Implement for the removal of insects or the like from plants
BACKGROUND OF THE INVENTION 
     The present invention relates to implements for the removal of insects or the like (i.e., insects and other small pests against which pesticides are used on plant foliage) from live plants on a commercial scale through the use of suction and forced air streams. 
     Presently, there is a heightened interest in non-chemically dependent methods of insect control and eradication. Such interest is in part caused by public concerns regarding the environmental dangers and risks presented by chemical pesticides. In addition, chemical pesticides are increasingly being rendered ineffective due to the evolution of pesticide-resistant strains of insects. Finally, pesticides are a substantial and burdensome recurrent cost for the farmer. 
     Various attempts at manufacturing effective and commercially practicable suction machines for removing insects from plants in the field have been undertaken in the past. Most of these early attempts are comparatively inefficient due to an inability to remove insects from a multiplicity of plant rows simultaneously. In addition, the machines which could treat more than one plant row simultaneously rely in large part on elaborate manifolds or duct work to focus the suction action on the plant row. Such arrangements decrease the efficiency of the suction action because of the inherent resistance to air flow imparted by the manifolds and duct work. Finally, these earlier devices are not readily adaptable in regard to the type and size of plants which can be treated. 
     The invention herein disclosed represents significant improvements over the prior art. The invention contains a dedicated fan unit for each plant row unit to remove insects from the plants of the respective row. This invention has the added feature of destroying the insects so removed. In the preferred embodiment these fans are axial flow centrifugal fans. Such fans are reliable and uncomplicated and also facilitate insect destruction. In addition, the support frame of the implement can be articulated and driven so as to permit relative positioning movement of fan units while the fans are driven and running; thus facilitating the continuous use of the implement in different applications, including folding of the support frame. This feature also enhances the ease of navigation, transportation and storage. Furthermore, an encompassing fan housing may be used which redirects a portion of the exhaust of the fan in the form of a continuous air blast to the plant foilage; thereby dislodging insects and contributing to their collection through the intake. This air blast maximizes insect removal by assisting the suction and collection action of the fan unit. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide an improved means for removing and destroying insects from plants. 
     Another object is to provide an implement which is adapted for use with conventional farm equipment such as tractors. This implement receives its power from the tractor engine via belt drives, drive shafts, hydraulic motors, or the like. It is further contemplated that the implement could be powered by an independent power source such as a dedicated internal combustion engine. 
     Another object is to provide a vacuuming-type of machine with a simple fan arrangement which efficiently collects insects from the foliage of plants and destroys those insects. 
     Another object is to provide an implement which eliminates extensive duct work and maximizes removal power. 
     A further object is to provide an articulated frame and related drive means which allows fan unit position adjustment to be undertaken while the fans are kept running via a mechanical drive interconnection; thereby facilitating continuous operation during turn-around as well as convenient transportation and storage and permitting custom adaptation of the implement for particular applications. 
     It is still another object to provide an encompassing fan assembly with an integrated channeling means; whereby exhaust of the fan is directed to the lower portions of the plant; thereby dislodging insects to enhance removal into the intake. 
     In summary, there is described and depicted an implement which dedicates at least one axial flow centrifugal fan per plant row unit, each such fan unit having a direct axial intake immediately adjacent the plant positions. A plurality of fan units can be mounted on one frame so as to permit insect removal from a multiplicity of rows simultaneously. 
     The mounting frame can be articulated, a feature which promotes at least two attributes. First, by articulating the frame, transportation and storage are facilitated by effectively decreasing the lateral dimension of the implement. Second, the accompanying drive means is coaxial with and symmetrical about the articulation axis, which allows for custom adaptation of fan unit position to be undertaken while the fans are driven and running, such as during turns between successive traverses of a field and to adjust to various crop sizes and conditions. 
     In addition, the fan units can be constructed in an encompassing arrangement. This arrangement includes a channeling means to direct exhaust of the fan back to the plant, which facilitates the dislodgment of insects from the plant. This construction still permits a direct intake of air into the fan; thus, suction power is maximized because the absence of extensive intake duct work minimizes resistance. 
     All fan units are similar in that the intake air stream passes through the axial flow centrifugal fan; whereby any insects present in the air stream are destroyed by the fan. Thus, the various embodiments described herein remove insects from crops and destroy the insects so removed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For the purpose of facilitating an understanding of the invention, reference is made to the accompanying drawings wherein: 
     FIG. 1 is a perspective view of a four row implement employing teachings of this invention; 
     FIG. 2 is an enlarged, partially cut away view of a fan unit of the implement of FIG. 1. 
