(1) Field of the Invention
This invention relates to agriculture, more specifically to the distribution of treating liquid onto growing plants.
(2) Description of the Prior Art
In modern agriculture, it is often desirable to treat plants with certain liquids. E.g., at certain times it is desirable to apply insecticides to plants. In other situations, it is desirable to apply growth stimulants directly to the foliage of plants. The most common application is herbicides to weeds.
Previous applicators of herbicides to weeds have been primarily by having a unit which senses the presence of the weed, and responsive to that presence operates a spray so that herbicide is sprayed from a nozzle onto the weed. The weed may be detected by a photoelectric cell as shown by ROSE, U.S. Pat. No. 3,609,913. Others have suggested a mechanical finger to feel the weed such as GARDNER, U.S. Pat. No. 3,016,653. ALLEN, U.S. Pat. No. 3,959,924, has suggested a device to measure the electrical conductivity between a contact member and the ground which changes upon contact with a weed.
In certain instances selective herbicides have been used. I.e., herbicides which kill broad leaf plants and these herbicides leave grasses relatively uneffected. In such cases, the herbicide can be sprayed indiscriminately upon all the plants. In other instances, the selective herbicide can be mixed with a waxy substance and formed into a bar and this drug along a lawn or the like to kill broad leaf plants growing within a lawn.
Recently, there have come into commmercial use "rope wick applicators". These applicators provide a constant supply of liquid herbicide to the ends of a rope. Capillary action carries the liquid through the rope. Then, when the rope rubs against a weed, the liquid herbicide is applied to the weed. However, difficulty has been experienced with adjusting these so that there is sufficient herbicide applied to the rope so that the rope is always moist and capable of applying herbicide to the weed, yet, to prevent an over supply of herbicide being supplied to the rope so that the rope does not drip herbicide upon beneficial crops. Part of the problem is that weeds are not regularly spaced in a crop. I.e., there may be areas in the field where the weeds are very thick and there is a heavy removal of the herbicide from the ropes. In parts of the field there may be long spaces without weeds where there is no removal of herbicide from the rope. If there is a constant addition of herbicide to the rope, it may be seen that in certain areas of the field the rope will tend to become over supplied with liquid and in other portions of the field, the rope will tend to become under supplied with liquid.