the person reaches the end of the row (usually 100 feet), the twine is looped around the end stake and then returning along the other side of the plants, again looping each stake until it is finally tied at the beginning of the row where the person started.
A new string is strung after one foot of new growth is produced, until three or four strings have been added. The tomato vine growth is then supported between the two strings that are strung on both sides of the row.
Researchers have reported that using the stake and weave system causes tomatoes to mature earlier because of the initial pruning of the suckers, which are shoots originating between the main stem and a side branch. With most tomato varieties, suckers are pinched out, leaving one just below the first flower cluster. This sucker will then become another main stem, resulting in a two-stem plant.
The “stake and weave” system, popularized by Florida growers, is labor intensive, requiring the driving of stakes into the ground, suckering and stringing the plants. If the stakes are not well anchored into the ground and/or a heavy fruit load is weighing on the trellis, they can easily blow over in a storm, making it very difficult to bring the plants to an upright position again.
Cages
Cages are made out of concrete reinforcing wire with a six-inch mesh to facilitate hand placement through the wire to harvest the fruit.
Wearing a pair of heavy gloves, a four-foot length is cut with a pair of bolt cutters to give a four feet wide by five feet tall piece. The center wire is removed to produce two, two-foot cages with six inches of exposed wire to press into the ground. This makes a 16-inch diameter circle inside the cage. The cage is held together by using three hog rings that are evenly spaced up and down the cage and crimped around the two ends of the cage to hold them together. We found that this worked better than making small hooks at the ends of the five exposed horizontal wires to hold the cage together. The ends were easily clipped off with the bolt cutters, eliminating the chance of a worker being scratched or cut if the exposed wires were not cut.
Caging tomatoes takes more land area than staked plants by spacing them three feet apart to allow for the growth of an unpruned plant. Caged plants are allowed to grow randomly inside the cage, with the stems trained to grow inside, without removing suckers. Staked plants are usually spaced 1.5 feet between plants in the row.
It was hypothesized that by taking 30 feet of row and planting 20 plants, spaced 1.5 feet apart (staking treatment) and taking another 30 feet of row and planting 10 plants, spaced three feet apart (caging treatment), that the caged plants would not yield as much early in the season, but would catch up and overtake the staked plants later on in the season. Suckering and training the plants were assumed to cause stress on the plants, thereby lowering yields, whereas not pruning the plants would allow the plants to produce more total fruits on non-stressed plants.
This study was undertaken to see how the two growing systems (caging vs. staking) would perform in the Northern Piedmont of North Carolina. Randy Gardner, tomato breeder at the North Carolina Mountain Horticultural Crops Research Station in Fletcher suggested the use of the Mountain Spring cultivar as it would not tend to be overly vigorous in its growth and not grow out of the top of the cage as compared with other determinate tomato cultivars.
Results
The 1996 growing season consisted of cool temperatures early in the season, with moderate temperatures throughout the remainder, with temperatures rarely getting above 90°F in August. Leaf spot diseases were able to remain in check with judicious applications of fungicide by Carr. However, soil diseases such as southern blight and internal pith necrosis were encountered with the latter affecting only a few stems per plant that died, with the remainder of the stems surviving to produce adequate fruit.
Summer storms blew over about six cages from time to time but they were easily uprighted. However, one of the staked plots blew over, snapping the stakes, and having most of the leaves and fruit to lie on the black plastic. In 1997, southern blight and internal pith necrosis were not encountered and summer storms did not upset cages or stakes.
Yields between the caging and staking systems were reported in several ways and are outlined below.
Early season
Yield per plant: In 1996, yields in pounds of fruit per plant between cages and stakes were higher but not statistically significant for the staked treatment for U.S. #1, U.S. #2, culls, and total marketable yield. (Table 1) The cage treatment produced significantly more #1 fruits with wire marks. In 1997, results were similar to 1996 with the exception of the stake treatment producing a significantly greater amount of #2 fruits per plant, and no differences in unmarketable fruit due to string or wire marks.
Yield per plot: In 1996, yields in pounds of fruit per plot between cages and stakes were higher and statistically significant for the staked treatment for U.S. #1, U.S. #2, and total marketable fruit. (Table 2) The cage treatment produced significantly more #1 fruits with wire marks. In 1997, results were similar to 1996, with the exception of no significant differences between cages and stakes with fruits with string or wire mark damage.