     FIG. 3 is a front perspective view of such a four row implement in a working environment; 
     FIG. 4 is a schematic cross-sectional view of a typical fan unit; 
     FIG. 5 is another perspective view of such a four row implement in a working environment; 
     FIG. 6 is a cross-sectional view of another fan unity; 
     FIG. 7 is a perspective view of an eight row implement employing further teachings of the invention in a working environment with the outer fan units in a lowered position; 
     FIG. 8 is an elevation view of the eight row implement with the outer fan units in a raised position; 
     FIG. 9 is an enlarged perspective view of the articulated interconnection when the outer units are in a raised position; 
     FIG. 10 is a perspective view of a multiply articulated embodiment in a working environment; 
     FIG. 11 is an enlarged perspective view of the multiply articulated embodiment in one working array; 
     FIG. 12 is a front perspective view of the multiply articulated embodiment illustrating the articulated drive system; 
     FIG. 13 is a front perspective view of another implement which includes encompassing fan units employing teachings of the invention; 
     FIG. 14 is rear perspective view of the implement of FIG. 13; 
     FIG. 15 is a side perspective view of the mounting section of the frame of the implement of FIG. 13; 
     FIG. 16 is a rear perspective view of the mounting frame of FIG. 15;; 
     FIG. 17 is an enlarged fragmentary perspective view of an upper portion of an encompassing fan unit; 
     FIG. 18 is another fragmentary perspective view of an encompassing fan unit; 
     FIG. 19 is a schematic cross-sectional view of the encompassing fan unit; 
     FIG. 20 is a top perspective view of an encompassing fan unit; and 
     FIG. 21 is a partial perspective view of a blast guide plate mounting in the embodiment of FIG. 13. 
    
    
     DETAILED DESCRIPTION 
     Referring to the drawings, FIGS. 1 through 6 depict a four row embodiment (20) of a field machine employing teachings of the invention for use in collecting and destroying insects from plants, and details of an exemplary fan unit (22). This embodiment contains many features that are included in the other embodiments. This embodiment, and the others as well, is designed so as to permit the powering of the device via conventional tractor power takeoffs through the use of belt drives, shaft drives, or hydraulic motors. This embodiment, as well as the others, also positions or dedicates at least one axial centrifugal fan unit for each crop row unit. As used herein, &#34;crop row&#34; shall be understood to mean an aligned series of discrete plants or plant clumps, such as individual plants or &#34;hills&#34; of plants, and &#34;crop row unit&#34; shall include not only a &#34;crop row&#34; but also any multiplicity of plants in a delineated narrow band which is treated as a single row for various husbandry purposes. For example, tomatoes are sometimes planted in double plant rows closely adjacent one another on a single ridge. Such an arrangement is considered to be a single crop row unit. 
     FIG. 1 shows an implement which is generally a plurality of fan units (22) mounted on a rigid frame (24). The frame is appropriately supported on a tractor (T) by attachment to a front-mounted three-point hydraulic hitch system (not shown). Each of the fan units is an axial flow centrifugal fan with its axis oriented vertically and having an axially aligned direct intake extending downward to a shaped restricted inlet opening (47). This inlet normally is to be disposed immediately adjacent the foilage of the plants in the crop row when the machine is in operation for collecting and destroying insects from the crop. 
     Each fan unit is powered by a drive pulley (26) and V-belt (28). This pulley (26) and belt (28) arrangement is an efficient and uncomplicated preferred means for supplying power to each individual unit. However, it is possible to use other means of transmitting power to each fan unit; such means include the use of gear boxes with drive shafts between each fan unit or individual hydraulic motors for each fan unit. 
     The embodiment (20) is supported by a tractor mounting and a pair of adjustable wheel assemblies (30). The vertical adjustability of the wheel supports 30 may be by any known means, including a vertical series of holes for selectively receiving attachment bolts as at 31a and 31b, or by clamps, jackscrews or hydraulic cylinders, as desired. The adjusting capability of the tractor mount and the wheel assemblies (30) permit height adjustment of the implement and particularly the fan intakes for crop type and size so as to maximize removal efficiency. 
     FIGS. 2 and 6 depict the major components of each individual fan unit (22). The exterior or housing portions of the fan unit (22) comprise a top plate (32), a circular housing (36), and a bottom plate (38). The top plate (32) includes a protective exhaust screen (34). The bottom plate (38) includes an axial flow velocity-enhancing venturi inlet (39). 
