in describing the preferred embodiments of the invention illustrated in the drawings , specific terminology will be resorted to for the sake of clarity . however , the invention is not intended to be limited to the specific terms so selected , and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose . to overcome the problems associated with prior art agricultural spray systems , the present invention proposes a method and an apparatus for spraying arborescent plants and bushes with a treatment product and for recovering excess treatment product . ( b ) incorporating an atomized treatment product with nozzles into the air stream ; ( c ) passing the product - charged air stream through plants , or the like , to be treated with the treatment product ; ( d ) on the other side of the plants , separating excess droplets of the treatment product from the air stream emerging from the treated plants with a gas - liquid separator ; and ( e ) recovering and the excess treatment liquid and possibly returning it to the spray circuit . the present method and apparatus allow for improved recovery of excess treatment product while maintaining a good coverage of the plant with the treatment product . the excess treatment product may be recovered for recirculation , as mentioned hereinabove , or for ulterior disposal thereof . the present invention overcomes the problems associated with the prior art recirculating spraying systems for trees and bushes by using air - pervious recovery panels of desired surface independently of any vacuumed airflow . the support of the weight of these recovery panels by the chassis and their passive mode of action permit much larger recovery surfaces thus improving recovery performances . the manifold can be oriented to allow the airstream direction to be adjusted in view of the vehicle &# 39 ; s travel speed travel speed and longitudinal wind . protection from the wind , as in “ tunnel sprayers ”, is offered by the wind - barrier while the light inflatable ducts and associated structure permit greater travel speeds . it allows for the use of smaller droplets while reducing the drift and associated pollution . the use of flexible guiding vanes in the elbows allows for a reduction in the power required and results in obtaining sufficient air velocities at the manifold outlet for crossing the plant to be treated and creating turbulence . the combined use of an inflatable manifold and a flexible wet spray boom , which can both bend , protects this structure in the event that it encounters an obstacle and prevents damage thereto upon operator errors . fig1 illustrates a spray apparatus a in accordance with the present invention which comprises a frame 13 mounted on a chassis 11 equipped with wheels 12 and adapted to be attached with hitch 10 to a tractor or other motorized vehicle , the front and rear wheels 71 and 70 , respectively , of which being schematically illustrated in fig4 . a horizontal boom 14 is rotatably mounted to the frame 13 for pivoting about a vertical axis and along a horizontal plane and is adapted to extend in a substantial horizontal direction over a row of trees 9 ( see fig2 and 4 ), bushes , or the like , to be treated . in its working position , the boom 14 is generally held substantially perpendicular to the displacement direction of the apparatus a , as seen in fig1 and 2 , whereas it is folded to its storage position shown in fig3 for non operational travel purposes ( where the boom 14 is generally aligned with the direction of travel of the spray apparatus a ). a hydraulic manifold cylinder 15 is adapted to rotate the manifold section 38 along arrows 72 and with respect to elbow 33 b for selectively adjusting the orientation of the outlets 39 and nozzles 43 . this adjustment allows for aiming the air flow and spray towards the separator panel 50 and so compensating for various factors , e . g . travel speed of vehicle , wind , etc . other means for adjusting the aim of the air flow and spray towards the separator panel 50 could be used , such as rotating , or translating back and forth , the boom 14 and to maintain it in a set position . the cylinder 15 is connected by hydraulic hoses on hydraulic plugs ( not shown ) located , usually , at the back of the tractor such that the manifold section 38 can be operated from inside the tractor &# 39 ; s cab . a rotating shaft 20 attached to a tractor &# 39 ; s utility standard , 540 rpm , pto , drives a pump 21 and a fan impeller 30 ( the latter being located within impeller housing 31 at the entrance of a proximal first elbow 33 a of an inflatable overhead duct 37 , as seen in fig2 to 4 ) by means of a collection of belts and pulleys 23 , gearbox 22 and auxiliary shafts 24 . either one of both the pump 21 and the fan impeller 30 could be provided with an independent hydraulic motor or flexible shafts . the present preferred solution permits driving of the pump 21 and of the impeller 30 via the power takeoff of a tractor , thereby requiring less maintenance and lowering the spray apparatus &# 39 ; cost . the impeller 30 is adapted to blow air through the overhead duct 37 