1. Field of the Invention
The present invention relates to a method and machinery for harvesting of vegetables or fruits growing on low plants such as tomatoes, and particularly to such plants grown on plastic mulch covered beds.
2. Description of the Prior Art
Tomatoes are typical of the type of crop to which the present invention is eminently suited. In the prior art, it is well known to harvest tomatoes by manual labor and by mechanical harvesters. Mechanical harvesters are available that cut vines free from their roots and transport the cut plants and its fruits to processing equipment which removes the tomatoes from the vines, separates the tomatoes from the foliage and dirt, and sorts the tomatoes as to size and quality.
Typical harvesters are described in the following U.S. Patents: Ries et al, No. 3,078,926; Button, No. 3,390,768 and No. 3,437,151; Seem, No. 3,921,723; Bettercourt et al, No. 3,986,561; and Johnsen, No. 4,090,568. Each of these prior art machines is characterized by cutters that operate at or just below the surface of the soil. Cutters include fixed sweeps, double rotating metal or rubber disks, reciprocating bar sickles, and rotating rods, with all designed to operate below the ground surface. Problems encountered with these types of cutters include: picking up of soil along with the tomato plants; damage to the tomatoes from soil and rocks; and damage to the tomatoes in the separation of soil and rocks. In addition, soil is quite abrasive, wearing out moving parts and causing costly maintenance. Dirt clods are a particular problem and special devices have been necessary in prior art machines for removing such clods.
When tomatoes are grown without stakes and supporting lines as is necessary for mechanical harvesting, the foliage grows in a matted fashion with the lower fruit weighting the matted vines to lie on the surface of the soil bed. The lower hanging fruit is subject to damage by the harvester, even with the cutters operating below the bed surface.
Over the past fifteen years, the technique of growing tomatoes and other plants on plastic mulch covered beds has been developed. Although the method is particularly effective for use in sandy soil, it has proven to have many other advantages: cleanliness of the fruit; good control of weeds; improved action of soil fumigants; reduction of root rot; reduction of soil moisture evaporation; prevention of soil erosion; and protection against freeze damage. The plastic mulch is becoming more widely used; for example, during the 1976-77 season in Florida, about 75% of the 13,700 hectares of fresh market tomatoes produced in that state were grown on plastic mulch covered beds. Planting is through holes punched or burned in the plastic film. It is also common to include drip irrigation tubing along the bed underneath the plastic mulch for watering and fertilizing of the bed. This system of growing tomatoes has proven to be more energy efficient per unit of product than the traditional system of growing the plants on bare ground. Thus, the technique may be expected to become more widespread throughout the United States.
Available mechanical harvesters have proven unsatisfactory for operation over plastic mulch beds. The plastic film becomes torn and shredded, causing clogging of conveyor belts, separators, and other moving parts of the machinery, and the irrigation tubing is usually damaged. For this reason, tomatoes and other produce grown on plastic mulch must be harvested manually. In addition, stakes and lines must be provided for ease of hand picking, which significantly increases costs. With shortages of field labor becoming common, losses can occur from failure to harvest tomatoes on time since this crop can change daily. Delays in harvesting often result in overripeness, sunburn, insect damage, mold and the like.
For the reasons discussed above, there has been a long felt need for a practical, effective mechanical harvester head that can cut plants slightly above the surface of the bed and which can be used over both soil and plastic mulch beds without picking up soil or damaging plastic film and irrigation tubing.