     The interior components of the fan unit (22) include the fan wheel or impeller (40) and the impeller drive shaft (42). This shaft (42) has the drive pulley (26) attached at its exterior end. In addition, a velocity-enhancing coaxial inlet venturi section (44) is formed as a part of the bottom plate (38), or it may be a separate element, to define the inlet (39). The rotational motion imparted to the centrifugal fan impeller causes high velocity intake of air axially through the inlet 39 which results in the vacuum action of the invention. The attendant exhaust is vented out of the top of the fan unit (22) through the protective exhaust screen (34). Within the fan, the initially axial inflow stream makes a rather abrupt right angular change to radial flow through the impeller blades, beneath impeller top end plate 45, then another and more abrupt right angular change between the impeller tips and wall 36 to a generally axial discharge through the upper end guard screen 34. 
     A coaxially aligned intake transition piece (46) having an inlet opening (47) may be attached to the distal side of the bottom plate (38). The inlet opening (47) is disposed adjacent to the plant foliage. The transition piece (46) permits a directing and focusing of the air intake. Such use of a transition piece (46) is optional. 
     Each fan unit generates a high velocity flow of air through and immediately adjacent the plant foliage and into and through the inner fan components. By way of example, one typical fan unit may comprise a 28&#34; diameter housing with a fan wheel which is 19&#34; in outer diameter, a venturi throat diameter of 11&#34; and having a rating of about 8000 cfm at 2200 rpm, which can be readily attained with the power available from conventional tractors. With an inlet opening (47) on the order of 7&#34; by 28&#34;, external air velocities may be in the range of 100 fps adjacent the inlet openings. 
     The high velocity intake air stream dislodges insects from the plant foliage and sweeps them into the fans, to their destruction as noted below. The air stream also causes considerable disturbance, agitation and fluttering motion of the foliage, which is believed to assist in dislodging the insects therefrom and thereby contributes to their collection from the plant environment into the fan unit. 
     Any insects present in the intake air stream are destroyed when they pass through the axial flow centrifugal fan. Such fans are uncomplicated and reliable and serve to facilitate insect destruction. At present it is believed that insect destruction is primarily by forceful impingement of the insects upon the fan components and most predominately by being thrown against the outer housing (36) as a result of the abrupt angular change in flow direction from radial to axial in this area. Such impingement is a result of the two ninety degree turns the air makes as the flow first passes through the fan blades and then as it is directed to the top exhaust screen (34), see also FIG. 4. 
     FIGS. 3 and 5 depict the four row embodiment in a crop environment. As shown in FIG. 3, shrouds (48) extend over the sides and adjacent areas of the plants and thereby create a partially confined collection chamber adjacent the fan intake. Such shrouds can maximize both crop foliage exposure to the vacuum action of the fan unit (22) and capture of the insects. Such shrouds may be used to separate, lift and guide the foliage in each crop row unit to avoid crop damage and to maximize exposure of the foliage and the immediate environs to the vacuuming action of the fan units. In addition, such shrouds may be used to confine the air inflow, further agitate the foliage and/or assist in preventing escape of insects as they are disturbed from the plants. Such disturbance is a result of either the general disruptions caused by the passage of the implement or the peripheral lower velocity air flow patterns relatively remote from the inlet opening. This shroud (48) may be attached to the distal end of the transition piece (46) or directly to the fan housing or the frame. 
     Shields (50) can also be attached to the top plate (32) of the fan unit (22) in order to protect the operator from the insect debris and other debris that may be entrained in the exhaust of the fan units. 
     Only the intake transition piece (46) is present in the area adjacent to the crop row in FIG. 5. Note that this implement utilizes a hydraulic motor (52) driven by a hydraulic power unit in the tractor in order to transmit power from the tractor engine to the implement. The motor (52) is attached to the fan wheel shaft (42) of one of the interior fan units (22). Rotational drive motion is imparted to the remaining fan units via a flexible V-belt and pulley drive system (26,28). The drive pulleys in FIG. 5 are obscured in part by the pulley and belt guards (54). The drive to the pulley (26) on each fan drive shaft (42) is taken from an output pulley (not shown) on the next inboard drive shaft (42). 
     Turning to FIGS. 4 and 6, therein are depicted cross-sectional views of fan units (22). Air is taken in through the intake transition piece (46), which results in the vacuum-action as noted above. The transition piece (46) can be formed with arcuate (FIG. 4) or straight (FIG. 6) converging side panels. 