which includes the aforementioned proximal first elbow 33 a , a straight horizontal section 29 , a distal second elbow 33 b and a downwardly extending manifold section 38 which defines a series of substantially vertically aligned outlet openings 39 on a side thereof facing towards an air - liquid separator recovery panel 50 located on the frame 13 and thus facing towards the plant 9 . the overhead 37 is made of fluid impervious material . on the frame 13 , there is mounted a reservoir 40 capable of holding the treatment product , generally pesticides or fungicides . the pump 21 is adapted to convey with a series of flexible conduits 41 a and 41 b the treatment product from the reservoir 40 to a wet boom 42 which extends vertically along the manifold section 38 of the overhead duct 37 , as best seen in fig2 and 3 . a filter is provided between the reservoir 40 and the pump 21 . the wet boom 42 is provided with a series of nozzles 43 distributed at spaced locations along the wet spray boom 42 and through which the treatment product is sprayed . the pressure and flow control of the treatment product in the flexible conduits or tubes 41 a and 41 b is adjusted by a plurality of valve means ( not shown ). the size of the droplets which result from a mixture of the treatment product being ejected through the nozzles 43 and incorporated to the pressurized air provided in the overhead duct 37 and coming out of the outlet openings 39 is adjustable by means of the pressure of the treatment product in the line and the selection of the nozzles 43 . it is to be understood that the wet spray boom 42 is in fluid connection with the pump 21 . corrosion resistant flexible hoses are preferred for fluid connection of the reservoir 40 to the nozzles 43 . the wet spray boom 42 may be made of flexible material ( e . g . pvc ) and / or may be additionally provided with a mechanical hinge so that it will bend with the inflatable manifold section 35 of the overhead duct 37 when encountering an obstacle and then return to its original position thereafter . the gas - liquid separator panel 50 comprises aluminum perforated and profiled sheets 52 ( see inset in fig4 ) placed side - by - side in a frame 54 . the sheets 52 are preferably vertically or obliquely disposed within the frame 54 . in fig4 the sheets 52 are shown in a vertical orientation and at an angle with respect to the air curtain . this passive recovery device allows a wider recovery surface than in cross - flow sprayers where it is limited to the suction hood and only the droplets in the vacuumed air are recirculated . furthermore , since the panels of the present invention allow air to go through with only few restrictions , the air stream and the airborne droplets are not deviated . the choice of creating the air stream from the distant side of the plants is motivated by the fact that larger recovery surfaces can be achieved if the air - liquid separator panel 50 is mounted on the frame side . the separator panel 50 may be provided with front and rear auxiliary panel sections 50 a and 50 b ( see phantom lines in fig4 ), angularly adjustable with respect to the plane of the main panel 50 for increased recovery of the excess treatment product . the angular disposition of the panel sections 50 a and 50 b may serve as guides for recirculating air not flowing through the separator panel 50 , in a vortex shaped flow . the panel sections 50 a and 50 b also include gutters or channels at their lower ends for recovery of the treatment product and conveying same to the sink 53 . many other configurations are commercially available but , for cost reasons , a simpler configuration is preferred for recovering actually 80 % of the spray treatment product still present in the air stream . this configuration also presents ease of cleaning as many debris like leaflets or petals may clog the more sophisticated conventional panels during their operation . the number and dimensions of these panels can be modified to further increase the recovery surface . a portion of the airborne droplets , that is part of the fine aerosol not intercepted by the gas - liquid separator panel 50 , may be recirculated in the ventilation circuit , i . e . through the duct 37 . channels 51 are located at the bottom of the panel 50 for receiving the recovered treatment product separated by the profiled sheets or grating 52 of the air - liquid separator panel 50 . the recovered treatment product then flows into a sink 53 located at the bottom of the chassis 11 , the sink 53 also recovering the portion of the treatment product that has condensed on the frame 13 , on the inner side of a wind barrier 60 and in the fan impeller 30 of the spray apparatus a . a recirculation pump mounted on the frame 13 returns the recovered treatment product from the sink 53 to the main reservoir 40 or to an independent reservoir ( not shown ), with a filter being provided between the sink 53 and the recirculation pump . the independent reservoir can be mounted atop the main reservoir 40 and can , for instance , flow by gravity therein . a pump coupled with one of the auxiliary