Maximizing tomato yield 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. Keeping fruits off the ground by supporting the plants by staking or caging will eliminate fruit rots due to soil contact.
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 by many growers is the “stake and weave” system, which utilizes a close spacing of 1½ feet between plants in the row and involves pruning of 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 before the first flower cluster.
After the transplants are set into the ground, a wooden stake, 1 inch square and about 5 feet long is driven into the ground about 1 foot, placing one stake between every other plant. After the plants reach 1 foot tall, 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 no more than 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 where the person started.
A new string is strung after 1 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. 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 is labor intensive. 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 are made out of concrete reinforcing wire with a 6 inch mesh to facilitate hand placement through the wire to harvest the fruit. A 4 foot length is cut with bolt cutters to give a 4 foot wide by 5 foot tall piece of wire. The center wire is removed to produce two-2 ½ foot cages with 6 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. This works better than making small hooks at the ends of the five exposed horizontal wires to hold the cage together. The ends are easily clipped off eliminating the chance of a worker being scratched or cut.
Caging tomatoes takes more land area than staked plants by spacing them 3 feet apart between plants in the row, 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 1½ feet between plants in the row.
It was hypothesized that by taking 30 feet of row and planting 20 plants, spaced 1½ feet apart (staking treatment) and taking another 30 feet of row and planting 10 plants, spaced 3 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 them to produce more total fruits on non-stressed plants.
This study was undertaken to see how the two growing systems would perform in the Northern Piedmont of North Carolina.
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 significantaly higher yield.
This means that a grower can get approximately the same yield on the same amount of land by growing tomatoes in cages instead of using the stake and weave system. Cages take 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, spreading 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. The cages can pay for themselves in one-two years in saved labor costs, depending on the rate paid per hour.
The cages can be saved and re-used for six-seven years, making the cost of materials per year lower than stakes, which need to be bought every other year. If cages are painted with an enamel paint, they would 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 plant 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 vs. stakes, and a total marketable yield increase per plant and per unit of land area, makes caging profitable for tomatoes