     The air flow then passes through the velocity-enhancing venturi (44) and thereafter passes through the impeller, which is an axial flow centrifugal fan. Although the axial flow centrifugal fan is advantageous in these implements and is the preferred means of creating the airflow and insect destruction, the invention in its broader aspects should not be considered to be limited to this type of fan. Finally, the air exits the fan unit through the protective exhaust screen (34). All or virtually all insects captured in the intake air stream are destroyed as they pass through the fan. 
     FIGS. 7, 8 and 9 depict an eight row embodiment in the lowered and raised positions respectively and illustrate the articulated system features of this invention. This eight row embodiment is articulated at two points so as to permit a folding of the two exterior end units at each end of the implement. This capability facilitates navigation of the tractor-implement combination, such as during turning maneuvers at each end of a field, transportation of the implement between work sites, and storage of the implement. The implement can be used with the transition piece (46) alone or in combination with the foliage guide shroud (48), as desired. 
     The eight row implement comprises a four fan unit interior section (20a) which may be on a single rigid frame (24a), and a pair of two fan unit end sections (20b, 20c). Each end section (20b, 20c) includes a frame portion (24b, 24c) and is attached to the left or right end of the frame (24a) of interior section (20a) via a horizontal fore-and-aft axis pivot hinge arrangement (56). The basic mode of operation of each individual fan unit is identical in the eight-row and four-row machines. 
     The interior section is supported by a pair of adjustable support wheel assemblies (30a) corresponding to the assemblies 30 described above. FIG. 7 shows that each end section is also supported by a similar adjustable wheel assembly (30b) when the section is in a lowered position. 
     An articulated drive system is included in this embodiment so as to permit continuous fan unit operation while the end sections are adjusted to and maintained in the raised, lowered, and various intermediate positions This drive system comprises dual junction pulleys (58), which are fixed to rotate together, disposed with their axis of rotation coaxial with the pivot hinge (56). Power transfer pulleys (60) are centrally located on the two fan units immediately adjacent to each side of the hinge (56) and are positioned in relatively the same vertical plane as the respective junction pulley (58). Drive V-belts (62) connect each of these pulleys (58) with one of the transfer pulleys (60). 
     A pair of double acting hydraulic cylinders (64) are provided for pivoting each end section (20b, 20c) to a raised or lowered position. Such cylinders are the preferred means of effectuating section position adjustment and maintenance; however, this invention is not limited to the use of hydraulic cylinders to position the exterior sections. 
     FIG. 9 is a detailed depiction of the articulated frame and drive system located on one side of the implement. The construction of the opposing side is a mirror image of that illustrated here. The hydraulic cylinders are omitted in this figure for the sake of clarity. 
     The fan units of the interior section (20a) which are immediately adjacent to the hinge (56) transmit power to the adjacent exterior sections (20b, 20c). A gear box (66) is located on the fan shaft (42) of each of these adjacent fan units. Each gearbox (66) provides right-angle drive connection between the respective fan wheel shaft (42) and a horizontal power shaft (68). Each horizontal shaft (68) has a transfer pulley (60) affixed at its exterior end. The transfer pulley (60) on the interior fan unit thus imparts rotational drive of the junction pulley (58) via a drive belt (62), which in turn imparts via another drive belt (62) rotational drive of the transfer pulley (60) of the exterior fan unit immediately adjacent to the hinge (56) to drive the exterior units. Idler pulleys (70) maintain proper tension on both drive belts (62). 
     Alignment holes (71) are provided in the respective ends of the frame members remote from the pivot axis (56) to receive pins for locking the end wing sections (20b, 20c) in their extended positions if desired. 
     It will be appreciated that by virtue of the coaxial relation of the intermediate drive pulleys 58 with the pivot axis of the respective end unit 20b, 20c and the fixed position of each of the pulleys (60) on the respective pivoted end frame, the radial dimensions and hence the drive connection are maintained throughout the pivotal adjustment of each of the end sections. Thus, the operator need not stop the fan drive for adjusting the end sections relative to the center main frame, such as when raising the end sections during turning movements at the ends of the crop rows. 
     Although the eight row implement is depicted as being mounted on the rear of a tractor, it also could be front mounted. A protective covering (72) is provided over the fan units of the interior section (20a) in order to protect the operator from the exhaust air and debris. A front mounting would require shielding over all of the fan units. 
     FIGS. 10, 11, and 12 depict a multiply articulated embodiment. The depicted embodiment utilizes three fan units, but it is possible to use more or fewer units depending on the application. A mounting frame (74) allows the implement to be supported on the rear of the tractor, such as on the three-point hitch. 