Mid-season yields
Yield per plant: In 1996, yields in pounds of fruit per plant between cages and stakes were higher and statistically significant for the cage treatment for U.S. #1’s, U.S. #2’s, culls, and total marketable yield. (Table 1) Caged plants produced significantly more fruits with wire marks. In 1997, results were similar except #1 fruits produced between caged and staked plants were not statistically significant. The weight of cull fruits produced did not show statistically significant differences between treatments.
Yield per plot: In 1996, yields in pounds of fruit/plot between cages and stakes were not significant for U.S. #1, U.S. #2, culls, and total marketable fruits. (Table 2) The cage treatment gave significantly higher fruits with wire marks. In 1997, results were similar to 1996, along with no significant differences among cages and stakes with fruits containing string or wire marks.
Late season yield
Yield per plant: In 1996, yields in pounds of fruit per plant between cages and stakes were higher and statistically significant for the cage treatment for U.S. #1’s, U.S. #2’s, culls, and for total marketable yield. (Table 1) There were no fruits with wire or string marks that affected late season marketable yield. In 1997, there was no significant yield differences between the two treatments, with the exception of the cage treatment producing more cull fruits per plant.
Yield per plot: In 1996 or 1997, there were no significant yield differences in pounds of fruit/plot between cages and stakes in U.S. #1, U.S. #2, and cull fruits. In 1996, the cage treatment had significantly more fruits per plot with wire marks but not in 1997. In 1996, the stake treatment had significantly more fruits per plot than the cage treatment. In 1997, yields per plot between cages and stakes were not statistically significant.
Total yield
Yield per plant: In 1996, yields in pounds of fruit per plant between cages and stakes were higher and statistically significant for the cage treatment for U.S. #1’s, U.S. #2’s, culls, and total marketable yield. Caged plants produced significantly more fruit with wire marks. In 1997, results were similar except caged plants produced more #1 fruits than staked plants but were not statistically significant. Also, marks on fruit caused by string on staked plants versus marks caused by cage wire were about equal and not statistically different.
Yield per plant: In 1996 or 1997, total season yield in pounds per plot did not significantly differ between caged and staked treatments, for U.S. #1, U.S. #2, culls, marks, or total marketable fruit, with the exception of the cage treatment having more fruits with wire marks in 1996.
Conclusions
Caging produced similar early season total marketable yields, and higher mid, late, and total season marketable yields per plant than staked plants in 1996 and 1997. For the same amount of land area, staking gave a greater early season total marketable yield per plot than caging in 1996 and 1997. However, mid, late and total season total marketable yields per plot were not significantly different in both years between cages and stakes with the exception of the 1996 total marketable late season yield, where the staked treatment produced a higher yield.
This means that a grower can get approximately the same yield on the same amount of land by growing in cages instead of using the stake and weave system. Cages take one-half the number of plants per acre to provide the same yield as staked plants would.
The initial cost to purchase and make cages is high. However, the labor for constructing the cages is done only once, and can be done long before the growing season as a winter project, to spread the labor over a long period of time. Once the cages are made, the amount of labor needed to grow caged tomatoes is drastically reduced as compared with staking, which involves suckering, driving stakes, and stringing every year (Table 5). The cages can pay for themselves in one to two years in saved labor costs, depending on the rate paid per hour (Table 5).
The cages can be saved and re-used for six to seven years, making the cost of materials per year lower than stakes, which need to be bought every other year (Table 4). If cages are painted with an enamel paint, they could probably last longer. They can be stored outside and need a large storage area because of the cages remaining closed in a circular shape. The hog rings could be removed and the cages stored in a flat position, but this adds more labor and cost each year.
Despite the slight difficulty in harvesting the first fruit clusters on the plant when growing in a cage, and some of the first fruits being pressed against the cage wire and stems, the amount of fruits affected is not significant. It was also found that string marks on fruit from staked plants occurred as frequently as wire marks on fruit from caged plants. The labor savings, cost of materials, re-usability and stability of cages versus stakes, and a total marketable yield increase per plant and per unit of land area, makes caging profitable for tomatoes.
|
|