shafts could be used to convey the recovered product from the sink 53 to the reservoir 40 , but preferably a small pump ( powered with a 12v source ) located near the bottom of the sink 53 is used as the recirculation pump as it does not have to be charged and a 12v source can usually be found on tractors . the aforementioned flexible wind barrier 60 is mounted on the frame 13 and on the separator panel 50 to prevent lateral winds from interfering with the droplet - charged airstream . although the airflow generating means may comprise hydraulically or electrically actuated airblower means arranged along the vertical boom and held up and suspended on the other side of the plants , it is preferable to mount the blower means , e . g . the fan impeller 30 , on the frame of the spray apparatus a and extend air guiding ducts in order to keep the boom as light as possible . a lighter boom will reduce stress on hinges and on the frame when encountering bumps during operation . the blower means are thus preferably mounted on the frame and preferably comprise , as described hereinabove , the axial fan 30 oriented upwardly and mounted in the upper part of the chassis in order to recirculate parts of the mist not condensed in the gas - liquid separator 50 . the fan housing 31 may be made of galvanized steel and is preferably mounted separately on the frame in order to make it lighter , simplify its design and reduce vibrations which may be transmitted thereby . the housing 31 is preferably further provided with a sink to recover droplets condensed on the fan blades and dripping from its bottom edge . at the top of the fan housing 31 , there is fixed a support shield , e . g . at least one bar 32 ( see inset in fig4 ), to prevent the flexible overhead duct 37 from folding inward and possibly come in contact with the blades of the fan impeller 30 . a grid may be , for instance , used instead of the bar ( s ) 32 . fig5 a to 5 c show a more detailed view of the elbows 33 a and 33 b which each comprise flexible guiding vanes 34 for reducing pressure losses . resilient flat bars 35 are located on the border line of the guiding vanes 34 to keep them straight . also the guiding vanes 34 are slightly shorter than the width of the elbow 33 a / 33 b for a given distance from the bottom ( see fig5 b ) so that , when the elbow 33 a / 33 b is inflated under the static pressure , the guiding vanes 34 are extended and held straight . guiding vanes deformed under dynamic pressure exerted by the air would increase instead of lessen the pressure losses in the elbows . these simple air guiding means permit to reduce head losses , the associated required power from the tractor and the size and price of the power transmission components . it is preferable to use large inflatable ducts for transporting air . for a given volume , the velocity is lowered and thus , pressure losses through the circuit are reduced . the parts of the overhead duct 37 may all be fixed together ; however , it is preferable to provide duct subsections which are detachably mounted together , for instance with loop - and - hook fasteners 36 , also called velcro ™, as such an assembly is easier to clean , repair or replace . flexible water impervious material is preferred for the inflatable ducts and it may be sewn according to the desired shape . with respect to rigid ducts , the inflatable duct used in the spray apparatus a ( see the overhead duct 37 ) present an invaluable advantage in matter of weight and cost and the boom can be alleviated . with the present arrangement , the droplet - charged air stream emerging from the manifold duct section 38 and the wet boom 42 progresses through the foliage of the tree ( plant , bush , etc .) from one side thereof to its opposed other side thereby exposing all of the foliage of the tree to the droplet - charged air stream . gas - liquid separators are current in industrial processes for purifying air from liquids in suspension . embodying the present air - liquid separator panel 50 in the apparatus a renders possible a new configuration in agricultural sprayers for trees or bushes with improved proportion of treatment product overspray recovery , as exemplified herein by the apparatus a . since the spraying apparatus a herein presented is adequate for spraying dwarf trees , anyone skilled in the art will understand that other configurations than that shown in fig1 to 5 can be utilized for example to adapt for treating bushes , vines and smaller trees , which will certainly result in even better recovery rates for the shortest distance between manifold outlets ( 39 ) and gas - liquid separator ( 50 ). for narrower and smaller plants , the adaptation could mainly lie at the level of dimension changes and sizing of the main components of the spray apparatus a . such an apparatus for treating bushes , vines and smaller trees would be lighter and smaller . another possible embodiment would include a frame provided with connecting elements for mounting the agricultural sprayer on the three - point of the tractor . the reservoir 40 may then be mounted somewhere else on the tractor , e . g . at the front thereof . another preferred embodiment which could allow for the treatment of fruit trees and vines with the same apparatus would simply replace the boom 14 and the straight duct section 29 of the inflatable duct 37 by shorter ones while changing the manifold 38 with another exempt of outlets at its upper section . the present spray apparatus a could also be provided with a mechanism for varying the elevation ( i . e . the vertical position ) of the boom 14 , and thus the position of the air outlets 39 and nozzles 43 . the span of the overhead duct 37 may be adjusted , for instance , by providing the straight duct section 29 with telescoping sub - sections . a plant detection system may be provided on the spray apparatus a to interrupt the flow of treatment product to the nozzles 43 when no vegetation is present within the overhead duct 37 . this detection system would preferably include at least one emitter and one receiver provided on one and the other of the proximal and distal sides of the spray apparatus a and working together in a line of sight mode . the emitter ( or receiver ) located on the distal side should be forwardly off set from the receiver ( or emitter ) provided on the wet boom 42 or on the manifold section 38 to provide an adequate delay for the activating , or de - activating , of the spray activity of the nozzles 43 . such a detection system reduces treatment product losses . the spray apparatus a may also be provided with additional nozzles located at one or both of the proximal and upper sides of the vegetation . the additional nozzles may be fed with treatment product with the same conduit system feeding the distal nozzles 43 , or with a different conduit system . treatment product dispensed by these additional nozzles must be projected with sufficient momentum to reach and sufficiently penetrates the vegetation as these sprays are not air - assisted ( as are those of the nozzles 43 with the air emitted through outlets 39 ). therefore , at least one such additional nozzle is provided above the vegetation for downwards dispending of the treatment product thereon . also , at least one such additional nozzle is provided on the proximal side of the apparatus a for dispensing the treatment product towards the proximal side of the vegetation . these additional nozzles are oriented such that the treatment product penetrates the vegetation in front of the air curtain created by the outlets 39 and such that excess treatment product from these additional nozzles is entrained by the air curtain towards the separator panel 50 . now referring to fig6 there is shown a variant spray apparatus a ′ also in accordance with another preferred embodiment of the invention which is designed for applying the spray treatment product on two rows of trees , plants , etc ., at the same time . a y - shaped divider duct 80 is clamped on the downstream side of the outlet of the fan impeller 30 and is connected with two horizontal straight duct sections 29 and their respective elbow 33 b and manifold section 38 . the divider duct 80 basically embodies two oppositely directed elbows , such as elbow 33 a of apparatus a of fig1 to 5 . the y - shaped divider duct 80 may comprise guiding vanes that can be sewn with the outlet straight duct 29 . guiding vanes ( similar to the vanes 34 of the apparatus a of fig1 to 5 ) with flat bars ( e . g . flat bars 35 of apparatus a ) are also provided to reduce head losses . the inlet surface is equal or a slightly superior to the total surface of the two outlets of the y - shaped divider duct 80 . while a preferred embodiment of the present invention has been illustrated and described herein , it will be appreciated that various changes and modifications as may be therein without departing from the spirit of the invention as defined by the scope of the appended claims .
an apparatus for spraying treatment product on plants , trees , bushes , etc ., and for recovering excess treatment product comprises a fan which conveys pressurized air through a duct located over the plant and vertically distally thereof at a manifold section of the duct . the treatment product is supplied with a pump from a reservoir to nozzles of a wet boom extending within or along the manifold duct section and is atomized and incorporated into the air stream exiting from the outlets of the manifold duct section which are oriented towards the plant and an air - liquid separator panel supported proximally of the plant on the frame of the apparatus . the manifold duct section can be rotated by a device to compensate air stream deviations due to travel velocity . treatment product which does not adhere to the plant to be treated is carried by the air stream to the separator panel such as to condense thereat . the treatment product recovered in liquid form is filtered and returned to the spray circuit or accumulated in a separate reservoir . a flexible wind - barrier assists in preventing interference from lateral winds and in recirculating part of the excess treatment product not recovered in the separator panel into the ventilation circuit .