     Each fan unit includes the same general transfer pulley (60), horizontal shaft (68), gear box (66), and fan wheel shaft (42) arrangement as the fan units described previously in respect to FIG. 9 except that each fan wheel shaft (42) of the pivotally movable units is driven through a gearbox (66) and hence need not have a drive pulley attached at its exterior end. The basic construction and mode of fan unit operation are otherwise identical in the multiply articulated implement as in the other described embodiments. 
     The fan unit (22e) located immediately adjacent to the tractor mount is pivotally attached to the mount frame adjacent the exhaust end of the fan unit, i.e., between the upper frame elements (21e). This attachment forms hinge axis (56a). The position of this fan unit, and therethrough the entire outboard implement, can be adjusted and maintained by a pair of double acting hydraulic cylinders (64e); see FIG. 10. These cylinders at hinge axis (56a) are not depicted in FIGS. 11 and 12 in order to more fully illustrate the hinge region. A dual junction pulley (58) is located coaxially with this hinge joint in order to impart, via V-belts (62) and transfer pulley (60a), drive to this first pivotable unit (22e) in the same manner as described above with respect to FIGS. 7-9. 
     The next outboard unit (22f) is pivotally attached to unit (22e) between the lower frame sections (23f) of the respective fan units to form hinge axis (56b). A junction pulley (58b) on the pivot shaft along this axis (56b) and further belts (62) joining transfer pulleys (60a, 60b) to pulley (58b) drive the unit (22f) through its respective power shaft and gearbox similar to the arrangement FIGS. 9-11. Double acting hydraulic cylinders (64f) are provided to adjust and maintain the pivot position of this next fan unit (22f) relative to the first fan unit (22e). 
     Turning to FIGS. 11 and 12, the fan unit (22f) at its other side is pivotally attached to a second outboard fan unit (22g), the point of attachment also being located adjacent the intake end of both units, e.g., at the lower frame sections (23f). This attachment forms a hinge axis (56c). A pair of double acting hydraulic cylinders (64g) are mounted between these fan units in order to facilitate position adjustment and maintenance of the outboard unit (22g) relative to unit (22f). A dual junction pulley (58c) is located at this hinge, and transfers the rotational drive from the transfer pulley (60b) of unit 22f to the transfer pulley (60c) of the second outboard fan unit (22g) to drive this latter fan unit. It will be appreciated that the transfer pulleys (60a and 60b) also are double sheaves. 
     The above described arrangement permits all three fan units to be belt driven from a single power takeoff. This arrangement also permits adjustment of the relative position of each of these fan units while the implement is driven and running. 
     FIGS. 13 through 20 depict an embodiment which uses encompassing fan units (80) with each unit (80) to receive one such double row crop row unit. These encompassing fan units (80) redirect a portion of the exhaust air back down to the primary foliage zone in order to assist in the dislodgement of insects and thereby facilitate insect removal, collection and destruction. 
     A plurality of encompassing fan units (80) are attached to an outrigger frame (82) support by frame (83). This outrigger frame is supported by an adjustable wheel arrangement (84) and a tractor mount frame (86) shown supported on a typical 3-point agricultural tractor hitch system (87). The outrigger (82) is pivotally attached to the mount frame (86); thus allowing the outrigger to be transported lengthwise as a trailing unit behind the tractor rather than in an extended outrigger position. When the implement is to be operated, the implement is swung out to its outrigged position, with its axis perpendicular to the longitudinal movement axis of the tractor. The unit can be held in this position by a locking mechanism between the outrigger frame and the mount frame and by a tension chain or cable attached to and extending from an outer portion of the implement, e.g., adjacent the upper end of support 84, to the front portion of the tractor. 
     This arrangement provides for treatment of crops on only one side of the tractor. However, it is contemplated that a similar outrigger can extend from each side of the tractor so as to permit simultaneous treatment of crop rows on both sides of the tractor. 
     The tractor mount (86) includes a drive assembly (88), which comprises appropriate drive shafts and a gear box. The drive assembly (88) imparts rotational motion to a main drive pulley (90), which in turn imparts rotational motion to the unit drive pulleys (92) by appropriate interconnecting belts (91, 93). The intermediate pulleys (92a) are double sheave pulleys for power reception and transmission purposes. 
     FIGS. 17-19 further depict the lower portions of the encompassing fan unit. Blast ducts (94), which serve as air channeling means, are positioned at the left and right sides of each encompassing fan unit. These blast ducts are bolted to the fan unit housing in order to facilitate removal and attachment. For example, the inner walls (95) may have an upper lip (95a) which engages a slot formed by a bracket (95b) affixed to the fan housing wall (38) and flanges (95c) on the outer walls secured to flanges (95d) on the fan housing (36c) by bolts (95e). The ducts can be constructed in a variety of sizes and heights thus allowing the fan units to be readily adaptable for various crops at all stages of crop growth. 
     The blast ducts (94) communicate with radially outward portions of each fan housing, being attached at the intake end of each fan housing and extend from that attachment point downward to and along and adjacent lateral side of the foliage zone of the crop row unit. Each of the ducts (94) may be of rectangular configuration in side view, as in FIG. 18 or tapered toward the bottom, as illustrated in FIG. 20. A pair of diverging plaint foliage guides (96), which are &#34;L&#34; shaped panels, are pivotally attached via hinges (97) along vertical axes near the central region of each blast duct (94). These guides, which are optional, serve to direct the crops foliage into the central removal zone of each encompassing fan unit. The positioning of each plant guide (96) can be adjusted via support arms (98) which are adjustable in length e.g., the illustrated turnbuckles or by any other suitable support element. 
     Turning specifically to FIGS. 18 and 19, the positioning of the blast duct (94), plant guides (96), and hinges (97) is evident. Along the center axis of the inside surface of each blast duct (94) therein is located a plurality of exhaust ports. These ports permit exhaust air flow generated by the fan to be channelled back towards the plant. Air scoops (100) focus and direct the resulting air blasts upwardly towards the upper portions of the plants. A lower end air scoop (102) can also be added at each side as in FIG. 19 to extend laterally toward or even beneath the plant foliage. These air blasts enhance the dislodgement and collection of insects; thereby facilitating their removal and destruction. 
     The air blast guides (100) can be bolted to the blast duct (94) or slidingly engage in edge guides along an opening or openings through the inner wall (95). For example, referring to FIG. 21, slideway guides (104) are attached along each side of an opening (106) through the wall (95), with a stop member (108) therebelow, to receive and position a plate member (110) which includes an opening therein and carries the guide (100). A flat closure plate may be substituted for the guide plate member (110) when supplemental air blast through one of the openings is not to be used. Guides plates with different sized openings and variously shaped guides may be substituted. Somewhat similarly, a single elongated opening may be provided over the height of each wall (95) with guides (104) of similar length to receive and retain a series of outlet air blast guides and blocking plates in accordance with the location and relative quantity of the openings desired for supplemental air blasts. If an air blast is not desired, the air scoop can be removed and a closure plate substituted therefor, as noted. 
     FIG. 19 also depicts the many similarities the encompassing fan unit embodiment has with the other embodiments. Each encompassing fan unit includes an axial centrifugal fan as the fan wheel (40) and a velocity-enhancing venturi (44). The axial centrifugal fan (40) intakes air through the venturi (44) and the axial flow intake area (99) to draw the insects from the plant and its environs. This air passes through the fan, where the insects collected in the air stream are destroyed. A portion of this exhaust air is then allowed to escape the fan unit through the screened or louvered side vents (112) or the screened inspection port (114). The louvers on the side walls insure impact of the stream and insects on the louvers and sides as the stream exits. This exhaust portion also may be controlled by control of the effective areas of these exhaust openings. The remainder of the exhaust air enters the ducts (94), where this air is directed back against the plants. The exhaust air exiting the ducts serves to dislodge insects from the plants; thereby facilitating insect removal and destruction. 
     The blast ducts can be constructed in alternative arrangements. Such arrangements include the use of side slots with other types of shutters to control the effective amount and/or position of the recirculation blast openings. 
     It will be appreciated that improved systems have been provided for the removal and destruction of insects from living crops, which meet the aforestated objects. Fan units dedicated to each crop row unit maximize insect removal and destruction. The direct inlet axial centrifugal fans are efficient in collecting and removing the insects and in destroying them. The support frames for the implement can be articulated and driven in such a manner so as to permit adjustment of fan unit positions while the fan units are driven and running. This articulation facilitates implement adaptability, maneuverability, transportation, and storage. The fan units can also be constructed in an encompassing design, which directs part of the exhaust back to the plant in the form of a continuous air blast. This air blast assists in the removal of insects through dislodgement. 
     The foregoing has concentrated on the preferred embodiments of the claimed invention. However, it is to be understood that changes in the construction, combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as claimed.